A Comparative Analysis Of Plant Species Richness And Diversity In Managed Versus Unmanaged Urban Green Spaces In Botanical Gardens And In Abandoned Lots Of Lusaka, Zambia

Urban green spaces are increasingly recognised as critical reservoirs of plant biodiversity in rapidly growing cities of sub-Saharan Africa, yet comparative data on species richness and community composition across contrasting management types remain scarce for Central African cities. This study presents findings from a quantitative comparative analysis of plant species richness and diversity in managed and unmanaged urban green spaces in Lusaka, Zambia. Using a stratified random sampling design, a total of 60 vegetation quadrats (10 m by 10 m) were surveyed across two contrasting site categories: the formally managed Lusaka Botanic Garden in Longacres (n = 30 plots distributed across three management zone strata) and abandoned lots in three residential townships, namely Kalingalinga, Chilenje, and Matero (n = 10 plots per township). A structured questionnaire was administered to 35 respondents comprising garden management staff (Version A, n = 21) and lot occupants or owners (Version B, n = 14). Botanical garden plots recorded a significantly higher mean species richness of 20.9 species per plot (SD = 3.87) compared with 14.4 species per plot (SD = 1.87) in abandoned lots (Welch t-test: t(58) = 5.21, p < 0.001). Across both site types, 269 unique vascular plant taxa were recorded from 84 families. The botanical garden harboured a higher proportion of exotic and cultivated species (58.3 percent) while abandoned lots contained a significantly larger proportion of native Zambian plant species (67.9 percent). Shannon diversity indices were significantly higher in botanical garden plots (mean H\\\' = 2.70, SD = 0.15) than in abandoned lots (mean H\\\' = 2.21, SD = 0.13). Non-metric multidimensional scaling and PERMANOVA confirmed highly significant compositional differentiation between the two space types (R² = 0.310, F = 26.4, p = 0.001). Questionnaire data revealed that 85.7 percent of garden staff perceived funding constraints as limiting management intensity, and 71.4 percent of lot occupants expressed willingness to participate in community-led conservation programmes. The findings highlight that both managed and unmanaged urban green spaces in Lusaka contribute complementary and non-redundant plant diversity values, and that conservation policy must recognise both categories as components of an integrated urban biodiversity strategy.