1980s与2020s青藏高原南部土壤质量变化

Variations of soil quality in the southern Qinghai-Tibet Plateau during 1980s to 2020s

青藏高原地区气候变暖、冻土融化造成水土流失及土壤质量下降,明确青藏高原土壤质量年代际变化状况,是科学认识该地区土壤资源的基础,是植被恢复和生态重建的关键。本研究选取1980s和2020s青藏高原南部土壤有机质、全氮、全磷等8项指标,通过计算土壤质量指数(SQI)对山地针叶林地带(西藏自然地理分区Ⅱ区)和山地灌丛草原地带(Ⅳ区)土壤质量进行了评价,采用变差分解(VPA)明确造成土壤质量时空分布异质性的原因。结果表明:近40年各自然带土壤质量均呈下降趋势,Ⅱ区SQI从0.505下降至0.484,Ⅳ区SQI从0.458下降至0.425。土壤养分和质量在空间分布上具有异质性,在不同时期,Ⅱ区土壤养分状况及质量均优于Ⅳ区。VPA结果表明,气候变化、土地退化和植被差异的相互作用是造成土壤质量时间变化的主要原因。气候和植被的不同可以较好地解释SQI的空间变化。

Climate warming and thawing of permafrost in the Qinghai-Tibet Plateau have resulted in soil erosion and the decline of soil quality.Determining the decadal variation of soil quality in the Qinghai-Tibet Plateau is the basis for scientific understanding of soil resources and the key to vegetation restoration and ecological reconstruction.In this study,we used eight indicators(including soil organic matter,total nitrogen,and total phosphorus)to eva-luate soil quality of montane coniferous forest zone(Tibet’s natural geographical division zoneⅡ)and montane shrubby steppe zone(zoneⅣ)by calculating soil quality index(SQI)in the southern Qinghai-Tibet Plateau in the 1980s and 2020s.Variation partitioning(VPA)was used to examine the drivers for the heterogeneity of the spatial-temporal distribution of soil quality.The results showed that soil quality in each natural zone showed a downward trend in the past 40 years,with SQI of zoneⅡdecreasing from 0.505 to 0.484 and that of zoneⅣdecreasing from 0.458 to 0.425.The spatial distribution of soil nutrients and quality was heterogeneous,while soil nutrient condi-tions and quality in zoneⅡwere better than those in zoneⅣin different periods.The VPA results indicated that the interaction of climate change,land degradation,and vegetation differences was the major cause of temporal variation in soil quality.Differences in climate and vegetation could better explain the spatial variation of SQI.