庞泉沟自然保护区典型森林土壤大团聚体特征

对庞泉沟自然保护区内4种典型森林(云杉-落叶松-杨桦针阔混交林(简称针阔混交林),杨桦阔叶林,沙棘灌木林和华北落叶松林)和撂荒地(对照)0—20cm土层内土壤大团聚体含量及稳定性进行了研究。结果表明,和撂荒地相比,林地土壤大团聚体含量及稳定性显著增加(P0.05)。不同林地0.25mm土壤团聚体含量顺序为:针阔混交林杨桦阔叶林沙棘灌木林华北落叶松林撂荒地。林地0.5mm湿筛水稳性大团聚体含量显著大于撂荒地。根据团聚体破坏率和土壤团聚体水稳性指数,土壤团聚体稳定性由大到小顺序为:针阔混交林沙棘灌木林华北落叶松林杨桦阔叶林撂荒地。根据干湿筛团聚体平均重量直径(MWD)差值分析得稳定性顺序为:杨桦阔叶林针阔混交林沙棘灌木林华北落叶松林撂荒地。相关分析表明,土壤有机碳含量和粘粒含量与干、湿筛土壤大团聚体含量之间呈极显著正相关(P0.01),粘粒含量与MWD(干)和MWD(湿)的差值之间呈极显著负相关(P0.01),土壤容重、土壤通气孔隙和毛管孔隙等也显著影响着土壤大团聚体含量及其MWD(干)和MWD(湿)的差值(P0.05)。研究结果可为该区森林资源的合理经营提供一定的科学依据。

Characteristics of soil macroaggregates under typical forests in Pangquangou Nature Reserve

The content and stability of soil macroaggregates in 0-20cm soil layer were studied for four typical forests (the coniferous and broad-leaved mixed forest (by the composition of Picea meyer,P. wilsonii,Larix principis-rupprechtii,Populus davidiana and Betula platyphlla), the broad-leaved forest of P. davidiana and B. platyphlla,the shrub of Hippophaer hamnoides and the Larix principis-rupprechtii forest) and an abandoned land (control) in Pangquangou Nature Reserve.The results showed that the content and stability of soil macroaggregates under the four typical forests were significantly increased (P < 0.05) by compared with the abandoned land.The content of soil aggregates >0.25mm under the four forestlands was in the following order:the coniferous and broad-leaved mixed forest > the broad-leaved forest > the shrub > the Larix forest > the abandoned land.The wet sieve test also indicated that the content of water-stable aggregates >0.5mm under the forestlands was significantly greater than under the abandoned land.Based on soil aggregate breakage rate and soil aggregate water-stability index,the soil aggregate stability was in the order:the coniferous and broad-leaved mixed forest > the shrub > the Larix forest > the broad-leaved forest > the abandoned land.According to the difference between the mean weight diameters (MWD) determined with the dry sieve and the wet sieve methods,the stability of soil aggregates followed the order:the broad-leaved forest > the coniferous and broad-leaved mixed forest > the shrub > the Larix forest > the abandoned land. Correlations analysis indicated that the content and stability of dry or wet sieve soil macroaggregates were very significantly (P < 0.01) positively related to soil organic carbon (SOC) and clay particles. The MWD was very significantly (P < 0.01) correlated negatively with clay particles.Soil macroaggregate content and the MWD were significantly (P < 0.05) affected by soil bulk density,soil aeration porosity and soil capillary porosity.This study provides certain scientific evidence for rational management of the forest resources of the reserve.