吴起县退耕还林后主要植被类型土壤质量评价

为明确吴起县退耕还林后形成的主要植被类型土壤质量状况,文中以吴起县王洼子典型退耕植被作为研究对象,对比分析不同植被类型土壤理化性质差异,并综合主成分分析法、敏感性以及相关性分析法,建立了研究区土壤质量评价指标最小数据集。结果表明:1)不同植被类型间土壤物理、化学性质差异显著(P<0.05);山桃×沙棘混交林在土壤孔隙度、持水性以及有机碳含量方面表现较优;刺槐林在土壤pH和电导率方面表现较优;沙棘林、柠条林在富集氮、磷、钾元素方面优势明显;草地土壤指标整体表现较差。2)适用于研究区不同植被类型土壤质量评价的最小数据集指标为土壤有机碳含量、毛管持水量、电导率和有效磷。3)不同植被类型均在不同程度上有效提高土壤质量,但研究区土壤质量指数整体仍较低,其中山桃×沙棘混交林对土壤质量提升效果最好,其次为灌木林(柠条、沙棘),乔木林(刺槐、杜梨、山桃)和草地。因此,研究区在今后进行低效林改造、林分结构调整与植被恢复重建等林业生态工程时,优先选择以沙棘、柠条为主的灌木林或者小乔木与灌木相结合的混交林(山桃×沙棘混交林)。

Soil quality evaluation of main vegetation types after conversion of farmland to forest in Wuqi County

In order to clarify the soil quality restoration status of the main vegetation types after returning farmland to forests in Wuqi County,this study took the typical vegetation of reclaimed farmland in Wangwazi Town of Wuqi County as the research object.According to comparing and analyzing the differences in soil physical and chemical properties among different vegetation types,and integrated principal component analysis,sensitivity,and correlation analysis,a minimum data set of soil quality evaluation indicators was established for the study area.The results showed that:(1)The soil physical and chemical properties of different vegetation types were significantly different(P<0.05).The Prunus davidiana×Hippophae rhamnoides mixed forest performed better in terms of soil porosity,water holding capacity and organic carbon content.The Robinia pseudoacacia forest performed better in terms of soil pH and electrical conductivity.The Caragana korshinskii and Hippophae rhamnoides forest had obvious advantages in nitrogen,phosphorus and potassium.The overall performance of grassland soil indicators was poor.(2)The minimum data set indicators that are applicable to evaluatie soil quality of different vegetation types in the study area are soil organic carbon content,capillary water holding capacity,electrical conductivity and available phosphorus.(3)Different vegetation restoration models could effectively improve soil quality to different degrees,but the overall soil quality index in the study area were still low.Among them,the Prunus davidiana×Hippophae rhamnoides mixed forest had the best effect on improving soil quality,followed by shrubs(Caragana korshinskii,and Hippophae rhamnoides),arbor forest(Robinia pseudoacacia,Pyrus betulifolia Bunge,and Prunus davidiana)and grassland.Therefore,when the forestry ecological projects such as low-efficiency forest reconstruction,forest stand structure adjustment,and vegetation restoration and reconstruction were probably to be carried out in study area in the future,it was preferred to choose shrub forests with Hippophae rhamnoides and Caragana korshinskii,or mixed forests combining small trees and shrubs(Prunus davidiana×Hippophae rhamnoides mixed forest).