TY  - JOUR
T1  - Climate Change and Orchid Adaptation: Evaluating the Ecophysiological Responses of Wayanad's Endemic Orchids
AU - Sabu, V.U. AU - Paulose, Jincy 
JO  - Environmental Research Journal
VL  - 19
IS  - 1
SP  - 1
EP  - 5
PY  - 2025
DA  - 2001/08/19
SN  - 1994-5396
DO  - makerj.2025.1.5
UR  - https://makhillpublications.co/view-article.php?doi=makerj.2025.1.5
KW  - Wayanad orchids
KW  - climate adaptation
KW  - pseudobulb water storage
KW  - stomatal conductance
KW  - CAM photosynthesis
KW  - microhabitat
KW  - epiphytic orchids
KW  - Western Ghats biodiversity
KW  - leaf water potential
KW  - phenological shift
AB  - 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.
ER  -