高寒植被生态系统变化对土壤物理化学性状的影响

在黄河源区选择典型样地,对土壤有机质(SOM)、全氮(N)等化学性状及土壤机械组成、容重和土壤导水率等物理特性进行分析.结果表明,植被退化导致土壤物理化学性状显著退化.灌丛草甸草地土壤表层有机质(SOM)从179.58 g·kg^-1降到49.48 g·kg^-1,表层碱解N流失率为30%,退化嵩草草甸表层有机质SOM减少53%,碱解N损失率为28.4%.沼泽地有机质SOM减少了15.11 g·kg^-1.退化后的土壤土层厚度变薄,土壤颗粒变粗,土壤水分分布和含量出现变化,土壤出现沙化,土壤容重增大,土壤导水率与植被盖度有很好的相关性.研究表明,高寒植被生态系统的变化引起了土壤理化特性的强烈变化,高寒土壤环境出现退化.

Response of Soil Physicochemical Properties to the Changes of the Vegetation Ecosystem on the Tibetan Plateau

The investigation of soil physicochemical properties in the source regions of the Yellow River indicates that the degeneration of vegetation ecosystem on the Tibetan Plateau results in great soil environment change.By the study of chemistry characteristics of soil organic matters (OM),organic nitrogen (TN),and physical identities,including mechanism form,bulk density and conductivity coefficient in typical sampling area,it is found that soil chemistry and physical properties are in regression obviously in the vegetation degenerating process.The SOM in surface layer of the meadow soil decreased from 179.58 g·kg^-1 to 49.48 g·kg^-1,the hydrolysable nitrogen has lost 30%.53% of the soil SOM in the deteriorated grassland has been lost,and the hydrolysable nitrogen has lost 28.4%.The soil SOM in swamp land has lose 15.11 g·kg^-1.The soil layer is thinning,but the particle size has been coarsening.During the degradation,the soil moisture distribution and content in the topsoil are changing,such as bulk density increasing and desertification.The investigation also shows that the correlation between the plant coverage and conductivity coefficient of soil is quite obvious,and the soil characteristics,physical and chemical,are changing evidently,with a degeneration of alpine ecosystem.