climate change biology test #3
How can CO2 affect the distributions of plant functional types directly and indirectly?
change in CO2 can have a significant direct effect on vegetation distribution throughout the world, but largely neutralized by indirect effects of climate change. changes in CO2 alone only show changes in major patterns of vegetation across the globe, climate change only shows larger changes
Generally, what kinds of changes do freshwater systems show in response to climate change?
changes that are important on both these short- and long-term scales include alterations in streamflow and temperature, watershed fragmentation and capture, lake drying and filling, and change sin lake thermal zonation and mixing
Considering this information, what approach is recommended to avoid these problems when developing SDMs and making predictions about extinction risk for endemic species?
changing the type of SAR applied: because it is not wise to expand the SDM to nonendemics a different kind of SAR is needed, on that applies particularly to endemics like the EAR. endemics-area relationship is similar in principle to SAR but it is derived especially for endemics, its also a curve with an exponent that determines the rate of species accumulation, however species accumulate more slowly using EAR because it counts only endemics
What is the typical output of a gap model?
chart of species composition at that particular point in a forest gap rather than a map , has become possible to join multiple gap models together to simulate growth and competition over small regions
Is there evidence that gap models do a good job of modeling changes in forest composition in relation to climate?
have been tested for their ability to simulate known forest compositions and spatial variation of forest composition and have reliably reproduced the general altitudinal zonation features on several mountain ranges on different continents and because altitudinal zonation is a result of a climate gradient this increases confidence in their ability to simulate changes in forest composition as climate changes
What is the relationship between extinction and warming in deep time (past 500 million years)?
high CO2 warm periods have had a significant correlation with higher rates of extinction
Where would we want to apply intensive management or translocation?
high priority where resilience is low
What evidence is there that even just moderate amounts of climate change could translate into major extinction risk?
hot spots study showed that even moderate amounts of climate change could translate into major extinctions risk and that the largest extinction risk in the long term may lie in the tropics
So, why does the author say the tropics may be vulnerable to climate change?
narrow niche breadth in many tropic species, may also experience severe biological changes due to climate change, product of the magnitude of change and sensitivity, sensitivity high in tropical organisms even though magnitude greatest near the poles
As noted above, climate change is believed to have been involved directly or indirectly in all five major mass extinctions. Does climate change always lead to extinction?
no always, small animals and water-dwelling species can survive while large animals and terrestrial species go extinct, not all climate change produces extinction, major shifts in climate have often, but not always, come with large numbers of extinctions
Was this info sufficient to estimate how many species would go extinct or how many species would be vulnerable to extinction? Explain.
no, need a method for assessing extinction risks in multiple species over the long term- like the SAR
We know that coral growth rates are strongly and positively correlated with water temperature up to a certain point, past which we get coral bleaching. What other factors influence coral growth?
CO2 and pH levels, salinity and turbidity, calcium carbonate saturation state
If we wanted to study the interaction effects of human CO2 pollution of the atmosphere on the distributions of plant functional types, which kind of model would we use?
DGVM
Do SDM results support a Clementsian or Gleasonian view of communities? Explain.
Gleasonian- communities are ephemeral collections of species brought together by similar climatic affinities, don't respond as a unit to climate change by as individual species within plant and animal communities and move at different paces and in different directions in response to alterations in temperature and rainfall resulting in disassembly and reassembly of species combinations as climate changes
For which of the five mass extinctions do we have evidence that direct climate change was a factor? How did climate cause the extinctions?
Ordovician-Silurian extinction 440 mya, climate suddenly shifted from greenhouse to icehouse conditions, condwanaland passed over the pole initiating a period of galciation that altered ocean temperatures and wiped out many life-forms, lowering of sea level eliminated many shallow seas and changed near-shore habitats causing many other extinctions, the rebound of sea levels as glaciation retreated may have led to further loss of species
How does one use a SDM to simulate the future range of a species (after climate change, for example)?
SDM substitutes climate data from a future, elevated CO2 run from a GCM into the statistical model developed for the current climate and then the model predicts species presence or absence based on the suitability of the future climate in a cell, climate data for both present and future are obtained for a series of grid cells across an area and each grid will have a series of climatic variables associated with it provided by interpolation of data from either weather stations (current) or a GCM (future), model then returns a result of probability of species presence or absence for each cell in the study area
What are the advantages and disadvantages of SDMs, DGVMs, and gap models?
SDMs deliver species-dominated results appropriate for biodiversity at relatively fine scales because the statistical models involved are not mathematically complex but it may require modeling of hundreds or thousands of species to arrive at conclusions about changes in vegetation or ecosystems and competition between species for novel climatic space is not explicitly addressed, gap models simulate competition between species and provide species-dominated results but they address individual points rather than producing a map relevant to study a region unless many are joined together and the data required may be available for only a limited number of tree species. DGVMs address competition and produce geographically explicit results for the globe or individual regions but they do not give information about individual species
What evidence indicates that some species may lose much or all of their range due to temperature changes on the order of only 0.5 C?
