Increasing liana biomass and carbon stocks in tropical dry evergreen forests of southern India

Abstract

Tropical forests act as a great carbon reservoir covering about 30% of the global carbon content, however, structural alteration of these forests caused by forest disturbances adversely affects the carbon cycle. One such structural change happening in these tropical forests is the increasing dominance of lianas (woody climbers). Among various tropical forest types, lianas are an integral constituent of the tropical dry evergreen forests (TDEFs) found in peninsular India. A re-inventory of lianas was carried out to observe temporal changes in basal area and carbon stock in two 1-ha permanent plots of two disturbed tropical dry evergreen forest sites (TDEF; Oorani -OR and Puthupet - PP) over a 19-year interval (2001-2020). The total basal area in OR and PP increased respectively by 2.26 m2 ha-1 and 0.93 m2 ha-1. The total biomass and the carbon stock in OR and PP increased by 82% and 51% respectively. The dominant species Strychnos lenticellata showed an increase in its basal area by three-fold in OR, whereas, in PP, a marginal increase of 4% was observed. The lower diameter class (1-6 cm) showed an increase in basal area in OR and PP by 101% and 16% respectively. The mid-diameter class (6-11 cm) was the top contributor of the total biomass/carbon in both OR and PP in the latest re-inventory (2020). The present results show that lianas, although known to negatively affect the forest biomass/carbon stock, play an important role in carbon sequestration, thus providing insights into their ecological importance which will certainly be useful in proposing strategies for the conservation of this forest type dominated by lianas.