Assessment of Plant Species Diversity in the Riparian Forest of River Kaduna, Kaduna State

Riparian forests serve as critical biodiversity reservoirs and hydrological buffers, yet those bordering River Kaduna in North West Nigeria face increasing pressure from agricultural encroachment and human settlement. This study assessed the plant species diversity and vegetation structure of the riparian forest along a 5-kilometre stretch of River Kaduna within Kaduna South Local Government Area. Systematic line transects and nested quadrat methods were used to sample vegetation at three riparian zones representing the river bank, mid-slope, and upland transition. Species richness, Shannon-Wiener diversity index, Sorensen similarity index, and importance value index were calculated for each zone. A total of 94 vascular plant species from 51 families were recorded. Species richness was highest on the river bank zone (72 species) and declined progressively toward the upland transition zone (48 species). Shannon-Wiener index values ranged from 2.87 to 3.61, indicating moderate to high diversity. Ficus sycomorus, Khaya senegalensis, and Daniellia oliveri were the dominant tree species by importance value. The upland transition zone showed the lowest diversity, coinciding with the highest incidence of cultivated crop species and exotic invasives. Chromolaena odorata was the most abundant invasive herb recorded. The study concludes that the River Kaduna riparian forest retains considerable plant diversity but is under measurable anthropogenic pressure. Urgent riparian buffer zone demarcation and invasive species management are recommended for the Kaduna State Forestry Commission.

Keywords: plant species diversity, riparian forest, River Kaduna, Shannon-Wiener index, invasive species