子午岭植被演替过程中土壤剖面有机质与持水性能变化

Change of soil organic matter and water holding ability during vegetation succession in Ziwuling region

研究表明,自然植被正向演替对土壤剖面有机质积累有显著促进作用,表现为:由弃耕地、草地、灌木、乔灌群聚到乔木的植被演替过程中,0～25cm土层有机质含量逐步增加,且演替初期的增加速度较快,而后增加速度相对变缓.植被演替过程中土壤有机质含量变化的主要原因在于植物凋落物归还量的变化.在同一时间测定的土壤剖面水分含量以及0～5cm土层田间持水量、容重、总孔度等与土壤持水性能相关的指标都与有机质含量呈极显著或显著相关,表明随剖面有机质的积累,土壤持水性能得到改善.

This study was aimed to understand the interactions between development of vegetation succession and soil conditions in semiarid regions,based on investigations carried out at different types of vegetation at Ziwuling in the Loess Plateau.Results indicates that as vegetation succession changed from arable crops to nativelyrecovered grasses (the early stage of vegetation succession),mixed grassbush or busharbor systems to and finally the mature grassland systems or arbor systems,organic matter content in the upper 0~25 cm soil layer continuously increased,with factors ranging between 1.30~3.3 folds.Soil water content,water holding capacity and bulk density were all closely related to the contents of soil organic matter.This suggests that as return of the development of vegetation successions,the consequent increase in soil organic matter largely improved the ability to hold ware in soil,providing batter water conditions for the growth and development of vegetations.