Site Ecology final
Community
a group of species that occupy a given area, interacting either directly or indirectly. It is a spatial concept - the collective of species occupying a place within a defined boundary.
FPOM
fine particulate organic matter ( also a term used in flowing water ecosystems for a type of food source for organisms -FPOM consists of fragmented CPOM and invertebrate feces.
DOM
dissolved organic matter (food source typically found at bottom of stream order 6-10) (ex: putah creek)
Isolation
distance from neighboring patches. Isolation decreases the probability of colonization. Increasing patch size decreases decreases probability of extinction. (Smith p.246) Remote islands have fewer species (Lecture 15 slides). From the Island Biogeography Theory.
6) Describe the various types of species interactions: mutualism, predation, competition, commensalism, parasitism, amensalism.
mutualism- benefits both, predation - benefits one harms one, competition - negative on both, commensalism - benefits one without influencing the other (epiphytes - plants that grow on another plant without harming them), parasitism - benefits one and at the expense of another, and amensalism - harms one without effecting the other (allelopathy - eucalyptus leaves inhibit germination of seeds).
hedgerow
native vegetation along natural corridors such as a water channels. (in class example: natural grasses along river corridor in an agricultural matrix).
Sere
the series of successional stages on a given site that lead to a terminal community. Example: the sequence of communities from grass to shrub to forest.
Decomposers
Organisms that obtain energy from the break-down of dead organic matter (detritus) to simpler substances; most precisely refers to bacteria and fungi.
Scavengers
An animal that feeds on dead animals (Carian) or on animal products, such as dung.
Thermocline
layer in a thermally stratified body of water in which temperature changes rapidly relative to the remainder of the body.
Lotic
pertaining to flowing water
17) What is a patch metrics? Give an example.
values of perimeter, area, and edge amounts for patches. Perimeter to area ratio: P:A where A is patch surface area, and P is patch perimeter. the polygonal area or perimeter circumference
Ecosystem
A biotic community together with its physical environment.
7) What is a keystone species? Give and example.
A keystone species is a species whose activities have a significant role in determining community structure and diversity. It is not the most abundant species (which is dominant), but a species that plays a critical role in community. An example of a keystone species is the African elephant in the savanna. The elephant destroys trees, which opens canopy and allows for grass to grow which provides food for other herbivores in the community. Another keystone species is a sea otter in kelp bed communities. Sea otters eat urchins which feed on kelp. The kelp provides rich habitat for other species.
35) Describe how cottonwood trees reproduce on rivers.
A passive dispersal process, cottonwood trees utilize natural flooding. They release their seeds during periods when the waterway is flooded, the seed is then dispersed on the waters surface; as the water recedes the seed is deposited onto the soil. It is at this point the seed germinates and grows.Cottonwood seeds are only viable for three days so they have to set their roots down fast.
15) How are patches formed? What are their origins? What is a natural remnant?
A patch can be formed by being part of a remnant space (e.g. group of evergreen trees that have never been cut down), regenerated space (e.g. cut down evergreen trees allowed to regrow), introduced space (man-made/ e.g. an orchard planted where there was previously a forest), environmental space (soil type changes within a forest e.g. riparian zones), or disturbance based (e.g. fire or other natural disturbance)Patches, relatively homogenous community types (such as crop fields, forest, pond, or lawns) differ from their surroundings both in structure and in species composition. Patches making up the landscape mosaic result from the interactions of several environmental factors, including regional variations in geology, topography, soils, and climate.They vary in size, shape, and type and are embedded within a complex mosaic of surrounding patches from which they are often separated by distinct boundaries. Various patches in the landscape have their own unique origin, from remnant patches of original vegetation, to introduced patches requiring human maintenance.
Saprophytes
A plant that draws its nourishment from dead plant and animal matter, mostly the former.
Producers
A primary producers is a green plant or chemosynthetic bacterium that converts light or chemical energy into organismal tissue (autotrophs).
Closed system
A system that neither receives inputs from nor contributes outputs to the external environment. (accept inputs from inside boundary, thus does not have inputs beyond its boundaries)
22) Types of dispersal. How might a population become isolated? Describe 3 potential consequences of a popul. completely isolated from interacting with other populations.
