ECOLOGY TEST 3 !!! GET AN A!!!!!, Ecology chapter 10 & 11 EXAM 3

Relative abundance of five species of tiger beetles along a distr urban environment gradient in Venezuela - PRIMARY FOREST GRAPH A: This one's got a little more, but you know, it's 40, 30, 30, that's not that's not too dominant. And then there's two others that they saw later, but they didn't see them at all in The primary forest. That doesn't mean they weren't there. That just means their their numbers were very very low. They DIDN'T even make 1 relative abundance of the whole forest when the forest was partly disturbed (just partly two species were lost) -when partly disturbed the red and green species were gone, yellow species is there about the same abundance that it was in the primary forest (graph A) -PARTLY DISTURBED FOREST GRAPH B: NOW the low species that wasn't even detected in graph A, it became dominant and replaced the two species lost (green and red) -DISTURBED FRED GRAPH C: blue becomes EVEN MORE dominant its up to 70 now, now we see the emergence of the fifth species. the Aqua one that again it's numbers were too low to detect in the primary the partly disturbed forest (graph a) But in highly disturbed areas there it was it's still under 10% but it was detectable. -4 indicator species; red and green were sensitive because as soon as you disturbed the forest they were gone. that means they either died out or they failed to reproduce or something happened. You have 2 disturbance tolerant species (blue is really good) the aqua one will fill in some space, yellow has declined a bit -disturbance tolerant (blue and aqua), yellow one (isn't a disturbance indicator at all) -It's like when we're looking at open and closed communities, there were some species that just were there across the gradient and that's what's happening with this. It doesn't seem to mind it's there when there's no disturbance & it doesn't seem to mind disturbance, so we wouldn't call the yellow one an indicator species.

-And the disturbance they've done was logging out the it wasn't pollution, but they were logging, taking all the trees out. -And so they were obviously disturbing the soil. & they were looking at 5 species of tiger beetles that inhabited the soil. -And in the primary forest, the undisturbed forest, they saw three species of tiger beetles and all three species were Approximately similar in their abundances. So, you know, we didn't have a clear dominant species here.

Community ecology -So it may shift to a little bit more drought tolerant, but then it will come back to this -Back in the 1980s, Houston went through a not a really bad drought, but just sort of um a long term less rainfall, not enough rainfall to sustain the landscapes that we have. And there was uh the there was a lot of work toward zero escaping but it was planning yards with more drought tolerant species and so everybody was yanking out their bushes and their and their landscape and and replacing it with stuff that looked more like san Antonio which is drier than Houston. And sure enough, within a couple of years our rains returned and then all that zero escaping died because it had too much water on it. That's a minor disturbance. MAJOR DISTURBANCE: -If the disturbances, major different things happen in a major disturbance there is not working again, a major disturbance can shift the community permanently. And this would be something like a drought that lasted five years or 10 years.Or global climate change where our temperatures are getting warmer or sea level increase where a lot of areas that used to be coastal learn now. Well there used to be inland are now more coastal that will shift these communities permanently towards something else. -So the dynamic stability just means that with minor disturbances with most disturbances, the community is going to shift a little bit but it'll tend back toward what it was.So there's the dynamic nature and then it wants to go back to stability. it will change completely if you have a major disturbance on it. DYNAMIC : will shift with minor disturbances one way or the other depending on what you're talking about. But it tends to go back to the way it was. MAJOR DISTURBANCE: may not go back to community A BIG BEND NATIONAL PARK; used to be a very arid grassland but a very severe two year drought plus bad bad ranching practices turned it into a desert. So it's not going to go back to a grassland, it's now a desert. So that that those are major disturbances.

-Dynamic stability of a community forest on community A, what will change a community? -something that disturbs it and then and then it's likely to change. So if that disturbance is minor, let's say it's a a flood like harvey flood. Now we said harvey flood was major but it was minor in that it only lasted a few days. (Drought, tornado) minor disturbances because in terms of the community there, their short term or they don't or they don't have a big effect. ex: if we had a drought -will cause a die off of species that need a lot of water so it may shift this toward a community that will have a little more um tolerance for dry, dry areas for lower rainfall, but if it only lasts for a year a season, (into community C to mind or disturbances) -then the rain will come back and that will allow the seed bank or individuals that survive this initial disturbance to regain their dominance in the community. That's for minor disturbances.

Fig. 18.4 (p. 356): Primary succession on mudflow deposits on Studebaker Ridge, south side of Mt. St. Helens, following May 1980 eruption

-I mean there's nothing that is showing anything like that that is progressed out of the pioneer stage yet. So with the Glacier Bay study they found the pioneer stage really lasted only about 30 years or so.

Primary succession on Mount St. Helens

-So a lot of our information on what happens in succession came from the studies on Glacier Bay. -So when Mount ST Helens had its it's major disturbance, it was thought that succession might occur in the same way and that's what they expected. Didn't happen same way. -So this is Mount ST Helens on May 18th, 1980 41 years ago coming up on it, there was a massive explosion and the eruption basically leveled or sterilized. Um Most all of the area around the volcano.

Fig. 18.3 (p. 355): Number of species occurring in 1-m2 quadrats in the Studebaker Ridge area on Mt. St. Helens

-So they studied it for years and years and years. It's been 40 years now, this is what they have come up with. This is the number of species in their quadrants in one area. -And you can see that it took it took almost what 5 or 6 years before they saw anything growing on it. And in 40 years they only have about 20 species. And the species are not it's not forest. Those some of those species can cover the ground, but they're still basically in the pioneer face after 40 years

Shannon-wiener diversity index

-So what's the difference between community 1 & 2?They both have the same number of species, Species richness is the same.Both have two species. They both have the same number of individuals. What's the difference? One has dominance, the other has heterogeneity. When you have a heterogeneous community, it's going to have a higher species diversity than if you have dominance in the community dominance drives down the diversity.

Fig. 18.5 (p. 358): Succession models -ABCD represent different succession all communities. -A is pioneer (going to succeed to B) plus sign (+) says that community A is facilitating the environment, they're doing something to that environment to make it possible for community B to live there. Species in A are very different from B! -community A is also making the environment not conducive to its own progeny. -B & C are transitional -B is going to succeed to C & C to D (D replaces itself) -D is climax (every single one of these models is the climax community) you know, it's the climax community because it's got this this circular arrow on it, which means that this community is going to replace itself -that's what facilitators do. It's all for the next community and it's it's at their own peril. So that's what the plus (+) sign is for. A- Is making it possible for for community B to come in there. -if it continues with the facilitation model community B. Is going to make the environment conducive for community C and these are all different species here at its own peril. Community B will disappear and community C. does the same thing to D than D replaces itself. -And a really good example of this is nitrogen. Okay nitrogen is a nutrient that all these plants need , the pioneers probably don't need nitrogen because they have nitrogen fixing bacteria. As they live there couple of generations they're going to be putting nitrogen in the soil. So the nitrogen the little bit of nitrogen they put in the soil is now enough nitrogen for community B but too much nitrogen for A. So A disappears is replaced by B. Then B puts more nitrogen into the soil. C needs more nitrogen B now there's too much nitrogen and now we have community C!! -That's facilitation. Each community is making the site better for the next one to follow at the same time.

-You can see some of them are pretty old Clements. Clements was a super organism theorist. He thought there was a divine order to nature. the ones we're going to look at are the ones that were proposed by Connell and slasher in 1977. -Connell and slather proposed 3 models to describe how succession occurs in ecological communities. -first one is facilitation model, they all basically describe what theyre doing in the facilitation model -each sere/community in each sere is facilitation the succession of the next group of species (So they're they're creating an environment that will make it easier for the next group of species to come in and live)

Fig. 21.19, p. 442: Number of land-plant species on the Galapagos Islands in relation to the area of the island

-bunch of islands different shapes different sizes -they counted the number of different terrestrial plants species, there's a number of plant species and they looked at the area of each of the islands -and they plotted them on log log scales. Okay this is log arrhythmic and this is log arrhythmic. when you plotted the area, the log of the area versus log of the number of plant species, you get a direct relationship, the larger the island, the more species you have on it.

Soil pH changes at Glacier Bay, Alaska, under different types of pioneer vegetation

-different phs in these soils, based on the species that were growing on them. You can see if nothing is growing on it, that the ph didn't change over What 30 years here didn't change. -But once you got some species growing on them, these species, the nutrients and other organic carbon they're putting in the soil would start reducing the ph of the of the soil. -not zero of the glacial marine, this is zero from when the species showed up. So the alders show up about 30, 40 years into it. So this is like zero for the altars. But by the time the alders disappear, they've they've done most of the neutralizing of the PhD., very effective

Fig. 21.20, p. 442: Species-area curve for amphibians and reptiles of the West Indies

-log area of island -log number species biggest islands in the West Indies or Cuba, Hispaniola, Haiti, Dominican Republic, the Puerto Rico, Jamaica, Monserrat sava redonda -really nice direct relationship, everyone's on the line -but as you increase the log area you increase the log species. -You can do this for plants, you can do this for animals. And it pretty much holds up that if you increase the area you're going to increase the number of species. And it's a log log relationship

Glacier recession at Glacier Bay fjord complex, southeastern Alaska (facilitation model) -we're gonna be looking at nutrients they put in the soil, the plants, plant communities put in the soil and how they modify the ph

-some examples of succession, is really hard to measure because it takes so long, it's slow. -in Glacier bay Alaska Over the last 200 5300 years, this glacier has retreated as the area has warmed up slowly and as the glacier retreats are basically melts away, it has left what we call glacier moraine, which is basically rock, there's no topsoil, just all really rocky, there's no nutrients in the soil is just sterile. -they've been able to track the retreat of this glacier back in 1760 when Lewis and Clark went through there. It was all the way down here and it has been moving its way north ever since then.And I think this stops in 1950 or so, but now they can see how succession has occurred all way along this. -So this is the newest Glacial marine up here. This is the most recently uncovered land and this is the oldest land down here. -This is it's 300 years since it was covered by a glacier. And so what they see up here is the pioneer communities and then transitional communities and then climax communities down here. And so they can actually see how long it takes to progress from a pioneer 2 different transitional communities to the climax community. And they've also been able to study the soils to see what each of these communities is doing now.

