Ecological dilemma: Invasive Gliricidia sepium improves carbon sequestration but decline diversity during secondary succession in tropical dry deciduous forest communities of Central India

Abstract

Invasive species, the ecosystem engineers can act as one of the important solutions to curtail the negative impacts of climate change by rapidly sequestering CO₂ in forests, due to their higher production function capability and survivability under extreme environmental conditions and/or nutrient poor soil. Assessment of their impacts on ecosystems, particularly in secondary forests could provide valuable insights on their usability in restoration programs during the present decade of ecosystem restoration. In the present study, we have assessed the impacts of invasive Gliricidia sepium on carbon sequestration rate and biodiversity during the secondary succession in forest communities by conducting field investigations in Gliricidia invaded and uninvaded secondary forests. Results of the present study showed that invaded forest community was significantly higher in stem density (1059.2 ± 37.94 individuals/ha), total biomass (94.45±10.27 Mg/ha) and carbon sequestration rate (8.01±1.50 Mg C/ha/yr) as compared to the uninvaded forest community. In invaded forest community, Gliricidia alone contributed 56.99 % to total biomass which is significantly higher than the other dominant and codominant species. Structural equation modelling clearly indicated that Gliricidia invasion had impacted carbon sequestration rate both directly and indirectly; however, the latter was mediated by stem density. In the present study, we found that second-growth forests invaded by Gliricidia although quickly accumulated carbon, it impeded biodiversity. We suggest that the plantation of invasive species might create obstruction to achieve the goals of REDD+ and UN resolutions on ecosystem restoration. Further, occupation of vacant niches by inducting early successional natives might act as an important way for sustainable ecosystem restoration.