Climate change, deforestation and ecosystem functioning in the Amazon and Andes

Yadvinder Malhi, Oxford University

The possible "die-back" of the Amazon rainforest has become one of the iconic yet controversial images of global climate change. I explore the probability of such large-scale degradation over the 21st, highlighting in particular some of the field research being done by my research group. Recent field studies in Amazonia suggest that intact rainforests are more resilient to a moderate enhancement of drought than, through processes of soil water retention and hydraulic uplift. There is significant evidence of an increase of forest growth and biomass, possibly as a response to atmospheric carbon dioxide, and this response may be altering the composition and dynamics of Amazonian forests. Tropical montane forests of the Andes are likely to play an important role as refugia for lowland species ill-adapted to the increasing warmth, but suffer their own vulnerability through rising cloud levels and the challenges of upslope migration. The interaction of intact forests with nearby areas of deforestation and degradation greatly increases the vulnerability of forests, through increasing the amount of forest edge and the degree of penetration of forest fires.