Primary succession (progressional diagram)

-we have exposed rocks, nothing growing on here. The first organisms that can come in there and live on those rocks don't need much in the way nutrients. They're going to get what they need out of the air and out of the water that falls on them. -So we have very simple organisms, lichens and mosses here. But as they live and die, they're going to be adding nutrients to this. So it's not gonna be the same rock than it was before. -Then we're going to end up with our weeds and in smaller basis plants and get into shrubs and then eventually this is going to be broken up enough and there's gonna be enough soil there because that's what they're doing is they're creating soil along the way that it will support the growth of trees. -go from rocks to a forest with trees on it , never going back to a rock takes a long time, but still wont be a rock.

Succession models (Connell and Slatyer 1977) -Now, sometimes you can have the facilitation model working for the pioneers and then it sort of shifts to the tolerance model later on. It does, if it starts in the facilitation model, it doesn't have to be that way forever.

1) Facilitation model - communities change due to physical / chemical modification of the environment by the pioneers or preceding communities: • increasing nutrients • changing pH • changing soil structure - climax species tend to replace themselves

Succession models (Connell and Slatyer 1977)

1) Facilitation model - only specific pioneer species can become established due to hostile environmental conditions (don't let anything else live there): • nutrient or organic matter deficiency (rock) • poor substrate • extreme pH (acidic/alkaline) (something most plants cant live on) -pioneers modify environment to increase suitability for later successional species, while decreasing suitability for their own progeny (they add nutrients, they add organic matter. They change the substrate, this would be like primary or they moderate the ph and as they do that, they increase its suitability for the later species, but at the same time decrease the suitability for their own progeny.) -creating a better environment but they cant live in it

Succession models (Connell and Slatyer 1977)

1) Facilitation model - summary: pioneers → change environment → facilitate for → next group of species (transitional) → change environment → facilitate for → next group of species (transitional) → → → climax community that replaces itself

Models for community organization (2 models) -they're different, but they can be working together in the same community. Sometimes sometimes they're not, but sometimes they are, but they're very different. -reason they call it the River model is because if you imagine yourself in an airplane, the airplanes flying along and you look out the window and a rivet pops out what's going to happen to that airplane?Well, nothing. But if you have enough of those rivets pop out of the wing that's holding the plane, the body of the plane is holding the wing on, the wing is going to fall off, which will lead to the collapse of the airplane. -So what they're saying is that there's not extra rivets in that in that construction, that all the rivets are very important. RIVET MODEL: -if we have a community that has some endangered species in it, it could be that removing just one species from the community may lead to the loss of that endangered species. So this is important in communities that don't have very many species.They may have very few specialist species in it. REDUNDANCY MODEL: -says that there are communities where there are a lot of species and the species in the community overlapping functions so that if you lose one others will come in and take over. Ex: rocky intertidal zone community -So we have a rocky intertidal zone on Galveston island, It's the groins, we have barnacles and crabs, and um arthropods, crabs are arthropods, but Cnnmoney's and all kinds of critters living there. And it's comparable to a rocky intertidal zone in Oregon the East Coast, or europe, or anywhere where you have a hard surface and the ocean is is um beating up against against it on a regular basis. All of those communities will have barnacles and crabs and seeing them in these and other stuff in them. But they're NOT the same species. The species differ in different places, but their functions are the SAME.

1) Rivet model (by Paul and Anne) how they study endangered species - Ehrlich and Ehrlich, 1981 - each species has a specific and vital role - removal of just one species may lead to collapse of community 2) Redundancy model - Walker, 1992 - many species in the community overlap in function - loss of function of one species can be covered by others So in this case we have a lot of of species that do the same thing. And so if you lose one, it's not so important. So so both of these models are important, it's not that one replaces the other, They both have their roles. So a couple of major ideas behind how we define the community.

Current thought on succession -Because unless you have like a major fire or pine bark beetles or something that destroys the whole thing most of the time are disturbances are just going to be in small areas. So that means that you might have part of the forest in climax part, might be in transitional & so it's not homogeneous. --when you have that, then you have increased species diversity. If you have lots of different communities present in the same place

1) Succession occurs in mosaics across the community - forests are not homogeneous in succession due to spatial nature of disturbances - contain both early and late successional stages present in same area → increased species diversity

Succession models (Connell and Slatyer 1977) -any species can be pioneers -certain set that are adapted to the environmental conditions and in the tolerance model. It's everybody, it's a free for all, Everybody gets there.

2) Tolerance model - any species can colonize site following perturbation; there are no specific pioneer species - pioneers do not alter environment and do not influence survival of later occupants, they're all there. (like they do in facilitation model) -the later species are present in pioneer community but grow slower and gradually outcompete the early species because they can better utilize the space or tolerate the environmental conditions. (but they can tolerate the conditions and then eventually went out over everybody else.)

Succession models (Connell and Slatyer 1977)

2) Tolerance model - succession continues until no new species can invade and grow in the presence of the resident species - characteristics of the later species •longer life history • slower growing • more tolerant to whatever limiting factor is (e.g., shade, moisture, nutrients, grazing pressure, allelochemicals, etc.) • eventually outcompete and replace the species that dominated the community earlier in the pioneer transitional communities.

Succession models (Connell and Slatyer 1977) -So the ones that make it to the lab, they're all present at the start the community of species that makes it to the end have been able to tolerate whatever the conditions were all the way to the end & they basically went out they become the climax community because they have out competed all the rest for whatever that limiting factor was. -tolerance and inhibition models re not the same

2) Tolerance model - summary: all or many later species present in early successional community → competition removes some species → next community consists of more tolerant species → competition removes some species → next community consists of more tolerant species next group of species → → → climax community of best competitor species

Current thought on succession -So even if it's not a decision is hardwood community, the plants get thicker. And this is the thing I was trying to say, the age distribution reflects all age classes of all species that are there.

2) What is a climax community? - characteristics of climax communities • biomass increases over time • age distribution reflects all age classes of all species present (e.g., saplings needed to ensure future of species) • diversity increases from pioneer stage to transition and decreases from transition to climax

Current thought on succession -the ivy league Ecologist back in the sixties that it had to be um deciduous hardwoods. And so they claimed that the only hard are the only climax forest in north America would be oak maple forest.Like we see in New England, you know the ones that change color and are real pretty in the fall. We don't have that in all the States. It's only sort of up in New England and in the midwest in texas, we don't have oak, maple hardwood for us. -If you look at east texas, the hardwoods there are beach and magnolia, But they are not dominant. What's the dominant species in east Texas? It's pines, but they still have beach of Magnolia. (So originally back in the 60s, the east Texas forests were labeled transitional because they have the transitional pines and they had some beach magnolia trees, in there, but they weren't dominating. it was thought to be a force to transition. it's called the piney Woods because they are replacing themselves. -if we were like the Northeast us, then we would have beach magnolia climax forest. now the rule of thumb is to look at force that are replacing themselves. -but then you're seeing an increase in the species, that would be in the next transitional group, then you know that forest is changing. -But if you see all life stage sizes over a long period of time, you know, you're at the climax because you've got old individuals, young individuals and then lots of seats that are germinating. That's a that's a pretty good indication that the force is not changing.

2) What is a climax community? - classic idea of the climax community: mesic hardwoods • oak-maple hardwood forest: NE U.S. • beech-magnolia forests: E. Texas • pines transition between grasslands and hardwoods - what about mountains, deserts, tundra, coastal Areas? They're very different even from what we see in east texas. climax community on sand dunes is going to be sand dunes. you're not going to have deciduous hardwood forest on sand dunes, it's just not going to happen. So ecologists have vastly changed their idea of what constitutes a climax community instead of being hardwood forest. Now it's just a community that replaces itself over time. -How would we figure out why we don't have a beach magnolia dominated forest in east texas? Why is it dominated by pines? -You go back to those four factors. You look at the moisture, you look at the soil type, our soil types different what they have in New England. You look at grazing, you look at fire regime, even though humans have changed it. The fire regime through texas is a lot more frequent than we allow it. I think they said prior to humans, it was about every 100 125 years or so. Our force in Texas would burn, don't do that anymore. -but that's what would keep the pines growing and not have hardwoods there.