SDMs of 92 endemic Australian plant species, numerous montane species in Queensland
Can freshwater species adapt metabolically to climate change? Explain.
almost all are cold-blooded and are left with little metabolic adaptability to climate change because metabolic activity matches the temperature they are surrounded by
Why is dispersal an issue for extinction that is caused by climate change?
a species that cannot move such as a plant species will inevitably find its suitable climate shrinking: its suitable climate in the future will simply be the overlap of its suitable present climate with suitable future climate, and on the other hand a species that is well dispersed will be able to move with changing climatic conditions fully occupying its suitable future climate
How do temperature changes in glacial cycles affect highland freshwater systems?
act in an analogous manner in highland freshwater systems, with interglacial warm periods resulting in habitat fragmentation- in glacial periods global temperatures are cooler and result in expanded and connected highland cold water habitats which then in interglacial periods shrink upslope and become isolated in mountaintop fragments, during periods of fragmentation speciation can occur
When we talk about adaptation in the context of climate change, what do we mean? What is biodiversity?
adaptation is a response to climate change that reduces impacts, intentional actions to reduce impacts will allow social development to continue in the face of climate change, and for natural systems adaptation of conservation strategies and management will play a critical role in reducing impacts- adaptation actions that may help conserve biodiversity and ecosystems as climate changes. biodiversity is the variability of living organisms and ecological complexes they are apart of or all different forms of life at different levels or organization
How might we increase species representation for those species that have lost representation due to climate change?
adding additional protected area can reverse the decline in species representation- need to place these new protected areas in locations where suitable climate for the species is maintained
Do you agree or disagree with the claim by the press release for the 2004 Nature paper that there are 1 million species at risk of extinction due to climate change? Explain.
agree: although million species at risk comes from press release and not the actual study in which the author too the average percentage extinction risk from the six regions studied and applied it to the earth as a whole by multiplying it by the estimate of 5 million species worldwide and the range of estimates for number of species is between less than 4 million and more than 100 million and the estimate of the proportion of species at dis is based on assumption that six regions studied are representative of the entire world, the species number estimate is in agreement with mainstream estimates of number of species on the planet and the six regions studied were distributed on 5 continents and in more than 12 biomes so enough to be reasonably considered representative. and although it may have overrepresented hot spots, hot spots represent more than 2/3 of world's species as endemics so inclusion of hot spots should increase the confidence in the result. reasonable first estimate
We cannot test the DGVMs against known future conditions; so, how can we gain confidence in how well the models predict?
all will either overpredict or underpredict certain types of vegetation in some regions, ability to reproduce current vegetation is very important, semi-independent tests like use of evapotranspiration values from the models to predict river flows and comparing the DGVM-derived estimates to actual flow volumes
Would you use the distribution of corals as an indicator of past climate? Why?
although growth rates in corals correlate strongly to temperature and are widely used to infer past climates, the distribution of corals is not a reliable indicator of past climate
What are the important criticisms of the SDM/SAR approach?
analogy of loss of land area to loss of climate space has one important difference: land areas are shared by many species but suitable climatic space is unique to each species and thus to use SAR for estimates of climate change based extinction risk some way has to be found to combine the suitable climate area estimates for each species so that they can be fit to the SAR relationship. important criticism is that SDM/SAR methods can't be tested- whereas the SAR is derived from many careful measurements in the real world reassembling SDM range losses into a SAR extinction risk estimate cannot be confirmed by real-world measurements, at least not until the range shifts and extinctions have taken place, at which point it will be too late. not entirely clear that SARs built up over evolutionary time by the interaction of natural forces and geography will decompose on the same line owing to climate change, and as a result some scientists accept the SDM/SAR approach as the best available whereas others reject it as a theoretically flawed and untestable extension of SARs
What do we mean by area of occupancy (AO)? Give an example that is not in the book.
area within the EO that a species actually occupies, always smaller than EO
What would a look at past climate effects suggest about extinctions due to human-induced climate change?
associations between extinctions spasms and past climate change would increase the prospects for heavy extinctions associated with human-induced climate change
Same as the previous question, but what kinds of issues would you want to consider in monitoring?
at risk species, structured and taxon-stratified sample of all species, enhanced collection of climate/weather data, biotic survey, iterative feedback to management planning and action
On what basis might you predict that human disturbance will tip tropical reefs into a state that is very different from what now occurs?
based on past dominance of noncoral reefs under different climatic conditions it seems possible
Suppose we ignore the anticipated effects of climate change when setting up a reserve network. What will be the likely consequences?
be based on incomplete information about species' ranges and irreplaceability causing it to be less effective and more expensive in the long term
Why is climate change different from other threats to protected areas?
because can't be reduced by protection, it's an indirect threat that has the potential to alter management of all of these other factors
Why are SDMs also known as "niche models"?
because the simulate a species climatic niche in the current climate or the change in the niche as the climate changes
How are these models able to account for the effect of CO2 on plant growth?
because they run from photosynthetic equations
What is meant by resilience to climate change?
better able to recover once damaged
What has been the effect of the major extinction events on biodiversity since deep time (> 100 million years ago)?
biodiversity increases over time, after each extinction event the number of species slowly recovers and overtime and interrupted by minor and major extinction events, biodiversity returns to previous levels and slowly increases. long-term trend is a marked increase in the number of species on earth and extinction events slow the process of species accumulation but only temporarily
If you wanted to minimize the extinction of climate-sensitive birds, what geographic locations would you be most concerned about in the world? Why?
bird species found in hot spots occupying narrow elevation bands on the slopes of mountains because are likely to have small temperature tolerances because the top and bottom of their ranges are divided by relatively small temperature gradients up the mountain slope- TROPICAL ANDES HOT SPOT
What kinds of models are used to make predictions in aquatic systems? What kinds of information do these models use?
both biological and physical models- physical models of ocean chemistry and temperature suggest changes in range limits and biological models examine ecophysiological tolerances and food web interactions with less emphasis on geographic range shifts than in terrestrial models, modeling physical depth is particularly relevant
If EO expands but AO shrinks, what kind of a problem can develop?
can lead to underestimation of the threat to a species unless AO is properly recognized
How can local or regional events like asteroid impacts or volcanic eruptions end up causing major mass extinctions around the world?
