Impact of plot size on tropical forest structure and diversity estimation / Impacto del tamaño de la parcela en la estructura y estimación de la diversidad de los bosques tropicales

Abstract Introduction: Inventories are essential for forest management, but, in the Amazon region, the absence of standardization produces information loss, low accuracy, and inconsistent measurements. This prevents valid comparisons and compromises the use of information in networks and software. Sampling unit size is of key importance in the inventory of native forests, particularly regarding accuracy and costs. Objective: To identify a plot size that provides adequate precision for dendrometric parameters in the Amazon. Methods: In Cotriguaçu, Mato Grosso, Brazil, we tested four plot sizes with six repetitions each: 2 500, 5 000, 7 500, and 10 000 m². We measured diameter at breast height, population density, basal area, and biomass. We applied Shannon and Jaccard indexes; Weibull 2P and Gamma functions to fit the diametric distribution; and the Akaike Information Criterion for the best model. Results: There was a directly proportional relationship between plot area and population similarity, but diversity did not indicate significant alterations. Plot size did not affect dendrometric attributes and diametric distribution. Larger plot areas led to lower coefficients of variation and smaller confidence intervals. The Gamma function was the best model to represent the distributions of different plot sizes. Conclusions: For similar forests, we recommend the 2 500 m² plot to evaluate diameter at breast height, population density, basal area, and biomass.

Resumen Introducción: Los inventarios son fundamentales para la gestión forestal, pero en la Amazonía la ausencia de estandarización produce pérdida de información, baja precisión y mediciones inconsistentes. Esto impide comparaciones válidas y compromete el uso de información en redes y programas. El tamaño de la unidad de muestreo es de importancia clave en el inventario de bosques nativos, particularmente en lo que respecta a la precisión y los costos. Objetivo: Identificar un tamaño de parcela que proporcione una precisión adecuada para los parámetros dendrométricos en la Amazonía. Métodos: En Cotriguaçu, Mato Grosso, Brasil, probamos cuatro tamaños de parcela con seis repeticiones cada una: 2 500, 5 000, 7 500 y 10 000 m². Medimos diámetro a la altura del pecho, densidad de población, área basal y biomasa. Se aplicaron los índices de Shannon y Jaccard; Funciones Weibull 2P y Gamma para adaptarse a la distribución diametral; y el Criterio de Información de Akaike para el mejor modelo. Resultados: Hubo una relación directamente proporcional entre el área de parcela y la similitud poblacional, pero la diversidad no indicó alteraciones significativas. El tamaño de la parcela no afectó los atributos dendrológicos y la distribución diametral. Las áreas de parcela más grandes dieron lugar a coeficientes de variación más bajos e intervalos de confianza más pequeños. La función Gamma fue el mejor modelo para representar las distribuciones de diferentes tamaños de parcela. Conclusiones: Para bosques similares, recomendamos la parcela de 2 500 m² para evaluar diámetro a la altura del pecho, densidad de población, área basal y biomasa.

Optimal selective logging regime and log landing location models: a case study in the Amazon forest / Regime de corte seletivo ótimo em modelos de locação de pátios de estocagem de madeira: um estudo de caso na floresta amazônica

ABSTRACT Reduced-impact logging is a well known practice applied in most sustainable forest management plans in the Amazon. Nevertheless, there are still ways to improve the operational planning process. Therefore, the aim of this study was to create an integer linear programming (ILP) to fill in the knowledge gaps in the decision support system of reduced impact logging explorations. The minimization of harvest tree distance to wood log landing was assessed. Forest structure aspects, income and wood production were set in the model, as well as the adjacency constraints. Data are from a dense ombrophylous forest in the western Brazilian Amazon. We applied the phytosociological analysis and BDq method to define the selective logging criteria. Then, ILP models were formulated to allow the application of the constraints. Finally, 32 scenarios (unbalanced forest, UF, and balanced forest, BF) were generated and compared with real executed plans (RE). Robust results were achieved and the expected finding of each scenario was met. The feasibility to integrate ILP models in uneven-aged forest management projects was endorsed. Consequently, the UF and BF scenarios tested were efficient and concise, introducing new advances for forest management plans in the Amazon. The proposed models have a high potential to improve the selective logging activities in the Amazon forest.

