为辨识长江流域陆地生态系统植被的时空变化特征及其对水热条件的响应,根据长江流域2000—2015年MODIS NDVI(Normalized Difference Vegetation Index)资料和气象资料,利用时间序列分析技术研究长江流域及主要陆地生态系统NDVI和水热条件的年际变化及相关性特征。结果表明:①近16 a来,全流域及主要生态系统NDVI均呈现出显著的增加趋势,农田、森林、水体与湿地生态系统NDVI增长率较大;②降水量整体略微增加,具有明显的空间差异性,积温(≥10 ℃)增加明显,且在空间上普遍呈现出增加的趋势;③受气候条件和生态系统类型差异性的影响,不同水热条件分区上NDVI与降水量和积温(≥10 ℃)的相关性有所差别,但整体而言,由于长江流域水量相对丰沛,降水量并不是长江流域植被生长的限制性因子,降水量与NDVI相关性并不显著,但对于森林、草地和荒漠生态系统而言,植被NDVI与积温呈现出较为明显的正相关关系,表明热量条件是长江流域植被生长的限制性因子。研究成果可为长江流域主要陆地生态系统变化的监测和预测提供一定的数据和技术支撑。
Abstract
In order to identify the spatiotemporal variations of NDVI in terrestrial ecosystem in Yangtze River Basin and its response to hydrothermal condition, we analyzed the interannual changes of NDVI, accumulated temperature, precipitation and their correlations in the Yangtze River Basin based on the MODIS NDVI, temperature and precipitation data in 2000-2015 using time series analysis techniques. Results revealed that: (1) The NDVI displayed a significant increasing trend in the Yangtze River Basin in recent 16 years. The growth rates of NDVI in farmland, forest, water and wetland ecosystem were larger than those of others. (2) Precipitation increased slightly in the whole basin with evident spatial heterogeneity. Accumulated temperature above 10 ℃significantly increased and generally presented increasing trend in spatial scale. (3) Due to differences in climate and ecosystem patterns, the correlation between NDVI and precipitation and accumulated temperature above 10 ℃varied in different zones. In general,precipitation is not a restrictive factor for vegetation growth in the Yangtze River Basin. The correlation between NDVI and precipitation is not significant. But for forest, grassland and desert ecosystems, NDVI and accumulated temperature present a more significant positive correlation, indicating that heat condition is a restrictive factor of vegetation growth in the Yangtze River Basin.
关键词
陆地生态系统 /
NDVI /
时空变化特征 /
水热条件 /
长江流域
Key words
terrestrial ecosystem /
NDVI /
spatio-temporal change characteristics /
hydrothermal condition /
Yangtze River Basin
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基金
国家重点研发计划项目(2017YFC1502404);国家自然科学基金项目(41890821,51709008);湖北省自然科学基金项目(2018CFB655);中央级公益性科研院所基本科研业务费项目(CKSF2017061/SZ,CKSF2017029/SZ);河南省高等学校青年骨干教师培养计划项目(2016GGJS-224)