Conservation Bio Midterm 2 prep
Lecture 10:
Many factors contribute to Species richness including:
Over-exploitation and disturbance
Habitat loss
Habitat fragmentation
Invasion
Climate
Climate Change
In the last 90 years, mean temperature globally has increased by ~2.1C
Primarily explained by increases in the three ‘greenhouse gasses’ - CO2, methane, nitrous oxide
Model projections: increased mean and variability of climate (precipitation and temperatures)
The predictions…
Arid deserts in southwestern US. will shrink as precipitation increases
Savanna / shrub / woodland systems will replace grasslands in the Great Plains
Eastern US. - Forests will expand northerly - weather conditions will become more severe
Southeastern US. increasing droughts will bring more fires, triggering a rapid change from broadleaf forests to grasslands
It's not just about warmer average temperatures across the planet.
Long term change in grassland plant production: temperature and precipitation (multiple changes, not just one…)
Global production increases in many (not all) areas because growing seasons are longer…
Every location is getting warmer, but half the world is getting drier.
Interhemispheric temperature asymmetry
The difference between the hemispheric mean surface air temperatures Northern Hemisphere (NH) minus Southern Hemisphere (SH)
The South is warming less quickly … but experiencing more drought
The south has more ocean.
Key questions:
How do present day challenges compare to the past?
How is the climate changing: rate of change, type of change (precipitation vs. temp), location of changes?
Diversity responses: die, move and adapt… ?
How can we conserve biodiversity, when the impacts of global change transcend the scale of typical conservation management strategies?
How can we upgrade conservation strategies to account for climate impact?
Key challenges
Detection:
Data are patchy and qualitative
Climate is ‘naturally variable’ by season, by latitude and by year.
Context:
Covariance with other co-occurring human-based impacts on the environment
Buffering: response lags.
Publication bias: focussing on the studies that show impact?
Warming and acidification are not happening in isolation.
Example - Crested Wheatgrass
One of the most successful introductions in the history of introductions - planted after 1930s “dustbowl”
Produces 3-5x more aboveground biomass than native grasses … leading to assumption of competitive superiority driving invasion success.
Hidden reality: phylogeny of CWG exactly matches the new climate: emerges far earlier in the spring than the native grasses, and has much higher mid-summer water demand than native grasses.
Lecture 11
Evolutionary, morphological and distributional responses to climate change: The evidence.
Climate responses:
Rapid evolution hypothesis: strong and immediate climatic-based selection on population traits - evolutionary change (across-generation)
Plasticity Hypotheses: strong and immediate climatic-based adjustments in growth, phylogeny, and reproduction - ecological change (within-generation)
Migration hypothesis: strong and immediate climatic-based adjustments in a population distribution - migration or ‘ecological selection’ (across generation).
Rapid Evolution of Geographic Cline in Size in an Introduced Fly
Native Europe: longer-wings in northern climates
US introduction: all flies had the same wing length.
20 years later: the exact same pattern as Europe emerged in the US [California to Oregon]
Implication: wild species respond quickly to local climate
Challenge: one of few cases documented of rapid change… how prevalent?
Plasticity or Adaptation?
Plasticity: shifts in morphology with no genetic change.
Adaptation: shifts in morphology a result of natural selection…
Difficult to tell the difference: identical impacts on population frequency
Both may buffer climate change: no negative effects
Eg. growth shifts assumed to reflect duress, but this duress may produce not necessarily affect population fitness (adaptation).
Overview: A “cleistogamous” plant, with separate outcrossed and selfed flowers. Selfed flowers: risk of inbreeding depression but can ensure seed production of outcrossed flowers fail
Methods: increased temperature by 3.5C, eliminated rainfall: an extreme climate event …
Results: we observed buffering - no net change in population size or population structure (% juveniles), BUT all compensatory responses involved inbreeding [self-pollination]...
