基于土地利用的北方农牧交错区碳固定和土壤保持时空变化

Spatial and temporal changes of carbon sequestration and soil conservation based on land-use in the farming pastoral ecotone of north China

为探讨农牧交错区土地利用变化及其对生态系统服务的影响,以内蒙古达茂旗为研究区,通过土地利用转移矩阵和变化动态度的计量,采用模型模拟生态系统服务碳固定、土壤保持功能的方法,分析2000—2015年该旗碳固定和土壤保持演变特征。结果表明:草地、未利用地和耕地是主要的土地利用类型,16年间,草地、建设用地、未利用地、林地面积明显增加,耕地面积显著减少。土地利用类型变化主要是从耕地向草地、从草地向建设用地转移。2000—2015年,全旗碳固定量从183.25万t减少到181.65万t,土壤保持量从170.58万t减少到107.32万t,这一变化主要是由于研究区草地质量的降低使得单位面积提供的生态系统服务减少。各土地利用类型提供的碳固定和土壤保持均表现为草地>耕地>未利用地>建设用地>灌木林>林地>盐碱地>水域>沙漠。综上,在今后的生态治理中,应考虑在扩大草地面积、保护农田的基础上,适度利用草地、农田等生产生活用地,提高草地质量,科学优化土地利用结构,保障生态系统良性演化,提高生态系统服务功能。

To provide scientific support for the planning and management of land resources in the farming pastoral ecotone,land-use change and ecosystem services evaluation should be carried out.In this study,the land-use transfer matrix and change dynamic degree of Damao Banner from 2000 to 2015 were measured,and the evolution characteristics of ecosystem services soil conservation and carbon sequestration were analyzed for the same period.The results showed that grassland,unused land,and cropland were the main types of landuse.In the past 16 years,grassland,building land,unused land,and forest areas had increased significantly,whereas cropland areas had decreased significantly.Land-use types had mainly changed from cropland to grassland and from grassland to building land.From 2000 to 2015,carbon sequestration throughout the banner decreased from 1832500 t to 1816500 t,and soil conservation decreased from 1705800 t to 1073200 t.These changes were mainly due to the decrease in grassland quality in the study area,which resulted in a decrease in ecosystem services provided per unit area.The services of carbon sequestration and soil conservation provided by various landuse types were grassland>cropland>unused land>building land>shrub>forest>saline alkali land>water>sand.In future ecological management,grassland and cropland areas should be used moderately to protect and expand production land.Moreover,the quality of grassland and cropland should be improved and the land-use structure should be optimized scientifically to effectively improve ecosystem services.