Assessing the Ecological Niche and Conservation Status of Dioscorea spp. across Microclimatic Gradients in the Western Ghats

Abstract

The distribution of wild yam (Dioscorea spp.) is significantly influenced by fine-scale microclimatic and edaphic variations within tropical forest ecosystems. This study investigated the ecological distribution and niche specialization of five Dioscorea species across two distinct forest habitats in the Western Ghats, Kerala, India: the high-altitude evergreen forests of Wayanad Wildlife Sanctuary and the moist deciduous region of Vazhachal. Utilizing a random quadrat sampling design, we analyzed the correlation between species occurrence and environmental variables, including canopy cover, light intensity, soil moisture, and pH. Our results demonstrate a clear niche differentiation: specialist species such as D. pentaphylla and D. alata are highly dependent on the stable, mesic conditions of dense evergreen forest interiors, showing strong positive correlations with high canopy cover and litter depth. Conversely, generalist species like D. bulbifera and D. oppositifolia exhibit high ecological plasticity, thriving across fluctuating environmental gradients. Morphological analysis suggests that tuber architecture—ranging from deep-seated cylindrical to massive, lobed forms—functions as an adaptive strategy to optimize nutrient storage under site-specific pressures. Based on these findings, we developed a Conservation Priority Index (CPI), identifying D. pentaphylla and D. alata as high-priority candidates for targeted conservation. These results emphasize that forest management policies must prioritize the preservation of intact microclimatic refuges to safeguard the genetic diversity of Dioscorea within the Western Ghats.