Active= mobile (emigration, immigration) and Passive= plants using gravity, wind, water. A species may become isolated if it is distributed to an patch with resources but is no longer able to interact with surrounding patches limiting diversity in geneflow. Consequences: lack of genetic diversity(specialist species), possible population bottleneck (small pop) in isolated node, allopatric speciation
Distinguish between alpha, beta, and gamma species diversity.
Alpha: within a community Beta: between communities Gamma: regional to continental
18) What is an edge habitat and the edge effect?
An edge is described as the outer portion of a patch where the environment differs significantly from the interior of the patch. Edge and interior, look and feel differently. EX: vertical and horizontal structure, width, and species composition and abundance, in the edge of a patch differ from interior conditions, and together comprise the edge effect. Boundaries may also be political, may or may not correspond with natural boundaries. (See Landscape Ecology Principles book pg. 28-32 for diagrams)
9) What is an endangered species? Describe 5 main causes of species endangerment. Name three endangered species in the greater Davis region. What is a species of "special concern"?
An endangered species is a species in danger of extinction in all or a significant portion of its range. Reasons for endangerment: Population bottleneck,Loss of habitat,Outbreeding,Inbreeding,Invasive/exotic species introduction,Selected pressures (disease, predators, loss of resources). Tiger salamander, Giant garter snake, Swainson's hawk.5 causes of endangerment: 1. habitat destruction/degradation 2. exotic species 3. pollution 4. over-harvesting 5. disease. A Species of Special Concern (SSC) is a species, subspecies, or distinct population of an animal that currently satisfies one or more of the following (not necessarily mutually exclusive) criteria:
44) What is an environmental ethic? Describe the economic and non-economic values of biodiversity.
An ethic is a set of morals or principles and environmental ethics deal with why humans should conserve a species or ecosystem. Economic reasons: direct (food, timber medicine), indirect (flood control, land fertility), option value (future food, medicines, existence value, biological diversity, biological, continued ecological and evolutionary processes. Ethical reasons (intrinsic value, species are interdependent, human responsibilities, etc.) Arguments regarding the importance of biodiversity can be grouped into three categories: economic, evolutionary, and ethical. The economic argument is based largely on self interest. It focuses on products derived from natural resources. The evolutionary argument suggests that extinction of modern species limits to potential evolution of species diversity in the future. Ethical arguments focus on the extent to which human activities cause the extinction of species
10) What is an exotic species? Are all exotic species a problem for management? Describe the process of species invasion and the management actions that can be practiced to control it.
An exotic species is an alien, non native species introduced to a place or region. Not all extoic species are hard to manage, their manageability is determined by their invasive nature as well as if there are native predators to keep their population in check. Process of invasion: source -> transport -> establishment -> spread -> impact: high:pest species, Low: integrated into landscape. management- plants: mechanical removal and grazing, herbicides, prescribed fire, flood, clean off tires. Animals-trapping, relocation, hunting, poisons, birth control.
Consumers
Any organism that lives on other organisms dead or alive (heterotrophs)
32) Describe the impacts of dams, levees, and diversions on river ecosystems. How do these impacts affect the flood-pulse and productivity of the river?
The flood pulse concept argues that the annual flood pulse is the most important aspect and the most biologically productive feature of a river's ecosystem. It is a geomorphological concept that describes hydrological conditions in lotic systems. The flood pulse concept describes "the dynamic interaction between water and land" within the aquatic/terrestrial transition zone (ATTZ). Dams, levees and diversions on a river ecosystem work to reduce peak flow and reduce the impact of flooding. This was once considered good, but these practices have a negative impact on the productivity of the river. An example is that the fish that travel through the Yolo bypass during flood conditions are much larger than those that travel through the leveed section of the Sacramento River because in the bypass fish are able to enter a terrestrial zone that provides a rich food supply of terrestrial insects and plants.
21) What is floristic resolution? How are plant communities defined in the California Native Plant Society System(Sawyer and Keeler-Wolf 2009)? Hint species dominance is key..Does the CWHR vegetation classification system use the same communities? Which system is more detailed?How does NDDB differ?
