土壤厚度对天然草地植被盖度和生物量的影响

土壤厚度是土壤肥力存在和植物生长的重要物质基础.本文调查了内蒙古东部地区多伦、锡林浩特和巴林左旗3个长期保护天然草地的土壤厚度和植被盖度等植物生长状况.结果表明,天然草地植被盖度、地上生物量和高度随土壤厚度的增加而增大.当土壤厚度小于20 cm时,植被盖度和地上生物量随土壤厚度的降低急剧减小,当土壤厚度小于10 cm时,植被类型为非地带性植被,盖度小于30%,地上生物量小于150 g/m2;当土壤厚度大于20 cm后,植被盖度一般大于80%,地上生物量接近或大于200 g/m2,而且土壤厚度大于20 cm后植被盖度和地上生物量随土壤厚度的继续增大变化平缓.研究区地带性天然草地植被正常生长的最低土壤厚度为20 cm左右.

Effects of Soil Depth on Vegetation Cover and Above Ground Biomass in East Part of Inner Mongolia

The purpose of this study was to analyze the effects of soil depth on vegetation cover and above ground biomass of natural grasses protected from grazing in the east part of Inner Mongolia through field survey.The results show that when soil depth was under 20 cm,the vegetation cover and above ground biomass decreased sharply as the soil depth decreased.When soil depth was less than 10 cm,the vegetation types were different from that of normal vegetations,and the vegetation cover and above ground biomass were very low(less than 30% coverage and 150 g/m2);When soil depth was greater than 20 cm,the vegetation cover and above ground biomass were greater than 80% and 200 g/m2,and changed slowly as soil depth increased.The minimum soil depth in this area should be at least 20 cm for the natural grasses to grow healthily.