干旱区生态环境知识资源中心

This study examines variations in the spatial patterns of soil-vegetation properties in the vicinity of subsidence-related ground fissures caused by groundwater over-pumping over an arid ecotone situated in northeastern Iran. It was assumed that subsidence-related fissures have a possible effect on the soil-vegetation structures. Vegetation metrics ( mean canopy area, mean volume, vegetation cover percentage) and soil properties ( EC, pH, CaCO3, particle size distribution) were measured for locations with differing spatial expanses of ground fissures, including surface ground fissures, deeper ground fissures, as well as those exhibiting no signs of ground fissure. Statistical analyses indicated significant differences ( P < 0.05) in the spatial patterns of vegetation and soil properties for locations with different expanses of ground fissures. Greater degradation of soil-vegetation, presenting as mortality of plants and the formation of impermeable layers on the soil surface, was observed around deep fissures linked to groundwater over-pumping, in comparison with other locations. These findings confirm the relationship between heterogeneities in patterns of vegetation and soil properties and variations in structure and extent of ground fissures, as well as indicating that the expansion of groundwater overpumping-induced surface ground fissures can promote soil-vegetation degradation over time, leading ultimately to barren soils.