太行山油松人工林土壤微团聚体变化特征及其影响因素

Change Features of Soil Micro-aggregates of pinus tabulaeformis Plantation at Different Developmental Stages in the Southern Taihang Mountain and Its Relationship with Soil Nutrients

土壤微团聚体是土壤水分和养分保储与释供的关键载体。本研究以太行山绿化先锋树种油松人工林为研究对象,基于空间代替时间序列的思想,综合采用分形维数(D)、特征微团聚体组成比例(PCM)、平均质量直径(MWD)、几何平均直径(GMD)等指标分析油松人工林恢复过程中土壤微团聚体的变化特征,探讨土壤微团聚体变化特征与土壤养分之间的定量关系。结果表明:随着油松人工林恢复,0.25~0.05 mm粒级土壤微团聚体含量先增加后减少,而<0.02 mm粒级土壤微团聚体含量减少后增加。33~49 a油松人工林土壤微团聚体PCM、D分别增加65.57%和3.44%,而MWD与GMD分别减小约26%和33%。不同恢复年限土壤微团聚体D与MWD、GMD及PCM显著相关,而且与碱解氮和全磷相关紧密,说明D在一定程度上能够反映土壤颗粒的粒径分布状况及土壤养分状况,可作为表征土壤结构稳定性及土壤肥力的一个重要指标。

Soil micro-aggregates stability is one of the most important properties in soils and affects water erosion,soil aeration,nutrient recycling,as well as plant growth.Therefore,a better understanding of the composition of soil micro-aggregates during vegetation restoration is essential to maintain structural stability in soils.In this study,it took the Taihang Mountain greening pioneer tree Pinus tabulaeformis plantation as the research object,and based on the idea of space instead of time series.Fractal dimensions(D)combined with characteristics micro-aggregates proportion(PCM),mean weight diameter(MWD),geometrical mean diameter(GMD)was used to investigate the soil micro-aggregates change process and its fractal characteristics in Pinus tabulaeformis restoration,then the relationship between soil micro-aggregates D and soil nutrients was studied.The results showed that the proportion of 0.25~0.05 mm fraction in soil micro-aggregates displayed a sigmoidal pattern,first rapidly growing from 33 years to 45 years and then gradually decreasing,while the proportion of<0.02 mm appeared an opposite pattern.The PCM and D of soil micro-aggregates increased by 3.44%and 65.57%from 33 a to 49 a,while MWD and GMD decreased about 26%and 33%,respectively.With Pinus tabulaeformis restoration,soil micro-aggregates D was not only significantly correlated with soil micro-aggregates MWD,GMD and PCM,but also was closely related with available nitrogen and total phosphorus,indicating that soil micro-aggregates D could be regarded as a considerable parameter to reflect variations in soil properties.