Pool complexity and molecular diversity shaped topsoil organic matter accumulation following decadal forest restoration in a karst terrain

作者：Shuotong Chen, Feng Xiao, Qingmei Lin, Chun Liu, Kun Cheng, Xuhui Zhang, Rongjun Bian, Xiaoyu Liu, Yan Wang, Μάριος Δρόσος, Jufeng Zheng, Lianqing Li, Genxing Pan · 发表于：Soil Biology and Biochemistry · 年份：2022 · DOI：10.1016/j.soilbio.2022.108553 · 被引用次数：60 · 研究领域：Soil Carbon and Nitrogen Dynamics、Geology and Paleoclimatology Research、Soil erosion and sediment transport

Fast accumulation of soil organic matter (SOM) following forest restoration shifted from cropland has been widely reported, but how the pools and molecular composition change across soil aggregate fractions remains unclear. In this study, undisturbed topsoil (0–10 cm) samples were collected across a decadal chronosequence of forest stands (RL10, RL20 and RL40) restored for 10, 20 and 40 years following maize cropland (CL) abandonment in a karst terrain of Guizhou, Southwest China. SOM changes were explored using the size and density fractionation of water-stable aggregates, 13C isotopic signalling and biomarker analyses as well as 13C solid-state NMR assays. Compared to that of CL, SOM content was increased by 24%, 79% and 181%, mass proportion of macroaggregates increased by 136%, 179% and 250%, and particulate organic matter (POM) increased by 13%, 108% and 382%, respectively at RL10, RL20 and RL40. With biomarker analyses, the relative abundances of plant-derived organics (lignin, cutin, suberin, wax and phytosterols), mostly protected in aggregates, increased, while those of microbe-derived OC, predominantly mineral bound, decreased in response to prolonged forest restoration. Calculated as per the Shannon diversity index (H’), changes in SOM pool complexity and molecular diversity were parallel to the SOM accumulation trend. The pool size ratio of POM to MAOM (mineral-associated organic matter) and the molecular abundance ratio of PL (plant-derived lipids) to ML (microbe...