Floristic composition and plant functional type diversity of the basalt cliffs of Western Ghats, India

Cliffs in India, as understudied rock outcrops, provide valuable opportunities for studying plant communities. This study quantifies the plant communities on basalt cliff faces in the Northern Western Ghats (NWG) region of India, aiming to explore floristic composition and examine vegetation responses to environmental variations. We employed the Plant Functional Types (PFTs) classification system, which is particularly well-suited for the unique characteristics of the cliff ecosystem. We recorded 231 vascular plant species across 39 locations spanning altitudes from 100 m to 1300 m and latitudes from 15° to 21° N, using the transect-quadrat method. A total of 480 quadrats measuring 1-m² were sampled across 80 transects on the cliff faces. Nine PFTs were identified in NWG cliffs with dominance of carnivores and therophytes. We examined the impact of environmental filters on PFT distribution and their interactions through bivariate and multivariate analyses. Significant variations in PFTs were observed across altitudinal and latitudinal gradients. The principal component analysis identified temperature and precipitation as primary influencers, outweighing altitude and latitude. Redundancy analysis indicated that stress-tolerant PFTs predominated in hotter, drier conditions, whereas stress-avoidant PFTs thrived in areas with higher precipitation, typically found at lower to mid altitudes. Our study underscores a stronger correlation between plant communities on cliff faces and altitude rather than latitude in the NWG. In conclusion, our study elucidates the characteristics of cliff vegetation in the Northern Western Ghats, emphasising the pivotal roles of temperature, precipitation, and seasonality as significant environmental factors influencing plant community structures across our study sites.