Abstract

Urban greenbelts are vital for biodiversity and ecosystem services but face threats from urban expansion. This study assessed the population structure and identified potential threats to woody plants in Arusha city’s greenbelts (nature areas and riparian forests). Woody plants were sampled across 53 grid cells (200 m × 200 m) using stratified random sampling and the Braun-Blanquet relief method. Remote sensing processed 2015 and 2022 satellite images. ArcGIS 10.8.2 software facilitated field data collection coordinates, the satellite imageries and spatial analyses. Standard plot sizes of 400 m2 were systematically selected for data collection. Significant differences in tree species diversity and abundance were observed within nature areas (t = 18.6, p = 0.001; t = 5.48, p = 0.001) and riparian forests (t = 21.4, p = 0.001; t = 13.8, p = 0.001). No significant differences were found between eastern and western nature areas (t = 1.06, p = 0.338; t = −1.55, p = 0.181) while within riparian forests, only species diversity differed significantly (t = 2.66, p = 0.011). However, tree species abundance differed significantly between nature areas and riparian forests (t = −2.97, p = 0.01) with riparian forests having higher abundance of native trees compared to nature areas and with significant abundance of native trees compared to non-native trees (t = 14, p = 0.001). These findings emphasize the conservation of Arusha’s greenbelts, aligning with SDGs 3 (well-being), 6 (water quality), 11 (sustainable cities) and 15 (ecosystem conservation).

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