Epiphyllous bryophyte diversity in lowland rain forest and lowland cloud forest of French Guiana

Tropical lowland cloud forests (LCF) are only reported from French Guiana but may be widespread in the tropics. They are botanically distinguished from lowland rain forest (LRF) based on the diversity and composition of epiphyte communities in the forest canopy. To facilitate the detection of LCF, reliable ground-level indicators are needed. A first comparison of epiphyllous bryophyte diversity in the understory of LRF and LCF of French Guiana revealed a five times higher species richness in LCF. Species abundancy was also much higher in LCF. Sampling efficiency was about 80% in each forest type. Six species (11%) were found in both forest types, 43 species (80%) were found only in LCF and five species (9%) only in LRF. Species exclusive to LCF were not unique to cloud forest at a larger scale, however. Lejeuneaceae Rostovzev contributed 100% to epiphyll diversity in LRF and 70% in LCF. The lower representation of Lejeuneaceae in LCF agrees with the notion that epiphyte species diversity in LCF is similar to that of montane forests. Epiphyllous bryophyte diversity, more than species composition, may be a suitable tool for recognition of lowland cloud forest at ground level, without application of tree climbing.