Succession models (Connell and Slatyer 1977) -The last one the inhibition model is this one you can see there's little negatives here. So you can start out with all the species present. But this whatever species gets there first is going to inhibit all the other species. -But the one that gets there first is the one that's gonna be the the climax is the one that's going to get to stay. So it can they can inhibit that's the negative here. They can inhibit everything else that's there with them. Either by allopathy, remember that or you know, just growing over them, there's any number of ways Most of the inhibition model is not by plants, this would be more like animals. -ex: We see this in coral reefs where the first coral to establish its place, especially hard corals, then none of the other corals can grow there. -We do see it in some plant communities like Mesquite communities where they basically poison the soil around them. So it limits the number of species that can be in that community. -But in inhibition model, the first ones, they're the ones that usually are going to be the the the dominant or the climax community. And the only way that will change is if you have some disturbance in there, a major disturbance that destroys that dominant community, then it's a free for all again, and whoever gets there first is going to be the one that inhibits the others. So, these kinds of communities, when you visit them From time to time, might be totally different.

3) Inhibition model - any species can colonize site following a perturbation -the first species present occupy the space to the detriment of later species (negative signs) and prevent their establishment, done by; • physical growth over other species • allelopathy • roots

Succession models (Connell and Slatyer 1977) -And so you only get a change in this succession model when the early species either die out or removed by some some disturbance. -examples of succession are going to occupy Office are going to be facilitation or tolerance or a combination of the two.

3) Inhibition model - replacement occurs only when the early successional species die out or are physically removed - very few examples, e.g., sessile marine animals inhabiting rocks

Succession models (Connell and Slatyer 1977)

3) Inhibition model - summary: all species have the same chance of establishment → species that become established first prevent establishment of later species → remain until a disturbance opens up the area to invaders

Community structure in TIME/SUCCESSION

All species that live in particular type of habitat have all the relationships of competition, predator prey, their own population ecology, but they're all interacting together with their environment.

Fig. 18.6 (p. 361): Influence of type of succession and environmental severity on major successional processes that determine change in species composition during colonization (C), maturation (M) or senescence (S) stages of succession. C ≈ pioneer M ≈ transitional M-S ≈Climax -seed arrival buried seed. All right, so this is more important one here. So this is relative importance for species change for stochastic events. This is these are sort of random, random environmental events. Very important for the pioneers, also important for the climax, but less important in the in the of intermediate communities. -down on the bottom here, insect herbivorous and pathogens are much more diverse in climax communities than they are in the changing communities. -So they sort of get established along with those with those climax community species. And then mammalian herbivore Is higher in the early stages than it is in the low stages. We have carnivores. We have insect of wars, but we don't have a lot of um animals eating the plants where the animals are eating, the plant, mammals are eating the plants all are grazers are mainly in the early

But the C are the primary, I'm sorry. Pioneer communities MSR their transitional communities and ss are their climax communities. -And this is some different things that we've been talking about through the course and how they change with the community type. So this is relative importance for species change. So that means that in the early succession a little and this is primary succession secondary. But in the early stages we see lots of species change quickly in both of them. Once you get up into climax, you don't see species changing anymore. And as you approach climax, you don't see a lot of species change in primary.

Succession models (Connell and Slatyer 1977)

Comparison of models: later successional species (late intermediate and the climax species and the facilitation model) - facilitation model: later species present because of early species (because of what the pioneers did to modify the environment.) - tolerance model: later species present in spite of early species (just because the earlier species were, there makes no difference to them. They just they did it in spite of it.) - inhibition model: later species inhibited by early species, present only if early species are removed

Fig. 18.5 (p. 358): Succession models second model is called: TOLERANCE MODEL (requirements for light) -Let's say community A.'s grasses community B as shrubs community, C as pines community D as hardwood just like in our classical model. -So out of those fourth they're all have seeds here in the same soil. The ones that grow fastest are the grasses, so they dominate this first this pioneer community (grow fast need a lot of light over time) -the perennials (grow slower) the shrubs, the pines & the deciduous trees, they grow slower and when they're really small they can tolerate shade. But after some time the shrubs are going to grow faster than the pines and the hardwoods. So community B, Now the shrubs are dominant because they're at the top of where they can get light and they've shaded out the grasses so the grasses can't tolerate the shade and they're gone. So now we've got some time and the shrubs are dominant. But the pines and the hardwoods are growing and eventually the pines are going to shade out or they can tolerate the shade of the shrubs. -Eventually the pines are going to shade out the shrubs and the shrubs are going to disappear, the hardwoods are still shade tolerant, but the hardwoods now are going to get taller than the pines. (It's a model doesn't always happen) then they will shade out the pines and they will become the dominant species.

Connell and slather model (1977) -Community A, has species that are in B,C & D. That are all resent in community A but community A dominates. -Then something happens and community B now dominates it. Community A disappears but community B as dominant. Still community C & D are there but they're NOT dominant. -Then community C dominates , D is there but its not dominant -Then community D dominates and none of the other communities are there. -Community D is replacing itself

Diversity gradients -these are the um diversity gradients that are related to the Macarthur wilson species area curves and um we'll start with this one. -But if you get down here into Central America Panama, you can see that this is the number of tree species in these gradients and we have 56 100 down in here & then as we as we move northward through Central America up into Mexico we see those those numbers are sort of dropping & then when we get into the continental Us, we're in the 100 or were in the like 100 to 1 50 you get up into Canada and europe into the 1/10 and then you get up in the northern Canada and you're down into the fifties.

Fig. 19.6, p. 382: Number of tree species in Canada and U.S. Number of species of land bird species in North and Central America -from high number of species to low number of species (there are couple other things involved here, elevation, mountainsides and peninsulas) -we've got the Appalachian mountains, Rockies can also affect -general pattern; going from high to low general latitude

Diversity gradients -this is summarizing all the bird species richness.. -There's the equator you can see as you go north & south, you're dropping off the number of bird species & the reason it goes further in the North is because we've got land all the way up here, we don't have land all the way down to -80 in the southern hemisphere.

Fig. 19.7, p. 383: Bird species richness for the biogeographic regions of the earth Species richness of mammals in North and South America in relation to latitude -Again the same thing at the equator, you've got the highest number of species. Um And then as you increase ladder to you, decrease the number of species.

Fig. 19.2, p. 380: Relative abundance of tropical rainforest trees >10cm diameter on a 50-ha plot on Barro Colorado Island, Panama, 2005 (Hubbell et al. 2005)

Log normal -most species will have few individuals

Fig. 21.21, p. 442: Equilibrium model for biota on a single island (MacArthur and Wilson 1967) -when there are no species present, you can't you can't have any leave, you can't lose any. So the extinction rate is really low. But as you get new species coming in, then that's going to cause the rate of some species leaving, they're going to be replaced by other species until your highest species extinction rate is going to be. - When you have the highest number of species you can possibly have in that, its the number of species its not qualitative, doesn't say what species are there it just says that this is the total number of different species we can possibly have & they might be exchanging themselves out again with species diversity. -We're not necessarily looking at the kinds of species. We're looking at the number of species. -S is species richness, where two rates intersect the immigration, new species and the immigration. number of species at whatever this the conditions are that we put on that. (Starting with this model) slide 15)

Looking at the number of species present on the island going from zero up to P, which is the maximum number of species that you could act that you could have on that island. So when we have no species present, what's the chance of immigration of new species going to be? -It's going to be one, Because if there's nobody there, the first species To get there is a new species from that point on, you know, individuals are coming in, going out, coming in, going out. -what we're looking at here is the rate of the immigration of new species. Because starting from the first one, a new individual coming in, May or may not be a new species and it only counts here if it's a new species. -were not saying you're that individuals aren't moving in and out were saying that you're not getting any new species. -so the immigration of new species is going to decrease from the very start of occupying the island until you get the total number of species that could possibly occupy that island. -balanced with this is what is called species extinction (only from island not from earth), kind of like competition where one wins ones locally extinct.

Diversity gradients -more species in the tropics than you have in the arctic -So if we look at this as latitude and all the number of species declines as you move from the equator northward, this is looking at mammals. Again, the number of species from the central America up here through Southern United States nor the United States. Canada same thing. -So that the general trend is that you have more species in the tropics. And then as you move in higher latitudes toward the north you get fewer species. -we've seen it in trees, birds, mammals and we're seeing it in um some invertebrates as well. North America has been studied more than any other continent. But it is true for south America to its true for Asia on the north is true for africa and Australia on the south. -But it's it's a little bit harder to do in asia than are in the eastern hemisphere than the western hemisphere because of just the shapes of the continents.

Number of species of calanoid copepods in top 50 m of transect from tropical Pacific to Arctic Ocean Fig. 19.9, p. 384: Species density contours for mammals in continental North America (number / 150m2 quadrats)

Community organization looking at environmental gradient (could be moisture temperature or something else, but let's just look at it in terms of space)

Open or closed community? graph A is closed, ecotone or something else graph B is Open because from west to east theres no demarcation, but there is a small one so it may be closed. Because there is a differnet set of dominant species. graph C is open: because if if each one of these is a different species and they all um they all sort of overlap and they all come have the same densities. You really can't tell where one starts, the next one stops. Its continuous graph D is open if lookin at large scale but its more closed, where you can make 4 communities. There's a Lot of lines crossing. When looking at species present it becomes closed.

Fig. 19.8, p. 383: Species diversity of Alcid seabirds and seals / sealions in relation to latitude (Proches 2001)

There is an except there's always exceptions to the rules and this is what we see for seals, where the seals or cold water mammals and they are least plentiful at the equator, and then they are more plentiful as you get into the colder waters.

