中文关键词撂荒恢复团聚体土壤稳定性有机碳储量(TOC)贡献率 英文关键词the restoration of abandoned landaggregatesoil stabilitysoil organic carbon stock(TOC)contribution

作者	单位	E-mail
王兴	西北农林科技大学农学院, 杨凌 712100 陕西省循环农业工程技术研究中心, 杨凌 712100	wangxing1996@nwafu.edu.cn
钟泽坤	西北农林科技大学农学院, 杨凌 712100 陕西省循环农业工程技术研究中心, 杨凌 712100
张欣怡	西北农林科技大学农学院, 杨凌 712100 陕西省循环农业工程技术研究中心, 杨凌 712100
吴少君	西北农林科技大学农学院, 杨凌 712100 陕西省循环农业工程技术研究中心, 杨凌 712100
卢绪巧	西北农林科技大学农学院, 杨凌 712100 陕西省循环农业工程技术研究中心, 杨凌 712100
杨改河	西北农林科技大学农学院, 杨凌 712100 陕西省循环农业工程技术研究中心, 杨凌 712100
任成杰	西北农林科技大学农学院, 杨凌 712100 陕西省循环农业工程技术研究中心, 杨凌 712100
韩新辉	西北农林科技大学农学院, 杨凌 712100 陕西省循环农业工程技术研究中心, 杨凌 712100	hanxinhui@nwsuaf.edu.cn

中文摘要 为探究撂荒地恢复过程土壤团聚体组成结构及其对土壤碳库累积的影响，本研究选取陕北黄土丘陵区恢复10、17、27和42 a撂荒草地为研究对象，以坡耕地FL作为对照，分析不同年限撂荒草地以及耕地土壤（0~20 cm）与（20~40 cm）土层团聚体粒径分布、土壤全土有机碳储量以及团聚体有机碳储量动态特征，从而探究撂荒地土壤团聚体与有机碳之间的相互关联性.结果表明：①耕地恢复为撂荒草地后，土壤大团聚体（>2 mm）和中团聚体（2~0.25 mm）数量、平均重量直径（mean weight diameter，MWD）和几何平均直径（geometric mean diameter，GMD）随着撂荒年限显著上升，而土壤微团聚体（0.25~0.053 mm）数量显著下降（P<0.05）.土壤大团聚体数量、平均重量直径和几何平均直径在层次之间差异显著，表现为0~20 cm显著高于20~40 cm.②经过长期撂荒恢复后，土壤总有机碳储量、大团聚体有机碳储量以及中团聚体有机碳储量显著上升（P<0.05），分别上升了1.92、10.2和3.61倍，而微团聚体有机碳储量显著下降.撂荒恢复促使土壤碳氮化学计量比升高，但在42 a时出现了显著下降趋势.③土壤团聚体对于总有机碳储量的贡献率有80%来自大团聚体，且大团聚体数量随着恢复年限显著增加是大团聚体贡献率高的主要原因.总体而言，撂荒恢复过程中，微团聚体数量持续下降，而大团聚体数量显著增加并促进了土壤有机碳的累积. 英文摘要 Soil aggregates are important carriers of soil organic carbon (SOC) accumulation, and play an important role in the evaluation of soil structure and quality. Natural recovery can promote change in soil aggregate structure and quantity via the redistribution of SOC in the aggregates. Natural restoration from farmland is an important vegetation restoration model on the Loess Plateau. The changes in soil aggregate structure and soil carbon stock after natural restoration have received extensive attention. However, little is known about the continuous study of soil changes on the abandoned grassland during the recovery process. Therefore, to understand how SOC accumulates in the process of natural recovery and quantitatively analyze the contribution of aggregates to the total soil carbon pool, we selected four abandoned grasslands of different restoration ages on the Loess Plateau, China, and studied the changes in soil structure, soil total organic carbon (TOC), soil C:N, soil aggregate distribution, soil aggregate stable index (mean weight diameter, MWD; geometric mean diameter, GMD), and aggregate-associated SOC changes as well as their correlations from 0-20 cm and 20-40 cm soil layers in abandoned grasslands. In addition, we calculated the contribution of aggregates with different sizes to soil TOC stock. The results showed that:① natural restoration increased the macroaggregate amount, MWD, and GMD, but decreased the amount of microaggregate and silt-and clay-sized fractions. There are significant differences in the distribution and stability of aggregates between different soil layers; the promotion effect of the surface was higher than that of the subsurface soils. ② In the 42 years after abandoning recovery, soil TOC stock, macaggregate-and mesaggregate-associated SOC stock increased significantly, and varied with soil depth and years of abandonment (1.92 times, 10.2 times, and 3.61 times). In contrast, micaggregate-associated SOC stock decreased significantly, and silt-and clay-sized fractions-associated SOC stock showed no distinct change. In addition, natural restoration promoted the ratio of C:N; nevertheless, the ratio of C:N under the surface showed a reduced phenomenon after 42 years of abandonment. ③ The improvement in soil TOC stock depends primarily on changes in the macaggregate-associated organic carbon stocks, which account for 80% of macaggregate, and the significant increase in the amount of macaggregate is the main reason for the high contribution.The results of our study suggest that natural restoration is conducive to the accumulation of soil organic carbon, and improvement in soil structure and stability. Macroaggregate is the key factor in soil organic carbon accumulation and soil structure improvement in the process of natural restoration.

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