Lecture 9a: global climate change impacts: biodiversity Flashcards
Global climate change: impacts on biodiversity
*Over this century, climate change is predicted to become one of the greatest drivers of biodiversity loss
*The ways that climate change impacts manifest are varied, and this will be our focus today
Some examples of avian recent arrivals in the UK
Eurasian spoonbill
Purple heron
Little bittern
Tree-lichen beauty
Response to climate change: What are the options?
- Move
- Adapt
- Die
^ as conservationists we aim to reduce outcome 3 by facilitating 1 and 2
How have species adapted in the past?
Species on the move: UK and Europe
species on the move, UK:
*Fauna of the UK over the last 130K has included examples of what we currently consider tropical, steppic and arctic communities.
*Lion, hippo, spotted hyena were in UK as we had a tropical climate
*Przewalski’s horse, muskox, Norway lemming when we had an arctic steppe type climate
*Grey wolf, pika, saiga antelope – more like our current climate
*These species used to occur in the UK and, for the large part, they still exist somewhere in the world today, despite substantial climatic changes – probably as a result of range shifting.
Species on the move in Europe:
*We can document these past ranges shifts in some taxa to a high resolution.
E.g. Using pollen to trace shifts in tree species across Europe since the last glacial
*Pollen is however limited in that some species show up more easily, and conditions of preservation might vary with latitude
How have species responded in the past:
Range shifts
As climate improves:
*Limits at a range edge relax
*Propagules always disperse beyond margins
*Usually fail to establish but can establish as climate alters
*Species range margin advances – dynamic equilibrium with climate
Where climate becomes less favourable:
*Mortality within range increases, establishment declines
*Margin shifts
Quaternary record abounds in evidence of such responses
*Confident that such responses will occur now and in future
The dominant response of species to large scale climate change…?
Species staying and adapting?
*Relatively easy to determine distribution from fossil record
*Adaptation in situ is harder to detect (usually in morphology)
Example: Moss chrysalis snail. (bigger as it gets colder in situ)
^see notes for diagrams
They are Included here to make the point that although past changes may have been adaptive, spatial responses are the most likely way by which many species will respond.
*Do see a range of sizes that might broadly map to climate and show change in morphology with climate
*But … never evolved beyond current size range
*Might have moved as well as changed morphology
How have species responded in the past:
Dominant evidence is range shifts but adaptation plays a role
See Davis and Shaw 2001 (Science)
another pollen study, blue represents ice sheet
*This example is included to show that different species have shifted in different ways, which suggests that the underlying mechanisms driving range shifts are not the same
*The fact that oak pollen has lingered in SW USA pollen cores demonstrates that there were populations that could withstand and thrive in warmer temperatures than present 21ka
^oaks appear to have adapted in situ
Extinction
*If adaptive and range shifting responses don’t occur, or occur at too slow a rate, species may go extinct
*Examples of extinct large mammals across Europe include Mammoths, ‘giant deer’ and the auroch which is a cow-like ancestor.
Extinction will occur when:
*Conditions to which adapted are no longer present
*Are present but spatially separated
*Are present but with a temporal discontinuity
e.g. difference between flowering time and pollinator presence
*Shift so rapidly that species cannot keep up
Numerous extinction candidates in the face of future Δ climate
*High latitudes and elevations most vulnerable
*Geographically restricted distributions
*Long-lived taxa (slow to mature)
Running out of livable habitat
However, which species are most vulnerable is still debatable
Notwithstanding extinction - dominant observed response is spatial
We need some idea of magnitude of impact
*Importance for biodiversity conservation
*Allows us to plan adaptive conservation measures
We must identify which species/habitats are most vunerable
We can fit static models relating distributions to climate :
*If good relationship - simulate potential future distribution under a forecast future climate
We have explored this for plants, butterflies, birds, reptiles and mammals:
*Models usually fit well or very well
If we can predict the spatial response of different species, we can start to plan conservation strategies to facilitate range shifts. In the next series of slides, I will very quickly give you an idea of how we project potential distributions under future climate change.
Introduction to species distribution modelling : MTWA, PRECIP & MTCO
MTWA (mean temp of warmest month) :
*For a period in time for which we have distribution data for a species we can extract climatic data such as temperature.
*This plot displays mean temp of the warmest month across Europe.
MTCO (Mean temp of coldest month)
(as above)
other important climatic variables can determine species range margins, such as PRECIP: precipitation
*these can be used to derive additional bioclimatic variables e.g. growing degree days, actual to potential evapotranspiration
To predict where the species of study occurs and will occur in future
- often of more relevance to the occurrence of species
Observed vs. model
Observed: Bioclimatic data can be used with species distribution data to produce a model simulating occurrence in relation to climate
Simulated: simulation models can use a variety of different methods
e.g. Locally-weighted regression, GAM, GARP, ANN, MAXENT
^ All fit a mathematical relationship to describe the species’ distribution in terms of bioclimate variables and with this information, we can then test the model to see how well it describes the known range .
Assess the agreement between the observed and the simulated distribution
(e.g. Kappa values >0.85 is an excellent fit)
This simulated distribution can also be mapped in “climate-space” to reveal the relationship between a species and climate using future climate projections allows us to simulate where suitable climate will occur in the future
see: Huntley et al. (2007) A climatic atlas of European breeding birds
figure Mapping probability of occurrence against diff climate variables
*We can visualise the model predictions in climate space or by projecting them onto a landscape.
