作　　者： (姚楠）; (赵英）; (张建国）; (何海龙）; (司炳成）; (焦瑞）;

机构地区： 西北农林科技大学资源环境学院

出　　处： 《水土保持研究》 2017年第5期132-138,共7页

摘　　要： 内蒙古草原地处季节性冻土区,与放牧强度相关,土壤冻融过程对该地生态和水文过程有着显著影响,但相关研究相对欠缺。该文重点研究了内蒙古锡林郭勒草原3种放牧条件下UG79(1979年以来禁牧)、UG99(1999年以来禁牧)、HG(1979年以来持续放牧)季节性冻融期的土壤水热动态,以期准确理解放牧这一当地主要土地利用模式对土壤生态水文过程的影响。结果表明:与地上覆盖度相关,不同放牧条件下地表积雪厚度有明显差异,其中HG处理积雪厚度远小于其他处理,其土壤温度变化也最为剧烈。与不同处理土壤冻结速率相关,土壤冻结时HG,UG79和UG99的"聚墒区"分别为20—30cm,10—20cm和10—30cm,其中UG99"聚墒区"分布范围最广,且集中在牧草根系发达区域,对来年牧草生长提供了更好的水分条件。换言之,由于冻后聚墒效应,土壤消融期水分含量在土壤表层高于冻融前,其中UG99处理最大,达到了0.19m^3/m^3。该研究结果为内蒙古草原季节性冻土区控制放牧及合理的禁牧措施提供理论依据。 Inner Mongolia grassland is located at seasonally frozen ground.The soil freezing and thawing processes,associated with grazing intensity,have a significant impact on ecological and hydrological process in this region.However,the relevant research is limited.This paper is mainly focusing on soil water and heat regime during seasonal freezing and thawing period in Xilingol grassland under three typical grazing treatments,i.e.,UG79(ungrazed site since 1979),UG99(ungrazed site since 1999),and HG(heavily grazed site since 1979),thereby clarifying how different extent of grazing affects rates and intensities of soil freezing and thawing,and snowmelting water infiltration.The results showed that snow thickness varied from different grazing treatments,and was the function of surface coverage such as litter.For instance,the snow thickness under HG site was far less than that in the other two ungrazed sites.Accordingly,the soil temperature fluctuated more strongly in HG.The area of unfrozen water content extended into 20—30cm,10—20cm and 10—30cm in HG,UG79 and UG99site,respectively,due to the water migration caused by soil frozen.This trend was the strongest in UG99 characterizid by the zone of the largest root system which provides a better moisture condition to grass germination in the coming year.In other words,the soil moisture content after soil thawing is higher than before soil freezing due to the hydraulic lift of soil frozen.Consequently,among the three sites,the soil moisture content in UG99 site was the greatest,which reached to 0.19m^3/m^3 after soil thawing.This result can provide the theoretical basis for reduction of grazing activity and reasonable grazing management in grassland of Inner Mongolia.

关 键 词： 锡林郭勒草原 放牧条件 冻融 水热状况