Hidden long-term effect: inbreeding depression - a delayed or lag effect response to climate change
Conclusion: population decline may be hidden in the short term, but than rapidly collapse as inbreeding effects intensify…
Lecture 12
Baxton climate change study
Long-term climate manipulations
+ Temp/water interactions 3x3 m plots, 5 replicates
No progressive change in composition after 13 years in 3x3 m plots
Major life form groups unchanged.
Species composition fairly stables (practically straight lines not any significant change in composition).
Microsite variation prevented species loss in response to climate change
Buffered at the community level but affects at the species level.
No observed change at the COMMUNITY level (no species extirpation)...
BUT large changes WITHIN the community, especially along the soil depth gradient
Content dependent. Deeper soils no change, shallower soils and large impact from drought conditions
Some proportions of the populations are being affected by climate change and other aren’t
9 out of 25 species exhibited a microsite-treatment interaction
Migration hypothesis
Examples: Crimmins 2011 (science 331:324)
“Changes in climatic water balance drive downhill shifts in plant species optimum elevations
Types of responses are not unidirectional. Responses will go both ways. We cannot assume climate change drives change only in one direction (but thats how these people conduct their research).
Uphill shifts well documented: leads to expectations of continued uphill shifts under future warming (ie. cooler uphill)
Altitudinal distributions 64 plant species: 1930s-2010
Climate changes: significant downward shift
Contrary to expectation… but readily explained by species’ niche tracking of regional changes in climatic water balance rather than temperature (ie. warming downhill but greater moisture availability).
Changes in snow melt, flowering time, and location in arctic Sweden
Walked a mountain every 5 days and documented plant species. The prof. Went and followed his stakes up the mountain.
An unprecedented century-long (1917-1919 vs. 2017-2018) dataset on migration and phylogeny for 83 arctic and boreal mountain species in northern Sweden
Dramatic distributional change associated with warming. 69% of species shifted uphill, averaging 6.1m per decade, especially boreal woodland taxa whose upward expansion reduced unforested arctic mountains habitat by 30%
Simultaneously, 20% of summit species shifted downslope, especially moisture-associated snowbed flora (like the Crimmins study).
What to make of these inconsistent results?
What are future impacts of climate change on wildlife populations?
Opens the door for skepticisim - publication bias by scientists?
There is no single response to climate change. Some species are highly resistant and other are not. The story thats being presented to the press may not be accurate. People don’t believe that climate change exists or that its a significant issue.
Parmesan & Yohe Nature 421:37
A meta-analysis combining data on 1700 species across the globe.
Species added independently of responses to climate.
The critics were right - almost 50% of all species were stable… (not changing, or changing slightly but NOT significantly)
For those species showing a significant change, most occurred in the direction of predicted responses.
Over the past 20-150 years, ~50% of the species exhibited significant responses of warming
Earlier flowering (plasticity hypothesis)
TIming of breeding (plasticity hypothesis)
Distributional shifts (migration hypothesis)
Abundance shifts (migration hypothesis)
Butterflies to trees, temperate to tropical, terrestrial and aquatic…
Explains the climate enigma: the range of inconsistent and contradictory responses observed across the globe…
Species responses so far have been highly individualistic [with much buffering]
Rapid evolution (Huey)
Adjustment by plasticity (Jones)
Range expansion - scale dependent (plot-level: Buxton study; altitudinal; Crimmins)
Lag effects: Jones violet study (hidden risk of inbreeding depression?)
Conclusions
A fundamental change is underway, in the distribution, abundance, and diversity of at least half the world’s species.
The long-term endpoint?
Unclear, but we can certainly guess based on out knowledge of the factors that create and maintain diversity.
Climate change and conservation
To date: only 2 extinctions attributable to climate change: golden toad, harlequin frog [Costa Rica]
But, massive shifts for SOME species and systems [eg. zooplankton abundance <80% of the coast of California, in association with warning]
Buffering: the ability to track the changing climate in time and location
Management: anticipate the changes and assist with the buffering…
Past emphasis in conservation: local issues [patch size, population size, species]...
