A CRENÇA, ÚNICO OBJETO DE DESEJO, GABRIEL TARDE

----

Individual tree attribute estimation and uniformity assessment in fast-growing Eucalyptus spp. forest plantations using lidar and linear mixed-effects models

Fast-growing Eucalyptus spp. forest plantations and their resultant wood products are economically important and may provide a low-cost means to sequester carbon for greenhouse gas reduction. The development of advanced and optimized frameworks for estimating forest plantation attributes from lidar remote sensing data combined with statistical modeling approaches is a step towards forest inventory operationalization and might improve industry e ciency in monitoring and managing forest resources. In this study, we first developed and tested a framework for modeling individual tree attributes in fast-growing Eucalyptus forest plantation using airborne lidar data and linear mixed-e ect models (LME) and assessed the gain in accuracy compared to a conventional linear fixed-e ects model (LFE). Second, we evaluated the potential of using the tree-level estimates for determining tree attribute uniformity across di erent stand ages. In the field, tree measurements, such as tree geolocation, species, genotype, age, height (Ht), and diameter at breast height (dbh) were collected through conventional forest inventory practices, and tree-level aboveground carbon (AGC) was estimated using allometric equations. Individual trees were detected and delineated from lidar-derived canopy height models (CHM), and crown-level metrics (e.g., crown volume and crown projected area) were computed from the lidar 3-D point cloud. Field and lidar-derived crown metrics were combined for ht, dbh, and AGC modeling using an LME. We fitted a varying intercept and slope model, setting species, genotype, and stand (alone and nested) as random e ects. For comparison, we also modeled the same attributes using a conventional LFE model. The tree attribute estimates derived from the best LME model were used for assessing forest uniformity at the tree level using the Lorenz curves and Gini coe cient (GC).We successfully detected 96.6% of the trees from the lidar-derived CHM. The best LME model for estimating the tree attributes was composed of the stand as a random e ect variable, and canopy height, crown volume, and crown projected area as fixed e ects. The %RMSE values for tree-level height, dbh, and AGC were 8.9%, 12.1%, and 23.7% for the LFE model and improved to 7.3%, 7.1%, and 13.6%, respectively, for the LME model. Tree attributes uniformity was assessed with the Lorenz curves and tree-level estimations, especially for the older stands. All stands showed a high level of tree uniformity with GC values approximately 0.2. This study demonstrates that accurate detection of individual trees and their associated crown metrics can be used to estimate Ht, dbh, and AGC stocks as well as forest uniformity in fast-growing Eucalyptus plantations forests using lidar data as inputs to LME models. This further underscores the high potential of our proposed approach to monitor standing stock and growth in Eucalyptus—and similar forest plantations for carbon dynamics and forest product planninginfo:eu-repo/semantics/publishedVersio

Beyond trees: Mapping total aboveground biomass density in the Brazilian savanna using high-density UAV-lidar data

Tropical savanna ecosystems play a major role in the seasonality of the global carbon cycle. However, their ability to store and sequester carbon is uncertain due to combined and intermingling effects of anthropogenic activities and climate change, which impact wildfire regimes and vegetation dynamics. Accurate measurements of tropical savanna vegetation aboveground biomass (AGB) over broad spatial scales are crucial to achieve effective carbon emission mitigation strategies. UAV-lidar is a new remote sensing technology that can enable rapid 3-D mapping of structure and related AGB in tropical savanna ecosystems. This study aimed to assess the capability of high-density UAV-lidar to estimate and map total (tree, shrubs, and surface layers) aboveground biomass density (AGBt) in the Brazilian Savanna (Cerrado). Five ordinary least square regression models esti-mating AGBt were adjusted using 50 field sample plots (30 m × 30 m). The best model was selected under Akaike Information Criterion, adjusted coefficient of determination (adj.R2), absolute and relative root mean square error (RMSE), and used to map AGBt from UAV-lidar data collected over 1,854 ha spanning the three major vegetation formations (forest, savanna, and grassland) in Cerrado. The model using vegetation height and cover was the most effective, with an overall model adj-R2 of 0.79 and a leave-one-out cross-validated RMSE of 19.11 Mg/ha (33.40%). The uncertainty and errors of our estimations were assessed for each vegetation formation separately, resulting in RMSEs of 27.08 Mg/ha (25.99%) for forests, 17.76 Mg/ha (43.96%) for savannas, and 7.72 Mg/ha (44.92%) for grasslands. These results prove the feasibility and potential of the UAV-lidar technology in Cerrado but also emphasize the need for further developing the estimation of biomass in grasslands, of high importance in the characterization of the global carbon balance and for supporting integrated fire management activities in tropical savanna ecosystems. Our results serve as a benchmark for future studies aiming to generate accurate biomass maps and provide baseline data for efficient management of fire and predicted climate change impacts on tropical savanna ecosystems

A CRENÇA, ÚNICO OBJETO DE DESEJO, GABRIEL TARDE

----

Etnografia e manejo de recursos naturais pelos índios Deni, Amazonas, Brasil Ethnography and natural resources management by the Deni Indians, Amazonas, Brazil

São raros os estudos envolvendo o uso múltiplo de recursos naturais por populações amazônicas. Este trabalho apresenta um panorama de como os índios Deni, habitantes da região de interflúvio entre dois dos maiores afluentes de água branca da bacia amazônica, os rios Juruá e Purus, utilizam dos recursos disponíveis em seu território. Os Deni são, atualmente, índios que vivem da exploração de recursos da terra firme e de regiões alagadas. São um misto de horticultores e caçadores/coletores, que utilizam toda a sua área para a obtenção de recursos para subsistência. Como regra, deslocam periodicamente seus assentamentos, evitando o esgotamento local de recursos, e provocando a modificação local do ambiente. Esta alteração aumenta temporariamente a disponibilidade de alimento. Áreas com aldeias, pomares e roçados abandonados, por sua vez, tornam-se locais onde se concentram inúmeros recursos da flora e da fauna, posteriormente explorados. O impacto provocado por este sistema é aparentemente mínimo. Os Deni estão contextualizados na periferia de um sistema capitalista, onde a única fonte de renda para adquirir bens que são hoje considerados pelos índios como indispensáveis para sua sobrevivência são os recursos naturais. Estes são e continuarão sendo explorados de maneira a produzir um excedente a ser comercializado para a obtenção de uma série de produtos industrializados, independentemente das opiniões externas. É sobre este patamar que devemos avaliar a sustentabilidade do atual manejo da área.<br>Studies concerning the use of multiple natural resources by Amazonian indians are scarce. This work presents a portrait of how the Deni Indians, inhabitants of an area between two of the most important white-water rivers of the Amazon basin (Juruá and Purus Rivers), exploit natural resources in their territory. The Deni exploit both the upland and floodplain forests. They are a mix of horticulturalists and hunter-gatherers, using their whole territory to obtain what they need to live. As a rule, they move their settlements periodically, avoiding local resource depletion. The Deni modify the landscape at a local level, causing an increase in resource availability. Abandoned villages, fruit orchards and crops are places where floristic and faunistic resources concentrate and are systematically exploited. The impacts of such management are apparently minimal. For the Deni society natural resources are the only way to get goods for survival, but it is inserted in the periphery of a capitalist system which exploits and will continue to exploit natural resources in order to produce a surplus for the acquisition of industrialized products, independently of external judgements. This should be the starting point to evaluate sustainability in this local management system