生态环境学报 ›› 2022, Vol. 31 ›› Issue (11): 2124-2133.DOI: 10.16258/j.cnki.1674-5906.2022.11.003

• 研究论文 • 上一篇    下一篇

基于GEE平台的1986-2021年黄土高原植被覆盖度时空演变及影响因素

赵安周(), 田新乐*()   

  1. 河北工程大学矿业与测绘工程学院,河北 邯郸 056038
  • 收稿日期:2022-08-03 出版日期:2022-11-18 发布日期:2022-12-22
  • 通讯作者: *田新乐(1998年生),女,硕士研究生,主要研究方向为植被动态遥感监测。E-mail: 1713647311@qq.com
  • 作者简介:赵安周(1985年生),男,副教授,博士,主要研究方向为城市扩张对生态环境的影响。E-mail: zhaoanzhou@126.com
  • 基金资助:
    国家自然科学基金项目(42171212);河北省自然科学基金项目(D2022402030);河北省自然科学基金项目(D2021402007)

Spatiotemporal Evolution and Influencing Factors of Vegetation Coverage in the Loess Plateau from 1986 to 2021 Based on GEE Platform

ZHAO Anzhou(), TIAN Xinle*()   

  1. School of Mining and Geomatics, Hebei University of Engineering, Handan 056038, China
  • Received:2022-08-03 Online:2022-11-18 Published:2022-12-22

摘要:

基于Google Earth Engine(GEE)云平台,对1986-2021年黄土高原的Landsat地表反射率数据进行去云和融合处理,计算得到归一化植被指数(Normalized Difference Vegetation Index,NDVI),并利用像元二分模型估算植被覆盖度(Fractional Vegetation Coverage,FVC),在此基础上,辅以趋势分析、偏相关和残差分析等方法分析了不同时间段(1986-1999、2000-2021和1986-2021年)黄土高原FVC时空变化及其影响因素。结果表明,(1)时间上,1986-2021年黄土高原FVC呈显著增加的趋势(Trend=0.0044 a-1P<0.01)。从不同时间段看,2000-2021年FVC的增加趋势(Trend=0.0058 a-1P<0.01)快于1986-1999年(Trend=0.0038 a-1P<0.01)。黄土高原所有植被类型的FVC均呈显著上升的趋势(P<0.01),其中草地的上升趋势最大(Trend=0.0066 a-1P<0.01)。(2)空间上,黄土高原FVC呈东南向西北递减的趋势,1986-2021、1986-1999和2000-2021年FVC呈显著上升的面积分别为53.65%、18.38%和48.12%。(3)地形因子中,高程和坡度对FVC的影响较显著。FVC值随高程呈“下降-上升-下降”的变化趋势,最大值(0.7790)出现在3000-3500 m。FVC随坡度的增加呈上升的趋势,最大值(0.7025)出现在25°-45°。中高等级FVC和高等级FVC比例随坡度呈正相关关系,其中15°-25°面积占比最大(73.93%)。(4)1986-2021年黄土高原FVC与年降水量、年平均气温和太阳辐射(Solar Radiation,RAD)的偏相关系数分别为0.239、0.093和-0.006,其中呈显著正相关(P<0.05)的像元占比分别为48.50%、22.51%和5.96%。残差分析结果表明,人类活动是黄土高原植被动态变化的主要驱动因素,且起正向作用的像元比例为73.20%。

关键词: GEE, FVC, 时空演变, 影响因素, 黄土高原

Abstract:

Based on the cloud platform of Google Earth Engine (GEE), Landsat surface reflectance data of Loess Plateau from 1986 to 2021 were de-clouding and fused. The Normalized Difference Vegetation Index (NDVI) was calculated, and fractional vegetation coverage (FVC) was estimated using the pixel dichotomy model. On this basis, with the help of trend analysis, partial correlation analysis and residual analysis, the temporal and spatial variations of FVC and its influencing factors in the Loess Plateau in different time periods (1986-2021, 1986-1999 and 2000-2021) were analyzed. The results show that (1) in terms of time, FVC on the Loess Plateau increased significantly from 1986 to 2021 (Trend=0.0044 a-1, P<0.01). In different time periods, the increasing trend from 2000 to 2021 (Trend=0.0058 a-1, P<0.01) was faster than that from 1986 to 1999 (Trend=0.0038 a-1, P<0.01). The FVC of all vegetation types on the Loess Plateau showed a significant increasing trend (P<0.01), among them, the grassland had the largest increasing trend (Trend=0.0066 a-1, P<0.01). (2) Spatially, FVC decreased from southeast to northwest in the Loess Plateau. The FVC of the total area showed significant improvement in 1986-2021, 1986-1999 and 2000-2021 by 53.65%, 18.38% and 48.12%, respectively. (3) Elevation and Trend of topographic factors had significant effects on FVC. The value of FVC first decreased, then rose and finally decreased with the elevation, with the maximum value (0.7790) between 3000 m and 3500 m. FVC increased with the increase of Trend, with the maximum value (0.7025) appeared in the range of 25°-45°. The proportion of middle and high coverage and high coverage increased with the increase of Trend, in which the area proportion was the largest in the range of 15°-25° (73.93%). (4) The biased relationship between FVC and annual precipitation, annual mean temperature and solar radiation in the Loess Plateau from 1986 to 2021 were 0.239, 0.093 and -0.006, respectively. The proportions of pixels with significant positive correlations (P<0.05) accounted for 48.50%, 22.51% and 5.96% of the total area. The results of residual analysis showed that human activities was the main driving factor of vegetation dynamic change on the Loess Plateau, and the proportion of pixels that played a positive role was 73.20%.

Key words: GEE, fractional vegetation coverage, spatiotemporal evolution, influencing factors, Loess Plateau

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