基于遥感土壤湿度因子的防风固沙功能估算模型改进及应用

Improvement and application on the estimation model of windbreak and sand fixation function based on remote sensing soil moisture factor

在生态系统防风固沙功能研究中,土壤湿度因子是重要参量之一。传统方法多使用气象站点观测的潜在蒸发量、降雨量和灌溉量等估算土壤湿度,在空间连续性和数据可利用性方面均具有较大局限。基于遥感技术在土壤湿度探测方面的发展,本研究选择4种土壤湿度的遥感指标(MODIS蒸散比值法、SMAP土壤湿度比值法、可见光-短波红外干旱指数法、遥感湿度指数法)对修正风蚀方程模型(RWEQ)中的土壤湿度因子的计算过程做出改进,并利用改进后的算法分析辽西北地区2001—2021年防风固沙服务的时空变化及驱动因素。结果表明:MODIS蒸散比值法计算的土壤湿度与传统气象方法的相关性最高,二者经拟合后得到的公式可用于RWEQ模型中土壤湿度因子的计算改进。2001—2021年,辽西北地区防风固沙能力呈现北部及东部地区较强、中部及西部地区较弱的空间分布特征。经Mann-Kendall趋势检验,辽西北地区72.7%的区域防风固沙能力呈上升趋势。应用地理探测器模型进行驱动因素分析发现,防风固沙能力的变化是一个多因素相互作用的过程,受土壤类型、年均风速以及经济发展水平的影响较大,且各驱动因素之间的交互作用对防风固沙的影响高于单因素的影响。本研究结果可为RWEQ模型估算做出改进,同时为辽西北地区长时间的生态功能形成机制与驱动力分析提供技术支撑。

Soil moisture factor is one of the important parameters in the study of wind and sand fixation functions of ecosystems.Traditional methods often use potential evaporation,rainfall,and irrigation observed by meteorological stations to estimate soil moisture,which has significant limitations in terms of spatial continuity and data availability.Based on the development of remote sensing technology in soil moisture detection,we selected four remote sen-sing indicators for soil moisture(MODIS evapotranspiration ratio method,SMAP soil moisture ratio method,visible shortwave infrared drought index method,and remote sensing humidity index method)to improve the estimation of soil moisture factor in the modified wind erosion equation model(RWEQ),and used the improved algorithm to analyze the spatiotemporal variations and driving factors of wind prevention and sand fixation services in the northwest region of Liaoning Province from 2001 to 2021.The results showed that the MODIS evapotranspiration ratio method had the highest correlation with traditional meteorological methods in calculating soil moisture.The formula obtained by fitting the two could be used to improve the calculation of soil moisture factor in the RWEQ model.From 2001 to 2021,the wind prevention and sand fixation capacity in the northwest region of Liaoning Province showed strong spatial distribution characteristics in the northern and eastern regions,while weak in the central and western regions.According to Mann-Kendall trend testing,72.7%of the regions in northwest Liaoning Province were showing an upward trend in their ability to prevent wind and fix sand.The application of geographic detector models for driving factor analysis showed that the change in wind and sand fixation capacity was a process of multiple factors interacting with each other,greatly influenced by soil type,annual wind speed,and economic development level.Moreover,the interaction between various driving factors had a higher impact on wind and sand fixation than that of single factors.The results could improve the RWEQ model estimation and provide technical support for the long-term analysis of ecological function formation mechanisms and driving forces in the northwest region of Liaoning.