Monitoring land Cover Changes and Fragmentation dynamics in the subtropical thicket of the Eastern Cape Province, South Africa

Adolph Nyamugama,Vincent Kakembo

doi:10.4314/sajg.v4i4.4

Adolph Nyamugama, Vincent Kakembo

Open Access

https://doi.org/10.4314/sajg.v4i4.4

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Abstract

Land cover change trends and fragmentation dynamics in the Great Fish River Nature Reserve (GFRNR) and surrounding settlements were monitored for a period of 38 years, in the intervals of 1972-1982, 1982-1992 and 2002-2010. Gaining an understanding of these trends and dynamics is vital for land management and combating desertification. Monitoring land cover change and fragmentation dynamics was conducted using LandSAT MSS, LandSAT4TM and LandSAT 7ETM and SPOT 5 High-resolution Geometric (HRG) imagery. The objected-oriented supervised approach and cross-classification algorithm were used for classification of the satellite imagery and change detection respectively. Landscape fragmentation was analysed using FRAGSTATS 3.3® class level land metrics. Overall, a decrease in the land area under intact and transformed thicket was realised. Degraded thicket, grassland and bare surfaces increased over the same period. Landscape metric analyses illustrated an increase in vegetation fragmentation over the 38-year period, as demonstrated by an increase in the number of patches (NP) and a decrease in the Largest Patch Index (LPI), particularly for intact and transformed thicket. Baseline land use/cover maps and fragmentation analyses in a temporal framework are valuable for gaining insights into, among other things, carbon stock change trends.Keywords: Land cover change, fragmentation; remote sensing; Geographic information systems (GIS)

Highlights

Human activities have become an important factor in global change processes (Petit & Lambin, 2002) in the wake of the surge in global population
Southworth et al (2004) observed that landscape fragmentation analysis is crucial for the interpretation of the effect of land cover changes on a particular habitat, through the calculation of each land cover class landscape metric
Based on the land cover analysis of Landsat MSS, TM, ETM and 2010 SPOT 5 High-resolution Geometric (HRG) data between 1972 and 2010, it has been identified that the decimation of intact thicket is the major vegetation change trend, at the expense of which degraded thicket, bare areas and grassland cover classes have increased

Summary

Introduction

Human activities have become an important factor in global change processes (Petit & Lambin, 2002) in the wake of the surge in global population. According to Green et al (1994), land use and cover, change processes are caused by the interaction between physical, biological and social forces. These processes can lead to the conversion of productive land into degraded land, loss of species and emission of greenhouse gases into atmosphere (Houghton, 1994, Ojima et al, 1994, Turner 1994, De Meuelenaere et al, 2013). Land cover analysis provides the basis for understanding historical land use practices, present use patterns and prospective trends (Lal, 2007). It provides baseline information for comprehending global carbon dynamics (Sanchez –Azofeifa et al, 2009). The integration of remote sensing and GIS, and landscape metrics can provide more spatially consistent and detailed information on landscape structure, which will facilitate the identification of the social and biophysical processes that drive these changes (Herold et al, 2005; Kamusoko and Aniya, 2006)

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