by Alex Nuffer

Atmospheric CO₂ has risen substantially due to an increase in fossil fuel combustion and the clearance of land for agriculture, significantly affecting global climate. Climate models predict that there will be an increase in temperature, as well as a change in precipitation patterns in the future. Variations in climate are likely to modify soil respiration and the soil carbon cycle, causing soil organic carbon to increase or decrease, which will either lead to a positive or negative feedback for atmospheric CO₂. Poll et al. (2013) investigated the manipulation of various climate change factors on soil respiration and soil carbon cycle in an arable soil at field-scale in a temperate agricultural ecosystem. The experiment was established on an arable field, where temperature, precipitation amount, and frequency were manipulated to simulate various climate change scenarios. For two years CO₂ efflux was measured weekly. Additionally, plant and soil microbial biomass were determined to accurately assess the effects of climate change factors on soil respiration. The results underlined the importance of soil water content to the response of ecosystems to climate change. There was a negative effect of increased soil temperature on soil moisture, which led to water limitation. Soil respiration and microbial biomass under increased soil temperatures were limited by water in the first year, but not in the second year. Altered precipitation showed only minor effects during the entire experiment. The study showed that the soil moisture regime under increased temperatures could determine whether soils are carbon sinks or sources. Continue reading →