基于GIS的甘肃省农牧交错带土地沙化敏感性时空分布格局

Temporal and spatial distribution pattern of land desertification sensitivity in agro pastoral ecotone of Gansu province

为探讨甘肃省农牧交错带土地沙化的变化规律,选择植被覆盖度、干燥度指数、≥6m/s起沙风天数、土壤质地4个因子,基于ArcGIS开展了甘肃省农牧交错带4个典型区域(青藏高原东缘高寒区、陇东黄土高原沟壑区、青藏高原-黄土高原过渡区、陇中黄土丘陵区)2001~2018年土地沙化敏感性时空分布格局的研究。结果表明:1)甘肃省农牧交错带干燥度指数、≥6m/s起沙风天数以低敏感和不敏感等级为主,随时间呈下降趋势。植被覆盖度以中敏感等级和不敏感等级为主,随时间呈上升趋势,在空间上由西向东的递增。2)农牧交错带土地沙化敏感等级随时间呈下降趋势,由高、中敏感等级下降至低、不敏感等级;高、中度易起沙尘地区逐渐过渡为不易起沙尘地区。高、中敏感等级的面积呈下降趋势,低、不敏感等级的面积呈上升趋势。

In order to explore the change rules of land desertification in the farming-pastoral transitional zone of Gansu province,vegetation coverage,dryness index,sand-driving days≥6 m/s and soil texture were selected.Based on ArcGIS,the spatial-temporal distribution patterns of land desertification sensitivity in four typical regions of farming-pastoral ecotone in Gansu province(the alpine and cold region in the eastern margin of the Qinghai-Tibet Plateau,the loess gully region in eastern Gansu province,the Qinghai-Tibet Plateau-loess Plateau transition region,and the Loess hilly region in central Gansu province)from 2001 to 2018 were studied.The results showed that:1)The dryness index and the number of days with sand-blowing≥6 m/s in the farming-pastoral transitional zone of Gansu province were mainly low sensitive and insensitive,and showed a decreasing trend over time.The vegetation coverage was mainly medium sensitive and insensitive,and showed an increasing trend over time,increasing from west to east in space.2)The sensitivity of land desertification in farming-pastoral ecotone decreased with time from high and medium sensitivity to low and insensitive sensitivity.High and moderate sand-dust prone areas gradually transited to non-dust prone areas.The area of high and medium sensitive grades showed a downward trend,while the area of low and insensitive grades showed an upward trend.