Factors driving the tree species richness in sacred groves in Indian subcontinent: a review

Sacred groves are areas of native forest that have been protected by the local people for centuries through socio-cultural and religious practices. Many of these sites are critical biodiversity hotspots. Hence, religious beliefs and myths are considered as the primary factor for their conservation in the majority of studies. In this review, we use Generalised Linear Models (GLMs) to identify the driver of tree species richness in sacred groves at a large spatial scale in Indian subcontinent by selecting 218 sacred groves from 33 research papers and 12 doctoral theses. Six variables were selected to explain tree species richness: grove area (hec.), survey method, site elevation (m), average annual precipitation (mm), annual mean temperature (°C) and religion of the community associated with sacred grove. Our findings indicated that the tree species richness in groves is influenced by multiple variables (except religion), and the relationship with area, and average annual rainfall was positive and significant (P < 0.05). Individual model with religion showed considerable uncertainty being below the null model. Floristic surveys reported slightly higher diversity of tree species than plot-based sampling. We recommend that larger sacred groves be prioritised for conservation and management as they support greater tree diversity.