climate change is the factor that turns regional events into global killers- effects these events have on global climate that transmits their impacts more broadly. spew massive amounts of particulate matter into the atmosphere that then intercept incoming sunlight and block solar warming of the earth, multiple volcanic eruptions or asteroid impacts can result in a major global cooling which can be fatal to animals, especially large organisms or species that can't thermoregulate and to plants sensitive to freezing, if the cooling is extreme both plants and animals may have difficulty moving to suitable climate quickly enough and drops in sea level as water is locked up in ice can devastate continental shelf habitats and eliminate entire shallow seas, with major repercussions for marine life. animal populations throughout the world would probably be decimated by rapid warming and infrared radition caused by material ejected by large asteroid impacts reentering the earths atmosphere
Based on previous research, if we ran this kind of model, what would we be likely to find out about the interaction effects?
climate change only shows larger changes in vegetation distribution, when run together in some areas CO2 and climate change work together and in other areas their effects oppose each other
Why is the answer to the previous question important to understand?
climate change will greatly impact freshwater systems and their species because the organisms will have little room to adapt to the changing temperatures
if you are trying to manage protected areas for better performance under climate-change conditions, what kinds of issues would you want to consider in site planning?
climate evidence explicitly incorporated through scenario-building, multiple time horizons to represent uncertainty and possible long-term future conditions, refinement of regional scenarios
What was the cause of the extinctions in the end-Pleistocene?
climate warming facilitated human arrival in North and South America and human hunting greatly reduced populations of large mammals and loss of habitat due to climate change finished off any survivors, example of the consequences of combined human impacts and climate change rather than the consequences of climate change alone
If we want species to persist through time, what factors do we have to plan for that will endure through time?
consider both pattern and process target and plan for persistence of both through time
On what basis is there reason to have confidence in SDMs for predicting the effects of future climates? What does this confidence in predictability imply about ecological niches?
considerable success SDMs have demonstrated in modeling current species ranges and in modeling the spread of invasives lends confidence to their application; support expectations from theory that species will move toward the poles and upslope as the planet warms and they also support the notion that species respond individualistically to climate change- species move independent of on another as climate changes that results in the tearing apart of vegetation and animal communities and the reassembly of species into new assemblages
Same as the previous question, but what kinds of issues would you want to consider in management actions?
coordinated with other reserves in region, planned using scenarios of climate change and range shifts, based on iterative monitoring feedback
Give an example of how physical models are being used to predict marine-organism distributions.
coral reef distribution- warming sea surface temperature driving corals poleward but also CO2 and ph of waters that alters saturation states of calcium carbonate driving corals to the tropics
What is meant by the species-area relationship? From what theory was the species-area curve derived? Explain the theory of island biogeography.
derived from island biogeography theory (species richness based on island size and isolation, more species result from less colonization and larger island size, closer to mainland also allows for more species), empirucakky measures relationship between the size of an area and the number of species it contains, the larger the area the greater the number of species present, been found to hold in virtually all terrestrial (oceanic island) studied, rate at which species accumulate with area seems to follow one of two paths- one curve for islands and another different curve for continental areas and main difference between the curves when the data are log-transformed is the slope of the curve
What evidence do we have that climate change does not always cause massive extinctions?
earth has cycled in and out of ice ages for the past 2 million years yet there have not been large extinction episodes with the onset and retreat of each ice age, these missing extinctions illustrate that even abrupt and major climate change is not always accompanied by massive extinction
What are the two assumptions that estimates of extinction risk from SDM/SAR must make?
either the species cannot disperse at all and is limited to ever-shrinking suitable climate within its present range or the species is perfectly well dispersed and can occupy all areas with suitable climate in the future
What are endemic species? Why would you want to develop a SDM only for species whose entire range falls within your study area?
endemic species are plants and animals that exist only in one geographic region; a species that has range outside of the region modeled has climatic tolerances that cannot be captured in the statistics of SDMs
What other names have been given to SDMs?
envelop models, bioclimatic models, range-shift models
in lakes, what is the difference between the epilimnion and the hypolimnion?
epilimnion is the mix and well oxygenated zone of (usually warmer) biologically productive water that receives inputs of sunlight to allow photosynthesis, the hypolimnion is the nonmixed (usually colder) water that is usually below the penetration depth of sunlight so primary production is limited and heterotrophic process dominate but oxygen may become depleted though it may remain and become distinct cold-water habitat for certain organisms (cold-water fish)
What is one way to assess risk of extinction from climate change?
examine biological responses in past times of rapid climate change
During population fluctuations in a species, what tends to happen to the population when mean population size is smaller than the magnitudes of the fluctuations?
extinction is highly likely to ensue
What are gap models?
fall between SDMs and DGVMs on the scale from species to ecosystems, attempt to simulate what happens in a forest gap after a tree falls- the growth of individual trees to fill the gap and competition between these individuals of different species
What kinds of information from lakes can be used to understand past climates?
fossil records from lakes and microorganisms, highly limited geographic scope of lake records and good temporal resolution and specialized taxonomic resolution favoring microorganisms to provide challenging and widely spaced snapshots of the past conditions, lakes preserve abundant fossil microorganisms that can be used to infer past climate, low and high lakestands indicted by geochemical and biological changes in sediments such as increased precipitation of minerals in drying conditions or increased biological traces in times of high water and high productivity, strongest for watershed of a particular lake but also implications for broader regions, isotopic and lake level indices, unique features such as pronounced stratigraphy, paleo-lake stands can yield information about phenomena such as el Nino events by reflecting precipitation changes in regional patterns typical of the teleconnection, rapid climate changes such as the warm reversal at the end of the Younger Dryas are uniquely revealed in some lake records by varves (annual layers created by biological or biochemical processes) that are especially important in studies of rapid climate change, lake records provide important confirmation of climate changes associated with Milankovitch cycles
What is one key disadvantage of using lakes to assess past climate?
