Changes in soil-plant-microbes interactions in anticipated climatic change conditions

Abstract

Ongoing global climate changes caused by human induced greenhouse gases (GHGs) represent one of the biggest problems in the twenty-first century. Terrestrial ecosystems play a major role in such climate change feedbacks because they release and absorb greenhouse gases such as carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) while storing large quantities of carbon (C) in living vegetation and soils, thereby acting as a significant global C sink. The influence of climate change on the soil C sink remains a major area of uncertainty, especially as there is scope for warming induced liberation of CO2 from soil to atmosphere due to enhanced microbial decomposition. The consequences of increased C flux from roots to soil for microbial communities and C exchange are difficult to predict, because they will vary substantially with factors such as plant identity, soil-food-web interactions, soil fertility and a range of other ecosystem properties. The interrelationship of soil microbes and C exchange include: (1) increases in soil C loss by respiration and as dissolved organic C due to stimulation of microbial abundance and activity; (2) stimulation of microbial biomass and immobilization of soil N, thereby limiting N availability to plants, creating a negative feedback that constrains future increases in plant growth and C transfer to soil; and (3) increased plant-microbial competition for N, leading to reduced soil N availability and microbial activity and suppression of microbial decomposition leading to increased C accumulation. In this chapter we will assess the complex interactions among plant, soil and microorganisms that influence climate change scenario.