Water harvesting is one of main measures to solve water shortage resulting from less precipitation and erratically seasonal dis- tribution in arid and semi-arid areas. Different types of anti-infiltration treatments i...Water harvesting is one of main measures to solve water shortage resulting from less precipitation and erratically seasonal dis- tribution in arid and semi-arid areas. Different types of anti-infiltration treatments including mechanical and chemical to micro-catchment and their runoff efficiencies had been reported. This paper, through 5 years experiment from 1992 to 1996, is aimed at studying the im- pacts of microcatchment water-harvesting system (MCWHS) with microphytic crust treatment on afforestation on semi-arid Loess Plateau. The results showed that after 3 years of crust inoculation, crust had covered majority of MCWHS and the function of water harvesting had also been demonstrated partially, there were significant difference in soil moisture of shallow soil layer in three typical spring stages be- tween crust cover and control treatments (0.05 level), and about 0.9%-6.04% increase of monthly mean soil moisture within 1m soil layer in spring of late 3 years. The impact of severe spring drought can be alleviated effectively. In the meanwhile, as crust developed on the treated surface, there are significant differences (0.05 level) for tree height (H), diameter at breast height (DBH) and diameter at ground level (DGL) at the end of the study period (1996) with the increases by 22.38%, 17.34%, and 20.49% respectively compared with the con- trol treatment. Microphytic crust, as one of biological infiltration-proof materials, may become the optimized option for revegetation in Chinese Great West Development Strategy due to its self-propagation, non-pollution to water qualities, long use duration and relatively cost effective. Further work should be focused on the selection of endemic crust species and their batch-culture in arid environment.展开更多
Introduction:Sagebrush ecosystems in western North America are being replaced by the invasion of annual grasses,particularly Bromus tectorum.In experimental situations and in localized landscapes,prior studies have do...Introduction:Sagebrush ecosystems in western North America are being replaced by the invasion of annual grasses,particularly Bromus tectorum.In experimental situations and in localized landscapes,prior studies have documented that biological soil crusts(biocrusts)can reduce annual grass presence and that biocrusts are highly vulnerable to physical disturbance.Practical conservation would benefit from verification of these patterms at scales that matter to local economies.This study tests if these patterns appear at a regional scale.Methods:A previously collected data set of vegetation provided sampling of biocrust cover across the Great Basin within the state of Nevada,USA Data were analyzed with non-par ametric methods including odds ratios and generalized aditive models(GAM).Results:From a data set of 608 vegetation plots within the Great Basin ecoregion,proportion of plots with high annual grass cover differed between sites with high versus low biocrust cover(p=0.0015).A negative relationship between annual grass cover and biocrust cover was confirmed with GAM(p=0.009).For a model of biocrust cover,cattle disturbance was found to be an explanatory variable(p<0.00001).Conclusions:The patterns do appear at the regional scale,with high levels of cattle activity corresponding to low cover of biocrusts,and low cover of biocrusts corresponding to high cover of annual grasses.展开更多
文摘Water harvesting is one of main measures to solve water shortage resulting from less precipitation and erratically seasonal dis- tribution in arid and semi-arid areas. Different types of anti-infiltration treatments including mechanical and chemical to micro-catchment and their runoff efficiencies had been reported. This paper, through 5 years experiment from 1992 to 1996, is aimed at studying the im- pacts of microcatchment water-harvesting system (MCWHS) with microphytic crust treatment on afforestation on semi-arid Loess Plateau. The results showed that after 3 years of crust inoculation, crust had covered majority of MCWHS and the function of water harvesting had also been demonstrated partially, there were significant difference in soil moisture of shallow soil layer in three typical spring stages be- tween crust cover and control treatments (0.05 level), and about 0.9%-6.04% increase of monthly mean soil moisture within 1m soil layer in spring of late 3 years. The impact of severe spring drought can be alleviated effectively. In the meanwhile, as crust developed on the treated surface, there are significant differences (0.05 level) for tree height (H), diameter at breast height (DBH) and diameter at ground level (DGL) at the end of the study period (1996) with the increases by 22.38%, 17.34%, and 20.49% respectively compared with the con- trol treatment. Microphytic crust, as one of biological infiltration-proof materials, may become the optimized option for revegetation in Chinese Great West Development Strategy due to its self-propagation, non-pollution to water qualities, long use duration and relatively cost effective. Further work should be focused on the selection of endemic crust species and their batch-culture in arid environment.
文摘Introduction:Sagebrush ecosystems in western North America are being replaced by the invasion of annual grasses,particularly Bromus tectorum.In experimental situations and in localized landscapes,prior studies have documented that biological soil crusts(biocrusts)can reduce annual grass presence and that biocrusts are highly vulnerable to physical disturbance.Practical conservation would benefit from verification of these patterms at scales that matter to local economies.This study tests if these patterns appear at a regional scale.Methods:A previously collected data set of vegetation provided sampling of biocrust cover across the Great Basin within the state of Nevada,USA Data were analyzed with non-par ametric methods including odds ratios and generalized aditive models(GAM).Results:From a data set of 608 vegetation plots within the Great Basin ecoregion,proportion of plots with high annual grass cover differed between sites with high versus low biocrust cover(p=0.0015).A negative relationship between annual grass cover and biocrust cover was confirmed with GAM(p=0.009).For a model of biocrust cover,cattle disturbance was found to be an explanatory variable(p<0.00001).Conclusions:The patterns do appear at the regional scale,with high levels of cattle activity corresponding to low cover of biocrusts,and low cover of biocrusts corresponding to high cover of annual grasses.
