基于景观格局演变的泾河上游土壤水空间格局形成机制与尺度效应

Soil moisture is the key factor for the vegetation restoration and stability. The change of landscape patterns caused by the vegetation restoration programme during the past decades in the Loess Plateau has resulted in declining of soil moisture, and thus become a threat for the vegetation restoration and water resource safety. To make a compositive utilizing and control of regional water-soil-vegetation system, the formation mechanism of spatial patterns of soil moisture under land use and landscape changes must be made clear, and the effects of land use on soil moisture patterns should be paid attention to especially. However, researches on the formation mechanism and scale effect of soil moisture upon different spatial scale is quite limited since soil moisture patterns is affected by multi-scale and multi-factors, it's difficult now to be applied in the management of regional vegetation and soil moisture. Based on field observation, statistics and model simulation on multi-spatial-scales from sample plot to watershed, the spatial-temporal changes of environmental factors including landscape patterns will be studied in upstream area of Jinghe watershed on Loess Plateau in this research. Distributed ecohydrological model is planned to be applied to simulate the spatial patters of soil moisture on multi-scales, and the effects of environmental factors on different scales upon soil moisture patterns will be analysed quantitatively, and what is the primary factor as well, thus the scale effect of the primary controlling factor upon soil moisture patterns could be revealed. Finally, the different formation mechanism of soil moisture patterns between rocky mountain area and loess area will be compared. We expected this research could improve the development of ecohydrology and the compositive management of the water-soil-vegetation resource in Loess Plateau area.

土壤水是干旱缺水区植被恢复与稳定的关键。近几十年黄土高原植被恢复等引起景观格局改变，导致土壤水含量下降，进而威胁到区域植被恢复与供水安全；要实现区域水-土-植被的综合利用与调控，亟需明确土地利用等景观变化下土壤水空间格局形成机制，尤其要关注土地利用等对土壤水格局的影响。然而土壤水空间格局受多尺度多因素的综合影响，导致对土壤水在不同尺度的格局形成机制与尺度效应认识不清，无法满足区域植被与土壤水管理的需求。本项目拟在黄土高原地区泾河上游，基于野外实测、统计与模型模拟等方法，在样地到流域的多空间尺度上，研究景观格局等环境因素的时空演变，应用分布式生态水文模型多尺度模拟土壤水空间格局，定量分析不同尺度环境因素对土壤水空间格局的影响及其主控因素，揭示土壤水空间格局主控因素的尺度演化特征与尺度效应，对比土石山区和黄土区土壤水空间格局形成机制差异，推动生态水文学发展和黄土高原水-土-植被资源的综合管理。

土壤水是干旱缺水区植被恢复与稳定的关键。由于最近几十年黄土高原植被恢复等引起景观格局改变，导致土壤水含量下降，影响威胁到这一区域植被恢复与供水安全。因此，要实现区域水-土-植被的综合利用与调控，就亟需弄清土地利用等景观变化下土壤水空间格局形成机制。然而土壤水空间格局受多尺度多因素的综合影响，导致对土壤水在不同尺度的格局形成机制与尺度效应认识不清，无法满足区域植被与土壤水管理的需求。本项目在黄土高原泾河上游，基于野外实测、统计与模型模拟等方法，在样地到流域的多空间尺度上，一方面通过实测研究土壤水在样地和坡面尺度随植被格局、气象因子、地形地貌等环境因素的时空演变，一方面应用分布式生态水文模型模拟流域尺度土壤水空间格局，定量分析样地、坡面和流域尺度上环境因素对土壤水空间格局的影响及其主控因素，基于分析揭示不同尺度上土壤水空间格局主控因素及其在不同气候-植被区的形成机制差异，探讨了不同尺度下土壤水时空分异的尺度效应。研究结果表明，土壤持水性能是影响土壤质量含水量沿坡差异格局的主要因素，表现为各月土壤含水量均与土壤孔隙度、持水能力显著相关；土壤含水量存在坡面尺度效应，表现为土壤含水量滑动加权平均值随水平坡长增加有明显变化，整个生长季及各月的土壤质量含水量的坡面尺度效应的变化趋势基本一致，但数值大小有所不同；对整个坡面平均土壤质量含水量而言，最佳代表性样地位于坡中部相对水平坡长0.57处，可由此样地的土壤含水量测定值代表坡面均值，由此可利用样地土壤水观测值建立统计模型，从而上推估计坡面土壤水含量均值，这为土壤含水量参数从样地到坡面尺度的外推提供了一种可能的途径，有助于推动生态水文学发展和黄土高原水-土-植被资源的综合管理。