Fig. 21.22, p. 443: MacArthur and Wilson's equilibrium model for biota on several islands of different sizes and remoteness -red lines looking at the extinction of species or the emigration of these species. (Red side were looking at size of island, blue side Is looking at the remoteness of the island) -So extinction will occur faster on small islands. Then it will on large islands because large islands can support a higher number of species. Then small ones can -so if you combine the size of the island and the remoteness of the island, then that will give you the projected number of species that you should have on each of those islands. -So here's a A is for large nearby islands, the continent have the highest potential number of species on it (large or small) far away from the mainland had the smallest. -if you look at the middle than, we could say that nearby small islands can have the same number of species on them as large far away islands. Graph will tell you; -how many species you should expect on any particular island. And then if you have more or less you can look and see if there's any human impact that is that is related to that.

This is what happens when we look at size and remoteness, so all of blue ones represent immigration of new species. -So, if the immigration is from near the islands the immigration is from continents that these islands are nearby, then the rate of immigration new species to start is going to be high. They don't have to go far to get on this island. -If those islands are far away, then the rate of immigration and new species is going to be lower, they still over time are going to make it to p, it's just going to take longer. -If the islands far away, then it will be if the island is close -4 blue lines, were looking at the immigration of new species from the mainland, whether the island is close or far away, except we're looking at the immigration of new species form th mainland. We're here island is closed or far away.

Characteristics of early and later successional species R & K selected species

Those can be related to early in late succession. Als species in um in succession as well. So early succession all species are basically are selected late succession. -All species are k selected.We looked at a lot of these characteristics in all species. But these are just looking at are are different succession plant species.

Floristic provinces of North America 4 intersect in Texas (Same as California but more than Alaska, no other state has more floristic provinces, were in a very ecologically interesting state) province changes over time as global change progresses. Dynamic stability, communities want to stay the same they don't want to change. When changes comes it's pretty slow and long term.

Used 15 differnet communities to discover floristic provinces! Light yellow is step area, tundra! -Floristic province three (III) which is the eastern deciduous forest and that that occupies a big part of the U.S.And it extends down here into northeast texas and down into sort of the eastern part of the hill country, that's the eastern deciduous forest. So the piney woods are considered part of the eastern deciduous forest, even though our community is pine based. It's still up here with the correlates with the eastern decisions force.That's the major type in this province. -The coastal plain is more of the pines, they're not necessarily dominating, but they dominate in certain pockets around here. So this this is dryer and colder than the coastal plain, which is moisture and warmer. -Then we have the grasslands and the grasslands. This is floristic province six (VI) So this is the tallgrass prairie up in here. Then we get down to coastal prairie, species down here in the coastal prairie are different than the species that are up here in the tall grass prairie, but they have the same function the same. they do the same thing that these species do but its a little more moist down here. -desert floristic provinces (X) very dry. chihuahuan desert and down in this area that goes up into the sonoran desert. But this is all desert floristic province. And you'll notice that the desert floristic province is all the way through far south texas. Its grassland but not the same kind of grassland as the floristic province. Its drier That's that's the thing about the floristic provinces, they're big and they encompass a lot of different kinds of communities based on their environments. Okay, the neat thing about Leaving from Houston is you can go 100 miles east, north or west and you'll be in a different floristic province and you can sort of see how they change as as you go

Growth form of the community

Vertical structure - Phytoplankton (single celled plants or colonies) • generally float near the surface • distribution limited by depth of light penetration - zooplankton (e.g., krill, copepods, larval crabs) • not confined to photic zone • vertical migrations from depths to surface, day to night → can move >100 m per day • migrations negatively stimulated by light - avoid visual predators - exploit different food sources at day and night

Secondary succession

WHAT HAPPENS; -So you already have soil here, You're not trying to create soil out of rock. -So you have soil, you get annual plants that succeed into perennial plants than shrubs. Then we usually think of pines as being an intermediate forest and then a finally immature deciduous forest. -THE DIFFERENCE FROM PRIMARY IS: you're not starting out with nothing, you're starting out with soil. So that allows the succession to re occur over and over again. If you have let's say a tornado comes through, knocks all these trees down. That's going To set this back to perennial weeds and grasses . -But given enough time it's going to turned back into a forest. That's sort of like the dynamic stability that we're talking about. Doesn't happen over night but can happen.

Fig. 19.1, p. 379: Relative abundance of Lepidoptera captured in a light trap in England (6814 individuals representing 197 species) (Williams 1964)

follows the log normal Where you've got, this is the number of individuals represented for each species. And this is the number of species that they counted. -So they had you know 36 species with one individual. And then you know up up to 10 individuals they call all these rare species. And then their common species might have 40 or more individuals in it. follows log normal

Species: area relationship (log:log) drew the log relationship lines, log scale/paper

if we're going to test the tenfold decrease in area versus losing half the species or the other way around. So, first, let's look at the right direction here. Okay, let's look at Jamaica. -Jamaica has an area of 7000 square miles, that's right here. And then if we draw the line over to the Y-axis, we see that Jamaica has 36 species. -so then we're gonna go up to this invisible island here because there's not one this size, but this is This is 700 square miles. So we've gone down one organ or order of magnitude. And if there was an island there it would have half the species, it would have 18 species. -But there is one monster, right? Which is uh 1/10 of this imaginary island 70 square miles and it has 9 species (counted not hypothetical) MONTSERRAT has 9 species in 70square miles, we increase it tenfold, then we increase so it would be doubling it to18 -we increase this tenfold and that would double the 18-36 so it works

FIG 18.2 (p. 355): Area affected by Mount St. Helens eruption

like a moonscape -good study and succession because the the volcano exploded in one direction. I think this was really west. It exploded west but it's north on it. -And so the actual ash deposits are the real = they call it pyroclastic flow. This is most of the heat and chemical from the volcano was limited to this area. Then the blast zone is this orange area here. then all the debris that sort of got blown down ended up in this river and float down this way. -So they thought this this would be a real interesting um uh a study in primary succession. So you see there's not much here. -it would they could study it for what pioneers came in and then what happened after that? Because this used to be forest here, beautiful alpine forest.

Total nitrogen content of soils recently exposed by glacial retreat at Glacier Bay, Alaska

this is looking at nitrogen into the soil. So without the without a lot of the plants on it, you can see there's not much in the way of changing the in the nitrogen a little bit here. -But with the with the plants there you can see that there's a lot of nitrogen added in soil. This is where the altars, I'm sorry some of the spruce come in and use up some of that nitrogen that's there.

Diversity and evenness

you get one. So it's got perfect homogeneity. And that's because every species in the community have the same number of individuals in it -community 1 had dominance, had 11 species dominated over the other and that's reflected in the evenness which is closer to zero.

Succession along glacial moraine in SE Alaska -It's not a nice demarcation between one community in the next, and that's because there's some changes going on there. But these these um these these 250 year old communities are probably still Heading toward this climax communities, which means that the climax community may take three or 400 years To completely establish itself.

• 0-30years: pioneer community - mosses, Dryus sp fireweeds (scrubby perennials, don't need much in the way of nutrients) - willows, cottonwoods , simple trees (scrubby → tall) • 0-50years: transitional community - dense stands of alder (Alnus sp) - nitrogen fixers → increase acidity of soil • 40-250years: transitional community - Sitka spruce (Picea sp) dense forest, 150-180 ft tall • 60-250years: climax community - western hemlock and mountain hemlock (Tsuga spp) → two different climax communities • sphagnum bogs (wet areas) • spruce-hemlock forests (dry areas) (So these are also the whole community is is conifers, but these are much more long lived conifers. And you can see there is some overlap in these years.)

Diversity gradients But these are diversity patterns in in different areas of the world and their related to latitude. -we're gonna look at land organisms, terrestrial organisms. We're not gonna look so much at um aquatics. It's a little different with aquatics.

• Abundance and diversity patterns - latitude (most important - elevation (adds habitat opportunities and their related to sort of what the shape of the continent is) - mountainsides - peninsulas

Succession along glacial moraine in SE Alaska -to completely establish itself. So, these are some of the changes that they saw in the soil that led them to discover that this is a facilitation model. -So in the 1st 30 years, the Ph is very alkaline in the soil. But as the vegetation grows on this and we have different changes in different communities, it decreases the ph to set aside solidifies the soil -And eventually the the the last species there now are ones that uh that need a more acidic or more neutral soil, not alkaline soil. -And the soil nitrogen..Ofcourse the trees need nitrogen. The pioneers, the fire weeds and the alders are all nitrogen fixers. And they will increase the soil nitrogen several fold before they're gone.And then you start getting some of these transitional communities that will actually use up some of that soil nitrogen.

• Accompanying changes in soil - soil pH • >pH 8 for 30 years in areas without vegetation • ↓ to pH 5 by time alders are replaced by spruce • alder leaves acidic → acid leaches into soil - soil nitrogen • Dryus and alders are N-fixers, ↑ soil N 5-fold before they disappear • soil N ↓ from alder to spruce since spruce require high levels of N

Latitudinal diversity gradients but more tree species in the tropics than in northern temperate same basic latitudinal trends

• Ant species - Brazil: 222 - Trinidad: 134 - Cuba: 101 - Utah/Iowa:63/73 - Alaska: 7 • Snake species - Mexico: 293 - U.S.: 126 - Canada: 22 • Freshwater fish species - Amazon: >1000 - Central America: 450 - Great Lakes: 172 • Treespecies - Malaysia (4 acres): 227 - Michigan (4 acres): <15

Measurement of biodiversity -started with islands because theyre very Easy to define -the area of the island is just what is around that island. And all the species in here are it's a close community. They're going to be separated from other such islands. -So they looked at the area of the island & the number of species not the number of individuals, the number of different species species richness. -And then they looked at the relationship between these two things and how far away they are from the source. -So they started looking at oceanic islands: They looked at the size of the island. They looked at how far they were from the nearest continent & they came up with some sort of groundbreaking at the time conclusions about how ecology and biodiversity works.

