Baseline Ecological Insights of Vegetation and Carbon Stocks Assessment in Probolinggo Natural Mangrove Forests

Flooding and sea-level rise are recurrent challenges in Probolinggo Regency, driven by the anthropogenic degradation of mangrove forests. Although restoration initiatives are ongoing, the vegetation condition of natural mangrove forests remain poorly characterized. The aim of this study was to provide a baseline ecological assessment of natural mangrove forests across Probolinggo Regency by evaluating vegetation structure and carbon stocks. Using a purposive sampling method, species composition, vegetation height, and diameter at breast height (DBH) were measured in 33 plots across eight subdistricts. Avicennia marina and Rhizophora mucronata were the dominant species, with relative abundances varying spatially. Saplings represented the most abundant growth stage. Kraksaan subdistrict exhibited the highest Shannon–Wiener diversity index (H’ = 1.8), whereas Sumberasih had the lowest (H’ = 0.9). Species richness (R) ranged from low to moderate, evenness (E) was consistently high, and dominance (C) was low in all subdistricts. Carbon stocks were highest in Dringu (508.1 Mg C ha−1) and lowest in Tongas (87.6 Mg C ha−1). Overall, the natural mangrove forests in Probolinggo Regency appeared to be in an early to mid-successional stage because of past degradation, highlighting the need for continuous monitoring to support vegetation recovery and sustain ecosystem services.