Arbuscular mycorrhizal fungal communities and global change: an uncertain future.

Arbuscular mycorrhizal (AM) fungi are amongst the most common and functionally important symbionts of terrestrial plants and are highly likely to be affected by global change. The potential consequences of this on plant growth and carbon and nutrient cycling has led to a growing demand for their inclusion in global change models. However, our understanding of their responses to environmental change remains limited. This review provides an overview of recent experiments attempting to predict the effects of atmospheric and climatic change on AM fungal community diversity, composition and functioning. This includes rising atmospheric carbon dioxide and tropospheric ozone levels, altered water availability, warming and nitrogen deposition. Changes detected are often highly variable and context dependent, but trends are emerging such as the similar responses of community composition to enhanced nitrogen deposition and atmospheric CO2, despite the likely contrasting effects of these environmental changes on carbon availability. The review also highlights shortfalls in our current knowledge and suggests priorities for future research, particularly advocating more integrated approaches linking the study of community characteristics and functions and examination of fine level genetic changes, wider geographical contexts and a greater range of AM fungal functions.