Carbonated tiger-high above-ground biomass carbon stock in protected areas and corridors and its observed negative relationship with tiger population density and occupancy in the Terai Arc Landscape, Nepal

Healthy natural forests maintain and/or enhances carbon stock while also providing potential habitat and an array of services to wildlife including large carnivores such as the tiger. This study is the first of its kind in assessing relationships between above-ground biomass carbon stock, tiger density and occupancy probability and its status in protected areas, corridors, and forest connectivity blocks. The dataset used to assess the relationship were: (1) Converged posterior tiger density estimates from camera trap data derived from Bayesian- Spatially Explicit Capture-Recapture model from Chitwan National Park; (2) Site wise probability of tiger occupancy estimated across the Terai Arc Landscape and (3) Habitat wise above-ground biomass carbon stock estimated across the Terai Arc Landscape. Carbon stock maps were derived based on eight habitat classes and conservation units linking satellite (Landsat 7 ETM+) images and field collected sampling data. A significant negative relationship (r = -0.20, p<0.01) was observed between above-ground biomass carbon stock and tiger density in Chitwan National Park and with tiger occupancy (r = -0.24, p = 0.023) in the landscape. Within protected areas, we found highest mean above-ground biomass carbon stock in high density mixed forest (similar to 223 tC/ha) and low in degraded scrubland (similar to 73.2 tC/ha). Similarly, we found: (1) highest tiger density similar to 0.06 individuals per 0.33 km(2) in the riverine forest and lowest estimates (similar to 0.00) in degraded scrubland; and (2) predictive tiger density of 0.0135 individuals per 0.33 km(2) is equivalent to mean total of 43.7 tC/ha in Chitwan National Park. Comparatively, we found similar above-ground biomass carbon stock among corridors, large forest connectivity blocks (similar to 117 tC/ha), and within in tiger bearing protected areas (similar to 119 tC/ha). Carbon conservation through forest restoration particularly in riverine habitats (forest and grassland) and low transitional state forests (degraded scrubland) provides immense opportunities to generate win-win solutions, sequester more carbon and maintain habitat integrity for tigers and other large predators.

Automated summary

This study assessed the relationship between above-ground biomass carbon stock, tiger density and occupancy probability in protected areas, corridors, and forest connectivity blocks. The results showed a negative correlation between above-ground biomass carbon stock and both tiger density and occupancy probability. Therefore, forest restoration in riverine habitats and low transitional state forests can provide carbon conservation and habitat protection for tigers and other large predators.