ABSTRACT

Grasslands are a major component of the natural vegetation in South Africa, it covers almost one-third of the country’s land surface. The current study focuses on assessing the impact of drought stress on communal and commercial grasslands in Eastern Cape Province using multi-temporal analysis of Sentinel-1 SAR data. Data analysis included retrieval of biophysical parameters of grasslands using Sentinel-1 SAR backscattering coefficients. Correlation analysis was performed between SAR data and NDVI values derived from Landsat-8 optical data. A linear mixed-effects regression analysis was performed for detecting the impact of drought on communal and commercial grasslands during a drought and non-drought growing seasons. Our results indicate that vegetation dynamics in grasslands in the study area are highly responsive to the climatic fluctuations. A significant correlation between backscattering coefficients of Sentinel-1 SAR data (VH and VV) and NDVI was observed for both communal and commercial grasslands (R² = 0.89). Results also demonstrated that communal grasslands are more affected by drought impact than commercial grasslands. In commercial grasslands, management activities can improve the growing conditions of grasslands, reduce the impact of drought, and subsequently increase the resilience and productivity of this ecosystem.

摘要

草原是南非自然植被的主要组成部分，几乎覆盖了该国三分之一的土地面积。当前的研究重点是使用Sentinel-1 SAR数据的多时间分析来评估干旱胁迫对东开普省的公共和商业草地的影响。数据分析包括使用Sentinel-1 SAR反向散射系数检索草原的生物物理参数。SAR数据和从Landsat-8光学数据得出的NDVI值之间进行了相关分析。进行了线性混合效应回归分析，以检测干旱和非干旱生长期干旱对公共和商业草地的影响。我们的结果表明，研究区草地的植被动态对气候波动具有高度的响应能力。²  = 0.89）。结果还表明，与商业草原相比，公共草原受干旱影响更大。在商业草地上，管理活动可以改善草地的生长条件，减少干旱的影响，并随后提高该生态系统的弹性和生产力。