Floristic diversity and forest structure in two protected miombo woodlands: Insights from permanent plots in Gilé and Niassa, Mozambique

This study investigates the floristic diversity, structural attributes, and spatial organisation of woody communities in miombo woodlands within Gilé National Park (GNP) and Niassa Special Reserve (NSR), two protected areas in Mozambique characterised by contrasting ecological conditions and disturbance regimes. Using seven 1-ha permanent sampling plots (PSPs—three in GNP and four in NSR), we quantified horizontal and vertical forest structure, species diversity, and spatial patterns of trees with DBH ≥ 5 cm. The objectives were to compare the structure of tree communities (adults and juveniles), assess alpha diversity using Shannon, Simpson, and Hill numbers, analyze spatial distribution through classical aggregation indices (Payandeh, Morisita and Hazen), and evaluate floristic similarity using Bray–Curtis clustering. A total of 1,753 adult individuals (DBH ≥ 10 cm), representing 92 species across 23 families, were recorded. Based on observed values, NSR exhibited slightly higher adult species richness (58 vs. 55) and greater tree density for both adults (982 vs. 771 individuals·ha⁻¹) and juveniles (1,160 vs. 540 individuals·ha⁻¹), reflecting active regeneration and structural maturity. In contrast, GNP showed greater species evenness (Pielou's J = 0.77 vs. 0.73) and higher localized floristic heterogeneity. Dominant species such as Brachystegia spiciformis, Julbernardia globiflora, and Pseudolachnostylis maprouneifolia strongly influenced these structural patterns, shaping spatial organization and contributing nearly half of the total basal area. Most species displayed moderate intraspecific aggregation, with conspecific individuals often clustered locally, whereas overall tree spacing tended to be regular—indicating limited interspecific mixing and the coexistence of species-level aggregation with stand-level regularity. These findings highlight the ecological distinctiveness of both forest systems and reinforce the need to expand and establish more PSPs for long-term monitoring and adaptive forest management within the framework of REDD+ and national biodiversity strategies.