Assessment of liana diversity and carbon stock in differently disturbed tropical dry evergreen forests of southern India

Abstract

Lianas are important components of tropical forests that play a crucial role in forest dynamics. We investigated biodiversity and carbon stock of lianas in two tropical dry evergreen forest (TDEF) sites, the relatively undisturbed Sendhirakillai (SK) and disturbed Palvathunnan (PT) by establishing one-hectare plot in each site. All lianas ≥ 1cm diameter (measured 1.3 m from rooting point) and trees ≥ 10cm girth (measured at 1.3 m from ground) were enumerated to ascertain species richness and stem density of lianas and trees with respect to site disturbance. Liana diversity totaled 24 species (16 in SK and 20 in PT) in the two studied sites. Liana density totaled 1182 individuals (744 ha -¹ in SK and 438 ha -¹ in PT). Fifty percent of species were shared between the two sites. A considerable variation in the density, dominance and basal area of different species was found between the sites. No dominant family was common to both the sites. Stem twining and zoochory was predominant in both disturbed and undisturbed sites. Lianas comprised 36.4% (SK) & 48.8% (PT) of the total woody species richness (lianas + tress) and 37% (SK) and 38.3% (PT) of the total woody species density. The mean aboveground biomass and carbon stock of lianas were 7.2 Mg ha -1 and 4.5 Mg ha -1 , accounting for 1.94% of total woody species community (trees + lianas). The aboveground biomass and carbon stocks were highest in undisturbed site SK compared to disturbed site PT. The extent of liana diversity and their contribution to the total woody plant abundance and biomass highlight the importance of lianas in forest functioning, dynamics and mitigating climate change. Considering the biodiversity TDEFs hold and the current level of human disturbance, a holistic approach in conservation is emphasized.

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

“…Tropical forests are considered as great carbon reservoirs which accommodate over 30% of the global carbon (Malhi, 2012). Structural alteration of these forests as a result of increasing forest disturbances and other 2 environmental drivers may have potential consequences on the global carbon cycle (Schnitzer and Bongers, 2011;Babu and Parthasarathy, 2019). One of the major structural changes occurring in tropical forests is the increasing abundance and biomass of lianas, which may have inordinate impacts on carbon dynamics (Philips et al, 2002;Lewis, 2009).…”

“…In mature tropical forests, lianas are an important structural component representing on an average 20 -45% of the woody biomass (Schnitzer and Bongers, 2002). In liana-dense forest areas, they contribute about 30% of total aboveground biomass (AGB) and generally about 10% of AGB in tropical forests (DeWalt and Chave, 2004;Babu and Parthasarathy, 2019). Depending mainly on trees for structural and physical support (Stevens, 1987), lianas can have deleterious effects on host trees, like inducing mechanical stresses (Pérez-Salicrup and Barker, 2000), reducing their growth, recruitment, and survival (Schnitzer, 2005;van der Heijden and Phillips, 2009;Schnitzer and Carson, 2010), and also competing with trees for aboveground and belowground resources (Chen et al, 2008).…”

“…Depending mainly on trees for structural and physical support (Stevens, 1987), lianas can have deleterious effects on host trees, like inducing mechanical stresses (Pérez-Salicrup and Barker, 2000), reducing their growth, recruitment, and survival (Schnitzer, 2005;van der Heijden and Phillips, 2009;Schnitzer and Carson, 2010), and also competing with trees for aboveground and belowground resources (Chen et al, 2008). Studies suggest that lianas are capable of reducing aboveground carbon (AGC) content to about 50% (Durán and Gianoli, 2013;Babu and Parthasarathy, 2019). In Amazonian tropical forests, lianas have been reported to bring about 18% of the variation in tree biomass (Laurance et al, 2014).…”

“…Like in any other tropical forests, lianas form an integral component of the tropical dry evergreen forests (TDEFs) found in India (Babu and Parthasarathy, 2019). The TDEFs are short-statured forests, occurring mainly in small patches on the Coromandel coast of peninsular India (Parthasarathy et al, 2008).…”

“…According to reports, TDEFs are considered as one of the liana-dense forests in Asia (DeWalt et al, 2015), and also studies from Indian TDEFs have reported lianas to be increasing in abundance over the years (Khadanga et al, 2015;Pandian and Parthasarathy, 2016;Nath et al, 2022). Even though inventories concerning liana diversity have been carried out in TDEFs (Reddy and Parthasarathy, 2006;Vivek and Parthasarathy, 2015;Babu and Parthasarathy, 2019), long-term monitoring data addressing their contribution to biomass and carbon stocks in these TDEFs are meagre or almost negligible (Pandian and Parthasarathy, 2016). Hence, the present study was undertaken to re-monitor the changes addressing basal area, biomass, and carbon stock of lianas at a 19year time interval in two disturbed tropical dry evergreen forest sites of southern India.…”