Chacteristics At Two Types Of Landscapes And Their Boundaries In Weibei Loess Plateau

Forest-grassland and forest-farmland are the main types of landscape in Weibei loess plateau.The boundary is the transition zone of material and energy between forestland and grassland(farmland).By field investigation and experimental work,the distribution and variation of vegetation composition,physical and chemical properties of soil on the two different landscapes were analyzed in Yongshou country,Shaan xi province.The main conclusions are as follows:(1)Soil within the range of 0-200cm,Average soil water in the grassland and farmland in higher by the depth increase,there be the lowest soil water in 50-100cm at grassland-boundary-forest gradients.In horizontal level,whether forest-grassland or forest-farmland,the average water content in 0-10cm of soil surface performance for forest＞boundary＞grassland(farmland),and in the 10-200cm in soil showed the opposite trend.(2) Soil physical properties(Water saturated content,Field capacity,Capillary porosity,Non-capillary porosity,The total porosity) The number of micro-organisms(bacteria,fungi and actinomycetes),activity of the enzyme(invertase,urease,catalase) and nutrient content (Organic matter,TN,AN,P,AP) In the two types of landscape are reflected in the type of surface(0-20cm) higher than the sub-surface(20-40cm).In forest-grassland,Soil bulk density for grassland＞boundary＞forest.Soil water saturated content,Field capacity, Capillary porosity,Non-capillary porosity and the total porosity performance for grassland＜boundary＜forest,but the soil physical properties in forest-farmland appearance opposite trend.(3) In horizontal level the soil nutrient content,the number of micro-organisms,activity and other indicators changes in the complex,has not shown the consistent rules.(4) There have 19 family 43 genus 52 species plant in the two different landscapes, Simpson Index,Shannon-Wiener Index,Margalef Index and Pielou Index for the boundaryt are significantly higher than forestland and farmland.The boundary has rich species diversity and shows an positive effect to increase species diversity.