Heritage conservation and environmental threats at the 192-year-old botanical garden in Pondicherry, India

Abstract

Urban botanical gardens conserve historical flora, improve the local environment and promote human well-being. Unfortunately they are often undervalued due to lack of public awareness or resources. Analysis of species diversity and turnover at long-lived gardens can improve the understanding of long-term plant resilience and help adapt management actions to align with rapidly changing urban contexts. Given the various threats faced by urban botanical gardens, we examined tree species diversity, historical changes and survival of plants at the Botanical Garden in Pondicherry (BGP), southern India, which was established 192 years ago by the colonial French government.A complete census of trees was carried out to compare current species diversity with two historical lists compiled 151 years ago and 57 years ago, respectively. These lists were also used to identify heritage trees. Effects of environmental threats, including the very severe cyclonic storm Thane (December 2011) and various damages to young stems, were analysed with Google Earth images and field inventories.There were 284 identified tree species, including 25 endangered/vulnerable/threatened species and 53 tropical dry evergreen forest species. Turnover had occurred, and approximately half of the historical species had been replaced with new species. Tropical Cyclone Thane caused severe damage to large trees and anthropogenic activities damaged saplings. Yet, at least 65 large resilient individuals had survived all the threats, and signifiy the adaptability and heritage value of the BGP.Our study revealed multiple values of this heritage green space in a rapidly developing South Asian city and suggests strategies for modernisation that are aligned with international conservation guidelines. We recommend better monitoring and utilisation of cyclone-damage data to guide future plant introductions at this coastal site.