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柴达木盆地典型地貌单元归一化植被指数变化特征
杨运航, 文广超, 谢洪波, 王琳
河南理工大学 资源环境学院, 河南 焦作 454000
摘要:
[目的] 探究柴达木盆地不同地形地貌单元植被空间分布特征及生态环境的变化趋势,为当地制定有针对性的生态环境保护策略提供决策支持与数据依据。[方法] 利用1998—2018年柴达木盆地的5期Landsat遥感影像,采用趋势线及相关分析等方法,研究近20 a来该区不同地貌单元的归一化植被指数(NDVI)的变化特征,并分析了其驱动力。[结果] ①柴达木盆地NDVI总体上表现为东南高,西北低,1998—2003年,受崩塌、滑坡、泥石流等自然灾害的影响,NDVI呈现出显著下降趋势;2003—2008年,随着国家生态环境治理力度的加强及公众环保意识的提高,NDVI表现出显著增加趋势,2008年以后,NDVI趋于稳定,生态环境保持良性发展;②不同地貌分区下,水源是限制植被生长的关键因子,冲积扇和洪积扇地区植被生长较茂盛;人类活动对生态环境的影响表现出两面性,在德令哈中海拔流水作用丘陵台地平原区(Ⅱ2),人类改造土地利用类型,种植枸杞等经济作物,使该区域NDVI增加明显,在达布逊中海拔、盐湖沉积平原区(Ⅱ3)湖泊周边,受人类采盐活动影响,NDVI表现出显著下降趋势;③受到气候、人类活动和植被类型的影响,NDVI和海拔高度表现出明显的正相关特性;④NDVI受坡度影响明显,坡度在2°~35°时,NDVI普遍较高。[结论] 水源和气候是影响植被变化的关键因子,人类活动和地形的改变,同样会导致生态环境的变化。
关键词:  植被变化  柴达木盆地  地貌分区  NDVI
DOI:10.13961/j.cnki.stbctb.2020.04.018
分类号:P942
基金项目:四川省自然资源科技计划项目“九寨沟景区地质灾害精细化监测预警与应急处置技术研究与示范”(KJ-2018-23);旱区地下水文与生态效应教育部重点实验室中心开放基金项目(2014G1502022)
Characteristics of Normalized Vegetation Index Under Typical Geomorphic Units in Qaidam Basin
Yang Yunhang, Wen Guangchao, Xie Hongbo, Wang Lin
Institute of Resources&Environment, He'nan Polytechnic University, Jiaozuo, He'nan 454000, China
Abstract:
[Objective] The spatial distribution characteristics of vegetation and ecological change trends under different topographic and geomorphic units in Qaidam Basin was explored in order to provide decision support and data basis for the local formulation of targeted ecological environmental protection strategies. [Methods] Based on the five-phase Landsat remote sensing image of the Qaidam Basin from 1998 to 2018, the variation characteristics of the normalized vegetation index (NDVI) of different geomorphic units in the area were studied by using trend lines and related analysis methods, and their driving factors were analyzed. [Results] ① NDVI in the basin was generally high in the southeast and low in the northwest. From 1998 to 2003, due to the impact of natural disasters such as rock avalanche, landslides, and debris flows, NDVI showed a significant downward trend. From 2003 to 2008, with the strengthening of national ecological environment governance and the improvement of public awareness of environmental protection, NDVI showed a significant increase trend, and the ecological environment of the basin continued to improve. After 2008, NDVI stabilized and the ecological environment maintained a healthy development. ② Under different landform zones, water sources were the key factors limiting vegetation growth, and vegetation growth in alluvial and flood fan areas was often prosperous. The impact of human activities on the ecological environment was two-sided. In Delingha, middle-altitude flowing water affects hilly platform plain area (Ⅱ2), human beings changed land use types, planting Lycium barbarum and other economic crops, which made NDVI increase significantly in this area. In the mid-altitude of Dabson, the salt lake sedimentary plain (Ⅱ3), the NDVI was affected by human salt mining activities, showing a significant downward trend. ③ Affected by climate, human activities and vegetation types, NDVI and altitude exhibited a significant positive correlation. ④ NDVI was obviously affected by the slope gradient. When the slope gradient was 2°~35 °, NDVI was generally higher. [Conclusion] Water source and climate are the key factors affecting vegetation change. The change of human activities and topography will also lead to the change of ecological environment.
Key words:  vegetation change  Qaidam Basin  geomorphic zoning  NDVI