Abundance
Indicator:
This indicator measures the degree to which a site is invaded by considering the combined abundance of all invasive populations present relative to the abundance of indigenous and invasive organisms. Relative invasive abundance is a useful indicator of the degree of stress on an ecosystem, and it can be used at a range of spatial scales.
Source data:
Kotze (2023) surveyed the extent of 14 of the most-widespread & abundant, terrestrial invasive alien plan taxa (approx. 40 species) in South Africa. Excludes invasions in transformed (i.e. cultivated, built-up & planted forest) landcover (click here for the 7GB of data in a 120MB ESRI Map Package)..
Rebelo et al (2021) detected invasive alien plants in the Savanna and Grassland Biomes of the uMngeni Catchment, using the free Google Earth Engine Platform .
Holden et al. (2021) used a novel, transdisciplinary approach, combining Google Earth Engine’s processing power, freely available Sentinel imagery (fusion of Sentinel-1 and -2), expert engagement (including researchers, managers and decision makers), drone technology and field trips, to provide an accurate and up-to-date understanding of the occurrence and density of invasive alien trees in an important water tower for the south-western Cape of South Africa at a 20 m resolution.
Kotze et al. (2019, 2020) established and implemented a cost effective, objective and statistically sound invasive alien plant monitoring system at a quaternary catchment level (click here for data)
Royimani et al (2018) reviewed the advancements in satellite remote sensing for mapping and monitoring of Alien Invasive Plant species (AIPs)
Main et al. (2016) conducted an assessment of remote sensing techniques in the mapping of invasive alien plant distribution, tree cover and biomass, in the Agulhas plains
Van den Berg (2013) investigated the detection, quantification and monitoring of Prosopis spp. in the Northern Cape province using remote sensing and GIS (click here for data)
Van Wilgen & le Maitre (2013) reported on rates of spread in invasive plants of South Africa
Rouget et al. (2004) assessed the climatic correlates of distribution of 71 important invasive alien plants, and analysed the implications of these findings for future invasions in different vegetation types in South Africa, Lesotho and Swaziland over the next few decades