New emphasis: regional-scale protected area networks
1. Reserves that allow for range shifts: corridors, gradients (area matters).
Map of mammalian movement between protected areas in North America
Mammalian movement between protected areas in north america. The bright yellow areas indicate high connectivity, especially between large protected regions, such as the Yellowstone to Yukon (Y2Y) corridor, critical for mammal migration across the Rocky Mountains. The darker purple regions represent more dispersed connectivity, while the black areas depict zones with minimal to no mammalian movement, challenges in areas like Labrador, with lower connectivity due to geographic barriers like peninsulas, are highlighted. The map also underscores the need for maintaining the integrity of southern Canadian protected areas, which are relatively isolated and the risk from urban encroachment. Overall, it models the major corridor routes and underscores the importance of wildlife corridors in maintaining species diversity and resilience in the face of increasing habitat fragmentation and climate change.
2. Reserves that capture population variability
Individuals are not genetically identical in their responses to climate … (genetic and trait variability matters).
Lecture 13
3. Identify and manage for non-climatic stressors that hamper adjustments and movements
Eg. invasions (giant hog-weed)
Road mortality (living bridges across highways)
Disease
4. Tackling climate change directly: carbon credits, biofuels, offsetting and soil carbon
Key premise: protecting natural areas and biodiversity can both help reduce levels of atmospheric CO2 - how?
Natural areas are a source of CO2.
Biodiversity also uses CO2 from the atmosphere for respiration.
The Carbon Cycle
There is less carbon in the atmosphere than there is in the soils and in the permafrost.
Soil carbon in roots and shoots
The “iceberg” phenomenon
90% of all biological activity in many terrestrial ecosystems can be belowground.
Protected area and carbon capture
Peatland captures lots of carbon in the soil
Wetland and grassland do the same.
Forests capture lots of carbon in the plants.
One of the inescapable conclusions of this study is that the protected areas in Canada play a significant role in terms of carbon sequestration and its value to Canadians. The 39 National Parks in Canada have sequestered a total of 4.43 gigatonnes of carbon in various pools. The soils and peatlands are the most important pool of carbon, storing little of 90% of the total carbon stored in national parks. Average density of carbon in national parks is very high at 170 tonnes per ha. Northernmost national parks are particularly rich in this resource. Total economic value of stored carbon in the national parks is estimated to be 72-78 billion dollars. However, this value could range from between 12$ and 2216 billion dollars, depending upon society’s valuation of carbon sequestration function of the protected areas.
Land-use change was the dominant source of annual CO2 emissions until around 1950. Fossil CO2 emissions now dominate global changes
Sod-busting on the Great Plains
The greatest efflux of CO2 into the atmosphere in the past 200 years.
The greatest environmental catastrophe in recorded history in North America (the 1930s dust bowl).
Food systems contribute 19-29% of global anthropogenic greenhouse gas emissions and are also likely to be profoundly affected by climate change, indicating the need for approaches that integrate adaptation and mitigation concerns in agriculture such as sustainable intensification and waste management.
New Acre Project - Across Canada
Clean Air - capture of GHG (greenhouse gases)
Clean water = nutrient retention
Biodiversity = habitat.
Farmers concentrate growth on the best part of their farmland and then the rest gets set aside for carbon capture, as grasslands or forests.
Getting to Net-Zero Carbon Emissions by 2050
Increase solar and wind capacity 3.5 times, to 500 gigawatts
Eliminate most electricity generation from coal
Maintain current natural gas generating capacity for reliability
Increase zero-emission vehicle sales share 50%
Increase sales share of building heat pumps to 50%
All new buildings and appliances meet strict energy efficiency goals
R&D (research and development) for carbon capture sequestration and carbon-neutral fuels
Build electricity transmission and pipelines for carbon dioxide and hydrogen gas.
Lecture 14
Energy use by source
Energy consumption by fuel source from 2000 to 2023, with growth rates indicated for the more recent period of 2018 to 2023
Fossil fuel use keeps growing… but coal has levelled off, while renewables are growing exponentially.
