The turnover of soil organic carbon (SOC) is primarily regulated by extracellular enzymes secreted by the microorganism. Land use change greatly alters quantity and quality of soil organic matter (SOM), as well as environmental properties such as soil microclimates and pH.
These changes lead to substantial variation in the SOC pool and microbial composition in various ecosystems, which can potentially impact soil extracellular enzyme activities. However, how soil C-decomposition enzymes respond to different land use change remains unclear.
Supervised by Prof. CHENG Xiaoli, ZHANG Qian, a doctoral student from Wuhan Botanical Garden of Chinese Academy of Sciences determined seasonal variations in C-decomposition enzyme activities including hydrolases and oxidases and C contents in woodland, shrubland, cropland, and adjacent uncultivated soils in Central China. The finding was published in Land Degradation & Development.
Researchers found that compared with the uncultivated land, higher hydrolase activities in afforested land were related to higher soil dissolved organic C and labile C contents, whereas in cropland soils, it might be attributed to higher labile C, nitrogen (N) fertilization, tillage, and lower C:N ratios.
Besides, they found that the highest oxidative enzyme activities in the cropland could be attributed to higher soil C recalcitrance Index and lower C: N ratio, and cropland increased specific enzyme activities compared with afforested land, indicating fast C turnover rates in cropland.
The results suggested that afforestation could not only increase SOC content by increasing litter input but also enhance soil C sequestration and stabilization by reducing soil C turnover rate driven by the soil extracellular enzymes.
Soils contain the major reservoir of organic C in terrestrial ecosystems, and decomposition of SOC by microorganisms potentially affects global C cycling.
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