Influence of land use types on the composition and diversity of orchids and their phorophytes in cloud forest fragments

Abstract

We analyzed the composition and diversity of orchids and host trees (phorophytes) in a set of cloud forest fragments, assessing how different land use types affects them. Terrestrial and epiphytic orchids were recorded in three habitats surrounded by different types of land use: mature cloud forest (MF), riparian forested belts (RF) crossing pastures, and shaded coffee plantations (SC). Within 30 sampled plots (10 × 10 m), placed in two sites per habitat, we found 101 trees, for which we measured their height, crown cover, and basal area. We selected 30 of these trees to climb in order to record the vertical distribution of epiphytic orchids. A total of 841 orchid individuals from 61 species and 38 genera were found. Most species were epiphytic (79%). The two RF sites showed the highest species richness (35 and 32 spp., respectively), the MF had intermediate values (28 and 20) and SC the lowest (14 and 12). Jacquiniella teretifolia was the most abundant epiphytic orchid (101 plants), found in all habitats. Clethra macrophylla, Quercus xalapensis, and Liquidambar styraciflua were the tree species hosting the highest orchid richness (≥15 species). Vertical distribution of epiphytic orchid richness was highest along the main trunk, whereas abundance was concentrated along the medium and lower layers of the tree canopy. The most abundant terrestrial orchid was Psilochilus macrophyllus (92 individuals), found in MF and RF. Again RF had the highest richness of terrestrial orchids (8 spp.), followed by MF (5), and SC (1). Richness of both orchids and phorophytes were significantly lower in SC than in the other two habitats. The type of land use, particularly the presence of forest fragments or large trees within agricultural landscapes, influences positively the richness and abundance of orchids and phorophytes.