ARTICLE: Green hydrogen project in Newfoundland to get 128 million dollar federal loan.
Germany plans to replace coal-fired power plants with hydrogen ones in the next 15 to 20 years.
Canada will ship some of its hydrogen to Germany starting in 2025 but unlikely to meet that time frame.
New loan for company is a signature moment for green hydrogen in Canada
Green hydrogen is considered the most climate friendly, produced using electrolysis to extract H from water with renewable electricity.
Proposed building of new wind farms.
Grey hydrogen, H produced from natural gas which leads to greenhouse gases that can escape into the atmosphere.
Blue hydrogen, escaped greenhouse gases are captured using carbon capture systems.
Germany only wants, generally, green hydrogen.
Habitat Loss and Habitat Fragmentation
Habitat Loss
Habitat: natural conditions where species live
Not all habitat is created equally
Demographic performance (niches, sources, sinks)
83% of the planet transformed
60% of all ecosystems highly transformed
Coral reefs: 20% destroyed, 20% degraded.
Habitat fragmentation is increasing worldwide. Map shows human footprint on earth. The human footprint is correlated with habitat fragmentation - analysis of the human footprint map indicates that 83% of the land’s surface is influenced by one or more of the following factors: human population density greater than 1 person per square km, within 15 km of a road or major river, occupied by urban or agricultural land uses, within 2km of a settlement or railway, and/or producing enough light to be visible regularly to a satellite at night.
Factors threatening species:
Habitat loss and degradation
Overexploitation
Invasive species
Disease
Pollution
Intrinsic factors.
Sometimes throughout time, areas become more forested.
Eg. Swift River Valley in Massachusetts in 1890 has extensive forest clearing, and in present day the same area is naturally reforested.
Some birds are now located on cattle pastures that aren't that different from their original habitats of the plains and grasslands.
Fragmentation affects
There are species that can survive on the edges of habitats edge species
Species that can only survive on the inside zones of the habitat, interior species
Fragmentation leads to similar area sizes but the interior species are less able to survive.
Its more than just less area the remaining area changes fundamentally.
Habitat degradation and Loss:
Problems:
Conversion to unsuitable habitat (the matrix surrounding the remnant)
Resource extraction, agriculture, settlements, pollution
Affects 60% of the earth’s ecosystems
Reduced habitat quality of remnants
Edge effects
The eternal external threat.
Progression occurs when an edge is created where forest area is removed. Initially, there is more light and wind and a greater variation in temperature. These added variables can result in tree mortality, under-story release and changes in species composition, including the addition of invasive plants.
1. Habitat degradation / loss on farm landscapes
Problem:
85-99% loss of wetlands and native grasslands in southern Ontario since 1800
Solution:
Build new ones with the “matrix”; 23 wetlands on 16 farms and 55 grassland “prairies”
Farms are setting aside plots of area to naturalize into buffer zones between cultivated land and natural spaces.
Remnant forest: a piece of forest that hasn’t been clear cut for fields as it's not physically possible or not profitable.
Retired grassland: Acts as a buffer region to help make the transition from the crop to the remnant forest less harsh’
Lots of bat calls on over the crops meaning the bats must be flying over these locations. This suggests that the bats may be eating the insects from the crops at night. Possible insecticide alternatives.
2. Habitat fragmentation
Problems:
The isolation of habitat type into fragmented patches
Less migration of individuals
Less gene flow
Reduced dispersal to remnants
Vulnerable species: limited dispersal and demographic variability.
On farm landscapes
Problem: 85% loss of wetlands in southern Ontario since 1800
Target: aquatic macro-invertebrates critical for birds and bats
Outcomes:
i) support 100s of species otherwise absent
ii) wetlands opportunistically built
Small and isolated
Macro-invertebrates are often passive or shorter distance dispersers…
3. Habitat gains on farmland landscapes
Problems: 85% loss of wetlands in southern Ontario since 1800
Soulution: build new oneal 23 wetlands on 16 farms
Target: selective marsh birds (SMBs) - bitterns, rails, coots
Outcome: wetlands opportunistically built - too small (<1 ha): most SMBs need 5 ha minimum.
