A GIS-based assessment of land cover changes and tree species suitability for urban greening policies in the city of Kitwe, Zambia

Abstract

<p><strong>Study Objective and Design:</strong> A change vector analysis (CVA) was used to determine land cover changes and identify tree species that are best for urban greening based on carbon sequestration and air pollution. The study assessed land cover change in Kitwe, Zambia, from 1990 to 2015. This study identified the most planted urban tree species along Kitwe's main roads and highways and evaluated typical urban tree species' pH, RWC, total chlorophyll, ascorbic acid, and biomass.</p> <p><br></p> <p><strong>Place and Length of Study:</strong> The urban trees in Kitwe, Zambia, make up the study population. The city of Kitwe is a thriving centre for mining and commercial activities and is situated in Zambia's Copperbelt Province. The investigation took place between 2018 and 2019.</p> <p><br></p> <p><strong>Methodology:</strong> The NDVI and BSI indices were created using spectral indices created from Landsat images of Kitwe taken in 1990 and 2015, respectively. The size and direction of the land cover were then determined using change vector analysis, and a district database of land cover changes was constructed using GIS. Urban trees from the built-up area were utilised to create an inventory of common urban tree species based on the land cover classification. The Anticipated Performance Index (API), which measures the suitability of tree species for improving air quality, and the Air Pollution Tolerance Index (APTI), which measures the suitability of tree species for urban greening, are two of the three assessment methods that were employed. In addition, above-ground biomass (AGB) was employed to quantify thecarbon sequestration contribution of the current urban forest.</p> <p><br></p> <p><strong>Results:</strong> The study discovered that between 1990 and 2015, mining activity and urban growth in Kitwe both contributed to changes in the area's land cover. While the central business district still exhibits a persistent presence as a result of the town's age, having sprung up before the 1990s with more expansions in the new areas, areas being monitored showed low and medium change intensity, mostly in the northeast of the district. In the currentinvestigation, there was a significant difference in the relative abundance of species (p = 0.05). In the study site, Mangifera indica (RA = 12.3%) and Delonix regia (RA = 15.9%) were the two most prevalent species. According to the study, eleven species were found, and each has accumulated carbon in a unique way throughout time depending on its allometry and age. These distinctions in physiological response (tolerance) to air pollution are noteworthy. Bauhinia variegata, Toona ciliate, Gmelina arborea, Eucalyptus grandis, and Delonix regia were all identified as suitable tree species.</p> <p><br></p> <p><strong>Conclusion:</strong> Over the past 25 years, more than 50% of the land cover has changed, with the majority of that change occurring in regions that are now classified as built-up areas. The majority of Kitwe's urban forests are found in the populated areas and are made up of a variety of ornamental trees that are frequently cultivated for their aesthetic value, attractiveness, and shade. According to the research, this mixture also includes opportunistic urban trees (invasive species) and fruit-bearing trees intermingled with native species. Overall, this study suggests the following species: For urban trees suited for greening programmes aimed at improving air quality and providing shade and beauty in green areas, residences, and sidewalks that have a low air pollution environment, consider Bauhinia variegata, Toona ciliate, Gmelina arborea, Eucalyptus grandis, and Delonix regia.</p>