摘要:
云南省物种资源丰富但生态系统十分脆弱,生态环境脆弱性保护与植被覆盖联系紧密。为此,该文采用2000—2022年MOD13Q1数据集的归一化植被指数(normalized difference vegetation index, NDVI),利用最大值合成法(maximum value composite, MVC)、Theil-Sen中位数趋势分析、Mann-Kendall显著性检验方法动态监测植被的时空格局变化。利用相关分析方法探讨植被对地形地貌、气候变化及土地覆被等影响因素的响应。研究表明: 2000—2022年,云南省整体植被覆盖度较高,年均NDVI值在0.74~0.90之间,呈波动上升趋势,其中增加趋势的面积占91.17%,滇东北增长速率最快; 植被覆盖在地域上存在差异,滇东南、滇西南的植被覆盖高于滇西北、滇中、滇东北; 在海拔3 900 m以下,云南省NDVI值比较稳定,3 900 m以上随海拔升高而NDVI值呈减少趋势; 坡度<3°时,NDVI值最低,随着坡度增加,NDVI值先增加后降低; 平面坡向的NDVI值最低,除平面坡向外,其余坡向对植被生长影响较小; 2000—2022年,滇中、滇东南、滇东北的植被覆盖与降水呈正相关,表明降水有利于植被生长; 而滇西南、滇西北与降水呈负相关。全区及各区域的植被覆盖与气温呈正相关,表明气温有利于植被生长。研究结果可为加强云南省生态环境建设和生态管理提供科学依据。
Abstract:
Yunnan Province has abundant species resources but fragile ecosystems, and the ecological vulnerability is closely related to vegetation cover. Hence, based on the normalized difference vegetation index (NDVI) from the MOD13Q1 dataset for 2000—2022, this study dynamically monitored the spatio-temporal variations of vegetation using the maximum value composite (MVC), Theil-Sen median trend analysis, and Mann-Kendall significance test. Moreover, this study delved into the response of vegetation to factors like topography, climate change, and land cover through correlation analysis. The results show that: ① From 2000 to 2022, the overall vegetation coverage of Yunnan Province was relatively high, with average annual NDVI values ranging from 0.74 to 0.90, showing a fluctuating upward trend. Of the whole area, 91.17% exhibited an increasing vegetation coverage trend, with the fastest growth rate seen in northeastern Yunnan; ② Regional differences were observed in vegetation cover, which was higher in southeastern and southwestern Yunnan compared to northwestern, central, and northeastern Yunnan; ③ The NDVI values of Yunnan Province were relatively stable below the altitude of 3 900 m, and decreased with increasing altitude in the case of over 3 900 m; ④ The NDVI values were the lowest with slopes below 3°, and with an increase in slope, they increased first and then decreased; ⑤ The planar slope aspect displayed the lowest NDVI values, and other slope aspects showed minimal impact on vegetation growth; ⑥ From 2000 to 2022, the vegetation cover in central, southeastern, and northeastern Yunnan was positively correlated with precipitation, suggesting that precipitation in these areas was favorable for vegetation growth. However, the vegetation cover in southwestern and northwestern Yunnan showed a negative correlation with precipitation. Additionally, the vegetation cover in the whole region and various areas was positively correlated with temperature, suggesting that temperature is beneficial to vegetation growth. The results of this study will provide a scientific basis for strengthening ecological environment construction and ecological management in Yunnan Province.
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