Abstract
Epiphytic orchids are common in subtropical forests, but little is known about the factors that determine their diversity. We surveyed two sites (north-facing Phulchowki and south-facing Shivapuri hills), in the sub-tropical forest in the Kathmandu valley, central Nepal. Along five transects per site, spanning an altitudinal gradient of 1525–2606 m a.s.l., we recorded all epiphytic orchids and the host species on which they were growing. The data were analyzed using a generalized linear model (GLM) and redundancy analysis (RDA). Species richness significantly decreased with increasing altitude and was higher in larger hosts and in places with high temperature. Species composition was affected by altitude, distance from the forest edge, host type, and precipitation. This study indicates that the most important factors affecting epiphytic orchid diversity was altitude, even if other factors were associated with patterns in composition. The low-altitude habitats with high species diversity are the best places for epiphytic orchids in this region. The altitudinal species richness and patterns in composition revealed by this study provide a baseline for further studies on epiphytic orchids.
Highlights
Diversity of plants and patterns in composition are commonly studied in order to understand the mechanisms underlying community assembly [1,2] and the underlying mechanisms determining the patterns [3,4,5]
Twenty-nine species of hosts were recorded on Phulchowki and 27 on Shivapuri
The most important host species that occurred throughout the altitudinal gradient were Quercus glauca and Quercus semecarpifolia
Summary
Diversity of plants and patterns in composition are commonly studied in order to understand the mechanisms underlying community assembly [1,2] and the underlying mechanisms determining the patterns [3,4,5]. Numerous factors directly or indirectly determine diversity and composition [6,7,8]; these may be, for example: (1) climatic variables, such as humidity, precipitation, temperature, etc. Additional factors that determine the diversity of epiphytic species of plants are host characteristics such as bark pH, bark rugosity, stem diameter, type of host (deciduous/evergreen), host habit (shrub/trees), host age, host height, canopy cover, bark water holding capacity, etc. Many plant species, including orchids, are widely threatened because of habitat degradation due to agriculture, forestry, construction and mining, illegal trade, unsustainable utilization, and climate change [17,18,19]. Many orchids are either threatened or rare because of their existence in small population sizes, limited distributions, and species-specific symbioses with pollinators and mycorrhizal fungi [20,21,22].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
