Climate resilience and agroforestry potential of palmyra (Borassus flabellifer L.) in Tamil Nadu, India

Abstract

The palmyra palm (Borassus flabellifer L.), designated as the state tree of Tamil Nadu, is an under-exploited climate-resilient species possessing outstanding agroforestry value in semi-arid tropical ecosystems. The palmyra palm shows outstanding resistance to drought, salinity, cyclonic storms, high temperatures and soil heterogeneity by a combination of mechanisms such as the presence of deep adventitious roots reaching the depth of 5–6 m, cuticular wax layer formation on leaf surfaces, water storage in trunk pith and malleable crown shape for wind-shedding. Field observations in the Thanjavur - Nagapattinam region after Cyclone Gaja in 2018 showed that the mortality rate in palmyra was < 5 % compared to 30–50 % in coconut (Cocos nucifera), thus establishing conclusive evidence of its superior structural resilience. Despite the fact that the palmyra tree has over 800 documented products, including food, fibre, timber and ecological services, with estimated annual returns ranging from ₹10500–22000 per productive tree, the palmyra palm population in Tamil Nadu has decreased from 100–50 million trees in the past decades due to urbanisation, lack of clarity in neera and toddy policies, shortage of tapper labour force, long juvenile period (15–20 years) and lack of institutional support. This review integrates the existing body of knowledge on the morphophysiological adaptation strategies, ecological roles and socioeconomic significance of palmyra in various agro-climatic settings of Tamil Nadu.