Use of multispectral satellite datasets to improve ecological understanding of the distribution of Invasive Alien Plants in a water‐limited catchment, South Africa

Abstract

Invasive Alien Plants (IAPs) pose major threats to biodiversity, ecosystem functioning and services. The availability of moderate resolution satellite data (e.g. Sentinel-2 Multispectral Instrument and Landsat-8 Operational Land Imager) offers an opportunity to map and monitor the occurrence and spatial distribution of IAPs. The use of two multispectral remote sensing data sets to map and monitor IAPs in the Heuningnes Catchment, South Africa, was therefore investigated using the maximum likelihood classification algorithm. It was possible to identify areas infested with IAPs using remote sensing data. Specifically, IAPs were mapped with a higher overall accuracy of 71%, using Sentinel-2 MSI as compared to using Landsat 8 OLI, which produced 63% accuracy. However, both sensors showed similar patterns in the spatial distribution of IAPs within the hillslopes and riparian zones of the catchment. This work demonstrates the utility of the two multispectral data sets in mapping and monitoring the occurrence and distribution of IAPs, which contributes to improved ecological modelling and thus to improved management of invasions and biodiversity in the catchment.

An assessment of long-term and large-scale wetlands change dynamics in the Limpopo transboundary river basin using cloud-based Earth observation data

“…The stratified random sampling approach was employed to collect the data, whereby the site for field measurements was divided into plot sizes of 900 m 2 . A minimum of 50 points representing different land cover classes (Table 1) were collected in each plot, based on the guidance provided by related studies such as Mtengwana et al (2020); Thamaga and Dube (2018); Mudereri et al (2021). The 900 m 2 plots were spaced 1 km apart to prevent overlap in the collected samples.…”

“…Following mosaicking, the Landsat 5 and 8 bands were resampled to a 10-meter spatial resolution to facilitate integration with Sentinel-1 data, which varied in spatial resolution from 10 to 25 m. This step aimed to enhance LULC features. The nearest neighbor resampling method was employed to resample the Landsat bands, and the final resolution used for the resampled bands was 10 m. The selection of this method was informed by several related studies such as Thamaga et al (2021); Mtengwana et al (2020). Subsequently, the resampled images were used to compute the following indices: Normalized Difference Vegetation Index (NDVI), Normalized Difference Phenology Index (NDPI), modified Normalized Difference Water Index (mNDWI), and Normalized Difference Built-up Index (NDBI), (Table 2).…”

Modeling the geographic spread and proliferation of invasive alien plants (IAPs) into new ecosystems using multi-source data and multiple predictive models in the Heuningnes catchment, South Africa

“…Figure 3 shows the distribution of IAPs and other land use and land cover classes across the catchment. The accuracy of the image classification results for the current land cover use yielded an overall accuracy of 71% (see Mtengwana et al 2020). The most common land use within the catchment is areas under cultivation, particularly in the northern parts.…”

Local community attitudes and perceptions towards benefits and challenges associated with biodiversity conservation in Blouberg Nature Reserve, South Africa

“…Despite natural and human livelihood benefits, biodiversity loss remains one of the major disturbing environmental challenges (Ntshane & Gambiza, 2016; Sieber et al, 2013). For example, land use changes (Matavire et al, 2015; Ntshane & Gambiza, 2016; Seutloali et al, 2018; Sibanda et al, 2016), climate change (Khare & Ghosh, 2016; Li et al, 2018), invasive alien species (Mtengwana et al, 2020; Thamaga & Dube, 2018) and unsustainable utilisation of natural resources, as well as pollution (Gumindoga et al, 2018; Thant, 2017) are some of the threats to biodiversity existence. In addition, human activities are also a cause for concern in biodiversity conservation (Kideghesho, 2008; Slingenberg et al, 2009; Thant, 2017).…”