The floristic system is the principal botanical classification scheme in use today. Under this scheme the plant kingdom is made up of divisions, each of which is subdivided into smaller and smaller groups arranged according to the relationships of plants. The classes, listed from broadest to most detailed are: class, subclass, formation, alliance, association. Floristic resolutions refers to the level of detail to which we classify community structure. The more specific the finer the resolution. They classify communities by the dominant species in community and the habitat type. They are classified based at the level of alliance and associations. They use the finest floristic resolution. No, they classify at the subclass level, which is a much more coarse(broad/general) resolution.The California Native Plant Society System is more detailed. The CNDDB classifies at the alliance level.
19)What is the interior to edge ratio?Why do some patches and corridors consist of only edge habitat?
The interior to edge ratio is the relationship of habitat patch size to edge and interior conditions. All habitat patches are surrounded by edges. Assuming that the depth of the patch remains consistent, the ratio of interior to edge increases as the habitat size increase(more interior). When large patches are fragmented, their interior to edge ratio decreases(more edge). The size and shape of patches affects the relative abundance of edge (or perimeter) and interior environments. Only when a patch becomes large enough to be deeper than its border can it develop interior conditions.
29) How are wetlands defined? What specific criteria are used? Describe 4 wetland functions. Name 2 wetland species we observed.
Wetlands are transitional areas between land and aquatic ecosystems and the water table is usually at or near the surface. They are defined based on their physiographic, hydrologic and vegetative conditions. Legal definitions vary, but most agencies consider a site a wetland if one of the following conditions are met: presence of hydrophytic vegetation, the presence of hydric soils (low oxygen, gleization), or that the area is saturated with water each year. The army corp of engineers only define an area a wetland if hydrophytic plants are present. 1. storage, 2. filtration, 3. habitat, 4. shoreline stability/storm protection. 1. Great blue heron, 2.tule
tail water pond
Where irrigation runoff water is directed to a pond found at the low end of an agricultural field.Acts like a retention basin. Sediments are settled at the pond, then the water is returned to the irrigation system. Reason: cost efficient for farmers and improves water quality.
41) Describe the various plant communities found along the Sacramento River. Which species dominate in the primary successional areas?
Willows, grasses, and forbs are the species that grow in the Primary Succession area of the gravel bar thicket
Corridor
a discrete linear landscape element that differs from the matrix
Patch
a discrete non-linear landscape element that differs from the matrix. An area of habitat that differs from its surroundings and has sufficient resources to allow a population to persist. Patches are relatively homogenous community types that differ from their surroundings both in structure and in species composition. They vary in size, shape, and type and are imbedded within a complex mosaic of surrounding patches from which they are often separated by distinct boundaries. Human development is a major force in shape and size of patches -> fragmentation and Jeffersonian grid. Natural factors that influence size and shape of patches is variation in geology, soil conditions, natural events such as fires and grazing.
8)When was the Endangered Species Act passed in Congress? Approximately how many species are on the list? What is the ultimate goal of the act?
1973. In 2011, 1241 animals and 796 plants. The goal is to increase the population size to sustainable levels.
Zonation
1. As you move across a landscape, the physical and biological structure of the community changes. These changes (spatial variation in community structure) are referred to as zonation. 2. Characteristic distribution of vegetation along an environmental gradient; this gradient may form latitudinal, altitudinal, or horizontal belts within an ecosystem. These changes result from various environmental changes across a spatial gradient. Patterns of zonation are common to all environments (aquatic, and terrestrial).
How do channel cut-offs occur (oxbow lakes) and what is the result? Why are they important habitat areas on the rivers?
Channel cutoffs often occur in when water levels are high and moving fast. Instead of following the river through a curve, it cuts the curve off and create a more direct path in the river channel. The crescent shape oxbow lake is a remnant of the previous river channel. Disturbance and succession play vital roles in habitat and species diversity. These changes in the river channel allow for a variety of habitats in different stages of succession to develop and grow providing a rich diversity of habitat and species.
What physical processes drive the regeneration of riparian forests? Why is riprap(bank revetment) a problem for the ecosystem?
