Gis approach to land cover change prediction in south african grasslands towards determining the catchment carbon-watersurface energy flux nexus

Lesley Gibson, Zahn Munch*, Anthony Palmer, Sukhmani Mantel

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Future land cover changes may result in adjustments to biophysical drivers impacting on: net ecosystem carbon exchange (NEE), catchment water use through evapotranspiration (ET), and even Global Circulation Models. The Land Change Modeller (Idrisi Terrset 18.08) and land cover for 2000 and 2014 is used to predict land cover for the S50E catchment in the Eastern Cape Province for the year 2030. In 2000, grasslands represented 61.5% of the total catchment area with this figure predicted to decrease to 52.1% by 2030 with losses likely to favour a gain in woody plants and cultivated land. The results show that the total change (gain and loss) in the landscape over all land cover classes was 21% for the period between 2000 and 2014 and 23% from 2014 up to the prediction for 2030, with the change intensity remaining constant at 1.5% per year. It was determined that the probability of grasslands persisting is around 80% with the highest probability of grasslands being lost to woody encroachment (~4.5%) and cultivation (~6.6%). Fraction of photosynthetically active radiation (fPAR) and leaf area index (LAI) measured and used in NEE and ET modelling respectively, indicate that both fPAR and LAI are lower for grasslands than for their transition classes. This transition thus represents a gain in both catchment NEE and ET, resulting in increased carbon storage, which from a climate change perspective can be seen as a positive change. However in an already water scarce catchment, further water demands by the vegetation will result in a decrease in the availability of water for other land covers. Finally, carbon offsets from sequestration may be counterbalanced by temperature increases linked to lower albedo increasing net surface radiation. This carbon-water-surface energy flux nexus requires further research in quantifying impacts.

Original languageEnglish
Pages (from-to)219-226
Number of pages8
JournalProcedia Environmental Science, Engineering and Management
Volume4
Issue number4
Publication statusPublished - 31 Dec 2017

Keywords

  • Albedo
  • Carbon
  • Grasslands
  • Land cover change prediction
  • Water

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