• Biogeography (Chapter 21) - Observations of relationships between • area and number of species thats occupy that area • distance from source - Island biogeography • E.O. Wilson (retired ,ant biologist)and MacArthur (dead)

Community structure -the structure of the community and we name them either based on the dominant species or more. -if we're looking at whole ecosystems, we will name them according to their growth form.

• Characteristics of community structure - Growth form • major terrestrial growth forms (and match them to their environments and we come up with those 15 ecosystems based on plants) • floristic provinces (based on plants) • leaf structure - Vertical structure - Phenology

Succession models (Connell and Slatyer 1977) -even though they have the same characteristics in the different models, they do different things.

• Characteristicsof pioneer or early successional species in all three models: - large number of propagules - good seed dispersal - long seed dormancy (they can they can roll around in the environment for a while until they get to the to some place. That's good for them to germinate and then they can grow fast maturity.) - fast growth to maturity •Comparison of the three models: pioneers and early successional species - facilitation model: pioneers facilitate later species, discourage survival of progeny (Making environment Better for the later species at the demise of their own) - tolerance model: pioneers less tolerant than later species, outcompeted by longer-lived, more tolerant later species - inhibition model: pioneers and later species are one in the same, inhabitants result of chance but are good competitors once established (But how they got there is it doesn't have anything to do with tolerance. It just has to do with the fact that they got there first)

Measurement of diversity -Pearson and MacArthur did their work in the 60s and they came up with this log normal distribution model.

• Commonness, rarity and dominance - Community organization • model 1 (log-normal) - a few very common species -many rare species -low diversity • model 2 (neutral) - a few very common and a few very rare species - most species of intermediate abundance -high diversity

Measurement of diversity

• Commonness, rarity and dominance - MacArthur's broken stick model • arrange the pieces of the stick by size (large to small) → log normal distribution • represents a few species with large abundances and many species with small abundances

Measurement of diversity -he took Preston's log normal distribution model and tried to figure out what the why it was occurring that way. And he brought it up concluded that it was basically just random math. -So the way he proved this is he took a stick and he broke it up at random points and he didn't have a computer at the time to do that. He just sort of picked with a random number generation. He picked different points for different measurements on the stick to break the stick. -Now they've redone this the same model using a computer to break up the stick and then you take all the sticks and you line them up by size. And what you end up with is you have a few large pieces, in many small pieces. -he took all and he organized by size and ended up with normal distribution -models are fractals, math oriented but there in nature and that most communities will be represented by a few species with large abundances in many species with small abundances and that sort of opposite from what we just said made a good biodiverse community where we wanted all of the species to have the same abundance's and that would increase the diversity

• Commonness, rarity and dominance - MacArthur's broken stick model (all math, same mcArthur that did the warblers in the pine trees) • stick broken up at random points • results in a few large pieces and many small pieces

Measurement of biodiversity biodiversity tells us "what species are common what species are rare in a community and if there is dominance of species in a community, communists is sometimes equated with dominance. commonness means: species has a high abundance in the community with dominance It means that it is overwhelming the other species in the community.

• Commonness, rarity and dominance - Preston's log normal distribution model (proposed for community organization) • a few common species with high abundances • many rare species with low abundances (most of the community was made up of) graph: -looking at the abundance of the number of organisms per species. And this is looking at the proportion of all species. So in this one it's almost 40 of the species in this community were represented by one individual. So those will be rare. most species are rare!!! If you connect the dots here, that makes a log normal distribution. -So it's sort of going backwards at the neutral model was what is this green line? Which would say that that there are no common species and they're not there are no rare species that there is the same. The same number of of species with all these different abundances.

Community organization -doesn't have time dimension, basically define what area were looking at (area can be big or small) IF BIG: -then we probably have interacting communities. So we want to make sure that the populations that we're talking about are actually interacting with each other and not interacting with somebody else. IF SMALL: -So a small community would be like a rotting log. A log that's falling apart is going to have insects, fungus, bacteria, it might have some birds working on it, all all those organisms that are working on basically deconstructing that log are in a community. ex: a coral reef can be looked as a community and an ecosystem (has abiotic components) can be big or small depending on how big the reef is The difference between a community and an ecosystem and the reason I'm going to put them all together here is basically um like an ecosystem is going to work with its a biotic environment where as a community is just we're just talking about the living organisms there.

• Community: association of interacting populations in a prescribed area or habitat - can be of any dimension • rotting log • coral reef • bottomland hardwood forest (name communities based on dominant plants that are basis of that communities) - can be from different approaches • zoologists view functional relationships • botanists view taxonomic or structural relationships So our campus sits in what is termed sometimes as a bottomland hardwood forest. And so what does that mean?What does a forest mean? -Okay, trees, lots of trees, there are two kinds of trees and we can loosely put them into hardwoods and softwoods and softwoods are our pines and hardwoods are deciduous trees. hardwood forest: means that the dominant trees is hardwoods, That doesn't mean there are no pines there. It just means pines are not dominant and if you have a pine forest that means pines are dominant. Doesn't mean there aren't hardwoods there. ex: we have piney woods northeast of us, have hardwoods but aren't dominant. Campus sits on hardwood but there are pines they're just not dominant. Bottomland; is an adjective that describes this hardwood forest and that means that it is low and it can flood. Okay bottom land is low land that floods. (Ex: bayou building) This bottom land doesn't mean that it's flooding from the bio. It's not it's just standing rainwater and it takes a while for that water to to seep into the ground. BOTANISTS: -So we have forest here, we know it's trees. If we were looking at grasslands, we could look at, we have some kind of prairie or some kind of grasslands. So these are the structural relationships. They're less interested in functional relationships. -Functional relationships are like food chains, who's eating, who who's competing with who, zoologists are really interested in that. (Like movie field of dreams) -If you have a forest, you're going to a forest, a plant bottomland hardwood forest. You're going to have a species of birds and mammals and reptiles that live in a bottomland hardwood forest. If you have a prairie grassland, you're going to have species of animals that live in prairie grasslands, You won't have the forest species in a grassland. -So zoologists depend on the plant ecology. -once you have the plant communities and the animals will follow. WHY? because the animals eat the plants adn that's how food chain works.

Species diversity -count of the number of species present, not a count of the number of individuals. It doesn't matter how many individuals are here. What matters for species richness is the number of different kinds of species present -Richness is just a count of the number of species present. It doesn't have anything to do with how many individuals are there. -And then the second element of species diversity is is that even as equitable bility, which I'll cover in a second here, But what we to increase diversity, that means that we have each species present in the community at about the same number of individuals. -Remember the tiger beetles in that in that primary undisturbed community, the three beetles that were present, three kinds of beetles that were present were all there in about the same percentage is so that makes a heterogeneous community. Alright, so species richness is the number of species, not the number of individuals.

• Comprised of - species richness: number of species present - heterogeneity of species • equitability or evenness • relative abundance of each species present in the community

Ecological succession (what plant community comes after whihc plant community) succession in plant communities -we dont talk about i animals except in some aquatic systems because the animals will follow whatever plant community is -So we usually think of overtime, the plant community is going to get more complex. So we start out with a simple plant community. It's got a few species of of certain types of species. Usually we'll talk about that as we go forward here and then as time progresses we get more & more & more species in there. -So again our communities are going to be labeled by the dominant species. So we have certain dominant species here early on. And then as the community becomes more complex, then we have different dominant species, they Change. -as the community might have a fast change over a certain period & then you might have a slow gradual change. So its NOT smooth but you can see wats happening over time the community is getting more complex. -by more complex we mean more species and more different types of structures to the community.

• Definition: directional, orderly change in vegetation over ecological time (directional because it really goes in one direction, the only thing that can set it back is a disturbance, so it's not going to go backward unless there's been a disturbance, it's called orderly because there is a set sort of process by which succession occurs) • Sere: community at one point in time(from sear to sear to sear only in one direction but not smooth) • Process goes in one direction but is not smooth

Species diversity

• Ecological communities differ in species number and composition - tropics > temperate - remote islands < large islands - continents > islands

Ecological succession -So we said that succession only moves in one direction unless you have a disturbance. Human interference is a is a very important disturbance when we log, when we keep power line easements clear, especially when we control fire. -these will all keep succession, allow succession to keep moving in the same direction. These are sort of minor, I should call minor disturbances. They're all disturbances that once they're finished they allow succession to start over again.

• Effects of human interference on natural successional processes - logging - power line easements - fire control - pollution: simplifies communities (The one a different thing here is pollution. Pollution may be the only thing that causes succession to run backwards. And that's because pollution tends to simplify communities and rather than let them head toward their natural succession will state, it may just cause them to run backwards) -And that's because pollution tends to simplify communities and rather than let them head toward their natural succession will state, it may just cause them to run backwards. So the pollution is a disturbance. -But it's a it's sort of a slow disturbance that will just simplify communities back to Probably not the Pioneer, but something that just low diversity that will tolerate whatever The pollutant is.