freshwater realm is tiny compared to overall land surface area, and so the insights from lake records may also seem tantalizingly incomplete
Why do the effects of climate change on freshwaters systems have very large consequences for biodiversity and human endeavors?
freshwater systems are most diverse and highly impacted, provisions of water for human consumption and use constitutes a huge set of ecosystem services provided by rivers and lakes and is largely oversubscribed, extinctions are highin freshwater systems as dams, diversions for human uses, and pollution take their toll on these habitats,
In what ways will the future for species not be like their past?
future climate and levels of habitat destruction will be very different from anything in recent past, present climate is warm and stable relative to past 2 million years and levels of habitat destruction are the highest in history of the planet, so set of conditions that species will have to navigate as climates warm will be unlike those any have faced for much of evolutionary history and so warming on an already warm climate will push species into uncharted climatic territory- montane species in particular may find they have nowhere to move and other species will find that conditions for which they evolved no longer exist and rare long-distance jumps to suitable climate will be even less likely because more than half the natural habitat has been replaced by human uses
What species went extinct and what patterns were apparent in the end-Pleistocene extinctions?
giant ground sloth of south america, camels, horses, mammoth, and saber-tooth cats in north america
For providing information about past climates, compare the advantage of using lakes over glacial ice.
global change sin mean temperature are often inferred from ice cores and regional temperature and especially precipitation changes are discernible from lake records and follow more complex patterns
What are biodiversity hot spots? What evidence is there to support species-based estimates of extinction risk?
hot spots: biogeographic region that is both a significant reservoir for biodiversity and threatened with destruction and areas of high species endemism. confirmed by two independent methods: DGVM and EAR to estimate extinction risk for biodiversity hot spots because endemic rates are known for hot spots and it can be assumed that loss of habitat type for a hot spot endemic is a global loss of habitat for that species and based on this assumption projection of future extent of vegetation types for a hot spot from a DGVM can be used to estimate extinction risk for hot spot endemics, if a habitat type decreased within a hot spot it is as if a small habitat island for the endemics occupying that habitat has just gotten smaller- DGVM hot spot approach applied EAR to areas of lost habitat within hot spots to estimate extinction risk. second test was modeling lizard population extinctions and then predicting population extinctions accurately on other continents- population extinction projections were used to estimate species-level extinction risk and the ecophysiological method projected lizard extinctions of 6% of 2050 scenarios and 20% of 2080 scenarios
What influence do you think human interference is likely to have?
human interference in such a complex system is likely to have unpredictable result: addition of large amounts of CO2 to the atmosphere is changing temperatures and acidity of seawater on very short time-scales, and how these changes will balance or interact, and the final endpoints of that process, is difficult to assess. additional human changes will included development of near-shore land and continuing fishing pressure, and these factors will influence turbidity and food-chain structure and function
How was the species-area relationship used to assess effects of future climate change on species extinction? What was the idea that was applied?
idea of applying SAR to future climates is that areas of declining climatic suitability are comparable to decreasing area of suitable habitat, and as a species' suitable climatic space declines its population should decline rendering it more vulnerable to stochastic extinction, this chance of extinction should be reflected in a relationship between area and numbers of species: just as larger islands hold more species than smaller islands smaller suitable climatic space should hold fewer species than larger suitable climatic space and because climatic space was declining for most of the species in the six regions studied this could be translated via SAR into an estimate of extinction risk
If you had one site that was resistant to climate change, one site that was resilient to climate change, and one site that supported endemics, which of these areas would you choose to protect first? Why?
if because of climate change resistant or resilience areas should be prioritized- resilience ensures protected areas will persist BUT endemics have priority for protection regardless of resilience or resistance because these species are only found in one place and so have to conserve them where they are and are completely irreplaceable so must be protected
Why is the interaction of climate change and human land use particularly worrisome for species persistence?
if this relationship is synergistic actual climate-related extinctions may well outnumber the estimates, all of which fail to take into account threat synergies. present estimates also fail to include human population dynamics, so simple expansion of human land uses and human responses to climate change may be more deleterious than current estimates reflect
How did climate change cause the extinction of the dinosaurs?
impact of an asteroid, debris from the impact shot up into space and some of it generated intense burning radiation as it reentered the atmosphere but much of the debris remained in the atmosphere for decades/centuries and blocked out sunlight, cooling the planet and altering living conditions so drastically that no dinosaur survived the change
If we are planning a series of protected areas for the purpose of preserving patterns, what strategy should we use to reduce the effects of habitat destruction?
important to start the process of protection in sites most threatened with habitat loss to prevent the intent of preserving pattern in the landscape from being undermined by habitat destruction
How is disturbance management used to conserve species?
includes control of fire and guiding recovery and restoration of areas affected by storms/grazing/other disturbances to conserve species and habitat
In deep time, reefs were formed by many different types of calcifying organisms, and these organisms were not the same organisms that form reefs today. What does this history indicate about tropical systems?
indicates that tropical systems are variable with several stable states relative to climate
How do scientists use the presence of organisms, or tests on these organisms, to reconstruct past ocean temperatures and other conditions?
individual shells from deposits used to identify foraminifera, discover where they occupied ancient oceans, compare these ancient ocean denizens to climatic affinities of modern foraminifera or by analysis of the isotopic composition of the shells
What are Earth system models? What are their advantages?