Channel meandering is a physical process that drives regeneration of riparian forests. It consists of Channel migration and bend cutoff's. Channel migration is the shifting of the river over time, when the water level of the river surpasses the height of the bank. A bend cutoff forms at the point at which the river is generally most sinuous ('curvy'). When the river overflows it connects or cuts to another section of the river, The section of the river that was bypassed then shifts towards the cutoff, while the cutoff shifts towards the bypasses section, forming an oxbow lake. This process creates new habitat, and acts as a regeneration source for riparian forests. RIPRAP = aggregate dumping (aka, boulders, concrete, cars, etc.) used to stabilize streambanks. Negatively impacts stream evolution processes (see model in slides), riparian succession, sedimentation processes, habitat, and biological community interactions. also decreases stream power.
34) Why are channel dynamics important to regeneration of riparian vegetation communities? How can this affect habitat quality for riparian dependent species?
Disturbance is an important process in the regeneration of riparian vegetative communities. It is important that rivers are allowed to remain dynamic in order for natural disturbance processes to occur. This dynamic system allows for there to be a variety of habitats in various stages of succession providing huge diversity. Having a variety of riparian habitat in different stages of succession can offer variety of habitat for the greatest number of species. It ensures the health and vigor of the overall riparian system.
40) What is a riffle-pool sequence? Sketch and describe a point bar and a cut bank and the typical vegetation that grows on each landform.
During low flow in many streams, the channel becomes partitioned into a distinctive sequence of segments called pools and riffles. The pools are quiet segments where water is deeper and slower and where the streambed is lined with fine sediment.They occur at the cut bank side of a point bar. The riffles are rough segments where the water is faster and shallower and the streambed is lined with gravel and cobbles. They are usually found at the inflection point (straight section of river). The spacing between pools and riffles is surprisingly regular. A point bar is a depositional feature made of sand and gravel that accumulates and forms on the inside bend of streams and river. They are crescent in shape. The typical vegetation that grows on a point bar at the lowest elevations are typically primary successional species such as grasses forbs and salix species common to the hydro-riparian zone, as you move up the point bar in elevation you come to the meso-riparian zone where cottonwoods and other riparian trees grow, finally the terrace or upland has mature old growth oak trees. These mature old growth oaks are also what grows on the cut bank side of the river.
26) Contrast early and late seral vegetation communities. Which is associated with the 'climax' community concept? What is a shifting mosaic?
Early successional species are the initial species that are usually characterized by high growth rates, smaller size, high degree of dispersal and high rates of per capita population growth. Late successional species have lower rates of dispersal and colonization, slower per capita growth rates, and they are larger and longer lived. The late successional species are associated with the climax community concept which is that succession is a gradual and progressive development of a community to the ultimate climax stage. A shifting mosaic is a constantly changing pattern of patches as each patch passes through successive stages of development.
43) Distinguish between the terms ecosystem restoration, creation, enhancement and rehabilitation.
Ecosystem restoration is the process of assisting in the recovery of an ecosystem that has been degraded, damaged or destroyed. It can be done through active restoration where human labor and design accelerate the ecosystem structure and function, or through passive restoration, that is a hands off approach, where natural processes restore ecosystem, or through process-based restoration, which relies on ecosystem processes for regeneration of ecosystem structure and function and often includes the manipulation of ecosystem processes such as fire and flood. Enhancement is the improvement or addition of habitat elements that would improve desired function. An example of this is the bird boxes used for song birds and wood ducks because there are not enough old growth trees for nesting habitat. Restoration means to restore to pre-disturbance conditions. Creation is completely changing what currently exists on a site to a new habitat type that has not existed at that site before for a desired structure and/or function.
5) What factors affect genetic variability in a population?
Factors that affect genetic variability are sexual/asexual reproduction, mutation, gene pool, gene flow, population bottleneck and Founder's Effect, genetic drift, inbreeding depression, outbreeding depression, and selection pressure. Describe the extinction vortices (see lecture notes and course website). Multiple processes lead to species extinction or extirpation. The intrinsic contributors are lowered effective population size (# of breeding adults), increased demographic variation, isolated subdivided populations (no gene flow), inbreeding depression, and more genetic depression (less ability to adapt).
42) What is conservation 'gap analysis'? How is it used to guide planning of conservation areas? What are some questions that gap analysis can answer?
