Vegetation Structure and Carbon Stocks of Sacred Groves in Oyo and Kwara States

Sacred groves are traditional conservation institutions that have preserved remnant forest patches across the derived savanna landscape of the Nigerian Middle Belt and southwestern zones, providing biodiversity refugia and ecosystem services in areas where formal forest reserves are absent. This study assesses the vegetation structure, species diversity, and above-ground carbon stocks of sacred groves in Oyo and Kwara States, comparing these with adjacent farmland and degraded vegetation. Twenty sacred groves were inventoried across ten Local Government Areas, with diameter and height measurements taken for all woody stems and species identified using taxonomic keys. Paired farmland plots of equivalent area adjacent to each grove provided comparative data. Shannon diversity, dominance indices, and basal area were calculated. Above-ground carbon was estimated using pantropical allometric equations. Sacred groves averaged 127 tree species per hectare, significantly exceeding adjacent farmland richness. Carbon stocks in sacred groves ranged from 68 to 184 tonnes per hectare, averaging 112 tonnes, compared to 4.3 tonnes in adjacent farmland. Several groves contained large emergent trees over 80 centimetres in diameter representing significant biomass accumulations absent elsewhere in the landscape. Community interviews confirmed active protection of grove boundaries by traditional custodians, though younger generations showed declining engagement with grove taboos. The study recommends formal recognition of sacred groves within state forest policy frameworks as complementary conservation areas, with traditional custodians empowered as legal grove managers. Keywords: sacred groves, vegetation structure, carbon stocks, traditional conservation, Oyo State