耕地废弃后，植物生产力和微生物组成驱动土壤碳氮固存。
Plant productivity and microbial composition drive soil carbon and nitrogen sequestrations following cropland abandonment.
机构信息
State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling, Shaanxi 712100, China; University of Chinese Academy of Sciences, Beijing 100049, China.
Institute of Soil and Water Conservation, Northwest A&F University, Yangling, Shaanxi 712100, China.
出版信息
Sci Total Environ. 2020 Nov 20;744:140802. doi: 10.1016/j.scitotenv.2020.140802. Epub 2020 Jul 11.
Understanding the variations in soil organic carbon (SOC) and total nitrogen (STN) stocks in the different ages of abandoned cropland ecosystems of different ages is essential for land use decisions to maximize C sinks or improve ecosystem services. However, knowledge of the dynamics of SOC and STN stocks and their controlling factors after cropland abandonment is limited. Thus, this study investigated the changes in the SOC and STN stocks of loessal soil (Calcaric Regosols) with a chronosequence of 3, 8, 13, 18, 23 and 30 years following cropland abandonment on the Loess Plateau. As a whole, we examined 42 field plots and implemented multivariable linear regression analysis (MLRA) and structural equation modeling (SEM) using 22 influencing variables related to plant, soil and microbial properties to quantify the controls of SOC and STN stocks. The results revealed that SOC and STN stocks significantly increased after cropland abandonment for 30 years, and there were minor decreases in C and N sequestrations in the early restoration stage (<18 years). The SOC and STN changes had significant positive correlations, in which that exhibited STN stocks shifted concurrently with the rate of relative SOC stock changes. The MLRA models demonstrated that the SOC stocks were primarily controlled by aboveground biomass, STN, fungi, and the ratio of fungi to bacteria, while STN stocks were mainly driven by root biomass, above-ground biomass, STN, fungi and the ratio of fungi to bacteria after cropland abandonment. The SEM models further demonstrated that plant productivity not only directly determined the variations in SOC and STN stocks but also changed the microbial community following post-cropland restoration. These results suggest that long-term (>18 years) cropland abandonment can be a successful approach for reinstating SOC and STN stocks, while plants and microbes together mediate microbial C and N stocks during vegetation succession in a semiarid region.
了解不同年龄阶段撂荒地生态系统中土壤有机碳（SOC）和总氮（STN）储量的变化对于土地利用决策至关重要，因为这些决策可以最大限度地增加碳汇或改善生态系统服务。然而，对于撂荒后 SOC 和 STN 储量及其控制因素的动态变化，我们的了解还很有限。因此，本研究通过黄土高原撂荒土壤（钙化正常新成土）的时间序列（撂荒后 3、8、13、18、23 和 30 年）调查了 SOC 和 STN 储量的变化。总体而言，我们研究了 42 个野外样地，并采用多元线性回归分析（MLRA）和结构方程模型（SEM），使用与植物、土壤和微生物特性相关的 22 个影响变量来量化 SOC 和 STN 储量的控制因素。结果表明，SOC 和 STN 储量在撂荒 30 年后显著增加，在早期恢复阶段（<18 年），C 和 N 的固存略有减少。SOC 和 STN 的变化呈显著正相关，其中 STN 储量与相对 SOC 储量变化率同步变化。MLRA 模型表明，SOC 储量主要受地上生物量、STN、真菌和真菌与细菌的比值控制，而 STN 储量主要受根生物量、地上生物量、STN、真菌和真菌与细菌的比值控制。SEM 模型进一步表明，植物生产力不仅直接决定了 SOC 和 STN 储量的变化，而且还改变了撂荒恢复后微生物群落的变化。这些结果表明，长期（>18 年）撂荒可以是恢复 SOC 和 STN 储量的成功方法，而植物和微生物共同调节半干旱地区植被演替过程中的微生物碳和氮储量。
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