Baseline ecological insights of vegetation assessment and carbon stock estimation in natural mangrove forests of Probolinggo Regency, Indonesia

Java Island is experiencing severe degradation of natural mangrove forests due to anthropogenic pressure, particularly in Probolinggo Regency. Although restoration programs have been widely implemented, the success rate remains very limited due to unsuitable planting technique and suboptimal species selection. This study provides the first baseline ecological assessment of vegetation status and estimation of carbon stock to support more effective restoration planning. Using a quantitative random sampling method, data on species identification, vegetation height, and diameter at breast height (DBH) were collected from 33 plots across eight sub-districts. Avicennia marina, Rhizophora mucronata, and Avicennia alba, are the dominant species with relative abundance varied by location. Saplings represented the most abundant growth stage, while trees exhibited the lowest abundance, indicating high past historical degradation. The westernmost sub-district exhibited the lowest Shannon–Wiener diversity index (H' = 0.9), suggesting higher anthropogenic pressures than others. Species richness, evenness, and dominance remain substantially varies across sub-districts. The total estimated carbon stock was 292 Mg C ha⁻¹, comparatively low for Indonesian mangroves ecosystems. The natural mangrove forests in Probolinggo Regency are in early-mid successional stage, reflecting strong past degradation. These findings highlight the urgency of restoration program to improve the total carbon stock across all sub-districts, particularly western areas, with careful consideration of site-species suitability. This research was conducted at the Warm-Temperate and Subtropical Forest Research Center, National Institute of Forest Science (Project No. FE-2022-04-2025).