内蒙古不同类型草原光合植被覆盖度对降水变化的响应

植被是影响土壤侵蚀过程的重要因素。论文基于MODIS遥感数据和同期降水数据,用相关和回归分析方法从不同时间尺度揭示了内蒙古草甸草原、典型草原和荒漠草原2002—2016年光合植被覆盖度(Fractional Photosynthetic Vegetation,f_(PV))的变化规律及其对降水变化的响应。结果表明:(1)2002—2016年间多年平均f_(PV)草甸草原为46.5%,典型草原和荒漠草原分别为36.3%和22.4%;草甸草原f_(PV)随时间变化呈不显著增长趋势(线性变化斜率为0.29%/a),典型草原和荒漠草原f_(PV)呈不显著下降趋势(线性变化斜率分别为-0.04%/a和-0.21%/a);相应时期年降水量随时间变化都呈现不显著波动上升趋势。(2)内蒙古草原的月植被覆盖度对月降水量存在明显的1—2个月滞后效应和显著的累积效应,且表现出草原类型越干旱,滞后效应越明显的特征;相比草甸草原和典型草原,荒漠草原植被对降水量变化更加敏感。(3)内蒙古3类草原年平均植被覆盖度对降水量的响应,均表现出年、季、月尺度上分别受当年降水量、生长季降水量以及6、7、8月份降水量的显著影响的特征;3类草原年植被覆盖度与生长季降水线性拟合结果都较好,内蒙古3种草原类型的年植被覆盖度与降水量具有的强相关性,可为区域土壤侵蚀动态评价提供科学依据。

Photosynthetic vegetation cover response to precipitation on the Inner Mongolian Steppe

Vegetation cover is an important factor in the process of soil erosion. This paper revealed the changes of photosynthetic vegetation coverage (f_PV) for meadow steppe, typical steppe and desert steppe in Inner Mongolia from 2002 to 2016 and their responses to precipitation in the annual, seasonal, and monthly scales. The MODIS derived data and corresponding precipitation data were used in the analysis. The results showed that: (1) from 2002 to 2016, the annual average f_PV of three steppe types was 46.5%, 36.3%, and 22.4%, respectively. The trend of f_PV over time for all three steppe types was not significant. For meadow steppe the annual change was positive with a rate of 0.29% per year, while for typical steppe and desert steppe it was negative with the rate of -0.04%/a and -0.21%/a, respectively. The annual precipitation for the three steppe types all showed an increasing trend without statistical significance. (2) The monthly vegetation coverage was clearly affected by the prior one to two month precipitation, and the cumulative effect was also evident. The more arid the steppe type, the more obvious of the lag effect. The coverage of dessert steppe was comparatively more sensitive to the change of precipitation. (3) The annual vegetation coverage of three steppe types in Inner Mongolia was significantly affected by the annual precipitation, growth season precipitation, and the precipitation in June, July, and August. The linear regression between the annual vegetation coverage and the precipitation in the growth season showed a good fit. The significant correlation between annual vegetation coverage and precipitation of three steppe types in Inner Mongolia provides a scientific basis for dynamic, regional soil erosion assessment.