Responses of terrestrial Antarctic ecosystems to climate change

Abstract

Antarctic terrestrial biota are generally limited by the inexorably linked environmental factors of low summer temperature and lack of available water. However, in parts of the Antarctic, both these factors are changing rapidly on contemporary timescales. Terrestrial biota have concurrently been faced with changes in the timing of UV-B maxima associated with spring ozone depletion. The region of the Antarctic Peninsula and Scotia Arc has experienced one of the most rapid rates of environmental warming seen worldwide over the last 30 -50 years. Together with local changes in precipitation, this has resulted in a rapid reduction in extent and thinning of many ice-fields and glaciers, exposing new terrain for colonisation while, at the same time, altering patterns of water availability in terrestrial habitats. The rapid development of communities on newly-exposed ground is also facilitated by the existence of soil propagule banks, which contain propagules of both local and exotic origin. In this paper we collate and review evidence from a range of observational and manipulative studies that investigate the effect of climate change, especially increased temperature, on the processes of colonisation and subsequent community development by plants in the Antarctic. Biological changes that have been associated with climate change are visible in the form of expansions in range and local population numbers amongst elements of the flora. Environmental manipulation experiments further demonstrate the possibility of large and rapid species and community responses to climate amelioration, with many resident biota responding positively, at least in the absence of increased competition from exotic colonists. Manipulation studies are also starting to elucidate more subtle responses to climate changes, at levels ranging from cell biochemistry to habitat and food web structure. Integrating such subtle responses is vital to improving our ability to understand the consequences of climate change, as these may lead to much greater consequential impacts on communities and ecosystems.

Bacterial diversity in rhizosphere soil from Antarctic vascular plants of Admiralty Bay, maritime Antarctica

“…A considerable increase in the number of both D. Antarctica and C. quitensis colonies in the western Antarctic Peninsula has been already reported, which seems to be a response to the increasing summer air temperatures (Convey and Smith, 2006). The soil bacterial community may change as less extreme weather conditions promote the activation of sporeforming cells.…”

Microbiology of Eutrophic (Ornithogenic and Hydrocarbon-Contaminated) Soil

“…A continent-wide increase in temperature of 0.12°C per decade has been observed over the 50 year period from 1957 to 2006 (Steig et al 2009). Increases in temperature are predicted to continue to drive decreases in snow and ice cover, increases in water and nutrient availability, and increases in vascular plant and bryophyte populations, which have already been reported along the Scotia Arc and Antarctic Peninsula (Convey and Smith 2006). Bacterial communities will likely show rapid and significant responses in structure, activity and diversity to the changes predicted by current climate change scenarios.…”

Evaluation of frozen ground conditions along a coastal topographic gradient at Byers Peninsula (Livingston Island, Antarctica) by geophysical and geoecological methods

“…The icefree environments correspond mostly to nunataks and small peninsulas distributed along the coastal fringes of those islands. It is in these deglaciated terrestrial ecosystems of Maritime Antarctica where biodiversity is greatest (Convey and Smith, 2006).…”