Soil Organic Carbon Dynamics: Drivers of Climate Change-induced Soil Organic Carbon Loss at Various Ecosystems

At roughly 2500 Peta gram (Pg) C, soil organic carbon (SOC) is the biggest carbon store in terrestrial ecosystems and is a crucial contributor to vital soil functions and ecosystem services, such as agricultural soil productivity. SOC stocks are in a dynamic equilibrium between C inputs, primarily from crop residues and organic manures, and C loss owing to decomposition and mineralization of soil organic matter (SOM) under long-term constant land management and environmental circumstances. In addition, the rate of C addition in native ecosystems is governed by the nature and productivity of the local flora, which is mostly influenced by climatic conditions. However, being a complex system, various factors, such as soil management and land-use change influence the soil C pool. Along with temperature gradients from temperate to tropical regions, SOC supplies were shown to be shrinking on a global and regional basis. This reflects the rates of SOM decomposition as a function of temperature, which fluctuates more rapidly than net primary production (NPP). SOM decomposition rates are also influenced by several parameters, including soil temperature and moisture, soil respiration and pH, and soil physical properties including texture and clay mineralogy. Nonetheless, increased temperatures as a result of climate change are thought to be the primary driver of accelerated decomposition, which results in considerable reductions in SOC supplies and sequestration. Furthermore, climatic change contributes to soil deterioration by increasing the mineralization of the SOC pool and causing desertification (irreversible expansion of desert landforms). Similarly, erosion is a degrading process that affects C dynamics and leads to terrestrial carbon loss through the breakdown of structural aggregates, as well as lower productivity in eroding areas due to a lack of soil nutrients. Thus, for an in-depth understanding of worldwide soil C dynamics and to provide support to C management and decision support systems to policymakers and land managers in the face of changing climates, comprehensive research on the influence of multiple climate-induced drivers on soil C is required.