Floristic Diversity, Structure, and Carbon Storage of a Sub-Andean Forest in Southwestern Colombia: The Case of the El Mangón

Sub-Andean forests of the Colombian Central Cordillera are among the most biodiverse and threatened Neotropical ecosystems, yet their floristic, structural, and carbon dynamics remain poorly documented. We characterized the floristic diversity, vegetation structure, and aboveground carbon storage of the El Mangón sub-Andean forest remnant (24 ha; 1,600–1,700 m a.s.l., Cauca, Colombia) using free collections across the total area and a structural inventory in five 50 × 4 m transects (498 individuals, 35 species). A total of 281 species, 209 genera, and 100 families were recorded; epiphytes represented 44.13% of species, exceeding typical values (25–35%) for this forest type. Diversity indices were intermediate (H′ = 2.55; DMg = 5.47; 1−D = 0.89). Palicourea crocea dominated structurally (IVI = 45.12) and concentrated 31.2% of total carbon storage (894.41 kg·ha⁻¹; total = 2,866.23 kg·ha⁻¹). Three novel carbon indices (CVI, CCEI, CSI) integrate storage magnitude with ecological efficiency and spatial stability. The CSI was highest in low-aggregation species (1,618.23), with no significant differences among spatial groups (Kruskal–Wallis, p = 0.088). El Mangón ranks among the most diverse sub-Andean remnants of southwestern Colombia, underscoring its conservation priority in an increasingly fragmented landscape.