Vegetation on rock outcrops in Western Ghats influenced by altitude, temperatures: study

The Western Ghats are one of the world’s most important biodiversity hotspots. Running parallel to India’s west coast from Gujarat to Kerala, it is home to rich flora and fauna endemic to this region.

Scientists from Pune-based Agharkar Research Institute (ARI) studied the characteristics of the vegetation growing along 30 rock outcrops located at altitudes ranging between 0 to 250 metres around the Konkan region and plateaus at 600-1,500 metres, above the mean sea level.

The areas along the Western Ghats under study. Source: Agharkar Research Institute

“Altitude at which the vegetation grows is one of the important factors that determines its growth,” Mandar Datar, lead researcher and ARI scientist, told The Indian Express.

The study, published in the journal Plant Diversity and Ecology, noted that besides elevation, the vegetation growing on the outcrops along the Western Ghats was directly dependent on the proximity to the sea and other climatic conditions like temperature and rainfall among others. Whereas, soil nitrogen, total soil carbon, latitude, and the mean diurnal temperatures did not influence the plant growth.

Rock outcrops are special landscapes having exposed bedrock caused mainly by natural weathering. The vegetation is classified on the basis of its bedrock, which can either be basalt or laterite. Often, these landscapes have sparse soil cover, have access to low nutrient availability, and experience intense wind and solar radiation.

Plants growing here have mechanisms that help them survive in high temperatures and periods of water scarcity. The temperatures close to which the vegetation here grows can, during summer months, go as high as 60 degree Celsius.

The exposed rock outcrop at the site. Source: Agharkar Research Institute

“These plants grow in such extreme conditions, where the region experiences uneven distribution of rainfall yet they have demonstrated high seasonal adaptability. Their characteristics could be showing signs of their climate resilience,” said Datar.

For instance, legumes were found abundant along regions of high altitude which received less rainfall. Whereas in low-altitude sites, due to the high prevalence of nitrogen and carbon concentrations, there was an abundance of carnivores, the study revealed.

Many distinct microhabitats are formed on the rock outcrops primarily because of varied soil depth, unequal water availability, and heterogeneous topography which results locally in a heterogenous microclimate, the study said.

Anjali Marar works at the Raman Research Institute, Bengaluru.