Monitoring of a long-term, large-scale restoration experiment in the thicket biome of the Eastern Cape, South Africa, using remote sensing

Authors:
Ruan de Wet

Publication Date:
2019

Abstract/Summary:
Intensive goat farming has transformed more than a million hectares of subtropical thicket in South Africa from a dense closed-canopy shrubland into an open savanna-like system. Restoration of the degraded thicket landscapes can be achieved by planting truncheons of spekboom (Portulacaria afra). To determine the efficacy of such restoration, a large-scale restoration experiment comprising 331 quarter-hectare, fenced plots with 12 different treatments (including inter alia different size and spacing of cuttings) was established over an area of ~75,000 kmĀ² in 2007. The experiment has only been monitored twice in 12 years, primarily because of resource constraints in collecting data from 331 plots over a distance of more than 1,000 km from east to west. Given that the plots are visible in satellite imagery, we used remote sensing data (NDVI) to derive an index of spekboom growth in each plot over 10 years. We plotted this index against on-the-ground measurements of spekboom truncheons (including stem diameter, canopy diameter, and survivorship) as well as a wide range of soil variables (including pH, sand, silt, clay, stone volume, N, P, K, Ca, Mg, Na, and C). The index was strongly positively correlated with all on-the-ground measurements of the truncheons, indicating that remote sensing is an appropriate, cost-effective way of monitoring the experiment. The quantified relationships between the index and soil properties (e.g. positive correlations with base cations and silt; and negative correlations with stone volume) are of value for restoration p ractitioners selecting landscapes for restoration using spekboom truncheons.

Resource Type:
Audio/Video, Conference Presentation, SER2019

Pre-approved for CECs under SER's CERP program

Source:
Society for Ecological Restoration