Gap analysis is a tool used in wildlife conservation to identify gaps in conservation lands (e.g., protected areas and nature reserves) or other wildlands where significant plant and animal species and their habitat or important ecological features occurs. Conservation managers or scientists can use it as a basis for providing recommendations to improve the representativeness of nature reserves or the effectiveness of protected areas so that these areas provide the best value for conserving biological diversity. It is a method used to prioritize conservation efforts and $$$. With the information that a gap analysis yields, the boundaries of protected areas may be designed to subsume 'gaps' containing significant populations of wildlife species that can enhance the long-term survival of a larger metapopulation of the species already within the managed or protected area, or to include a diversity of wildlife species or ecosystems that merit protection but are inadequately represented in an existing protected area network. Gap assessments can be done using the geographic information system: land maps that delineate topography, biological and geological features (forest cover, plains, rivers, etc.), boundaries, land ownership and use are overlaid with the distribution of wildlife species.
27) Give an example of food chain of a first-level autotroph, first level consumer, second-level consumer, and third-level consumer.
Grass(1st level autotroph) -> Rabbit(first level consumer) ->Coyote (second level consumer) -> Mountain Lion (3rd level consumer), or algae -> fish -> raccoon -> bobcat.
36) How can habitat fragmentation be reduced? Describe the potential role of ecological restoration. How can succession be altered using restoration techniques?
Habitat fragmentation can be reduced through proper planning and development. Clustering development in low impact areas, and leaving highly diverse areas intact. Ecological restoration efforts are being made to reconnect clusters of patches(nucleation sites) to create one larger patch. ex: ecocities. Habitat fragmentation can be reduced through defragmentation of nucleation sites through active, passive, and process-based restoration efforts. Specifically, active restoration and prescribed fires can be used to alter succession.
3) In the CWHR system, how is the average habitat suitability value calculated for a species? That is, how are the habitat ratings for feeding, reproduction and cover averaged together to produce one number? Describe both methods used for this purpose in the CWHR system. Which method is most conservative (produces the lower scores in many instances)?
Habitat suitability is rated on a score from 0 to 1 for each variable (Reproduction, Cover, Feeding) and then a mean suitability number is calculated. Suitability ratings are 0=none, 0.33 low, 0.66 medium, 1.0 high. There are two types of methods for calculating the mean, the arithmetic mean, which is basically taking the average of the three scores, and the geometric mean, which is taking the cubed root of the product of the three values. Of the two, the geometric mean is the most conservative because if any habitat type receives a zero, the whole measurement equals zero.
Some actions humans can take to avoid or reduce this kind of phenomenon (Tragedy of the commons):
Harvest food in a sustainable manner. The article uses overfishing in the ocean (commons) as a problem area, and this may be curbed by rethinking the way we fish. Stop trolling ocean floors, allowing sufficient time for fish to mature before catching, raising our own fish in a sustainable manner like what has been proposed with salmon being raised in the rice fields within the Yolo Bypass, etc.
37) What is the conversion formula to calculate the number of acres from square meters? Define a hectare and an acre.
Hectare to acre (ha to ac): ha ÷ 0.405 = ac (ex. If ha = 165 then ac = 407.723879421ac) Acre to hectare (ac to ha): ha = ac ×0.405 Hectare - a metric unit of square measure equal to 2,471 ac or 10,000 m² Acre - unit of land area equal to 4,840 yards² (.405 hectare)
30) What are the inflows and outflows of a wetland? What is a perched water table?
Inflows:1. precipitation, 2. tidal inflow,3. surface runoff, 4. groundwater inflow. Outflows: include evapotranspiration, groundwater infiltration, tidal outflow and stream discharge. A perched water table forms above an impermeable rock or clay layer that separates it from the main groundwater table below it.
14) Describe the path-corridor-matrix model
Landscape matrix- The dominant surrounding. Land cover within a natural-cultural landscape gradient Patch: a discrete (distinct) non-linear landscape element that differs from the matrix Corridor:a discrete (distinct) linear landscape element that differs from the matrix All landscapes consist of different combinations of these three elements. Area and connectivity can determine the landscape matrix.
31) Define and distinguish between each of the five systems of the National Wetlands Inventory (marine, estuarine, riverine, lacustrine, and palustrine).