Community characteristics

• Growth form and structure - categorization - stratification • Biodiversity • Relative abundance - dominance - commonness and rarity • Trophic structure

Growth form of the community -environmental conditions are basically going to be temperature and moisture. So you end up with grasslands where you have you can have higher low temperatures, but if you have low moisture, you end up with a desert or grassland. -If you have high moisture, you're going to end up with a tropical rainforest or some kind of a tropical grassland depending on them.

• Growth forms reflect environmental conditions • Similar adaptations in plants are observed in similar environments • If the important environmental factors are known, the physical structure of the vegetation can be predicted

Island biogeography

• Habitats considered as "insular" because they are isolated from other communities - caves - mountain tops (elevation, basically separated from each other) - some peninsulas (If the peninsula is really long, then organisms that live at the end of that peninsula are basically separated from other organisms because they're not going to crawl all the way to the top of the peninsula, go around) - wildlife or game preserves (by keeping organisms inside)

Quantifying species diversity -Let's say we have 100 individuals in each community and we would never have exactly 100 individuals. But this is just for this example ,mtwo extremes are that one species is very common and the other species is very rare or both species are equally. -comm 2 is heterogenous community -comm 1 is expressing dominance

• Heterogeneity of species - uses relative abundance to give more weight to common species - extreme possibilities in a 2-species community

Growth form of the community -Leaf structure tells us how the plants are adapted to moisture conditions, not so much temperature conditions but moisture conditions. So here's our needle leaved trees -needle leaf trees can conserve a lot of water, they don't have any surface to lose water on. (Often seen in places that have low water, not in hot places, theyre temperature confined like cooler places with low water. In east and southeast Texas, in places that are relatively dry. -most are broadleaves, they have stomata or pores on the underside, used for gas exchange and lose water through stomata. Adapted to places that have higher moisture levels, not seen in dessert.

• Importance of leaf structure - leaf size - water use efficiency

Ecological succession -you have just a small area that's affected. And so there's probably a seed bank there, or these different plants can grow into that gap. And so with minor disturbance, you go back to the original community pretty quickly. -if you have a gigantic fire, like the a lot of the fires that we're seeing in the Western States that haven't burned in 100 years and now when they're burning, they're just, they're just wiping out everything. Or bass drop state park 2011 got burned. Got set back to pioneers tolerance model because there's a lot of nutrients in the soil and it probably wouldn't be different than what they started with, but you might get different species as a result. -Bastrop State Park where they had a monster fire in 2011, they went back in and they planted, those lost pines that we talked about a little a couple of weeks ago, they were trying to control succession here to make sure that succession didn't bring in different species to preserve uniqueness of the area.

• Importance of the nature of the disturbance - minor disturbance (e.g., a tree falls, creates a small gap) • replacements likely to be same species • minimal effect on community (Dynamic stability) - major disturbance (e.g., pine bark beetle infestation) • large area affected, mature individuals disappear • creates sudden and extensive opening in community, can be invaded by a large number of different species • sets succession back further (probably back to pioneers) (this is a, a big disturbance to the community. It opens up a lot of area and you might have new species come in and they might be able to take or get a foothold in and it might change the community)

Island biogeography -they used oceanic islands, but you can actually apply their theories to anything you can call an island. -An island would be a well defined close community, It could be a a game reserve, a wildlife reserve could be a cave, it could be just about anything, as long as you could define the edges of it and make sure that every organism within that was sort of captive within that island.

• Island communities: well-defined, captive • Variables - size - degree of remoteness (how far away it was from the nearest source of species) - elevation (that by increasing elevation or giving elevation relief like mountains, You're providing more habitats) • Simple community structure (can't have really complex food chains on an island, theres just not that much, cant have that many species) • Increase in area → increase in number of species (looking at the increase in the number of different types of species)

Indicator species in communities -In a lot of cases, they are top predators that regulate the population size of every other species in the community, & if you take them out, that means that these the other species will start competing with each other and then you'll end up with a winner & if you get a winner then; that means they beat out all the other species in the community and your diversity goes way down. -KEYSTONE: So keystone species are really important because their role in the community to sort of feed on many levels is to keep the prey from competing with each other and it helps increase in, it helps keep the diversity in those communities high.

• Keystone species (most important of the indicators/ sometimes called community anchors) - anchor communities (are organized by rivet model); if lost the entire community changes - e.g., top predators that regulate population sizes of prey species - most ecologically important • Pollution or disturbance indicator species - tolerant (used a lot in ECOTOXICOLOGY where we go sample a community and then we see what's living there) - sensitive -And if we know from a reference area, what should be living there. And then we look at what is living there versus what is not living there & then we can judge those on whether they're tolerant or sensitive species.

Island biogeography -so a tenfold decrease would be like a 90 decrease results in the loss of half the species. And you increase the area by 10 and you're going to double the number of species. How does that work? It all has to do with log log. -These are used in a practical sense when a wildlife scientists or managers are trying to determine how big a reserve needs to be in order to preserve the greatest number of species and sometimes it's not a gigantic one gigantic area. Sometimes it might be to areas that are big enough, but in two different places so that you can increase the number of species.

• MacArthur and Wilson's species:area relationship - log : log relationship - 10-fold decrease in area → 50% decrease in number of species OR - 10-fold increase in area → doubles the number of species

Community ecology -The minimum properties that you have to have at more than two species IN ORER TO HAVE A COMMUNITY, so at least 3 (If you only have two species, then you have to Have interacting populations, which is what we covered in the last section.) -And usually it's a lot more than that, they're all living together in one area. Like I just mentioned that these same species re occurrence space and time. They may not be exactly the same species, but they will be the same function. -They re occur around the world where um you see similar environmental conditions and they last for a long time. Maybe they don't live individually for a long time. But they will be in that place for a long time. -WE SAY: they tend toward communities tend toward dynamic stability. And dynamic stability is sort of an oxymoron because dynamic means move and stability means don't move. So this is dynamic stability, move.Don't move, move. Don't move.

• Major ideas behind the definition of a community - minimum property of a community: several species together in one area - collections of the same species reoccur in space and time - communities tend toward dynamic stabilIty

Evenness -This is even this, this is our how we put a number on equitable bility. And so first you calculate your Shannon wiener diversity and then this is just a proportion. The evenness is just a proportionate tells you how perfect or how homogeneous how perfect the homogeneity is. And so you're going to divide this by the highest possible diversity. You could have for a community of that particular richness. -So all you do for a cheap maxes, you take the natural log of the number of of species that were in your community. And then you divide that by the diversity that you got. And that will tell you how homogeneous or how heterogeneous your community is. So these values range from near 0-1.

• Measurement of equitability among species in the community • Pielou evenness E = H' / Hmax E = Pielou evenness H' = calculated Shannon-Wiener diversity Hmax = ln(s) [species diversity under maximum equitability conditions] - values range from near zero to 1

Major formations and environmental correlates

• Needle-leaved forest - characteristic of cold regions with long winters and high rainfall; trees are coniferous, needle- or scale-leaved, may be large in size. W North America, N Europe, Siberia. • Evergreen hardwood forest - regions of "Mediterranean" climate with a dry summer and wet, mild winter; trees are generally small and leaves sclerophyllous. Australia, California, Mediterranean. • Savanna woodland - summer rainfall with long dry season (more extreme than monsoon forest); trees small, evergreen, in open formation, with ground layer of tropical bunchgrasses. Brazilian and African plateau, N Australia. • Thorn forest and scrub - tropical, dry climates; trees small, often thorny, deciduous; ground layer includes many succulents, annuals, grasses. Brazil, Africa, India. • Savanna - moist, tropical grassland, with or without trees; may owe origin to fire or adverse soil conditions or both. Pantropical.

Community organization OPEN: -So in this first group is open versus closed communities. Open communities have no distinct boundaries. They just, flow from one community the next. You can't really see where the change occurs. CLOSED: -Closed communities have a distinct boundary between them and it's real easy to to see them. These are two examples of closed communities and this one we've got an aquatic community uh adjacent to a land community and then we have what's known as an ecotone or a transitional ecosystem between the two of them. They're closed! (Forest pic) -you have turtles that are in the water and up on the land, you've got some emergent vegetation. These will make the ecotone. So this is what we often see along a lake side where you've got wetland plants here. So when we're classifying communities, it's a lot easier to classify a close community than it is an open community.

• Open communities - no distinct boundaries - continuum of environmental gradient • Closed communities - sharp delineations between communities - edges= ECOTONES -And then we've got this interface for this ecotone in here that has species that are not bog plants and they're not terrestrial forest plants. They're just some specialist plants that live in the In the zone between the two.

Growth form of the community (last of growth community) -summer got all leaves, doing the maximum photosynthesis. -fall leaves pull back nutrients and prepare for winter. Stimulated by day length and all leaves fall off -winter has skeletons tee stimulated by day length -spring; starts to flower then put on its leaved. -terrestrial plant flowering seasons are all part of phrenology. -Some of our herbaceous plants flower in the spring, some flower in the summer, some flower in the fall some flower in the winter. Not many, but some of them do again.

