黄土高原丘陵沟壑区2种起源油松林更新苗根际土壤酶活性和养分含量比较研究

为了解土壤酶活性在黄土高原沟壑区2种起源油松林更新苗根际土壤中的差异及其与土壤理化性质的关系,选择陕西黄龙山林区和甘肃子午岭林区具有代表性立地条件的油松人工林和天然次生林,以林下更新苗为对象,对根际土壤的酶活性和理化性质进行了测定。结果表明:1)土壤有机碳、全氮和速效磷含量总体表现为天然次生林>人工林,而土壤全磷含量与之相反。2)土壤酸性磷酸酶、碱性磷酸酶和脲酶活性总体上均表现为天然次生林>人工林,而蔗糖酶活性与之相反。3)土壤蔗糖酶、脲酶、碱性磷酸酶和酸性磷酸酶活性均与全氮含量呈现出显著正相关关系。4)主成分分析显示,林分起源与土壤全磷、有机碳、pH和含水量存在较大相关性。人工林和天然次生林油松幼苗根际土壤理化性质存在一定差异,引起了土壤酶活性的变化,影响了土壤有机质的矿化。

Comparison of the Enzyme Activities and Soil Nutrients in the Rhizosphere of Pinus tabuliformis Seedlings of Two Origins in Hilly and Gully Regions of Loess Plateau

In order to understand the differences in soil enzyme activities in the rhizosphere of Pinus tabuliformis seedlings during the natural regeneration process between secondary forests and plantations in hilly and gully regions of loess plateau and its relationship with soil physical and chemical properties,we slected typical mature stands of P.tabuliformis which could represent all the forests in Ziwuling and Huanglong,to test soil enzyme activities and physical-chemical properties.The results showed that 1) the total contents of soil organic carbon (SOC),total nitrogen (TN) and available phosphorus (AP) were all higher in secondary forests than in plantations;in contrast,the total contents of soil phosphorus (TP) were higher in plantations than in secondary forests.2) Soil acidity phosphatase (APase),alkaline phosphatase (AKPase) and urease activity (Urase) were generally higher in secondary forests than in plantations,while invertase activities were in opposite.3) Soil invertase,urase,AKPase and APase activities all showed significantly positive correlations with the content of TN.4) Principal component analysis showed that the forest origin was highly correlated with TP,SOC,pH and soil water content.The differences in soil physical and chemical properties in the rhizosphere of P.tabuliformis seedlings existed between plantation and secondary forest,which had influences on soil enzyme activities,and led to the discrepancies of the mineralization of SOC.