A spatio-temporal, landscape perspective on acacia dealbata invasions and broader land-use and cover changes in the Northern Eastern Cape, South Africa

Biological invasions are a wicked, social-ecological problem, interacting with numerous components within and across a range of spatio-temporal scales, with the potential to disturb broader socio-economic and ecological systems. Acacia dealbata is an invasive shrub in South Africa, widely naturalise...

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Main Author: Gouws, Aidan John
Format: Others
Language:English
Published: Rhodes University 2018
Online Access:http://hdl.handle.net/10962/62373
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spelling ndltd-netd.ac.za-oai-union.ndltd.org-rhodes-vital-281612018-04-05T03:54:41ZA spatio-temporal, landscape perspective on acacia dealbata invasions and broader land-use and cover changes in the Northern Eastern Cape, South AfricaGouws, Aidan JohnBiological invasions are a wicked, social-ecological problem, interacting with numerous components within and across a range of spatio-temporal scales, with the potential to disturb broader socio-economic and ecological systems. Acacia dealbata is an invasive shrub in South Africa, widely naturalised across the grassland biome. Although the deployment of a biocontrol agent on A. dealbata is apparently justified considering its highly invasive and ecologically destructive nature, it should proceed with caution due to the integration of the species into the livelihoods of rural communities. This study sought to understand the nature and extent of the A. dealbata invasion in the northern Eastern Cape. Research was conducted in nine villages in rural Matatiele, Mount Fletcher and Maclear, selected for the pervasiveness of A. dealbata around these villages. A time-series of aerial photographs were systematically classified according to designated A. dealbata and land-use/land cover (LULC) categories in ArcGIS to track changes in the extent and rate of spread of A. dealbata, while standard vegetation surveying techniques were used to determine the current abundance and productivity of A. dealbata in selected areas. A high degree of spatial variability characterised the extent, density and biomass of A. dealbata, as well as the annual rate of spread and biomass production. The growth, productivity and spread of A. dealbata were significantly positive, and relatively few biophysical conditions correlated with the invasion. This was indicative of the broad range of invaded and potentially invasible habitats, suggesting that the extent and abundance of A. dealbata will likely continue to increase, barring deliberate intervention. Broader changes in LULC were also apparent, multidirectional and spatio- temporally variable. Despite a net increase in A. dealbata, the invasion was found to be highly dynamic, with various LULC transitioning to A. dealbata, but in turn A. dealbata transitioning to other LULC. Indeed, biological invasions are dynamic, context-specific phenomena, shaped by the heterogeneity of landscapes. Management interventions to limit or control A. dealbata should therefore consider the spatio-temporal dynamics of invaded landscapes, as well as the local-scale abundance, productivity and biophysical conditions of the area, while taking into consideration the livelihood requirements of the local communities.Rhodes UniversityFaculty of Science, Environmental Science2018textThesisMastersMSc138 leavespdfhttp://hdl.handle.net/10962/62373vital:28161EnglishGouws, Aidan John
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description Biological invasions are a wicked, social-ecological problem, interacting with numerous components within and across a range of spatio-temporal scales, with the potential to disturb broader socio-economic and ecological systems. Acacia dealbata is an invasive shrub in South Africa, widely naturalised across the grassland biome. Although the deployment of a biocontrol agent on A. dealbata is apparently justified considering its highly invasive and ecologically destructive nature, it should proceed with caution due to the integration of the species into the livelihoods of rural communities. This study sought to understand the nature and extent of the A. dealbata invasion in the northern Eastern Cape. Research was conducted in nine villages in rural Matatiele, Mount Fletcher and Maclear, selected for the pervasiveness of A. dealbata around these villages. A time-series of aerial photographs were systematically classified according to designated A. dealbata and land-use/land cover (LULC) categories in ArcGIS to track changes in the extent and rate of spread of A. dealbata, while standard vegetation surveying techniques were used to determine the current abundance and productivity of A. dealbata in selected areas. A high degree of spatial variability characterised the extent, density and biomass of A. dealbata, as well as the annual rate of spread and biomass production. The growth, productivity and spread of A. dealbata were significantly positive, and relatively few biophysical conditions correlated with the invasion. This was indicative of the broad range of invaded and potentially invasible habitats, suggesting that the extent and abundance of A. dealbata will likely continue to increase, barring deliberate intervention. Broader changes in LULC were also apparent, multidirectional and spatio- temporally variable. Despite a net increase in A. dealbata, the invasion was found to be highly dynamic, with various LULC transitioning to A. dealbata, but in turn A. dealbata transitioning to other LULC. Indeed, biological invasions are dynamic, context-specific phenomena, shaped by the heterogeneity of landscapes. Management interventions to limit or control A. dealbata should therefore consider the spatio-temporal dynamics of invaded landscapes, as well as the local-scale abundance, productivity and biophysical conditions of the area, while taking into consideration the livelihood requirements of the local communities.
author Gouws, Aidan John
spellingShingle Gouws, Aidan John
A spatio-temporal, landscape perspective on acacia dealbata invasions and broader land-use and cover changes in the Northern Eastern Cape, South Africa
author_facet Gouws, Aidan John
author_sort Gouws, Aidan John
title A spatio-temporal, landscape perspective on acacia dealbata invasions and broader land-use and cover changes in the Northern Eastern Cape, South Africa
title_short A spatio-temporal, landscape perspective on acacia dealbata invasions and broader land-use and cover changes in the Northern Eastern Cape, South Africa
title_full A spatio-temporal, landscape perspective on acacia dealbata invasions and broader land-use and cover changes in the Northern Eastern Cape, South Africa
title_fullStr A spatio-temporal, landscape perspective on acacia dealbata invasions and broader land-use and cover changes in the Northern Eastern Cape, South Africa
title_full_unstemmed A spatio-temporal, landscape perspective on acacia dealbata invasions and broader land-use and cover changes in the Northern Eastern Cape, South Africa
title_sort spatio-temporal, landscape perspective on acacia dealbata invasions and broader land-use and cover changes in the northern eastern cape, south africa
publisher Rhodes University
publishDate 2018
url http://hdl.handle.net/10962/62373
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