Evaluation of Tree Planting Initiatives and Urban Biodiversity in Kaduna City

This study evaluates the outcomes of municipal tree planting initiatives and their contribution to urban biodiversity in Kaduna City, Kaduna State, North West Nigeria. Urban tree planting programmes are a common environmental management tool in Nigerian cities, but their effectiveness in establishing long-term tree cover, supporting native biodiversity, and surviving the challenges of urban growing conditions has rarely been systematically assessed. Field inventories were conducted along eight road corridors and in six public parks where formal planting exercises were carried out between 2018 and 2021. For each planted tree, species identity, survival status, canopy health condition, growth dimensions, and evidence of maintenance were recorded. Tree diversity and structural metrics were compared between planted sites and a reference urban forest remnant. Concurrently, bird and butterfly species surveys were conducted using standard transect methods at planted sites to assess biodiversity value. Results show that survival rates for road median plantings average 54 percent, compared to 71 percent in parks. Species diversity in planted sites is very low, dominated by three exotic ornamental species constituting 82 percent of surviving trees. Native species are present at only two of fourteen assessed sites. Bird and butterfly diversity at planted sites is significantly lower than at the reference forest remnant. Evidence of systematic post-planting maintenance is present at only three sites. The study concludes that current planting programmes prioritise installation over ecological outcomes. Recommendations include mandatory native species composition targets and a three-year post-planting maintenance commitment for all future urban greening projects in Kaduna. Keywords: urban trees, tree planting, urban biodiversity, Kaduna, native species.