Traditional field inventories have been the standard method for collecting detailed forest attribute data. However, these methods are often time-consuming, labor-intensive, and costly, especially for large areas. In contrast, remote sensing technologies, such as unmanned aerial vehicles (UAVs), have become viable alternatives for collecting forest structure data, providing high-resolution images, precision, and the ability to use various sensors. To explore this trend, a bibliometric review was conducted using the Scopus database to examine the evolution of scientific publications and assess the current state of research on using UAVs to estimate dendrometric variables in forest ecosystems. A total of 454 studies were identified, with 199 meeting the established inclusion criteria for further analysis. The findings indicated that China and the United States are the leading contributors to this research domain, with a notable increase in journal publications over the past five years. The predominant focus has been on planted forests, particularly utilizing RGB sensors attached to UAVs for variable estimation. The primary variables assessed using UAV technology include total tree height, DBH, above-ground biomass, and canopy area. Consequently, this review has highlighted the most influential studies in the field, establishing a foundation for future research directions.

This study aimed to assess the influence of the seasonality on the bark tannins content of Acacia mangium trees grown in the Northeastern Brazilian Region and the effect of soil preparation on the results. Two experimental plots of 1.0 ha each were submitted to different soil preparation methods, with two different intensities. The experimental design consisted of four treatments, two types of soil preparation and, two different bark collection seasons (end of the rainy and dry seasons). The bark of the trees was collected in each treatment and the contents of condensed tannins were determined. For each experimental treatment, 15 trees were harvested and debarked. Bark material was submitted to extraction with hot water, obtaining the total solids content (TSC), Stiasny index (I), and the condensed tannins content (CTC). There was no influence of the soil preparation method on the TSC, I, and CTC. However, there was a significant difference in these parameters for tree bark collected in the rainy season, with higher values. The less intensive soil preparation method is recommended due to its lower cost, and bark should be collected at the end of the rainy season for the best yield of condensed tannins.