integrate biological change into models of global climate, in their simplest form they are the coupling of DGVM with a GCM and allow for the effect of CO2 release from burned forest or transitions in vegetation to be included within internal model dynamics. in GCMs values for these biological carbon fluxes are external to the model and must be supplied by the model operator based on simplifying assumptions and thus a GCM cannot simulate the dynamics of vegetation change due to climate, releasing CO2 into the atmosphere thus driving additional climate change but and earth system model can
Explain what is involved in Earth system models.
integrating marine and terrestrial biology into models of atmospheric change- integrate vegetation and climate processes by joining a DGVM and representation of ocean primary productivity to a GCM, changes in vegetation and marine biomass then release and sequester CO2 which feeds back on climate, massive computing power required
Does species representation increase or decrease as climate changes?
it can do both: species move out of reserves in response to climate change and thus reduce their representation while other species may increase their representation by moving into reserves
What explanation can be offered for why there have not been mass extinctions with each onset of a glacial period?
length of the warm periods between ice ages was relatively short and species may be able to hold on through unfavorable climate as long as favorable climate returns within a few thousand years, once the extinctions at the onset of the ice ages removed species vulnerable to cold, the species that were left may have been relatively cold-adapted and these cold-tolerant species may then have been able to persist through relatively brief interglacials
What is meant by resistance to climate change?
less damaged by climate change
What do scientists think caused the end-Devonian extinction?
liked to the evolution of plants, removal of a large amount of CO2 from the atmosphere that cooled the planet and caused the extinction
What do you think might be a key factor that determines what state a tropical system settles into?
likely dependent on the climate history (warming and cooling) over both short and long time-frames
How can climate change lead to extinction?
literally everything we've ever talked about
If we want to get the most bang for our conservation buck, how should we select components for reserve systems?
look at irreplaceability (number of rare species in a site increases irreplaceability score), choosing sites with high irreplaceability minimizes the area needed in a system. prioritize by both threat and vulnerability to threat and less priority when resistant to threat because less vulnerability or more resilient- unless threat not reduced by protection and then value resilience
What advice about management would you give a reserve manager who is trying to minimize the loss of biodiversity?
managers should be aware of the impact of climate change on threatened or other managed species in their reserve and be aware that climate change may result in additional threatened species in need of management. be aware of climate change effects on current management objectives, such as threatened species or fire control. be alert for nonthreatened or nonobjective species or processes whose status may change significantly because of climate change. plan on longer time frames. consider interactions between management objectives that may be sensitive to climate
If both lowland and montane species lost the same absolute amount and proportion of their original range to climate change, for which group would you be most concerned in terms of long-term survival? Explain.
many lowland species are widespread so they begin with very large ranges and can suffer large area range loss and still retain relatively large range area while montane species are often arrayed in narrow elevation bands up the slope of a mountain and these species have small absolute range sizes so that relatively small absolute areas of range loss translate into large proportional range losses and even where widespread lowland species suffer large proportional range losses, they may retain range sizes that are large relative to those of montane species, thus large absolute and relative effects in lowlands may still leave lowland species with larger ranges than those of montane species and therefore statistical summaries of absolute and proportional range size must be viewed with caution because absolute range size is very important
What are some central challenges we will face in managing marine responses to climate change?
marine impacts of climate change manifest themselves differently in different regions and taxa, and some regions and taxa are dominated by temperature-driven species substitutions whereas others experience wholesale shifts in functional type and trophic structure due to ocean chemistry. managing all aspects of marine response to climate change will be an immense challenge for the future
In north temperate zones, what have SDMs predicted?
northward movement in a wide range of species and upslope movement in the mountains, significant loss of range in alpine plants due to effect of decreasing area as species move upslope
What kind of information do scientists use to understand past effects of changes in ocean chemistry?
ocean CO2 and pH levels because effects ability of organisms to form hard calcium carbonate structures
How are oxygen isotopes used to determine past temperatures and past climate shifts?
ocean waters high in 18O indicate cooler climates whereas lower 18O/16O ratios indicate warmer nonglacial climates and because some marine organisms fix oxygen in their shells the fossils of their shells can be analyzed for 18O/16O ratios to determine past temperatures and past climate shifts
Describe a scenario that would illustrate the idea of state-dependent forest composition.
once established mature trees may persist in climates that would be inhospitable for their establishment, replacement of these forests happens only with disturbance such as fire or death of the trees owing to old age, these living dead forests may prevent the establishment of replacement vegetation and then suddenly burn or die centuries later, opening up the landscape for a completely different vegetation type and in this way mixed conifer forest might be replaced by oak woodland as montane habitats warm, not in gradual transition by rather in sudden state switches when the coniferous forest dies or burns
How do gap models account for growth rates of different species of trees under different climate conditions and spacing?
parameters of the model are derived from known growth rates of various species of trees under different climatic conditions and spacing
What do we mean by planning for pattern and process? Give examples of important processes.
pattern targets are generally species or habitat types so planning for pattern means conserving a representative samples of species or habitat tayes and preserving some notion of their pattern in the landscape. planning for process means capturing temporal phenomena in the conservation plan, like wildebeest migrations in the Serengeti
What kinds of events does a gap model show or describe?
shows new species appearing, existing species dropping out, and major changes in dominance among species that persist at any given location
Why does the "perfect dispersal" assumption put a lower bound on the estimate of extinction risk of a species? Why does the "no dispersal" assumption put an upper bound on the extinction estimate of a species?
