Survey of Invasive Plant Species in Okomu National Park, Edo State

Invasive alien plant species represent a significant and growing threat to the ecological integrity of tropical forest reserves, outcompeting native vegetation and altering habitat structure for wildlife. This study surveys the distribution and abundance of invasive plant species within Okomu National Park in Edo State, within Nigeria's South South geopolitical zone. The park is home to Nigeria's largest surviving population of white-throated monkeys and a diverse array of forest wildlife, making the management of invasive vegetation a conservation priority. Systematic vegetation transects were established across the park's major vegetation zones, with all plant species recorded and invasive taxa identified using reference herbarium materials and regional flora databases. A total of 14 invasive plant species were recorded, with Chromolaena odorata (Siam weed), Lantana camara, and Panicum maximum being the most widespread and abundant. Invasive species density was highest at forest edges, disturbed sites along access roads, and former logging areas. Ecological impact assessments found negative correlations between invasive plant cover and native understory diversity. The study recommends the development of an invasive species management plan for the park, including manual clearance of high-priority areas, monitoring protocols, and prevention measures targeting entry points along roads and park boundaries. Training of park staff in invasive species identification and control is highlighted. Keywords: invasive plants, Chromolaena odorata, Okomu National Park, South South Nigeria, forest ecology