Marine systems consist of the deepwater habitat of the open ocean and the adjacent marine wetlands of the intertidal areas along the mainland coast and islands. The estuarine system is associated with coastal embayments and drowned river mouths and includes salt marshes, brackish tidal marshes, mangrove swamps, as well as deep-water bays. The riverine system is limited to freshwater stream channels according to the Marsh text, but Grecco said they can have some tidal influence. The lacustrine system is limited to standing water bodies, mainly lakes, ponds, and reservoirs. Both the riverine and lacustrine systems include deepwater habitat. The palustrine system only includes wetland habitat. It is the major system because it encompasses the vast majority of No. America's wetlands, namely marshes, swamps and bogs. Grecco's definition of lacustrine was freshwater over 6' deep and palustrine as fresh water less than 6' deep.
39) What is the meanderbelt associated with the Sacramento River? What is sinuosity? Sketch a highly sinuous channel
Meandering streams have single thread channels. The meander belt is the zone in which the river channel moves laterally. It's width is measured from the outer edge of the bends on one side of the river to the outside bends on the opposite side of the river. Meandering streams have lateral erosion through the meander belt that produces cut bank and point bar formations. In regards to rivers, sinuosity refers to the number and size of curves in a river. The greater the number and size, the greater sinuosity.
16) Functionally patches and corridors are species specific concepts. Explain the reason for this. What then constitutes a large patch?
Patches and corridors are species specific concepts because they are subject to scale. Patches can be as large as a forest, or as small as a single tree. This means that patches and corridors are realized based off the species size, as well as the size of their home range, and the quality of the patch (amount of resources available for species). A large patch is constituted by its ability to sustain viable populations of most interior species, provide core habitat and escape cover for most large home-range-vertebrates, permit near natural disturbance regimes. Each species have specific, unique requirements of habitat to meet their needs of cover, reproduction, food and movement. Patches and corridors are species specific concepts because of these specific needs. The patch or corridor needs to be the right size, have the right physical conditions and sufficient quantities of the right resources. Ex: A corridor for an otter is very different than a corridor for an elk.
38) Name 5 species of native riparian trees or shrubs (use scientific names). Where in the floodplain is each found? What is a toposequence?
Quercus lobata- Valley Oak forest Acer negundo var. californicum- Gravel bar (thicket) Populus fermontii- Riparian forest Baccharis pilularis- Garvel Bar (thicket) Sambucus mexicana- Riparian forest Topo Sequence- a sequence of related soils and/or plant communities that differ due to the influence of relative topographic positions.
How does species richness differ from species diversity? If 2 communities have the same species richness, but different species diversity values (ex. Simpsons Index), what does this imply about the community with lower species diversity?
Species richness (S) is the total number of species within a sampled community. Species diversity is a measurement used to determine how diverse a sampled community using a formula that takes into account the proportion of a specific species to the total amount of species. (See lecture 13 slides for formulas)
33) Summarize the river continuum theory. In which part of the river would a dominance of collectors be found? Why?
The River Continuum Concept is based on the idea that a watercourse is an open ecosystem that is in constant interaction with the bank, and moving from source to mouth, constantly changing. Although collectors can be found throughout the river channel, the majority of collectors are found at the mouth of the river. This is the low area of the river, the bottom where all the organic matter and particulates settle.
Matrix
The background land-use type in a mosaic, characterized by extensive cover and high connectivity. The dominant surrounding land cover with in natural/cultural landscape gradient
24) What is the Yolo Bypass? What is the main purpose of the bypass channel? What are two other land management objectives?
The bypass is a flood control basin for the Sacramento River. The main purpose is flood control. The other two land management objectives are farming and wild-life conservation.
23) Describe the species-area relationship and how immigration (colonization) and emigration (or extinction) are related in the theory of island biogeography.Describe the expected difference in numbers of species to be found on large vs. small island sizes proximal to mainland source population and the effect of distance (near vs. far).
