Current warming and likely future impacts - Climate Change: Biological and Human Aspects - page 276

(a)

Uniform Non-uniform

P r n F u e P r n F u e

A
________
A
____________ B
___________
B
________________

A
_______
B
_________
A
_____________ C
B _____________
__________________

C

C

C

(b)

Uniform Non-uniform

Future F u e

A A

Present P r n

B B

C A

A

C

B B

C

C

Fig. 6.2 (a)Verticalmigrationofspeciesandcommunitiesduetoclimaticwarmingisfrequentlynotuniform.

Individualspeciesrespondtodiferentenvironmentalfactorsdiferently.Consequentlythereislittle
reasonforuniformmigration.AnexampleisgivenrelatingtoFigure4.10.(b)Horizontalmigrationof
speciesisrarelyuniform(seeChapter4withreferencetoglacial-interglacialchange).Aswithvertical
migration,thisisduetodiferentspeciesrespondingwithdiferentsensitivitytodiferentenvironmental
dimensions,ofwhichclimate(itselfmulti-dimensional)isamongmanyotherfactors,whichtogetherwill
determineaspecies'spatialdistribution.Thismakespredictionofecologicalresponsetoclimatechange
difficult.

disjunction was worse, with plant species responding to only 0.02 ◦ C of a 1.11 ◦ C
warming: there was a larger temperature lag between plant communities in lowland
than highland communities.
The explanation for this is multi-faceted. First, highland areas are more moun-
tainous and so species only need to migrate a short distance horizontally to change
their altitude considerably, and hence their local climatic conditions. This is not so
with lowland species, which have a reduced number of short-distance escapes open
to them. Second, highland species, because of short-distance climate vagaries, are
naturally adapted to be more able to survive a degree of climate variability, and hence