A Remote Sensing-based approach to Evaluation of Trends and Impacts of Land Surface changes in the Mara Ecosystem

Abstract

The earth’s land surface is a key component of the earth’s climate system. Terrestrial plants, animals and human beings rely on the land surface for sustenance and existence. As such, the conditions prevailing on the land surface and its properties are essential to terrestrial life. Land cover is a major component of the land surface and changes to it constitute a form of land surface change. Modification, conversion and maintenance of land cover are all forms of anthropogenic interactions with the environment that result in a variety of vital changes to land cover and consequently the land surface, that either positively or negatively feedback to the environment and climate. These feedbacks, in turn influence the land surface state and its properties as well as the response and adaptations by plants, animals and human beings. The identification and monitoring of these Land Use/ Land Cover Changes (LULCC) is therefore important since changes in land cover, occasioned more often than not by anthropogenic land use, alter land surface-atmosphere interactions upon which ecosystem services rely thus resulting in climate change and variation. Land Surface Temperature (LST) is a property of the land surface and refers to the temperature of the interface between the earth’s land surface and the atmosphere. It is therefore an important variable in land surface-atmosphere interactions and a climate change indicator which varies spatially and temporally as a function of other land surface properties and components such as vegetation cover, surface moisture, soil types and topography as well as atmospheric conditions primarily characterized by meteorological measures. Vegetation cover is a major constituent of land cover that is subject to changes occasioned by natural events such as precipitation and impacted by activities on the land surface such as foraging and clearing. The ability to monitor and characterize changes in Land Surface Temperature and vegetation cover allows for investigation of causes and enhances the ability to anticipate changes and put in place adaptation measures. Remote Sensing provides us with the ability to monitor changes and establish trends and interrelationships between these and other land surface components and properties, thereby providing information on the state of the environment and climate change and variation. This study uses a remote sensing approach in one of the most ecologically rich and diverse ecosystems to investigate the Land Cover Changes and in particular vegetation change and Land Surface Temperature (LST) changes as indicators of land surface change. Further, the study evaluates the relationship between Land Surface Temperature and vegetation cover in the region using NDVI as a parameter to characterize and assess vegetation. The study area is in the Mara ecosystem located in South Western Kenya. LANDSAT satellite images for 1985, 1995, 2003 and 2010 are used to derive NDVI, LST and Land Use/ Land Cover maps. We found that human related Land Use/ Land Cover Change (LULCC) in the form of conversion of land for cultivation purposes has been and is taking place around the Maasai Mara National Reserve (MMNR). We also found that a negative correlation exists between LST and NDVI thus indicating that with decrease in vegetation cover, there is increase in Land Surface Temperature (LST) in the region.