Epiphytic Ferns for Sale: Influence of Commercial Plant Collection on the Frequency of Platycerium stemaria (Polypodiaceae) in Coconut Plantations on the Southeastern Ivory Coast

Abstract: On the southeastern Ivory Coast, two coconut plantations were compared with regard to the frequency of the epiphytic fern Platycerium stemaria on coconut trees as influenced by plant collecting for commercial purposes. At each of the two sites, 250 coconut trees were investigated for the presence of P. stemaria and signs of collecting activity. General species richness of vascular epiphytes at the study sites was low, with only three other epiphytic ferns ( Asplenium sp., Microgramma owariensis, Phymatodes scolopendria ) being present. At study site no. 1, which was located directly behind several flower stalls offering P. stemaria for sale, the number of coconuts bearing living P. stemaria was significantly lower than at site no. 2 with no flower stalls in the immediate surroundings. At site no. 1, the frequency of P. stemaria was lowest in the neighbourhood of the flower stalls and increased with distance. Within a distance of less than 50 m from the flower stalls, ca. 70 % of the coconuts showed signs of P. stemaria collecting activity. Compared with site no. 1, the number of palm trees with living P. stemaria at site no. 2 was considerably higher ( ca. 20 %) and only three coconut trees showed signs of Platycerium collection. Over much of the Ivorian rain forest region where the forest has been cut or converted into agricultural land, plantation trees are important phorophytes (in particular cocoa trees). In many West African regions plantation trees form the last remaining sites for vascular epiphytes, which often occur with considerable abundance. In the Ivory Coast, the collecting of P. stemaria in coconut plantations causes locally a drastic decline in the population size. However, much more threatening to the long-term maintenance of epiphyte communities in plantations is their conversion into non-tree plantations (e.g., pineapples, bananas) or their replacement by urban structures and tourist facilities.