Environmental Research Journal
ISSN: OnlineISSN: Print 1994-5396
Abstract
The montane ecosystems of Wayanad, nestled within the Western Ghats‐a recognized UNESCO World Heritage site and biodiversity hotspot‐support a remarkable array of endemic orchid species. These orchids, particularly epiphytic and lithophytic types, are highly sensitive to changes in microclimatic conditions, making them valuable biological indicators of ecological stress under changing climate regimes. This study presents the results of a four‐year ecophysiological investigation (2021–2025) into the adaptive responses of selected endemic orchids to climate variability, focusing on the impacts of increased temperature, irregular rainfall, and prolonged summer drought. Four representative species‐Rhynchostylis retusa, Bulbophyllum neilgherrense, Coelogyne nervosa, and Dendrobium aqueum‐were selected based on their ecological prominence and distinct growth forms. A combination of in‐situ fieldwork and controlled‐environment experiments was employed to evaluate physiological and morphological responses. Sampling was conducted across varied elevations (800–1500 m) and habitat types (evergreen, semi‐evergreen, and moist deciduous forests). Physiological measurements included stomatal conductance, leaf relative water content, leaf water potential, chlorophyll fluorescence (Fv/Fm), and phenological behavior. Anatomical assessments of root velamen, leaf cuticle thickness, and pseudobulb structure were performed using light and electron microscopy. Species such as B. neilgherrense and C. nervosa showed significant drought tolerance attributed to pseudobulb water storage and thick velamen layers, while D. aqueum exhibited facultative CAM photosynthesis during peak dry months, confirmed via δ¹³C isotope analysis. Multivariate regression analysis revealed that orchid survival and physiological performance were strongly influenced by canopy density (R² = 0.72), relative humidity (R² = 0.68), and elevation (R² = 0.64). Species located in higher‐elevation, closed‐canopy microhabitats maintained stable water potentials and photosynthetic efficiency even under extreme drought. Phenological records indicated delayed flowering and pseudobulb initiation in years with early summer onset, suggesting climate‐driven shifts in developmental timing. These findings emphasize the importance of microhabitat conditions and morphological adaptations in buffering orchids against climate‐induced stress. Conservation strategies must prioritize the preservation of shaded forest canopies, host tree diversity, and hydrological stability to maintain orchid‐rich habitats. This study contributes a foundational understanding of orchid ecophysiology in the Western Ghats and offers critical insights for formulating climate‐resilient conservation policies in tropical montane ecosystems.
How to cite this article:
V.U. Sabu and Jincy Paulose. Climate Change and Orchid Adaptation: Evaluating the Ecophysiological Responses of Wayanad's Endemic Orchids.
DOI: https://doi.org/10.36478/makerj.2025.1.5
URL: https://www.makhillpublications.co/view-article/1994-5396/makerj.2025.1.5