Survey of Epiphytic Orchids in the Afromontane Forest of the Mambilla Plateau, Taraba State

The Mambilla Plateau in Taraba State, North East Nigeria, hosts one of the most biodiverse afromontane ecosystems in West Africa, yet the epiphytic orchid flora of this habitat remains poorly characterised. This study surveyed epiphytic orchid species in the Mambilla afromontane forest across three altitudinal bands: 1,200 to 1,500m, 1,500 to 1,800m, and above 1,800m. Transect surveys of 500m x 5m were conducted in each altitudinal band during the peak flowering season. All orchid species found epiphytically on phorophyte trees were recorded, photographed, and voucher specimens collected for herbarium identification at Taraba State University. Phorophyte species, bark texture, and host height were also recorded. A total of 29 epiphytic orchid species from 18 genera were documented. Species richness peaked at the 1,500 to 1,800m band (23 species), consistent with the mid-domain effect. Bulbophyllum was the most species-rich genus (7 species). Phorophyte preference was observed in Polystachya for Syzygium-type hosts. Habitat disturbance from cattle grazing and fire was significantly negatively correlated with orchid species density (r = -0.69, p < 0.05). Three species were potentially new to Nigerian botanical records. The study concludes that the Mambilla Plateau represents a critical hotspot for epiphytic orchid conservation in Nigeria and recommends a dedicated orchid monitoring programme and stronger enforcement of the plateau's forest reserve boundaries. Keywords: epiphytic orchids, Mambilla Plateau, afromontane forest, species richness, Taraba State