What is “habitat”
Habitat: natural conditions where species live
All habitat not created equally
Demographic performance (niches, source and sinks)
Source: births exceed deaths, driving emigration
Sink: deaths exceed births, requiring immigration
Not all habitat loss has similar consequences
Oval = fundamental niche (l > 1.0)
“+” = occupied habitat
“o” = unoccupied habitat
“E1 and e2” = environmental factors.
Individuals must be able to reproduce in order to be considered a viable habitat.
Lecture 15
Source-sink dynamics: organism occurs outside the source link but cannot replace itself.
Dispersal limitation: Far more unoccupied suitable habitat in the source but not used.
Two locations with otherwise identical diversity, distribution, evenness, or any other measure that is typically measured. Which do you protect and why? Some may place a park in the yellow rectangle, but still species tend to disappear because they are largely outside of their habitat. (blue is habitat, black is occupied habitat).
Declining area reduces the proportion of species maintained at steady state. The amount of the reduction depends on the z-value. Assuming the latter, which is a typical archipelagic z, we would predict the least severe losses. But data shows that interprovincial z-values are close to unity.
Area loss really matters for habitat loss and fragmentation.
What are the ecological mechanisms that explain species loss with lost area?
1. The sampling effect
The random survival of a small subset of species following rapid and widespread habitat loss
Survival has nothing to do with traits, it’s strictly being in the right place at the right time
Those survivors become your new regional species pool, for better or worse
Remnant population was isolated so quickly it had nothing to do with selected traits. Present species pool is now what it is, whether the genes are good or bad adaptations, it's a random group that's left over.
An 81-species rainforest region … is reduced to 8 species.
Randomly save this small percentage. These individuals might not be suited for small patch sizes and if their not good at all the species may completely die off.
2a. Loss of density dependent species regulation
Density-dependence: population growth rate slows, as populations grow in density and size
Causes of decline: resource scarcity, higher mortality (eg. intra-specific competition predation)
Rarer ‘low-density’ species are favoured, thereby maintaining high species richness.
No juvenile trees here at all. No recruitment events since 1901. This is an extinction event just waiting to happen.
More seedlings closer to the parent
More insect damage closer to the parent
Less soil moisture closer to the parent plant.
Habitat loss, over-exploitation, and under exploitation.
Deers in BC population has exploded.
No hunting allowed, and all natural predators like wolves or cougars have been killed.
Deer can eat many new seedlings that start sprouting up, preventing growth of younger seedlings.
2b. Density dependent “Allee” effects
As population density declines, reproduction becomes more difficult
Density is so low the mating drops to 0 when below the yellow line.
As density increases, recruitment success also increases
The TV series “Appalachian Outlaws” shows you exactly the wrong way to harvest wild ginseng. Ginseng density is so low, that pollinators cannot find nor pollinate the ginseng.
Devil’s club: a Medicine Cabinet for Alaska tribe - Habitat loss and over-exploitation…
“The botanical name for Devil’s club is Echinopanax horridum which literally means prickly porcupine ginseng. What an accurate description! Devil’s club does belong to the same family as Oriental ginseng, and like ginseng, it's used as a body balancing and system strengthening tea. Southeast Alaska Natives believe that regular use prevents cancer.”
The prospect of increasing demand has the potential to increase the unregulated harvest. Could be bad because the shrub is sensitive to over-harvesting. Since Devil’s club is extremely important culturally, commercialization also raises concerns about the lack of recognition of and compensation for, the intellectual property rights of indigenous peoples from alaska to BC and Oregon
3. Constraints on dispersal
Forestation loss from 1600s to 2020s in Ontario.
Slightly returning forestation but the remaining groups are far apart affecting dispersal.
