2002-2016年华北平原植被生长状况及水文要素时空特征分析

基于MODIS增强型植被指数（EVI）资料，结合降水、GRACE重力卫星水储量（TWS）、地下水、土壤水等资料，分析华北平原植被2002-2016年间的生长状况及各水文要素时空分布特征。研究结果表明：（1）2002-2016年间华北平原植被呈好转趋势，降水、水储量、土壤水、地下水等水文要素值呈减少趋势。（2）黄淮平原区植被以农作物为主，植被覆盖度呈增加趋势，而降水、水储量、地下水、土壤水均呈减少趋势，超采地下水灌溉农作物是短期内保障粮食安全的重要措施。（3）燕山-太行山山麓平原区、冀鲁豫低洼平原区的城乡居民用地区域植被覆盖显著减少，而降水增多，水储量、土壤水、地下水减少，人类活动对植被和水文要素贡献量大。（4）山东丘陵农林区分布着林地和草地，这些区域生长季的植被指数呈减少趋势，与降水量减少呈正相关关系。在气候变化和人类活动影响的大背景下，探讨不同生态环境的植被生长特征，清楚植被对水文变化的响应机理，可以消除影响植被生长的不利因素，为制定合理用水制度提供理论依据。

Spatiotemporal changes in vegetation and hydrological factors in the North China Plain from 2002 to 2016

In this study we investigated the spatial-temporal dynamics and trends of vegetation and its association with changes in various hydrological factors in the North China Plain between 2002 and 2016, by combining the MODIS enhanced vegetation index (EVI) with precipitation, GRACE gravity satellite terrestrial water storage (TWS), groundwater, and soil moisture. Our results showed that:(1) from 2002 to 2016, the vegetation of the North China Plain exhibited an increasing trend, whereas there was a decreasing trend in the hydrological factors (TWS, soil moisture, groundwater); (2) being mainly covered by crops, the vegetation in the Huanghuai plain area increased during the study period. However, precipitation, TWS, groundwater, and soil moisture all decreased. Over-exploitation of groundwater to irrigate crops is an important measure to ensure food security in the short term; (3) the contrasting trends in the decreasing vegetation coverage, TWS, soil moisture, and groundwater with increasing precipitation over the urban and rural residential areas in the Yanshan-taihang mountains piedmont plain and Ji-lu-yu low lying plain may be a result of influences from intense human activities; (4) the natural forest and grassland ecosystems located in the Shandong hilly agroforestry region were positively correlated with precipitation during the study period, both showing decreasing trends. Results from this research will generate a better understanding of vegetation dynamics in different ecological environments and its response mechanisms to changes of different hydrological factors. This will guide the design of rational water-use strategies for a changing climate and increasing anthropological activities.