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Rock outcrops are unique habitats in terms of their geological and ecological specializations, soil availability, water seasonality, and environmental extremes. These habitats have attracted the attention of many researchers worldwide in the last few decades. Indian rock outcrops spread throughout the country with more concentration in the Western Ghats region, supporting many endemic and unique habitat specialist species. Despite Indian outcrops having become hotspots for novel species discoveries in recent times, ecological studies on them are still in their infancy. In the present review, we discuss studies, research gaps, and the scope for future investigations on Indian outcrops. We also compare outcrop studies across the world with the Indian systems in order to understand their uniqueness and peculiarities. Literature and observations revealed the presence of 390 taxa on rock outcrops of the Western Ghats with various adaptive traits such as desiccation tolerance, succulence, carnivory, and geophytism, a trend common to most of the tropical outcrops. The dominance of Poaceae endemics, large extents of monocotyledonous mats, and underrepresentation of succulence are unique features of Indian rock outcrops. In the light of various disturbances, faced by Indian outcrops, further studies that would lay a foundation on which conservation strategies can be formulated are a want of time.

Rock outcrops are habitats possessing large areas of exposed bare rock and extreme environmental conditions. In the biodiversity hotspot of Western Ghats, three types of rock outcrops are known: lateritic outcrops at high (HLF) and low altitude (LLF), and basalt outcrops at high altitudes (BM). Apart from these types, one study mentioned the possibility of a fourth rare type: low altitude basalt outcrop. However, previous studies did not report occurrence of such an outcrop. In this study, we report a low altitude basalt outcrop (Manjare, Maharashtra), document its vegetation and compare it with the other three types of outcrops. We recorded 76 taxa belonging to 24 families. Families Poaceae, Leguminosae and Cyperaceae were species-rich. Vegetation comparison with the other three outcrop types revealed that maximum species (76%) were shared with LLF, followed by HLF (62%) and BM (59%). A cluster analysis based on species occurrence using the Sørensen dissimilarity index showed that the Manjare outcrop separates from high altitude outcrops (HLF and BM) at the first level and from LLFs at the second level. Manjare supports a unique combination of species composition from HLF, LLF and BM, which offers a system to study species interactions and their relationship with the environment.

Ephemeral rock pools are a characteristic type of aquatic habitat formed on the rock outcrops throughout the world, which harbor unique flora and fauna. Due to their structural simplicity and small size, rocky pools form a unique model ecosystem for studying how local environmental parameters shape aquatic vegetation. We studied the species-environment associations between the aquatic flora of the rock pools from the Western Ghats of India to understand whether species occurrence is influenced by the environmental parameters and whether we can predict the species occurrence using environmental variables. Sixty-one rock pools from 26 rock outcrops occupying different altitudinal gradients of the northern Western Ghats were sampled along with their physical properties and chemical characteristics. Canonical correspondence analysis suggested that altitude, latitude, magnesium, sulphate influenced species occurrence in rock pools. Replacement of species belonging to genus Eriocaulon across the altitudinal gradient was observed. Analysis of Covariance showed that most of the species are influenced by altitude while for few species both altitude and baserock were important. Application of various supervised learning procedures suggested that Random Forest was the most efficient method to predict species occurrence based on environmental parameters of rock pools. Decision trees based on Random Forest classification showed that multiple environmental factors including physical and chemical parameters of rock pools simultaneously influenced the species occurrence in the rock pools of the Western Ghats.