The isolation enigma: Dispersal with isolation becomes increasingly important for gene flow, but natural selection can rapidly act against traits promoting gene flow. Why and how?
Areas outside of the patch are dangerous. The more you lay around and stay in your patch, the better your survival. This shows how dispersal is selected against in these scenarios.
Also seen in road crossings of animals. Road kill is an often occurrence for turtles and happens to only individuals who attempt to cross the road, so ones that stay put are positively selected for.
Habitat fragmentation reduces grassland connectivity for both short-distance and long-distance wind dispersed forbs.
Grasses are a wind dispersed species.
Remnant grasslands are practically isolated for seeds dispersed by wind, even for species with high wind dispersal ability
Remaining populations are decreasing in number and size and have low colonization capacity.
Lost dispersal: The disruption of dispersal-based social behaviour in migratory warblers.
Threat of predation is so high, they choose not to fly over open areas/
Norris & Struchbury.
Tracked birds in fragmented rural areas (radio-transmitters)
85% moved <40 m
No bird travelled >500m over open fields, despite being fully capable of flying that distance (they migrate 1000s of km each spring and fall)
40% of matings are mixed (“mating neighbourhoods”)
This social network breaks down with habitat isolation.
Anything over 500 km the birds weren’t flying over it.
4. Dispersal barriers: Disruption of migration
Urban areas with light pollution and tall buildings result in lots migratory birds’ death.
Highway proposed to be built directly across the migratory path of the wildebeest on the Serengeti, Tanzania.
5. Habitat degradation and “traps”
Appearance enigma: remnant habitat looks like a suitable habitat, but something is profoundly absent (“habitat degradation”)
Ecological trap: A sink that looks like a source
Remnant habitat appears favourable but lacks the resources to ensure a full reproductive cycle
Typified in many human-influenced regions, partially due to agriculture.
We live in the Hay and Dairying Region.
Grassland birds attracted by hayfeilds in early spring due to high food levels.
In summer, the fields are mowed before the completion of breeding cycles and the absence of food means that chicks may starve (if the nests survive the tractor…)
Lecture 16
6. Habitat degradation: “Novel environments”
See reverse speciation and homogenization
Natural selection: populations evolve in response to limiting factors on fitness (competition, dispersal, predation, abiotic limits including disturbance).
Global environmental change (the riders): fundamentally reconfigures habitat (the fitness or ‘adaptive’ landscape), but in complicated ways because it all can occur concurrently.
GEC (global environmental change) increasingly creates “novel” remnant habitat, to what was their before.
Increasingly selects for new suites of traits: including non-native species familiar [in adaptive sense] to human-influenced environments … (“it looks like grassland, but its not”)
The stereotypical English country… was fully forested 5000+ years ago.
The neolithic revolution, the expansion of agriculture.
Agriculture began in mesopotamia and expanded outwards from there.
Much of the worlds area is now either cropland or pasture in order to feed the tremendous size of the human population.
Colorado River - 1925
Draining 240 000 square miles, the Colorado River originates high within the mountains of western Wyoming, central Colorado, and northeastern Utah. With snowpack accumulating as high as 14 000 feet above sea level. The mainstream of the upper Colorado River receives large amounts of snowmelt from several major glaciers.
Formerly fast and cold-running … Now slow and warm running with flow consumed by irrigated agriculture, leaving little water to reach the Gulf of California.
7. Extinction Debts
Extinctions debts: the future extinction of species due to past habitat loss and isolation
The species are still present in the patches
Deaths exceed births, but births still occur (eg. L = 0.67)
Implies that species may go extinct due to past habitat destruction even if continued impacts cease, and that current reserves may not be sufficient to maintain the species that occupy them.
8. Dangerous Boundaries
One-sided relationships: sources to sinks
Poison: 1080 stations ringing Yellowstone for decades…
Presentations
Group 3: Beyond Predictions: Biodiversity Conservation in a Changing Climate.