• Phenology (seasonality) - changes in (plant) community structure with season (Ex. Tree how it functions in different seasons like summer/fall/spring/winter) - flowering seasons of terrestrial plants - leaf fall in deciduous plants os phenology. - coevolution of plants and pollinators (Not just pollinators but the the animals that feed and reproduce at different times of the year. It's all going to be based on what the plant community is doing) -If they're producing flowers and nectar in the spring, then you know, all the bees and the other pollinators that are necessary to pollinate this tree are going to be there gathering nectar and food for their reproductive cycles. -Most of the time in the summer. All the reproduction of these pollinators and birds is pretty much done unless the fruit of this of the tree is occurring maturing this summer & then you'll have fruit eaters in there. -the job the trees do in the summers, they make good hiding places for animals there still fed on by insects, but just a different role there - in the fall there's not much that is this tree is going to do for other wildlife in the fall. -But in the winter again it can produce, it can it can provide loafing places and just not the amount of protection here. -So the plants and or the animals that are associated with this treat different times a year can change you men have totally different species that are using the tree in the spring versus the summer, fall and winter. So that's all very important phrenology to describe a community.

Ecological succession -since Darwin made all of us realized that there really is no divine order in nature but there is some kind of order in succession. -ecologists now believe that the Seres are not of divine order that the species that are present in these different Sears are there because they are well adapted to whatever the environmental conditions are, and they may not be always the same species like we talked about earlier, but they're going to be species that are going to be related to species that are occurring each of those Seres.

• Post-Darwin view - seres are not integrated; each species is present because it adapts to the environmental conditions - the presence of species is random; there are no specific interrelationships (they are adapted to the conditions - succession is a consequence of the passage of time and local environmental conditions (you put those two together and your going to get predictable change in the vegetation) • biomass increases because plants are older and larger • species diversity increases because of the successful immigration of species from the outside over time • nutrients are retained naturally because of the increase in biomass

Ecological succession (there are two types; primary & secondary) -PRIMARY: can only happen one time because the process, the species that are there will do something to that environment, that habitat uh and change it physically or chemically. So it can't go back to the way it was. So they PERMANENTLY change the habitat. -It makes it impossible to go back to what it was, but it makes it possible than for more complex plant and animal communities to come in. -AUTOTROPHIC SUCCESSION EXAMPLE: So if you think about a log, a tree falls down, it's dead and then all of the animals that come in to create sawdust out of that log eventually at the end of it, you're not gonna see any evidence that that log ever existed, it's gone, so that's primary succession because it will never be able to go back to the way it was. (Same thing in DECOMPOSITION in animal carcass, can happen only one time) -HETEROTROPHIC EXAMPLE: If you think about a asphalt parking lot that nobody is taking care of, nobody drives on it anymore & you know, it's just been left to go. Then the heat and water are going to create cracks in that asphalt and little dandelions and weeds and grasses are going to come in and live in those little cracks, as they live and die, they're going to create nutrients and litter that go into that crack and their roots of their descendants are going to slowly break up that asphalt. you may not even recognize that parking lot was a parking lot. -So that's primary succession again, the plants have done the work now. It can't go back to north to what it was before now. (Asphalt parking lot Is NOT natural) -if the plants do the same thing naturally on rock, on glacial moraine, sand beaches, river makes a turn and leaves a sandbar. Eventually plants are going to grow on it. So it's not going to go back to exactly the same way it was. All primary succession

• Primary succession - one time process in which the physical and/or chemical properties of a site are modified in such a way that more complex plant/animal communities are possible - autotrophic succession • plant communities (do to accomplish primary succession but can happen in animal communities as well) - heterotrophic succession •decomposing log • decomposition of a carcass

Island biogeography -And so they looked at the distance from that source. First is the number of species on the island. -And they found that the further away from the mainland that island was the fewer number of species it would happen.

• Relationship between remoteness of island and number of species: - increase distance from mainland → decrease number of species - number of species present is dependent on immigration from mainland • rate is a function of the number of species already present on the island • number of species present = balance between immigration and extinction

Ecological succession (all based on minor disturbances/ or disturbances the community can recover from) 1)CLIMATE ; if we are in a hot, dry area, we're not going to see succession proceed the same way as if we're in a cold, wet area. So we won't see succession make a tropical rainforest out of someplace that looks like the chihuahuan desert, that's not going to happen. So we need to know the climate! 2)EDAPHIC FACTOR; has to do with the soil. (Not starting from rock, starting from soil, it might be clay/sand, diff types of soil depending on soil type we see different types of succession occur) -We're not going to have the same kind of succession on the beach at Galveston that we're going to have you know, the very rich farmland of Kansas, it's not gonna happen. 3)FIRE REGIME; If it is frequent, like every 10 to 20 years, then we're going to end up having a grassland. We're not going to be able to have tall trees because the fire, when it comes through, it's going to kill any woody vegetation, but grasses grow from their roots & when you burn off the tops of grasses that just basically puts fertilizer in the soil and then the grasses can grow back. BUT NOT good for trees! you might have small trees growing up very young trees, but a fire across the grassland is going to kill them. -On the other hand, if the fire regime is every 250-300-400 years, then that's going to give your big tall tree for us a chance to grow & that will be a different kind of succession there. 4)GRAZING PRESSURE; Deer grazers, buffalo are grazers, elk, all those ungulates animals. But the biggest grazers are the insects eating on these plants all the time. So if you have a lot of insects or even buffalo and deer, if you have a lot of grazers, they're going to tend to keep succession for proceeding where it might if the grazers weren't there. So when you see secondary succession and you know, these four factors, you can pretty much predict whether you're going to see a grassland in 50 years or if your going to see the start of a forest in 50 years, you can predict that -so succession on the, on the flip side of that, If succession is not proceeding the way you think it should, then you go back and look at these factors again and see if there's something that is preventing it from going the way you think it should. But you can only do this for secondary succession. You CANT PREDICT what's going to happen in primary succession

• Secondary succession (most succession because it can re occur in the Sam place over and over): - reoccurs in same place following temporary disturbances - led early ecologists to believe in some kind of order in nature (It turns out that it's not order in nature is just the way things happen.) -secondary succession can be predicted based on four factors 1) climate (temperature or moisture conditions) 2) edaphic factors (soil) 3) fire regime (how often natural fire runs through the are) 4) grazing pressure (what is eating the plants in this habitat)

Indicator species in communities

• Selection of one or more species in the community in which changes reflect the community as a whole - indicators of community type - indicators of community health (see Box 20.1, p.399)

Quantifying species diversity -It's not the only way to measure species diversity but it's the most common one. -Prime is our index of species diversity and it's equal to the negative some of this of this term. -And this term is the proportion of the total abundance represented by each species present. So you figure out what the proportion of the total is one of the species. And then you take the natural log of it and then you multiply these two together and you get one of these terms for every species in your community. That's s that's your richness. So then you some those up and take the negative and that's what you get.

• Shannon-Wiener diversity Function H' = Shannon-Wiener index of species diversity s = number of species in community pi = proportion of total abundance represented by the ith species

Quantifying species diversity

• Shannon-Wiener diversity function - values range from near zero to ??? (Can't be zero and there's no theoretical end to it.) - increased values indicate increased diversity - index has no units; value only as comparison between at least two communities

Island biogeography -they determine that small sized species would be found on more islands than large size species & that makes sense because small size species take up much space. (Use less resources, allowing more of them to be there) -when talking about animals, you'd have more herbivores than carnivores because the food webs that were going to deal with a little bit later today would be affected by what species are present. -And then they found the number of generalists would outnumber the number of specialists because it's really hard to be a specialist if you're on an island. So those are just some qualitative aspects of it.

• Small species are found on more islands than are large species • Number of herbivore species > carnivores • Number of generalist herbivore species > specialist herbivores

Measurement of species diversity -You're supposed to only count the residents. But like when we were doing our bird counts, we didn't know which necessarily which bird species were residents and which ones weren't. So most of the time we just count whatever the species are. -The problem with this is it treats species that are there in large numbers and species that are there in low numbers with the same weight. And so what we add heterogeneity and there is to give more importance to the species that are that are there in greater abundance.

