Relationship between soil physical and chemical properties and vegetation carrying capacity in Zoige desertified grassland
In order to explore the soil water availability and determine the soil water carrying capacity for vegetation(SWCCV)of different desertification degrees grassland in Zoige and provide basis for vegetation restoration of different degraded grasslands in this region,the moving extremely severe sandy land,severe sandy land,moderate sandy land,and mild sandy land in Zoige Steppe were selected as the research objects.Based on field investigation,laboratory experiment and model simulation,the soil physical properties,water holding capacity,soil water availability were analyzed and SWCCV was determined.The results showed that:(1)In the 0～60 cm soil layer,the soil bulk density of extremely heavy sandy land was the largest(1.43±0.12 g·cm-3),and that of mild sandy land was the smallest(1.30±0.20 g·cm-3).In the 20-40 cm soil layer,the soil bulk density of mild sandy land was significantly different from that of extremely heavy sandy land and severe sandy land(P<0.05).In the three soil layers of 0～20 cm,>20～40 cm and>20～40 cm,the aggregate of soil profile of the four kinds of sandy grassland as a whole showed the highest proportion of 0.25 to 0.5 mm grain size,with an average of 66.72±15.97%,56.28±14.44%and 44.67±12.57%,respectively,and it showed a decreasing trend with increasing depth.The non-capillary porosity and capillary porosity of>0～20 cm soil in extremely heavy sand and moderate sand were the largest(4.68%and 46.13),while those in>20～40 cm and>40～60 cm soil layers showed the best soil void characteristics in light sand,while those in extremely heavy sand were relatively poor.(2)The stable soil water content of mild sandy land was estimated at 16.45%and measured at 17.53%,the stable soil water content of moderate sandy land was estimated at 13.74%and measured at 15.62%,the stable soil water content of severe sandy land was estimated at 13.14%and measured at 15.56%,and the stable soil water content of flowing extremely severe sandy land was estimated at 9.1%and measured at 13.34%.(3)The SWCCV in mild sandy land was 4765 plants·hm-2 for Hippophae rhamnoides subsp.mongolica,3 200 plants·hm-2 for Salix taoensis,4 507 plants·hm-2 for Dasiphora fruticosa,separately,and the vegetation coverage is 52%.The SWCCV in moderate sandy land was 7 668 plants·hm-2 for Hippophae rhamnoides subsp.mongolica,5 255 plants·hm-2 for Salix taoensis,6 873 plants·hm-2 for Dasiphora fruticosa,separately,and the vegetation coverage was 76%.The SWCCV in severe sandy land was 6 933 plants·hm-2 for Hippophae rhamnoides subsp.mongolica,4 618 plants·hm-2 for Salix taoensis,5 980 plants·hm-2 for Dasiphora fruticosa,separately,and the vegetation coverage was 70%.The SWCCV in extremely severe sandy land was 5 755 plants·hm-2 for Hippophae rhamnoides subsp.mongolica,3 850 plants·hm-2 for Salix taoensis,5 165 plants·hm-2 for Dasiphora fruticosa,separately,and the vegetation coverage was 61%.The research results provide an important basis for revealing the vegetation restoration mechanism and technical reference in the degraded sandy area of Zoige grassland.
grassland desertificationsoil available watersoil water carrying capacity for vegetationZoige
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