As water supply is critical for plant growth, it plays a key role in determining the distribution of plants. Changes in precipitation are predicted to be less consistent than for temperature and more variable between regions, with predictions for some areas to become much wetter, and some much drier.
Environmental variables will not act in isolation, but also in combination with one other, and with other pressures such as habitat degradation and loss or the introduction of exotic species. It is suggested that that these other drivers of biodiversity change will act in synergy with climate change to increase the pressure on species to survive.
Direct impacts of climate change
Changes in distributions
Pine tree representing an elevational tree-limit rise of 105 m over the period 1915–1974. Nipfjället, Sweden If climatic factors such as temperature and precipitation change in a region beyond the tolerance of a species phenotypic plasticity, then distribution changes of the species may be inevitable. There is already strong evidence that plant species are shifting their ranges in altitude and latitude as a response to changing regional climates.
When compared to the reported past migration rates of plant species, the rapid pace of current change has the potential to not only alter species distributions, but also render many species as unable to follow the climate to which they are adapted. The environmental conditions required by some species, such as those in alpine regions may disappear altogether. The result of these changes is likely to be a rapid increase in extinction risk. Adaptation to new conditions may also be of great importance in the response of plants.
Predicting the extinction risk of plant species is not easy however. Estimations from particular periods of rapid climatic change in the past have shown relatively little species extinction in some regions, for...
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