• Species richness - number of species present in community - first and oldest concept of diversity - simplest estimate of diversity - only residents are counted - treats common and rare species with the same Weight

Major formations and environmental correlates

• Steppe and semidesert - occur in dry climates with winter rainfall (more extreme than evergreen hardwood forest); open shrublands with annual herbs and grasses, or dry grasslands. North America, Australia, Russia, Argentina. • Heath - like tropical savanna, heath in temperate regions is governed by fire, adverse soil conditions or both; ericoid shrubs with scattered larger shrubs and small trees. Worldwide locally. • Dry desert - warm regions of very low rainfall with open vegetation and special plant forms evolved in different parts of the world, e.g., succulent Cactaceae in North America, succulent Liliaceae, Aisozaceae, Euphorbiaceae in southern Africa, hummock grasses in Australia. • Tundra and cold woodland - semidesert of cold regions, short summer growing season; lichens abundant under sedges and grasses or stunted trees; on rocky areas, mosses dominant. N hemisphere in high latitudes. • Cold desert - edges of icecaps, glaciers and permanent snowfields; vegetation sparse, mainly herbaceous

Ecological succession (3 types) 1) PIONEER (CHANGE); they have certain characteristics that these others don't have. And the main thing is that they can survive in a pretty harsh habitat, and they will be there to help create a better habitat for these later species to come in and live. So that's the pioneers, the first ones to get there & they will be named again by the dominant species that are present there. 2)TRANSITTONAL/INTERMEDIATE (CHANGE); 3)CLIMAX/ULTIMATE; it will be replacing itself over time. It's not going to change, no more change

• Successional communities: 1) pioneer: first community to inhabit the site 2) transitional / intermediate: all communities between pioneer and climax 3) climax: ultimate community that replaces itself over time (LAST ONE)

Ecological succession -This is sort of a classical succession all process where you start with grasses and annuals(pioneers) and then you move in, you succeed to shrubs and perennials, you succeed the pines, and shrubs & pines are usually considered to be transitional communities, this is not just 2 communities. -transitional/intermediate communities are the shrubs & pines. -climax is the hardwood community!! -This succession process was um put together In the 1960s by ecologists in New England at the IVS in New England, this is how succession works in New England for a long time. -They said, this is how succession should work anywhere. But this the whole succession process idea is evolving now. To recognize that succession is not going to always go to hardwoods, you can have a climax community that doesn't involve assiduous hardwood trees, that's how it is in New England, that's not how it is, necessarily in a lot of other places. -succession says "I'm coming back"

• Successional process: grasses → shrubs → pines → hardwoods - simple: succession → grassland (never goes beyond a grassland) what might make it not go beyond a grassland? -look at 4 factors; soil/dry/fire/ grazing etc. -would go to hardwood forest - complex: succession → hardwood forest (if succession goes through all diff. Phases and ends up in a climax hardwood forest) - why is succession simple in places that look like it could be complex? You go back to four factor and see which ones might not be conducive to going all the way to a hardwood forest. - directional and predictable: only get a return to pioneer community does not occur unless there has been a disturbance or perturbation (it could be a weather event, it could be a gigantic fire, could be a drought, it could be a bulldozer, it could be any number of things.)

Open versus closed communities -its closed ! pinus rigida is down the slope of the mountain. -pinus Virginianais only found in the low elevation -pinus pungens is found in the upper elevations -take out the species that's present all the time and you concentrate on the species that change.

• Tree community along south facing slopes of the Great Smokey Mountains, TN

Major community plant growth forms evergreen means they lose leaves is our dominant form broadly deciduous, that's our bottomland hardwood. Or is it needle leave that be like up in the piney woods

• Trees (a single trunk hard or plant at least 3m tall as an adult and has a single trunk with branches and leaves, At some point above the ground) - needle-leaved (pines) - broadleaf evergreen (oaks,maples, ligustrum, elms, doesn't have needle leaves) - evergreen-sclerophyll broadleaf (thick leaves, places were water in an issue and have to store water in leaves) - broadleaf deciduous (loose leaves seasonally) some don't lose but they replace - thorn trees (most will be shrubs/dont see here) - rosette trees(dont see here) • Lianas (in the forest, predominantly big woody vines) • Epiphytes (plants that use other big trees and plants for support) • Herbs (herbaceous) (includes all our animals, predacious not wood) - ferns - grasses, sedges, etc. - forbs • Shrubs (like trees but less than 3m tall, with multi multiple trunks. So trees and shrubs are very much the same except here we have a single trunk that's tall and here we have a shorter tree that's multi trunk) - needle-leaved - broadleaf evergreen - evergreen -sclerophyll - broadleaf deciduous - thorn shrubs - rosette shrubs - semishrubs - subshrubs or dwarf shrubs • Thallophytes - lichens - mosses - liverworts

Open versus closed communities closed community!!! because species shift a the 2 dominant species blue adn purple. Not looking at geographic looking at soil. Green might be wet soil. Not dominant name communities based on dominance PLANTS only plants not animals

• Trees along a soil-moisture gradient at low elevations in the central Siskiyou Mountains of Oregon and California

Major formations and environmental correlates galveston falls under two summer green devious forest, & evergreen hardwood forest. were a mild winter and a hot summer, trees aren't tall but have simple structure a lot fo decisions trees. deciduous trees. -So we're sort of like that. We're sort of a combination of what's found in eastern north America and what's found in um an evergreen hardwood forest. so drier summers, wet, mild winters that sort of describes us. -we're sort of like a combination of a mediterranean and a eastern US temperature.

• Tropical rainforest - occupies regions of high and constant rainfall and temperature; forest is many-layered, leaves mainly evergreen, large, entire; trees tall and buttressed; epiphytes and lianas very common; flora very rich. Amazonia, Congo, Malaysia. • Subtropical rainforest - found in humid subtropical regions with some seasonal variation in temperature and rainfall; structure and composition reduced. Brazil, African highlands, SE Asia. • Monsoon forest - tropical and subtropical with a moderate winter dry season; forest is tall, many-layered, with predominance of deciduous species in canopy. Central America, India, SE Asia. • Temperate rainforest - high and constant rainfall in cooler regions; forest is moderately tall, dense, few-layered; leaves are evergreen, small; much moss and lichens. A variant, montane rainforest or cloud forest, is found on tropical mountains. Tasmania, New Zealand, Chile. • Summer-green deciduous forest - occupies regions with pronounced seasonal change of temperature; a cold winter with snow and a mild to warm, wet summer; trees are tall, structure simple, leaves broad, fine, deciduous. E North America, Europe, China.

Growth form of the community -since plants require light um in order to function, the stratification and aquatic community is going to be very important for what plants can survive there. -most of the plants that we're talking about are either rooted at the very edges or they might be floating plants or algae. -LIVE: only in places where they can get some sunlight everyday, below that point theres total darkness (no distribution of a plant community) -animals that are aquatic animals that depend on these plant communities species will be dependent on what species are present in the aquatic community. -dont describe aquatic communities on terms of plants.

• Vertical structure - stratification in aquatic communities: dependent on light, temperature and salinity -In terms of the plants, we describe aquatic communities basically in terms of the animals, but that's the only kind of community (corals are part of that) we will describe according to the animals that are present.

Growth form of the community vertical structure is basically will will affect the amount of light that can penetrate into the community. HIGHLY STRATFIED community means: many layers in. That community -This top layer is called the canopy and then we have the mid stories and then down on the bottom & the understory. And then down the bottom we have basically ground growing plants. -And if you look at the amount of sunlight that is reaching this community, 100 full sunlight is going to hit the top of the canopy. -And then because these crowns are shading out everybody below them, the amount of light that is penetrating these different layers is going to decrease until you get down to the ground in in a in a in a very highly stratified closed. -When you get down to some of the ground, it's basically shady down here at the bottom. So all of these plants are competing for light or they're going to be adapted to lower light conditions.

• Vertical structure (also applies to grassland communities/ tall/mid/low grasses) - stratification in plant / forest communities: competition for Light -but you've got a lot of big crowns in these trees that can block out About, you know, 1000, you have less than 1/1000 of a percent of full sunlight. -So you can describe the community in terms of stratification, where you can say that we've got a lot of canopy trees and nothing growing underneath the forest floor is clear because it's so shady or you can you define it by you've got vines that are growing up to the tops of the trees. OR -you can have a well stratified community with different layers in it. -So that's just another way that you can describe the vertical structure of a community.

Species diversity -And if you look on this, you don't see anything about number of individuals that doesn't count in here. It's all species richness and equitabilty -So it doesn't matter if you have 4000 individuals or five individuals, you're more likely to have more equity bility if you have a higher number, but it's not figured in there. So increased values we interpret as increased diversity in a community -you don't have to have the same species in both communities. You just because you're not you're not looking at the act we do in this model. But um you're not looking at the qualitative composition of the community. You're only looking at numerical stuff quantitative. -So you increased diversity is important, but you also need to look at what species are making up that diversity. You don't want to have a real diverse community of invasive species, or have a lower diversity that has got endangered species in it. So you often have to look at the species themselves. -Again, the index has no value or no units. It has value, has no units. And so you only use it as a comparison. -You can compare the same community over time or you can compare two different communities, like a reference and an impacted community to see if there's differences in the diversity.

• What increases species diversity (H')? 1) increasing the number of species in the community (s) 2) increasing the equitability of the abundances of each species in the community LIKEWISE; -if you decrease the number of species or you decrease the excitability, you're going to decrease the species diversity.

Indicator species in communities (all animals) (used to define communities) -classify a community by the animal indicators. This is not as ecological as the plant indicators, but we use them now because the general public has more of a tie to some of these animal indicator (not naming community by the animal but using as an indicator only) -when you see those animas then we might know what community type is. -umbrella example: as long as bears are there, bears have everything they need, jaguars/mountain lions. If they are there that means they have the habitat/space/food everything necessary to exist there. (Also bald eagles and some of our birds of prey are also an umbrella species.) -flagship: we make toys out of them for example pandas/teddy bears or a mascot for an organization, can be used to protect sensitive habitats/ species, wont tell us anything about ecology but they're important to people

•UMBRELLA species (usually top predators) - large area requirements - used to protect many other species within the community (And if we know that that umbrella species is present, then we'll know that the requirements that species has for shelter for food) -we use umbrella species to basically tell us that we've got all the elements for a healthy community present. (For a diverse community presents some examples of umbrella species would be like bears, they have large home ranges because they need to feed on different things) • Flagship species (no ecological role, they're just species chosen to put on pedestal and protect area around them, don't say much about ecology or health of the community but they're important to people) - popular or charismatic species that serve as conservation symbols because the general public likes them - can be used to protect sensitive habitats