淮河中上游植被变化及其对气象因素的多时空尺度响应

[目的]植被与气象因子关系的多时空特征有助于深入理解流域生态系统，对生态环境保护具有重要意义。[方法]基于MODIS EVI数据与气象观测资料，结合趋势分析、Mann-Kendall检验和Pearson相关性分析方法，分析淮河中上游2001—2015年植被动态并探讨流域至局地尺度的植被与降水、气温的相关关系。[结果](1)流域植被整体呈明显增长趋势(p<0.05),EVI指数增长速率为0.055/10 a,冬季增速最大(0.075/10 a)、夏季最小(0.047/10 a),不同地类增速差异显著。(2)年均EVI呈增加的区域占流域总面积的93%,其中呈显著(p<0.05)及极显著(p<0.01)上升趋势约占82%,华北平原(主要为耕地)增速最大，山区、山丘区增速次之，郑州市辖区等呈显著下降(p<0.05);EVI变化的时空分布差异明显。(3)流域尺度春季EVI与同期(3—5月)和2—5月降水呈显著正相关(p<0.05),冬季EVI与同期降水呈极显著负相关(p<0.01),月EVI在3月、11月与最低气温呈显著正相关(p<0.05),在12月分...

Multi Temporal and Spatial Scale Responses of Vegetation Dynamics to Climate Factors

[Objective]To profoundly understand the difference in vegetation response to climate at different spatiotemporal scales plays an important guiding role in ecological construction and sustainable agricultural development. [Methods] Firstly, the pattern and the dynamics change of EVI(enhanced vegetation index)and key driving climate factors(precipitation and the average, minimum and maximum air temperature were investigated using the GRC method and the Mann-Kendall trend test, and then vegetation activity responses to climate change at multiple spatial(from pixel scale to basin scale)and temporal scales(yearly, seasonal and monthly)were examined based Pearson correlation coefficient and t-test method. [Results] The average EVI of the middle and upper reaches of the Huaihe River basin showed a significant growth trend with a growth rate of 0.055/decade. EVI increased over 93% of the study area from 2001 to 2015, with a significant and extremely significant upward trend observed in 82% of the basin. The EVI in spring was significant positively affected by precipitation of the same period and the previous period(p<0.05), and EVI in winter was significantly negatively affected by precipitation(p<0.01). Monthly EVI showed a significant positive response to T_min in March and November and a negative response to T_max in September(p<0.05), and in December positive and significant negative responses to T_max and precipitation, respectively(p<0.05). The correlation between seasonal and monthly EVI and meteorological factors on a local scale was different in different regions. EVI of Gushi located in south of the Huaihe River was positively affected by precipitation in winter, while other regions in the north of Huai River have no such correlation. In February, November and December, vegetation of Zhumadian was mainly positively affected by the temperature(p<0.05). The precipitation in April and July had a positive effect on the vegetation in Xuchang(p<0.05), and the vegetation had a one-month lag response to the precipitation in May and August. From July to August, the EVI in Gushi had a significant positive and negative correlation with the precipitation and temperature(p<0.05)and a very significant negative correlation with the temperature in September, there was the one-month lag response of vegetation to temperature in October(p<0.01). [Conclusion] The correlations between watershed-scale EVI and local-scale EVI and meteorological factors effectively reflect the regional differences of the main vegetation growth characteristics and vegetation change drivers in the watershed, respectively, and human activities have obvious positive and negative effects on vegetation in the cultivation and urban areas, which can provide theoretical support for ecological construction and sustainable agricultural development in the watershed.