The definition of strategies for forest restoration projects depends on information of the successional stage of the area to be restored. Usually, classification of the successional stage is carried out in the field using forest inventory campaigns. However, these campaigns are costly, time-consuming, and limited in terms of spatial coverage. Currently, forest inventories are being improved using 3D data obtained from remote sensing. The objective of this work was to estimate several parameters of interest for the classification of the successional stages of secondary vegetation areas using 3D digital aerial photogrammetry (DAP) data obtained from unmanned aerial vehicles (UAVs). A cost analysis was also carried out considering the costs of equipment and data collection, processing, and analysis. The study was carried out in southeastern Brazil in areas covered by secondary Atlantic Forest. Regression models were fit to estimate total height (h), diameter at breast height (dbh), and basal area (ba) of trees in 40 field inventory plots (0.09 ha each). The models were fit using traditional metrics based on heights derived from DAP and a portable laser scanner (PLS). The prediction models based on DAP data yielded a performance similar to models fit with LiDAR, with values of R² ranging from 88.3% to 94.0% and RMSE between 11.1% and 28.5%. Successional stage maps produced by DAP were compatible with the successional classes estimated in the 40 field plots. The results show that UAV photogrammetry metrics can be used to estimate h, dbh, and ba of secondary vegetation with an accuracy similar to that obtained from LiDAR. In addition to presenting the lowest cost, the estimates derived from DAP allowed for the classification of successional stages in the analyzed secondary forest areas.

Tropical forests face increasing threats and are often replaced by secondary forests that regenerate after disturbances. In the Atlantic Forest, this creates fragments of different successional stages. The aim of this study is to understand how soil nutrients and light availability gradients influence the species composition and structure of trees and regenerating strata in remnants of lowland rainforest. We sampled 15 plots for the tree stratum (DBH ≥ 5 cm) and 45 units for the regenerating stratum (height ≥ 50 cm, DBH < 5 cm), obtaining phytosociological, entropy and equitability data for both strata. Canopy openness was assessed with hemispherical photos and soil samples were homogenized. To analyze the interactions between the vegetation of the tree layer and the environmental variables, we carried out three principal component analyses and two redundancy analyses and applied a linear model. The young fragments showed good recovery, significant species diversity, and positive successional changes, while the older ones had higher species richness and were in an advanced stage of succession. In addition, younger forests are associated with sandy, nutrient-poor soils and greater exposure to light, while mature forests have more fertile soils, display a greater diversity of dispersal strategies, are rich in soil clay, and have less light availability. Mature forests support biodiversity and regeneration better than secondary forests, highlighting the importance of preserving mature fragments and monitoring secondary ones to sustain tropical biodiversity.

This study presents a qualitative analysis of endangered species occurrences in conservation units of Rio de Janeiro, one of the largest Brazilian municipalities in population size. Increasing human activities trigger changes in biodiversity, promote fragmentation, and reduce species distribution ranges, which can ultimately lead to declines in population sizes. One of the main goals of protected areas (PAs), such as conservation units, is to protect and conserve biodiversity. Here, we compiled all vascular plant species recorded within Rio de Janeiro PAs by consulting the Reference Center for Environmental Information (SpeciesLink), Flora do Brasil (2020), and primary data records contained in management plans. We compared this compilation with the list of Brazilian endangered plant species, verifying whether the management plans presented specific programs for these species. Of the 60 surveyed PAs, 24 had records of endangered species and only 17 had management plans, 14 of which had a specific program that contemplated the monitoring and/or conservation of endangered species. A total of 70 endangered species were recorded. The highest numbers of endangered species were found in the Tijuca National Park (41) and the Pedra Branca State Park (17), the two largest PAs with the two largest forest fragments. Despite the high number of endangered species and the number of protected areas that harbor them, few internal programs address endangered species conservation and management. Thus, efforts to maintain endangered species in protected areas can be aided by field data collections that confirm their occurrence and maintenance in these PAs.

Urban forests have gained increasing attention as nature-based solutions, yet quantitative information on aboveground biomass and carbon storage in small urban forest remnants remains limited, particularly in small municipalities. This study aimed to quantify aboveground biomass, carbon stocks, and their illustrative economic valuation in an urban Tiny Forest located in southeastern Brazil. A complete tree inventory was conducted across a 2.76-ha area, including all living trees with a diameter at breast height (DBH) ≥ 5 cm. Aboveground biomass was estimated using an allometric equation developed for urban trees, carbon stocks were calculated using a conversion factor of 0.47, and an illustrative economic valuation was derived from a reference price in the voluntary carbon market. The inventory recorded 539 trees belonging to 68 species and 24 botanical families, with native species accounting for 79.0% of the individuals. Total aboveground biomass was estimated at 95.09 Mg (34.45 Mg ha⁻¹), corresponding to 44.69 Mg of carbon (16.19 Mg C ha⁻¹) and 163.88 Mg CO₂e. The illustrative economic valuation of the stored carbon was US$3,349.64. Native species accounted for 86.46% of the estimated carbon stock, with Moquilea tomentosa and Handroanthus impetiginosus among the main contributors. Carbon storage varied with species composition and tree structural characteristics, indicating that abundance alone does not determine species contributions to carbon stocks. These findings demonstrate that small urban forest remnants can represent measurable carbon reservoirs and provide local-scale information to support urban green infrastructure planning. However, the estimates represent carbon stocks at a single point in time and do not establish carbon sequestration rates or potential revenue from certified carbon credits.