perfect dispersal assumes that species can reach all suitable climatic area and thus shows when a species won't really lose suitable habitat and is at low risk for extinction and thus the lower bound, if they fall under no dispersal then their suitable habitat is ever-shrinking and thus are the most likely to go extinct and are thus at the upper bound of risk
What happens when corals are exposed to high salinity?
photosynthetic productivity drops rapidly with high salinity, so corals obtain less nutrients and starve
What biological processes are represented mathematically in DGVMs?
plant growth, photosynthesis, and respiration, sometimes coupled with empirically driven corrections
Why are past influences on marine systems so important to understand?
predicting and managing for the future can be aided by information from the past
in what sense is a SDM an "envelope" model?
simplest SDM uses values for climatic variables at points at which a species has been observed, compares these values to values of the same variable across a study area, and models the species as present where current climate is within the range and as absent where current climate is above or below the range, create an upper and lower bound of temperature or other niche requirements and simulates the species at all sites within the range
What are species distribution models (SDMs)?
simulate the distribution of species- their ranges- relative to climate, create a statistical model of the relationship between current climate and known occurrences of a species
Let's consider setting up a marine protection area for coral reefs again and expand a bit on the points we made earlier. What are the factors that can be taken into consideration that relate to resistance to coral bleaching?
promotion of water mixing (proximity to deep water and regular exchange with cooler oceanic water, localized upwelling of cool water, permanent strong currents), screening of corals from damaging radiation (deep shad from high land profiles, shading by complex reef structure/multilayered communities/steep slopes, orientation relative to the sun, presence of consistently turbid water), indication or potential preadaptation to temperature or other stresses (frequent exposure of corals at low tides, highly variable seawater temperature, history of corals surviving climate related bleaching, high diversity and abundance of coral reef species, wide range of coral colony size and diversity in different reef zones, high live coral cover), survival of at least some coral communities (stable salinity regime, large area with wide depth range and habitat variability, low risk of exposure to climate-related temperature stresses at the location)
If you wanted to improve the chance to conserve biodiversity in the face of climate change, what components of management of natural systems would you use?
protected areas, connectivity and conservation on productive lands, and management of individual species, including species rescue and translocation
Summarize the value of lakes for providing information about past climates.
provide information about climate change as well as about its past biological effects, one of best sources of information about past climates because preserve abundant microorganisms when compared to rivers and streams that seldom harbor conditions that yield reliably datable fossils because annual deposition strata are rare and because periods of bed cutting destroy incipient fossils, long-lived basins provide important information about past climate like low and high lake stands indicated by geochemical and biological changes in sediments such as increased precipitation of minerals in drying conditions or increased biological traces in times of high water and high productivity and these indicators are meaningful for freshwater systems and terrestrial and marine systems that surround them; lakes provide insights into regional climate changes, teleconnections, rapid climate change, and drivers of climate change- isotopic and lake level indices are important in most investigations and unique features like stratigraphy are crucial in few, lakes contribute knowledge not only of their own physical and biological changes by also of changes in regional climate and vegetation, interregional synchrony, and global magnitude, cycles, and speed of change and provide invaluable insights because their geographic coverage is much more extensive than glacial ice
Why are range shifts in response to climate change complicated? What are metapopulations?
range boundaries are not monolithic entities but rather a collection of metapopulations (group of spacially separated populations of the same species that interact at some level) that vary in time, increasing or decreasing more or less rapidly in response to climate change, a more sophisticated view of range shifts therefore includes metapopulation dynamics, species across both large and small ranges, and a variety of range movements across the landscape, the entire suit of range responses and protected areas must be considered together to estimate the net impact on conservation of the species
In what ways was climate a contributing factor?
rapid temperature change and sea level rise and fall are cited as driving extinctions but are set in motion by forces outside of the climate system like an asteroid impact or volcanic eruption
There have been five major mass extinctions on Earth. Climate has been implicated as either a direct or indirect (contributing) driver of these extinctions. In what ways was climate a direct factor?
rapid temperature change and sea level rise and fall are often cited as driving extinctions
Why are the existence and physical characteristics of freshwater systems very vulnerable to climate change?
realm is relatively tiny, limited systems are distributed unevenly across the face of the planet, accentuating this scarcity in many regions, as much as 1/4 is already being used by humans and pollution renders another significant portion unusable and unsuitable for natural habitat, base of freshwater food chains often microorganisms, ephemeral in geologic time and their very existence is dependent on the balance of precipitation and evaporation, making climate a fundamental determinant of their longevity. changing nature of freshwater systems leaves indelible imprints on the biota that inhabit them
What is the significance of the trailing edge of range shifts for a species?
rear edge of the current range shifts is the edge that has been most stable in glacial-interglacial cycles- collapse back into glacial conditions has repeatedly wiped out leading-edge populations whereas trailing-edge populations in warmer climates closer to the equator have endured. this means that the genetic richness of the rear edge may be greater than that of other areas of the range and may make rear-edge populations more important in resisting extinctions
What climate-related problems exist in the North Bering Sea, and how could a marine protected area help to reduce some of the problems?
recent changes due to loss of sea ice: makes a more active ecosystem in the water column as plankton that used to fall through to and be deposited in the benthos are now caught up in the food web and reducing energy and nutrients reaching benthos- large scale shift in species composition of benthic communities with mollusks decreasing in dominance and nutritional quality and being replaced by brittle stars. Walrus and speckled either that feed on these benthic communities are therefore faced with greatly declining nutrition. At the same time the retreat of sea ice means that the species spend more time resting in water then on ice and thermal losses in water are greater than those in the air so the switch from ice resting to water resting means the eater and walrus are burning much more energy at rest at the same time that they are getting less bivalve food from the bottom. If the species try to follow sea ice to maintain their thermal balance they find themselves in much deeper waters further from the continental shelf which means they must dive deeper to feed. Walrus and eater populations have declined dramatically because of these deteriorating conditions. To further complicate the situation there is a sill of cold water behind a ridge on the ocean floor of St. Lawrence island that excludes groundfish from the north Bering Sea. This cold water sill is breaking down as water temperature is warm and as it disappears groundfish will enter the north Bering sea and compete with walrus and eater for mollusks. Bottom trawling fisheries will probably follow groundfish when they enter the north Bering Sea disrupting the bottom and further reducing mollusk food sources.
