Distribution and Abundance of Native Orchids on Roadside Trees in a Global Biodiversity Hotspot

Trees play a vital role in supporting biodiversity, particularly in regions where human demand for resources is increasing and many species are experiencing population decline. Native orchids, especially those that are endemic, are particularly vulnerable to population decreases in biodiversity hotspot areas, with anthropogenic factors playing an increasingly significant role in this trend. A substantial portion of the northern district of Kerala, situated in southern India, falls within the biodiversity hotspot of the Western Ghats. The road network traversing the Western Ghats provides refuge for native orchids on various tree species. The present study examined a 60 km perimeter area encompassing 15 different sites located near small towns and built-up areas, regions where trees have already been lost due to settlement and infrastructure development. These roadside areas are lined with a mixture of native and exotic trees, including both naturally recruited fruit trees and exotic species. Approximately 600 trees, representing 72 different tree taxa, were recorded from the sampled areas in Wayanad. Nearly 10,000 orchids encompassing 13 species were observed, with 6 of these species, constituting 46%, being endemic to the region. This study revealed variations between sites, with some locations exhibiting high diversity and abundance of both trees and orchids. The diversity and abundance of native orchids, risks, and prospects of development mitigation are discussed in detail.