Institutional contribution to urban biodiversity conservation, productivity, and carbon sequestration: a case study of the Forestry Research Institute of Nigeria

Urban trees within developed areas provide essential ecosystem services that include carbon sequestration. But growing urban populations put pressure on vegetated urban ecosystem services and biodiversity. This study examined tree diversity, biomass, and carbon storage within the developed areas of the Forestry Research Institute of Nigeria (FRIN). A complete enumeration of 326 trees distributed among 57 tree species and 29 families was conducted. Biodiversity indices were computed using standard procedures, while biomass and carbon storage were estimated using a non-destructive method. Most species (61.4%) were indigenous, while 38.6% were exotic. Pinus caribaea, Khaya senegalensis, Entandophragma angolense, and Gmelina arborea were among the dominant tree species. About 65.6% of the trees were very stable given their low slenderness coefficient. The high biodiversity index values (species richness = 57; Shannon-Wiener diversity index = 3.84; Margalef index = 9.68) suggest that the developed areas of FRIN have good biodiversity conservation status. Total basal area and volume productions were 49.54 m² ha-1 and 660.32 m³ ha-1, respectively, corresponding to 447.90 tons ha-1 of biomass and 223.95 tons ha-1 of carbon. Despite their small land size, the developed areas of FRIN are a significant carbon sink compared to similar institutional landscapes in Nigeria. This study highlights the need for institutional green-space management strategies to be integrated into national climate change adaptation and biodiversity conservation policies for enhanced ecological resilience and sustainability.