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为了解土地利用方式对土壤有机碳库的影响,研究了湘中丘陵区6种土地利用方式(石栎+青冈次生林、杉木人工林、毛竹林、苗圃、农用旱地、水田)土壤水溶性有机碳(DOC)含量及其季节动态,分析了土壤DOC含量与土壤自然含水率、碳(C)、氮(N)含量之间的关系。结果表明:土壤DOC含量随土壤深度增加而下降,秋季土层之间差异最小,土壤DOC分配比例随土壤深度增加而增大;不同土地利用方式土壤DOC含量差异显著,与石栎+青冈次生林相比,毛竹林、杉木人工林、水田、农用旱地、苗圃依次下降了10%~12%、11%~12%、13%~19%、18%~25%和37%~42%,夏季不同土地利用方式之间差异最大。不同土地利用方式土壤DOC含量季节变化明显,均表现为:春、夏、冬季较高,秋季最低,秋季与春、夏、冬季之间差异显著;土壤DOC含量与土壤自然含水率、TOC、MBC、ROC、MOC、全N、水解N含量呈显著或极显著正相关。可见,土地利用方式显著影响土壤DOC含量及其空间分布,次生林转变为人工林或农用地后,土壤DOC含量明显下降。
In order to understand the impact of land use on soil organic carbon pool, the effects of six land use types (Lithocarpus glacialis + Cyclobalanopsis glauca forest, Cunninghamia lanceolata plantation, Phyllostachys pubescens forest, nursery, agricultural dry land and paddy field) on soil water-soluble organic carbon (DOC) content and its seasonal dynamics, the relationship between soil DOC content and soil natural moisture content, carbon (C), nitrogen (N) content was analyzed. The results showed that the content of DOC decreased with the increase of soil depth, and the difference between soil layers in autumn was the smallest. The distribution ratio of DOC in soil increased with the increase of soil depth. The DOC content of soil in different land use types was significantly different, The bamboo forest, Chinese fir plantation, paddy field, agricultural dry land and nursery decreased by 10% ~ 12%, 11% ~ 12%, 13% ~ 19%, 18% ~ 25% and 37% ~ 42% The difference between land use patterns is greatest. The contents of DOC in different types of land use changed significantly in the seasons, including spring, summer and winter, lowest in autumn, and significant difference between autumn and spring, summer and winter. Soil DOC content was positively correlated with soil natural water content, TOC, MBC , ROC, MOC, total N, hydrolyzed N content were significantly or very significantly positive correlation. It can be seen that the land use pattern significantly affected the DOC content and its spatial distribution in the soil. After the secondary forest was transformed into plantation or agricultural land, the DOC content in the soil decreased significantly.