*On the left here, we can see that Nightingale tends to occur only in areas where the mean coldest month temperature is above -5 and the summer warmth (GDD5) is above 2000 degree days
see notes for more bird examples - these models have been used to predict ranges for species across a range of different ecosystems
Background to climate change relationships
*Climate explains the range of most species at a large scale
Exception - massive habitat destruction or persecution
*At smaller and smaller scale - habitat becomes more important at determining the fine scale distribution
But habitat continuity may be an important determinant of range shift
*Climate might not be the direct driver (also affects distribution of habitat)
*At smaller and smaller scale, habitat is also linked to microclimate
If we apply these models of species-climate relationships to predictions of future climate, we can get an indication of where the species could occur in the future
Our modelled future response
Using a climate change scenario of ~2.5oC mean global warming by end of next century
For Europe we typically forecast:
*Large-scale range reductions at SW margin for Northern spp.
*Large-scale NE’ward range expansion for southern species
*Range margins of mid-European species shifting N’wards by 1000km or more
For species with small ranges – overlap very small – sometime absent
e.g. Hill et al 2002 butterfly study
The Silver-spotted Skipper simulations are typical for many species – a retraction in range at the southern margin and a potential to spread at the northern margin
Potential species responses
We calculate a best case (all new area occupied) and a worst case (overlap only occupied) scenario of range shift for each species
We can crudely classify potential responses dependent upon whether a species tracks climate perfectly (best-case)…or fails to spread into new areas but disappear from unsuitable areas (worst-case).
In reality, the truth will lie somewhere between.
Avian diversity across Europe
see maps in notes
1985-1990 Europe map shows highest diversity in Eastern Europe
2070-2099 simulation projects a shift to highest density in Northern Europe
So in the future the areas of highest spp. diversity could shift into Fennoscandia, and diversity could decline in e.g. Spain in the south
In general, for Europe we should modify conservation management plans to facilitate substantial range shifts to the north/north-east
For recent changes see EBBA2 2021:European bird atlas data
Conservation of species at high elevation and high latitude
Study of Doterrel (bird) and Euryops arabicus (shrub) see notes
^Are examples of a species that will be lost from UK as UK is its southernmost range area
^will be lost from red latitudes resulting in population isolation
We can also expect species that occur at high latitudes or at high elevations to have reduced populations in future.
e.g. dotterel (current southern limit = Scottish highlands, and high tops of Pennines in UK – but probably now gone as a breeding species from latter in the last decade. Range potentially shifting north (ad decline by end of century.
e.g. – mountain pipit (endemic to southern Africa. Polygons are PAs [though big polygon is outline of Lesotho). Note elevation increases from R to L towards Lesotho; blue on left = occupied areas at present, on right, red = predicted unsuitable in future, blue = predicted suitable in future. i.e.spp becoming restricted to higher elevation parts of highest elevation PAs
Similarly Apalis ruddi (bird) is a species whose future range is geographically distant from its current range might need a helping hand. Required shift is circa 750km across largely unsuitable landscapes
Impacts on protected areas (PAs)
*We can infer potential changes in protected areas in a number of ways:
- e.g. simply intersect suitable climate and protected areas
To infer changes in composition in protected areas we could simply intersect the gridded range projections with the protected areas. This gives a first approximation of species that might colonise/leave
see diagram in notes showing that protected areas in the right places could create stepping stones for movement to new range
Conservation strategies will need to be adapted:
*Buffer zones around reserves?
*Corridors between reserves?
*Stepping stone reserves?
*Softening the matrix? Making inhospitable transition areas more hospitable to allow movement
There are a variety of conservation tools that could be applied to help species cope with projected changes in climate
Some species are already responding
see distribution maps in notes
A whole range of species are altering their range across the UK, probably largely driven by climate change.
*Spp are (from top): comma, dartford warbler, marbled white, small skipper, purple hairstreak, little egret.
*Map shows range shift in comma between 1970-2000 (pink = expansion.
*All of the spp. Above with exception of Drtford warbler have colonised new areas of Co. Durham in recent decades, usually for the first time (MW example is unusual as we gave it a helping hand (covered later).
Species moving northward and uphill in the UK: see figure in notes from Hickling et al 2006 (global change biology)
Evidence of range shifts
Thomas and Lennon (1999) Nature
* 19km northerly shift in breeding margin for UK birds
Speckled Wood butterfly study
Parmesan (1996) Nature
* Going extinct in low latitudes and at low
elevations
Parmesan et al (1999) Nature
Of 35 non-migratory Euro butterflies:
*63% shifted N by 35—240km during 20th Century
*only 3% have Shifted to the south.
See also ‘Bioshifts’ - a large database of range shifts for many taxa
&
Lenoir et al Nat Ecol Evol (2020)
Recent and historic butterfly range shifts UK example Comma Butterfly
see maps of distribution at diff dates in notes:
One example of recent rage shift is that of the Comma butterfly which although formerly widespread, contracted its range in the 1800s to a minima at around 1917. However by 1999 it has once again expanded its range to occupy almost all of its fomer haunts. Whether this recent expansion was climate-driven or due to some other factor is unknown. Since 2000 has expanded well into Scotland
- a high mobility generalist that is tracking climate change
species-climate models show that this species now occupies close to the full availability of climatically suitable areas
Note - not all butterfly species responding in the same way e.g. By contrast, it appears that the Silver-studded blue has been unable to track recent improvements in suitable climate across the UK
One possible solution to conservation in climate change is translocation of species
See Willis et al 2009 butterfly translocation attempt appeared successful
As a test of species-climate models’ predictive ability. We introduced a population of Marbled White butterfly into a region close to Durham that we modelled to be climatically suitable but where it didn’t occur at the time (Wingate Quarry about 8 miles from Uni)
^ For over 10 years the populations has persisted and continues to expand, suggesting that these climate models are providing useable information about climate suitability for individual species. Top left = intro site, top right = localities of individual in 2009 breeding season. Bottom left = increase in population in years since introduction.
Translocation was successful
^Translocation can have invasive effects – this needs to be considered in conservation efforts
