Quantifying carbon benefits from protecting and restoring tropical forest landuse mosaics in Vanuatu

Forest loss and degradation in Vanuatu is a pertinent environmental issue, particularly for rural communities who are inherently reliant on subsistence-based agriculture derived from tropical forest landuse mosaics. Payment for Ecosystem Services (PES) projects provide a mechanism to diversify agricultural livelihoods while reducing deforestation and forest degradation and promoting ecosystem restoration. This study evaluates the Life & Land Project, a PES initiative working with communities at Whitegrass and Middlebush on Tanna, and South River on Erromango. Few primary studies in Vanuatu have quantified forest carbon stocks or evaluated changes in carbon stocks resulting from PES interventions.

These knowledge gaps are addressed by assessing: (a) forest carbon stocks and structural characteristics; (b) the drivers and rates of deforestation and forest degradation, together with pressures affecting forest health, to inform management interventions; and (c) the potential carbon benefits of implementing these interventions using a gain-loss approach.

Results showed high variability in structural composition and carbon stocks, reflective of differences in landuse and environmental pressures. The mature, predominantly primary tropical rainforest at Whitegrass had an average carbon stock of 490.7 ± 32.6 Mg C ha^-1, in contrast to the invasive vine-smothered degraded forests of Imanaka Creek (Middlebush) and the Forest Enhancement Zone of South River (107.3 ± 10.7 Mg C ha^-1 and 128.2 ± 22.7 Mg C ha^-1 respectively). Forest loss at Whitegrass was driven through logging, ad-hoc garden development, and quarry operations at an estimated rate of 3.55 ha^-1 year^-1, while invasive vines were the main impediment impacting forest health at most sites. To address pressures, a conservation area at Whitegrass (Forest Protection) was established with community developed and enforced by-laws, while Forest Restoration and Improved Forest Management interventions involved undertaking vine clearance, maintenance, and replanting with a mix of agro-forestry and native species (all sites). Overall carbon benefits are estimated at 6,688 Mg CO₂e year^-1.

The study helps Vanuatu and other Small Island Developing States, particularly those of the South Pacific, strengthen the platform from which other PES projects could be developed and implemented.