climate change part one: range shifts (lecture 10) Flashcards
Is climate change natural or human forced?
- historically temperature and CO2 have varied: from billions of years ago to recently
- more recently there has been a strong association between two
- CO2 recently moved permanently above 400ppm
- also other green house gases e.g. methane, NOx, CFCs
- observed climate change matches with anthropogenic AND natural forcing, not natural forcing alone
- biggest single contributor to forcing is increase in CO2
What are the major abiotic impacts of climate change?
- higher temperatures
- reduced rainfall
- ocean acidification
- sea level rise
How does species distribution relate to climate?
- controlled by winter cold limit, summer cold limit, summer moisture limit
How are species ranges shifting latitudinally?
- most species moving north
- some not moving
- 22% shift in opposite direction
- shifts are faster in areas with more rapid warming
- generally range shifts track climate change but far from always
How do species traits explain variation in latitudinal shifts?
- greater dispersal ability
- reproductive rate: generation time & number of offspring
- ecological generalisation
Does environmental quality explain variation in range shifts?
- if species are shifting range, likely to target high quality habitats
- good quality habitats like protected areas tend to fill up quickly
- overcrowding and subsequent extinction debt
How are species ranges shifting altitudinally?
- 300m increase in altitude = 1.5-3oC temperature fall
- shorter distance that latitudinal shift so expect a stronger response in elevational range shifts
e. g. small mammals shifted 500m up yosemite over last hundred years
e. g. geometrid moths shifted 65m up Mt. Kinabalu (Borneo) over 40 years
How to predict altitudinal shifts in range?
- elevational shifts more limited than latitudinal shifts
- species traits are poor predictors of altitudinal shape
- limited by slope or altitude?
- are vegetation shifts delayed?
How are bioclimatic envelopes used to predict range shifts?
- principle is to record the relationship between a species current distribution and the current climate
- feed predictions of future climate into this relationship to predict future distributions
What are general findings for range shifts?
- north eastern shifts in range boundaries, typically several hundred km
- average future range sizes 80% of that of current
- 31 species predicted to have as little as 10%
- average overlap of current and future species 38-53%
- mean for endemics 14-34%
- 10 species 0% overlap
What are problems with using bioclimatic envelopes to predict range shifts?
Not based on global ranges: climate distribution association may not be reliable
- e.g. thekla lark predicted to lose 75% existing range, only lost 35%
- species can cope with warmer drier climates
Spatial scale - based on average conditions in a large grid cell
- is it an appropriate spatial scale for conservation planning?
Ignores local adaptation - assumes that all
individuals have an identical response to
climate
- local individuals can have a “home advantage”
Assumes climate regulates range limits
- ignores dispersal, competitive interactions, human factors
Can bioclimatic envelope models work?
- marbled white and small skipper butterflies
- introduced to two areas north of range but bioclimatic envelope predicted suitable
- populations increased
(Willis et al., 2009)
What are the conservation implications of range shifts?
- Lawton (2010) white paper
- enhance connections between, or join up, sites, either through physical corridors, or through stepping stones
- create new sites e.g 12 nature improvement areas
identified in 2012 - assisted colonisation?
- within or between countries
