岩质公路边坡生态恢复土壤特性与植物多样性

Abstract

Soil is one of the main environmental factors which affects plant community composition and diversity in space and time.Especially during the restoration of rocky slopes,the properties of artificial soil play key roles in determining the generation and development of vegetation.Meanwhile,it is an important factor to assess the performance of slope eco-engineering.In order to evaluate the soil properties and recover vegetation features,field survey was carried out in Yantian Port of Shenzhen City in China,in which highway slopes have been ecologically restored using varied methods since 2002.This area locates in the sub-tropical maritime monsoon climate zone,Where annual rainfall is 948.8 mm and mean annual temperature is 22.4℃.The highway rocky slopes investigated are granite cut slopes and with slope ratio about 1 ∶0.75.Three approaches were applied in the slope vegetation recovery,i.e.,thick layer base material spraying method,external-soil spray seeding method and natural restoration,among which the artificial soils were about 10cm thick.Over ten years recovering,the plant communities of all rocky slopes investigated here are composed of woody,shrub and herb layers. In the present studies,the physic-chemical and enzymatic activity of soil as well as plant diversity were investigated on different restoration patterns.Furthermore,the relationship between soil property and plant diversity was also analyzed.The results were shown as follows:(1)The enzymatic activities,contents of water and nutrient in the soil from thick layer base material sprayed slopes were the highest,while those from natural restoration slopes the lowest among three restoration patterns.(2)There were 6 plant species of 5 genus of 5 families in the natural restoration slope,7 species of 7 genus of 6 families in the external-soil spray seeding slope,11 species of 11 genus of 7 families in the thick layer base material spraying slope,and 14 species of 13 genus of 12 families in the natural slope.The plant diversity indices evaluated by species richness(R),the Shannon-Wiener index(H) and Pielou evenness(E) were lower than those of natural slopes,although R and H of thick layer base material sprayed slopes were much higher than those of other two kinds of slopes.This result suggested that those plant communities recovered were still in the early succession stages—herb/shrub stage.(3)According to the correlation analysis,plant diversity was significantly correlated with the soil properties,i.e.,soil available N had significantly positive correlation with E and with H of woody layer;soil available P was highly significantly negative correlated with all plant diversity measures,while soil total P significantly negative to E;soil total K was significantly negative correlated with R and with H of herb layer,while soil available K highly significantly negative to E.(4)The soil enzymatic activities of urease and sucrase decreased with the order of thick layer base material sprayed,external-soil spray seeded,natural and natural restoration slopes.And activity of soil sucrase showed significant negative correlation with the evenness of herbs. Based on above mentioned results,it indicated that the thick layer base material spraying approach is more suitable for the restoration of rocky slope.