Synopsis
Current method of visualizing the effects of climate change - empirical niche model
Species vulnerability is the extent a a species is threatened with decline
Three keys to vulnerability
Exposure
Sensitivity
Adaptive Capability.
Empirical niche model
Uses a stats relationship between climate and species distribution
General circulation models referenced for predicted species ranges under new climate
Only considers inevitable exposure
Single faceted approach creates risk.
Integrated climate change assessment
Current responses to climate
Ability of a species to adapt
Paleoecology - responses to past climates
Ecological observations in real time
Ecological observations in real time → Intrinsic adaptive capacity for climate change → Biodiversity consequences of the past.
Article breakdown
Hypothesis
Climate envelope alone is not sufficient
Multiple disciplines should be used in vulnerability evaluation
Species climate sensitivity and ability to adapt need to be evaluated
Methods
Pulls evidence and data from multiple disciplines
Paleoclimate data, previous experiments among others
Data and evidence used to illustrate how much more effective this framework could be.
Rethinking conservation in a changing climate
Traditional methods aren’t enough
Adaptive and multi-faceted, not just predictive
Climate change is altering ecosystems unpredictably
Changes in species adaptations
A shift in focus
From preserving species to protecting ecological processes.
Ethical challenges in conservation
Should we intervene and move species/reintroduce extinct species
Balancing human development and conservation efforts
When does displacement become an irreversible loss?
Political, economic and Global implications
Dichloro-diphenyl-trichloroethane (DDT)
How to balance conservation with human well-bind
Local conservation policies are shaped by global priorities - how can we balance both?
Group 4: Ecosystem decay exacerbates biodiversity loss with habitat loss.
Paper summary:
Goal of the paper: Understand how habitat loss and fragmentation impacts biodiversity
Looking for relationship between habitat fragment size and:
Species abundance
Species richness
Species evenness
Ecosystem decay: is proposed as a phenomenon that increases the rate of biodiversity loss caused by habitat loss.
How does biodiversity loss occur? - two complementary hypotheses
Passive sampling hypothesis: species are lost in proportion to their original abundance and distribution
Ecosystem decay hypothesis:
Evenness: species are not evenly distributed in smaller patches (over half of the population is just the blue bug. Not very even
Individuals: density of individuals is disproportionately lower in smaller fragments.
Support for both ecosystem decay hypotheses!
Methods:
Goal of the study: understand how habitat loss and fragmentation impacts biodiversity
Methodology: meta-analysis of 123 studies on habitat fragmentation
Counted abundances of various taxa and categorized observed data based on sampling effort within each study.
Calculated standardized biodiversity indices (standardized species richness, evenness, asymptotic richness).
Compared fragment data using dissimilarity partitioning and many statistical analyses.
Sampling effort standardization
Sampling effort
The amount of effort (time, resources) put into sampling a fragment influences the quality and quantity of data collected.
Can affect species abundances, oversampling or undersampling in certain areas.
Importance of standardizing
Reduce biases
Allows comparability especially for meta-analysis
Improves statistical power
Problems:
Evaluating and comparing the results of 123 studies with varying studying designs and sampling efforts & differentiating the effects of the 2 (often confounded) hypotheses.
Critical analysis
Areas for improvement
Simulation vs. observation
Difficult to assess if results are significant due to decreased variation in simulated data
Line of best fit
Oversimplified or most effective?
Clarity and communication
Important information must be accessible in order to be applied by everyone (scientists, farmers, landowners).
Strengths
Large sample size
Global scale of study
Comprehensive visuals
Major implications for the future of conservation.
Next steps?
Looking for the MECHANISM of patch-scale ecosystem decay
Turnover hypothesis: species are more unique in plots sampled from larger patches (is fragmenting better or worse than habitat shrinkage?)
Habitat fragmentation debate: Single large vs. several small?
How do we apply this information in Ontario?
Proposed highway will fragment local ecosystems right here in Ontario. Some people call for this highway not to be built.