Volumetric yield coefficient: the key to regulating virtual credits for Amazon wood / Coeficiente de rendimento volumétrico: uma peça-chave para disciplinar créditos virtuais de madeira amazônica

In Brazil, all transport and storage of native forest products and by-products must be registered within the DOF (Document of Forestry Origin) system. This computerized platform exists to support control agencies in reducing the sale of forest products obtained illegally. However, this tool still shows only modest results in fulfilling its objectives, since gaps in the system allow illegal wood to be acquired and enter the system as legal wood. The objective of this study was to test whether the volumetric yield coefficient (CRV) of a sawmill on an industrial scale corresponds to the 35% established by Brazilian legislation. The focus was directed at a loophole that allows the accumulation of virtual credits in the DOF system by turning logs into lumber. For this purpose, we estimated the sawmill's CRV and mean percentage yield of 19 commercial species used by a timber company in the Brazilian Amazon with a sample size of 90 logs. The estimated CRV was 24.6 ± 2.4, showing 9.9% uncertainty. The mean CRV differed highly significantly (p < 0.001) from that proposed by the DOF, with a 10.35% difference. Based on these results, the difference between the observed yield and that proposed by the legislation can generate the accumulation of virtual log credits. With this accumulation, managers encounter difficulties in acquiring new logging permits and, consequently, do not meet the actual demand for logs to the sawmill's capacity.(AU)

No Brasil, todo transporte e armazenamento de produtos e subprodutos florestais nativos deve ser registrado no sistema DOF (Documento de Origem Florestal). Essa plataforma informatizada existe para apoiar agências de controle na redução da venda de produtos florestais obtidos ilegalmente. No entanto, essa ferramenta ainda apresenta resultados modestos no cumprimento de seus objetivos, uma vez que lacunas no sistema permitem que madeira ilegal adquira caráter legal. O objetivo desse estudo foi testar se o coeficiente de rendimento volumétrico (CRV) de uma serraria em escala empresarial corresponde aos 35% estabelecidos pela legislação brasileira. O foco foi direcionado para uma brecha que permite o acúmulo de créditos virtuais no sistema DOF, por meio da transformação de toras em material serrado. Para tanto, estimamos o CRV da serraria e os rendimentos percentuais médios de 19 espécies comercializadas por uma empresa de base florestal na Amazônia brasileira, com um esforço amostral de 90 toras. O CRV estimado foi de 24,6 ± 2,4, mostrando incerteza de 9,9%. O CRV médio diferiu altamente significativamente (p < 0,001) do proposto pelo DOF, com uma diferença de 10,35%. Com base nesses resultados, a diferença entre o rendimento observado e o proposto pela legislação pode gerar um acúmulo de créditos em toras virtuais. Com esse acúmulo, os gestores enfrentam dificuldades para adquirir novas licenças de exploração e, consequentemente, não atendem à real demanda por toras da capacidade instalada de sua serraria.(AU)

Integrating high resolution drone imagery and forest inventory to distinguish canopy and understory trees and quantify their contributions to forest structure and dynamics.

Tree growth and survival differ strongly between canopy trees (those directly exposed to overhead light), and understory trees. However, the structural complexity of many tropical forests makes it difficult to determine canopy positions. The integration of remote sensing and ground-based data enables this determination and measurements of how canopy and understory trees differ in structure and dynamics. Here we analyzed 2 cm resolution RGB imagery collected by a Remotely Piloted Aircraft System (RPAS), also known as drone, together with two decades of bi-annual tree censuses for 2 ha of old growth forest in the Central Amazon. We delineated all crowns visible in the imagery and linked each crown to a tagged stem through field work. Canopy trees constituted 40% of the 1244 inventoried trees with diameter at breast height (DBH) > 10 cm, and accounted for ~70% of aboveground carbon stocks and wood productivity. The probability of being in the canopy increased logistically with tree diameter, passing through 50% at 23.5 cm DBH. Diameter growth was on average twice as large in canopy trees as in understory trees. Growth rates were unrelated to diameter in canopy trees and positively related to diameter in understory trees, consistent with the idea that light availability increases with diameter in the understory but not the canopy. The whole stand size distribution was best fit by a Weibull distribution, whereas the separate size distributions of understory trees or canopy trees > 25 cm DBH were equally well fit by exponential and Weibull distributions, consistent with mechanistic forest models. The identification and field mapping of crowns seen in a high resolution orthomosaic revealed new patterns in the structure and dynamics of trees of canopy vs. understory at this site, demonstrating the value of traditional tree censuses with drone remote sensing.