The species-area relationship graph shows that number of species increases as area increases. On islands, a tenfold increase in land area leads to a doubling of the number of species..The Theory of Island Biogeography views the equilibrium number of species occupying a given patch as the balance between the process of colonization and extinction - the point where immigration = extinction. As immigration increases, extinction rates increase (competition) The greater the distance between the mainland and the island is the less likelihood that many immigrants will successfully complete the journey. The result is a decrease in the equilibrium number of species. Larger Island size can support more individuals of each species, and also contains a larger variety of habitat and resources, which supports a greater variety of species. This leads to lower extinction rates results in a higher equilibrium.Small far islands will have least # of species, large near islands should have largest.
45) Explain the concepts behind tragedy of the commons. What actions can humans take to avoid or reduce this kind of phenomenon?
The tragedy of the commons is the idea that within a system one attempts to obtain resources in a rapacious manner, continuously (unsustainably), without foresight, in a setting (the commons) of limited resources. One example given in the reading is a field shared between cattle owners, each owner attempts to maximize their profit by adding more and more cattle to their portion of the field (commons), not thinking about consequences (only about their own self-interest for profit), the end result is the field will become overgrazed and the profit for all the cattle owners will be eventually be zero (ruin). The focal point of the article is overpopulation and curbing population growth by educating the masses so they will eventually relinquish their freedom to breed.
25) Describe 3 types of abiotic disturbances and 2 biotic disturbances. Which of these are influenced by human activities? Define a disturbance regime and describe how it can be altered or constrained by human land uses.
Three types of abiotic disturbances are fire, wind, and flood, two biotic disturbances are disease and predation. Humans activity can influence fire and flood events, as well as disease and predation A disturbance regime defines a particular landscapes disturbance patterns. The main characteristics of a disturbance regime for a given landscape are 1. agent type (what kind of disturbance) 2. Frequency (recurrence or return interval) 3. Magnitude - how intense (severity) 4. Duration - how long (brief or prolonged) 5.Spatial extent. Disturbance regimes can be altered by human interference and land uses. A few ways that humans interfere are through fire suppression and flood suppression. A type of land use that interferes with fire disturbance is lawns.
20) How is tree height calculated? Draw a diagram.
Tree height is measured using a clinometer to estimate the top and bottom of the tree using a percent scale. Then use formula:Total height (meters)=(top measurement - bottom measurement) x (distance from tree)
28) Of the decomposers, give two examples of macro-organisms and describe the role of the micro-organisms (bacteria and fungi).
Two examples of macro-organisms are earthworms and nematodes. The role of bacteria is to decompose animal tissue. The role of fungi is to decompose plant tissues.
Sink habitat
a habitat area that receives immigrants from a source habitat, but in which the subpopulation would continually decrease in size because of mortality and poor reproductive success without continual immigration from excess individuals in a source habitat.
Littoral
a littoral zone is shallow water of a lake in which light penetrates to the bottom, permitting submerged, floating and emergent vegetative growth; also shore line of tidal water between high-water and low-water marks.
Dominants
a population possessing ecological dominance ina given community and thereby governing type and abundance of other species in the community, the converse of diversity. Often refers to greatest in number, but can also be based on size - the one that accounts for the most biomass.
Omnivores
an animal (heterotroph) that feeds on both plant and animal matter.
Disturbance
any relatively discrete event such as a fire, windstorm, flood, extremely cold temperatures, drought or epidemic that disrupts community structure and function. The disturbance regime has spatial and temporal characteristics including intensity, frequency, and spatial extent or scale.
Heterotrophic
are organisms that are unable to manufacture their own food from inorganic material and thus rely on other organisms, living and dead, as a source of energy and nutrients.
Autotrophic
are organisms that produce organic material from inorganic chemicals and some source of energy. An autotrophic community is a community whose energy source is photosynthesis, thus based on primary producers.
Source habitat
area of habitat in which a subpopulation of a species produces more individuals than needed for self-maintenance, thus contributing to emigration.
benthic zone
bottom of lake, deep water. Low penetration of light, colder waters.
River continuum
changes in environmental conditions from the headwaters of a river to its mouth (delta).
