宁南山区坡面不同土地利用方式下植被-土壤耦合关系评价

Evaluation on Coupling of Vegetation and Soil on Slopes of Mountain Area in Southern Ningxia

为实现宁南山区生态环境可持续发展,避免出现土壤干化及植被退化现象,以彭阳县王洼水保试验站坡面不同土地利用方式植被—土壤为研究对象,通过建立以11个植被因子和14个土壤因子为主的2级指标体系,采用层次分析法(AHP)和熵权法确定各植被、土壤因子的权重,以耦合、协调度模型评价二者间的协调程度,并用典型相关分析(CCA)确定了各因子之间的相关性。结果表明:林地、灌木地、弃耕地、草地和农地的协调度(D c)值分别为0.4460,0.4515,0.5059,0.5312,0.6046,植被—土壤耦合协调程度S(x)/P(y)的值分别为0.4908,0.5934,0.8212,0.8743,1.1874,即林地和灌木、弃耕地和草地、农地分别属于濒临失调、勉强协调、初级协调状态;濒临失调发展模式主要分布于坡面东北和西南部,勉强协调发展模式分布于坡面中西部,初级协调发展模式零碎状分布;CCA分析表明土壤系统中干燥化指数、水分亏缺指数、平均含水量、黏粒、容重等对植被系统的影响较大。综上,宁南山区农地、草地的耦合协调度优于林地、灌木地,合理的林草植被选取和搭配可确保区域植被—土壤系统的协调发展。

The purpose of the study is to realize the sustainable development of ecological environment and avoid the phenomenon of soil drying and vegetation degradation in the mountainous areas of southern Ningxia.Taking different land use types as research objects,we used AHP and entropy weight method to determine the weight of each soil and vegetation factor by establishing a two-level index system mainly composed of 11 vegetation factors and 14 soil factors.The coupling degree and coordination model were used to evaluate the degree of coupling and coordination between the vegetation and soil,and the CCA was used to analyze the correlation between the soil and vegetation factors.The results of the study showed that the D c values of forest land,irrigated land,abandoned arable land,grassland and agricultural land were 0.4460,0.4515,0.5059,0.5312 and 0.6046,respectively,and the S(x)/P(y)values were 0.4908,0.5934,0.8212,0.8743 and 1.1874,respectively,which indicated that forest land and shrub were in imminent imbalance state,abandoned farmland and grassland were barely coordinated,and agricultural land was in primary coordinated state;the imminent imbalanced development model mainly distributed in the northeast and southwest,the barely coordinated development model distributed in the central and western regions,and primary coordinated development model scattered across the region.The CCA analysis showed that the soil desiccation index,relative moisture deficit index,average water content,clay content and bulk density had great influence on vegetation system.In summary,the results indicated that the coupling coordination degrees of farmland and grassland were better than those of woodland and shrub land in the mountainous area of southern Ningxia.Reasonable selection and collocation of forest and grass vegetation can ensure the coordinated development of regional vegetation-soil system.