climate change part one: range shifts (lecture 10) Flashcards Preview

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1

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

2

What are the major abiotic impacts of climate change?

- higher temperatures
- reduced rainfall
- ocean acidification
- sea level rise

3

How does species distribution relate to climate?

- controlled by winter cold limit, summer cold limit, summer moisture limit

4

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

5

How do species traits explain variation in latitudinal shifts?

- greater dispersal ability
- reproductive rate: generation time & number of offspring
- ecological generalisation

6

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

7

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

8

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?

9

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

10

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

11

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

12

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)

13

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