RESUMO A exploração de impacto reduzido é uma prática bem conhecida e aplicada na maioria dos planos de manejo florestal sustentável na Amazônia. Todavia, ainda há a possibilidade de melhoria do processo de planejamento da operação. Diante da falta de métodos auxiliares à tomada de decisão, o objetivo do trabalho foi desenvolver modelos de programação linear inteira (PLI) para suprir esta demanda. Considerou-se a minimização da distância entre as árvores exploradas e os pátios de estocagem de madeira. Aspectos estruturais, econômicos e produtivos foram incorporados ao modelo, bem como restrições de adjacência. Os dados derivam de uma floresta ombrófila densa na Amazônia Ocidental. Previamente, utilizou-se uma análise fitossociológica e o método BDq como critério de remoção. Posteriormente, modelos de PLI foram formulados para exemplificar as aplicações. Finalmente, 32 cenários (para floresta desbalaceada, UF, e floresta balanceada, BF) foram gerados e comparados com o plano executado no campo (RE). Resultados robustos foram obtidos e atenderam às expectativas de cada cenário. A viabilidade da integração dos modelos de PLI em projetos de manejo de florestas ineqüiâneas foi testado. Os cenários UF e BF testados foram eficientes e concisos, confirmando seu potencial para aumentar a eficiência de planos de exploração madeireira e manejo florestal na Amazônia.

Occupational accidents footprint: new concept linked to chain of custody in sustainable forest management / Huella de la accidentalidad laboral: nuevo concepto asociado a la cadena de custodia en manejo forestal sustentable

The study, due to inconveniences in previous methods, proposes the new concept of "occupational accidents footprint", and its implementation and traceability in the chain of custody (CoC) related with sustainable forest management (SFM), through specially elaborated labor accident indicators. Data from primary sources related to fatal cases, accidents with temporary disabilities and lost time on forest operations accidents of 24 countries, plus production associated to those works, was compiled; and then, processed to get results in terms of fatal cases/million m3, total work accidents/million m3 and total lost time/million m3. Results show that is feasible to apply the concept of occupational accidents footprint to measure aggregated value to forest products certification of the CoC. In Production vs Fatality the cleanest occupational accidents footprint in the forests belongs to Germany, Belgium, Finland and Australia; for Production vs Accidents the best behaviors are for Sweden, USA, New Zealand and Belgium; while in Production vs Lost Time Finland, Belgium and Austria are leaders. Due to the convenience to make evident the labor accidents impact on forest products aggregated value, it is proposed the implementation of new safety indicators associated to the occupational accidents footprint, in order to be useful in the certification of CoC in SFM.

El estudio, debido a inconveniencias en métodos previos, propone el nuevo concepto de "huella de accidentalidad laboral", y su implementación y trazabilidad en la cadena de custodia (CdC) en manejo forestal sustentable (MFS), mediante indicadores de accidentalidad ocupacional especiales. Se recolectaron datos de fuentes primarias sobre casos fatales, accidentes con incapacidades temporales y tiempo perdido en siniestros ocurridos en operaciones forestales de 24 países, más producción asociadas a dichas faenas, siendo éstos procesados para obtener resultados de casos fatales/millón m3, cantidad accidentes/millón m3 y tiempo perdido/millón m3. Los resultados evidencian la factibilidad de aplicar el concepto de huella de accidentalidad laboral para medir agregación de valor a productos forestales en la CdC. En Producción vs Fatalidad la huella de accidentalidad laboral más limpia en bosques corresponde a Alemania, Bélgica, Finlandia y Australia; para Producción vs Accidentes los mejores comportamiento son de Suecia, EE.UU., Nueva Zelandia y Bélgica; mientras que en Producción vs Tiempo Perdido se destacan Finlandia, Bélgica y Austria. Siendo conveniente transparentar en los productos forestales el impacto de los accidentes del trabajo en su agregación de valor, se propone establecer indicadores asociados a la huella de accidentalidad laboral útiles en la certificación de la CdC en MFS.