BIODIVERSITY ASSESSMENT AND DEVELOPMENT OF AN ECOLOGICAL RESTORATION FRAMEWORK FOR DEGRADED GREEN AREAS IN POLYTECHNICS IN SOUTH-WEST NIGERIA

Abstract

Campus green areas are reservoirs of urban biodiversity and providers
of ecosystem services. This study assessed the biodiversity of campus
green areas in polytechnics in South-West Nigeria and developed an
ecological restoration framework for degraded areas. A field-survey
and framework-development design was used. The green areas of six
campuses were surveyed using 120 plots (20 m × 20 m) to inventory
trees, shrubs and herbaceous plants, biodiversity was characterised
using standard diversity measures, and degraded areas and their drivers
were identified. The framework was validated through expert and
stakeholder appraisal. The campuses contained 186 plant species, with
mean species richness of 92.7 per campus and a mean Shannon-Wiener
diversity index of 2.84. The most abundant tree species were Terminalia
catappa (18.4%), Azadirachta indica (14.6%) and Mangifera indica
(12.2%). Overall, 31.8% of green areas were degraded, mainly through
building development (38.4%), vegetation clearing (24.6%) and
encroachment (18.2%). Degradation reduced biodiversity support by
38.2%, carbon sequestration by 32.6% and air quality improvement by
28.4%. The framework (site assessment and prioritisation, native
species selection, restoration interventions, monitoring and evaluation,
and institutional arrangements) was rated highly for ecological
soundness (3.60), feasibility (3.40) and sustainability (3.80). The study
provides a biodiversity inventory, a condition assessment and a
validated restoration framework for Nigerian polytechnics.