The terrestrial biota of the polar regions are thought to be particularly sensitive to various aspects of climate and environmental change. Superimposed on the differing northern and southern historical templates of biogeography, this biota now faces the twin challenges of responding to the complex processes of climate change, and the direct impacts associated with human occupation and travel to and between the often very limited areas of terrestrial habitat. Given the magnified rates of change in some environmental variables being experienced at higher latitudes, combined with the relative simplicity of many terrestrial communities, these ecosystems are expected to provide important model systems and ‘early warnings’ of the type of responses that may be important in ecosystems globally. Focusing on terrestrial invertebrates and plants, this paper integrates and reviews information available relating to change responses from both ecological observation and manipulation studies in the Antarctic and Arctic, and will include consideration of impacts and responses seen at biological scales of organisation from the genomic to the ecosystem.
Results/Conclusions
In many instances (although there are exceptions), this biota is likely to benefit from environmental changes which increase available energy (i.e. temperature increase) and allow liquid water to be more available to organisms. Where these conditions exist, there is an expectation of increased production, biomass, population size, community complexity, and colonisation, all of which are supported by data from environmental manipulation studies along with more limited examples of direct observational evidence. In detail, many of these responses will be mediated through changes in allocations of energy budgets within organisms, and energy flow patterns within trophic webs, although few studies yet explicitly address these important subjects. However, the impacts of climate change may themselves be outweighed by other, direct, impacts of human activities. In particular, the introduction of non-indigenous organisms from which until now the terrestrial ecosystems (of Antarctica in particular) have been uniquely protected have become a reality over the last few decades to centuries, with human-mediated examples far outweighing those attributable to natural colonization events. Once established, such species can in some cases act as ecosystem engineers, causing drastic changes in ecosystem structure and function. Establishment events are expected to occur more frequently as regional climate warms, along with changes in distribution extents. Examples of synergy between climate change impacts on biota and these types of direct human impact on biodiversity are also already apparent.