Can managers effectively conserve the species in a reserve by focusing on factors within the borders of reserves?
reserves that manage threats only from their borders inward may find that climate change results in an increased number and magnitude of threats that they confront whereas management that looks outward and anticipates climate change effects may greatly reduce costs and improve the effectiveness of management responses, although in most cases requiring more management effort and budget than if climate change were not occurring
In the protection of marine areas, and in particular coral reefs, what kinds of sites get preference for protection?
resistant or resilient sites are selected over those that aren't, unless harboring biological value or irreplaceable species
How will changes in stream flow come about as a result of climate change?
result when precipitation and evapotranspiration vary and climate change is expected to exacerbate both drought periods and intensive storm events because of an enhanced hydrologic cycle coupled with warming- streamflow increases with increased precipitation and decrease or cease in droughts and timing will also vary with changes in snowmelt and storm intensity- snowmelt will generally be earlier as temperatures increase and late-season flows are reduced relative to current conditions. intensification of storm events may result in increases in annual streamflow but also a compression of the annual flow volume into shorter bursts, resulting in intensified low-flow conditions, increased streambed cutting, and resulting habitat alterations
Let's come back to the salinity issue. Corals are living in sea water, which is always saline, so why is salinity an issue? That is, in what ways does salinity change in the oceans?
salinity can change on regional scales in geologic time due to alterations in ocean mixing or thermohaline circulation and can vary between regions due to differences in evaporation rates
What would the DGVMs predict for future climates about various types of forest?
show northward expansion of boreal forests, expansion of some temperate forest types, and contraction of some tropical forest types most notably in the amazon, direct effect of CO2 seems more important in damping the loss of moist tropical forests occurring in response to climate change, wet forests in amazon shrinking in response to climate change
Give a general example of a resilient species and a resilient area.
site might be one in an area of high seed rain so plants are able to reestablished easily, species might be one with high reproductive potential or good long-distance dispersal
When the authors of the 2004 Nature paper applied the SDMs, what did they find?
some showed species' ranges disappearing altogether by 2050 whereas others showed species' ranges declining by 2050 and probably headed for extinction, but most showed some decline but not enough to definitively state that a species was headed for extinction but some of these declining-range species might become extinct
What is the geographic scope of the teleconnections that were discussed earlier in this chapter?
some weather patterns occur on such a large scale that they have repercussions throughout the world- changes in one area associated with changes in other regions or continents, El Nino conditions
What is the main method used to assess future extinction risk from climate change?
species distribution models coupled with the species-area relationship to estimate extinction risk, allows estimates of futures species' range size
How have ice ages had a major impact on lake ecology?
species spanning mid-latitudes and tropic were wiped out in higher-latitude habitats by cooling and so defined the divide between tropical and mid-latitude freshwater biology that is evident today, retreating glaciers have left a large number of lakes and freshwater connections and changes associated with the ice ages have affected freshwater systems far from the ice sheets, fragmentation of freshwater habitats resulting in speciation resulted from both seal level and temperature changes associated with glacial-interglacial cycles
Give a general example of a resistant species and a resistant area.
species with broad physiological tolerances or a site that is sheltered in a unique microclimate
What have gap models revealed?
state-dependent or hysteretic responses that arise when a forest may have multiple stable states under a given set of climate conditions, which stable state actually emerges depends on the history of the forest (history of climate change and biological history on the site)
How can a reserve manager manage threats or effects from climate change?
stopping climate change ultimately requires social and energy consumption changes across the planet- a change process that a reserve manager may participate in but not control. therefore the main management option for climate change may lie in trying to modify its effects by changing management of factors (threats, disturbances, species, and tourism) with which it interacts
How will climate change affect stream temperature?
stream temperature follows air temperature with shallower streams responding more quickly- short and shallow streams dominate stream and river systems so the proportion of temperature-sensitive waterways is high. streams and rivers with greater contributions from surface water relative to groundwater will also be more sensitive to changes in air temperature- high mountain systems contain unique cold-adapted species like trout warming may have major consequences for biological systems
What climate influences can alter the stratification regime of a given lake?
strongly related to seasonal temperature fluctuations, so reduced temperature difference between warm surface layer and deep water reduces the stability of stratification and mixing can occur, variations in climate that affect seasonality and temperature can alter the stratification regime- in periods of warming cold monomictic lakes have become dimictic and dimictic lakes have become warm monomictic, and the reverse of these changes have taken place in periods of cooling, ice cover of lakes also changes with climate
How have coastal freshwater habitats been affected by glacial cycles?
successively fragmented and reunited during glacial cycles, low-lying areas are flooded in the melting cycles and reexposed as sea levels drop, in interglacial high sea level stands lowland freshwater habitats are separated by barriers of ocean water and promote allopatric speciation
How do SDMs/SAR take into account species' dispersal capabilities?
