岩溶生态系统土壤及表生植被某些特性变异与石漠化的相关性

CORRELATION BETWEEN ROCK DESERTIFICATION AND VARIATIONS OF SOIL AND SURFACE VEGETATION IN KARST ECO-SYSTEM

岩溶山地石漠化是一种与脆弱生态地质背景和人类活动相关联的土地退化过程。本文以重庆市典型岩溶山地为例 ,探讨了岩溶生态系统土地利用方式与土壤机械组成、土壤水稳性团聚体、土壤有机质、土壤种子库、植被类型的关系。结果表明 ,经开垦利用后 ,岩溶环境土壤表层砂化现象更加明显。土地利用强度越大 ,对土壤团粒结构的破坏也越大 ,林地、灌草坡对水分的保持能力强 ,土地利用强度较大的土壤保水能力相对较弱 ,土壤有机质受土地利用强度的明显影响。土地利用强度越大 ,木本植物种子越少 ,草本植物种子越多 ,且以农田杂草为主。土地利用方式的变化 (如陡坡开垦 )是对次生植被及其种子库的主要威胁。

The rock desertification in karst mountains is a kind of land degradation processes correlated with vulnerable eco geology background and human activities. This paper chooses the typical karst mountains in Chongqing as an example to discuss the impact of different land use patterns on mechanical composition of soil, water stable aggregates, soil organic matter, the compositions of soil seed banks and bio diversity of karst eco system. The results show that the surface soil layer sandification is more evident after the reclamation, the more intensive land utilization, the more serious the destruction on soil aggregate structure. The soils of woodland and grassland systems have not only a superior soil water retention property but also a soil water supplying capacity than the soils with intense land utilization, and the soil organic matter is impressed by land using intensity distinctly. The amount of seeds of xylophyta species decreases with the increase in strength of land use, while the amount of seeds of herbaceous species increase, and most are farmland weeds. The changes of land use patterns have the dominant influence on secondary vegetation and their soil seed banks.