CPOM
coarse particulate organic matter (a term used in flowing water ecosystems for a type of food source organisms in this ecosystem - the CPOM which is mostly leaves that fall into a stream)
Hypolimnion
cold, oxygen poor zone of a lake, below the thermocline
Seral
communities experiences stages of succession. Each change in stage is called a seral stage Seral stage is a point of continuum of vegetation through time. *
Shifting mosaic
constantly changing pattern of patches as each patch passes through successive stages of development
4) What are the 5 demographic factors that influence the size of a population in the future? What is a life table utilized for? Define lx, dx, and qx.
current population size, births, deaths, immigrants, emigrants.(Nt-1=B-D+I-E) What is a life table utilized for? utilized for insurance purposes (demographic metrics (x: age, nx: # of individuals in age class, lx, dx, qx)) A life table is used to obtain a clear and systematic picture of mortality and survival within a population. A life table is simply an age specific account of mortality. Define lx, the number of individuals surviving to any given age as a proportion of the original cohort size. It represents the probability at birth of surviving to any given age - the overall survivorship rate. Define dx.the overall mortality rate. Define qx : The number of individuals that died during any given time period divided by the number alive at the beginning of that interval. It represents the age-specific mortality rate.
Species diversity
measurement that relates density of organisms of each type present in a habitat to the number of species in a habitat.
11) Clements' and Gleason's theories
organismic concept - Clements (1916) likened associations to organisms, with each species representing an interacting, integrated component of the whole. Development of the community through time (succession) was viewed as development of the organism. DISCRETE COMMUNITIES WITH NARROW OR ABRUPT ECOTONES. Few species in common between associations. This view implies mutualism and co-evolution are fundamental processes shaping the community. individualistic or continuum concept - States that the relationship among coexisting species (species within a community) is due to similarities in their requirements and tolerances, not to strong interactions or common evolutionary history. Gleason concluded that changes in species abundance along environmental gradients occur so gradually that is not practical to divide the vegetation (species) into associations. Unlike Clements, Gleason asserted that species distributions along environmental gradients do not form clusters but, represent the independent responses of species. Transitions are gradual and difficult to identify. Opposite of Clements approach. Emphasizes the individualistic nature of plant species tolerances and distributions. Plant species are grouped together by co-occurrence and similar life history characteristics (NOT CO-EVOLVED HISTORY). No clusters, but independent responses. WIDE ECOTONES. Changes are gradual.
Perennial vs intermittent wetland or stream
perennial refers to long lasting/enduring, so i'm assuming this just refers to temporary/seasonal (intermittent wetland/stream) and longer lasting/permanent wetlands/streams (perennial) (Nate).
Limnetic
pertaining to or living in the open water of a pond or lake. The limnetic zone is a shallow-water zone of a lake or sea, in which light penetrates to the bottom.
Lentic
pertaining to standing water, such as lakes and ponds; a population is limited by the lowest amount needed of an essential nutrient.
Channel aggradation
raising of stream bed elevation,an increase of the width to depth ratio, and a decrease in channel capacity, caused by sediment deposits in stream bed bottom.
Fragmentation
reduction of a large habitat area into small, scattered remnants; reduction of leaves and other organic matter into smaller particles.
Succession
replacement of one community by another, often progresses to a stable terminal community called the climax.
Edge species
species that are restricted exclusively to habitats on the edge or border environment.
Interior Species
species that require environmental conditions of interior habitat and avoid abrupt changes associated with border environments.
Guild
subdivision of trophic level - groups of species that exploit a common resource in a similar fashion. Species within a guild draw upon a shared resource -> leads to strong interactions.
Open system
system with exchanges of material and energy to the surrounding environment. (accept inputs from outside boundary)
Channel degradation
the lowering of stream bed elevation associated with erosion. The lowering of the streambed abandons floodplains, lowers the water table, and increases bank height, which adds to bank erosion and often leads to long-term instability. Causes of degradation are complex and can be related to many sources. Clear water discharge below reservoirs, urban storm drains, excess shear stress due to changes in flow regime, straightening of the channel alignment that alters slope, headward advancement (headcut) of base level shifts due to downstream alteration and excess shear through contraction and bed scour from bridges and culverts can all contribute to channel degradation.
Epilimnion
the warm, oxygen rich upper layer of water in a lake or other body of water, usually seasonal.
Ecotone
transition zone between two structurally different communities; wider borders that form a transition zone between patches