they state nothing about species dynamics or whether a species can reach its future suitable climate
What kinds of factors do you think would increase the vulnerability of a species or population to impacts of climate change? Explain how each would increase vulnerability.
temperature range shifts (a temperate occurrence on the low latitude or lowland periphery of a species' historic range), tropical range shifts (montane occurrence), ecosystem resilience (an exposed or management-dependent occurrence like forest edge ecosystem or small fire dependent community or a heavily exploited species), genetic richness (genetically impoverished occurrence), topography (homogeneous), extinction risk (occurrence without restricted range or extinction prone species), sea level change (on coastal wetlands unable to migrate inland), montane geography (on steep upper mountain slopes where upward dispersal is limited), disturbance regime (smaller than the minimum area necessary to accommodate natural disturbance cycles), landscape ecology (highly fragmented landscape)
What do we mean by extent of occurrence (EO)?
the convex hull that encompasses all known occurrences of a species, in essence a range map
What was the author's criticism of the 2004 Nature paper and its coverage in the press?
the estimate of one million species at risk was estimated in the press release for the paper and not part of the research itself, the paper only focused on one of several possible methods to assess risk and it is necessary to examine several lines of evidence across several disciplines to get a deeper view of extinction risk from climate change
In what sense is extinction a stochastic event?
the magnitude of fluctuations varies so extinction is a matter of change so populations and species go extinct stochastically and not deterministically
Based on past climate change effects, can we derive quantitative estimates of how many species may be lost or which species may be vulnerable? Explain.
the past tells that extinctions and climate change go together but not always so it does not shed much light on the probability of extinctions from human-induced climate change during the next few centuries, there is some indication that rapid and large climate changes are more likely to lead to extinctions and that climate change in concert with human activity lead to extinction- evidence that should raise alarm bells about possible future impacts of climate change, however for quantitative estimates of how many species may be lost or which species may be most vulnerable we have to turn elsewhere
Where are new and disappearing climates expected to be concentrated in the future? Why?
the tropics, tropics are vulnerable to climate change even though the magnitude of warming is considerably less in the tropics than at higher latitudes
Hot spots can be important in conservation. Is there any evidence that hotspots have moved due to climate change?
there is not evidence that current hotspots are shifting due to climate change. though climate change may make diversity hot spots hop hot spots of endemism won't move and they'll just get hotter
What kinds of marine sites are resistant to coral bleaching?
those with cool currents or upwellings because maintain cooler surface water temperatures. corals that have been bleached previously and survived because may have been naturally selected to have more resistant zooxanthellae or other natural mechanisms of survival or recovery. reefs in the shadow of a large mountain or with low doses of sedimentation because helps keep area cool
What kinds of threats interact with climate change?
threats, disturbances, species, and tourism
Give me an example of an interaction between climate and humans that can have an indirect effect on biodiversity.
tropical farmers rely on forests for supplemental or emergency income because when crops fail the sale of timber or collection of forest products can provide needed income. as climate change alters agricultural conditions, crop failures may increase and trigger increased use of forests which could indirectly impact the biodiversity of these forests
We said that turbidity also may be important. In what ways might turbidity vary?
turbidity is primarily a local phenomenon but can also vary over geologic time due to such factors as change in sea level and continental erosion, high turbidity occurs around river mouths where large sediment loads are released to the sea, may also be high where wave action stirs bottom sediments , more regional but less severe changes may result from upwelling or unusual events such as volcanic eruptions
How does turbidity affect corals?
turbidity reduces light input and decreases photosynthesis, causes corals to eventually starve
How does turbidity influence coral growth? That is, what is the mechanism?
turbidity reduces the amount of light available for photosynthesis by zooxantheleae which thereby reduces coral growth
What kind of output do you get from SDMs?
typically a map of a species' simulated range, either in present of in both present and future
Give an example of how biological models are being used to make predictions about marine-organism responses to climate change.
typically represent food web interactions and ecophysiological changes in productivity, wet counterpart of DGVMs, EcoSim food web model that uses ecophysical restraints to determine changes in primary productivity and has been used to assess changes in marine ecosystems surrounding Australia
What are dynamic global vegetation models (DGVMs)? How are they used to assess changes in plant functional types due to climate change? Do they make projections about species or ecosystems?
use first-principle equations describing photosynthesis, carbon cycling in soils, and plant physiology to simulate growth and competition between vegetation types, literally grow vegetation mathematically, fixing carbon from the atmosphere, distributing it to plant parts, and evolving a vegetation that it describes in terms as a number of plant functional types, if enough carbon is fixed and maintained to build a forest in a particular location, the DGVM registers the plant functional type at that point as a forest and if enough carbon persists only for a grassland the PFT is recorded as grassland, output of DGVM is a global map of PFTs, run from photosynthetic equations so are able to simulate the direct effects of elevated CO2 on plant growth and competition and indirect effects of the warming caused by CO2
How can SDMs be used to estimate how species' ranges may shift with climate?
used to simulate species' current ranges for a limited set of known observations, useful in this setting when a species' distribution is not well known but needs to be included in conservation planning, same type of model run using future climatic conditions and results can be compared to current distribution to obtain an estimate of how species ranges may shift with climate change
What key result has emerged from running Earth system models?
verification of important feedbacks between vegetation and climate, usually through CO2 or carbon pools like CO2 uptakes by borreal forests or drying of the amazon
in conservation, what do we mean by irreplaceability?
when a species is found in only one place that site is said to be irreplaceable and thus in a protected-areas network that seeks to represent all species, these sites must be included to meet the goal and are thus irreplaceable
Isn't the tropics expected to see little change in the magnitude of warming?
yeah
