Railway side mapping of alien plant distributions in Mpumalanga, South Africa

Abstract

Background: Alien plant invasions are among the major threats to natural and semi-natural ecosystems in South Africa on approximately 18 million hectares of land. Much of the available data are not suitable for planning of local scale management because it is presented at a quarter degree grid square scale, which makes accurate location and estimates of invaded areas difficult.Objectives: The aim was to identify the dominant alien plant species and quantify their areal extent along a 479 km railway corridor in the Mpumalanga province.Method: The extent of the invaded area was obtained by manual digitising of alien plant distribution and density from Satellite Pour l’Observation de la Terre 5 imagery and by further applying an Iterative Self-Organising Data Analysis technique of the unsupervised classification method. Species’ occurrences were located and identified in the field using a Global Positioning System.Results: The most dominant invaders in terms of the number of individual polygons and the infested area were Eucalyptus spp., Acacia spp., Populus alba L., Pinus patula Schltdl Cham., Salix babylonica L. and Caesalpinia decapetala (Roth) Alston. These species have also been previously classified as major invaders, although the Conservation of Agricultural Resources Act regulations permit their planting provided spreading to adjacent areas is avoided except for C. decapetala, which must be cleared under all circumstances.Conclusion: Knowledge of the species’ occurrence and their extent will assist landowners and relevant authorities to control the spread of alien plants, which impact rail safety, agricultural production, water availability and biodiversity.

Socio-Environmental Conflicts in the Limits of Natural Parks in Africa: Characterization and Strategies for the Resolution of Conflicts Between Communities and Wild Animals in Kibale National Park - KNP- Uganda

“…This species has come to be considered in some parts of Africa as one of the most invasive species, and has been identified as a species that can compromise conservation and production in agricultural fields (Mararakanye, et al, 2017). For example, this tree was declared in South Africa as an invasive species in 1983 (Bryne, et al, 2011).…”

Harnessing Ecosystem Services from Invasive Alien Grass and Rush Species to Suppress their Aggressive Expansion in South Africa

“…Therefore, A. donax (n = 5) was the most utilized invasive alien rush in South Africa, as measured by the number of ecosystem service benefits that it provides, followed by A. gigantea (n = 4) (Figure 1A). The provision of diverse ecosystem services by A. donax resembles its socio-economic and sociocultural value to many communities in South Africa and worldwide [27,37,164]; however, its widespread invasion confirms that this species does disrupt the functionality of ecosystems through habitat transformation [165,166]. The legal standing of A. donax implies that this species should be controlled through invasive alien species control programs [38,98].…”

Assessing the Effect of Seasonality on Leaf and Canopy Spectra for the Discrimination of an Alien Tree Species, Acacia Mearnsii, From Co-Occurring Native Species Using Parametric and Nonparametric Classifiers

“…The availability of space-borne sensors such as Sentinel-2 and Landsat-8 Operational Land Imager (OLI) could provide an opportunity to distinguish A. mearnsii at the landscape level. However, only a few studies have investigated the potential to map A. mearnsii using multispectral satellite data [48]. For this reason, we extended the research by including the multispectral dimension to the analysis.…”