Advances in Unmanned Aerial Vehicle (UAV) technology and data processing capabilities have made it feasible to obtain high-resolution imagery and three dimensional (3D) data which can be used for forest monitoring and assessing tree attributes. This study evaluates the applicability of low consumer grade cameras attached to UAVs and structure-from-motion (SfM) algorithm for automatic individual tree detection (ITD) using a local-maxima based algorithm on UAV-derived Canopy Height Models (CHMs). This study was conducted in a private forest at Cache Creek located east of Jackson city, Wyoming. Based on the UAV-imagery, we allocated 30 field plots of 20 m × 20 m. For each plot, the number of trees was counted manually using the UAV-derived orthomosaic for reference. A total of 367 reference trees were counted as part of this study and the algorithm detected 312 trees resulting in an accuracy higher than 85% (F-score of 0.86). Overall, the algorithm missed 55 trees (omission errors), and falsely detected 46 trees (commission errors) resulting in a total count of 358 trees. We further determined the impact of fixed tree window sizes (FWS) and fixed smoothing window sizes (SWS) on the ITD accuracy, and detected an inverse relationship between tree density and FWS. From our results, it can be concluded that ITD can be performed with an acceptable accuracy (F > 0.80) from UAV-derived CHMs in an open canopy forest, and has the potential to supplement future research directed towards estimation of above ground biomass and stem volume from UAV-imagery.

Light Detection and Ranging (LiDAR) has demonstrated potential for forest inventory at the individual tree-level. The aim in this study was to predict individual tree height (Ht; m), basal area (BA; m 2 ) and stem volume (V; m 3 ) attributes using Random Forest k-nearest neighbor (RF k-NN) imputation and individual tree-level based metrics extracted from a LiDAR-derived canopy height model (CHM) in a longleaf pine (Pinus palustris Mill.) forest in southwestern Georgia, USA. We developed a new framework for modeling tree-level forest attributes that was comprised of three steps: (1) individual tree detection, crown delineation and tree-level based metrics computation from LiDAR-derived CHM; (2) automatic matching of LiDAR-derived trees and field-based trees for a regression modeling step using a novel algorithm; and (3) RF k-NN imputation modeling for estimating tree-level Ht, BA, and V, and subsequent summarization of these metrics at the plot-and stand-levels. RMSDs for tree-level Ht, BA and V were 2.96%, 58.62% and 8.19%, respectively. Although BA estimation accuracy was poor because of the longleaf pine growth habit, individual tree locations, Ht, and V were estimated with high accuracy, especially in low canopy cover conditions. Future efforts based on the findings could help to improve the estimation accuracy of individual tree-level attributes like BA. RésuméLe lidar a démontré son potentiel pour l'inventaire forestier à l'échelle de l'arbre. Le but de cette étude était de prédire la hauteur individuelle des arbres (Ht; m), la surface terrière (BA; m 2 ) et le volume des tiges (V; m 3 ) en utilisant une imputation basée sur la méthode des forêts aléatoires et des k plus proches voisins (RF k-NN; Random Forest k-nearest neighbor) et de mesures à l'échelle de l'arbre extraites à partir d'un modèle de la hauteur de la canopée (MHC) Downloaded by [Boston University] at 03:50 29 June 2016 ACCEPTED MANUSCRIPT ACCEPTED MANUSCRIPT 3 dérivés du lidar dans une forêt de pins des marais (Pinus palustris Mill.) dans le sud-ouest de laGéorgie, aux États-Unis. Nous avons développé un nouveau cadre pour la modélisation des attributs forestiers à l'échelle de l'arbre composé de trois étapes : 1. la détection des arbres individuels, la délimitation des couronnes et le calcul de paramètres à l'échelle de l'arbre à partir de modèles MHC obtenus à partir du lidar; 2. la mise en correspondance automatique entre les arbres obtenus à partir du lidar et les arbres observés sur le terrain pour une étape de modélisation de régression en utilisant un nouvel algorithme; et 3. l'imputation par modélisation en utilisant RF k-NN pour estimer la Ht, la BA et le V à l'échelle de l'arbre et la synthèse ultérieure de ces mesures à l'échelle de la parcelle et du peuplement. Les REQM pour la Ht, la BA et le V à l'échelle de l'arbre étaient de 2,96 %, 58,62 % et 8,19 %, respectivement. Bien que la précision de l'estimation de la BA fût faible en raison du port et du mode de croissance des pins des marais, l'emplacement des arbres individuels, la...

RESUMOO avanço das fronteiras agrícolas, caracterizado pela substituição de ecossistemas naturais por áreas cultivadas, vem se intensificando nas últimas décadas, acarretando alterações na qualidade do solo e na dinâmica da matéria orgânica do solo (MOS). Assim, o estudo do impacto da adoção de diferentes sistemas de manejo é essencial na definição de melhores estratégias de uso do solo. Este estudo teve por objetivo avaliar diferentes frações da MOS e os estoques de C e N de Latossolo Vermelho distroférrico típico muito argiloso submetido a diferentes sistemas de uso e manejo: mata nativa (MTN), eucalipto (EUC), pinus (PIN), pastagem (PAS), milho no sistema de cultivo mínimo (MCM) e milho no sistema plantio convencional (MPC). As amostras de solo foram coletadas em setembro de 2004, nas profundidades de 0-10, 10-20 e 20-40 cm, para avaliação dos estoques de carbono orgânico (CO) e N total (NT); de 0-5 e 0-10 cm, para realização do fracionamento físico-densimétrico da MO; e de 0-5 cm, para avaliação do C da biomassa microbiana (Cmic). O estoque de CO na área de eucalipto foi maior do que o determinado na área de mata. A proporção relativa do CO nas frações da MOS aumentou na seguinte ordem: C-argila > C-silte > C-areia > C FL . A maior parte (> 90 %) do CO está associada à fração pesada da MOS, com valores próximos a 98 % nos sistemas cultivados com milho (MPC e MCM). Em relação aos teores de CO, o C mic e o C da fração leve (C FL ) são indicadores mais sensíveis das alterações decorrentes da adoção de diferentes sistemas de uso e manejo sobre os compartimentos da matéria orgânica do Latossolo.Termos de indexação: fracionamento físico-densimétrico, biomassa microbiana, mudanças climáticas globais, uso do solo, mudanças no uso do solo e reflorestamento.(1) Parte da Tese de Doutorado do primeiro autor desenvolvida no Departamento de Ciência do Solo da Universidade Federal de Lavras -UFLA. Recebido para publicação em março de 2006 e aprovado em agosto de 2007.

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3D-imaging technologies provide measurements of terrestrial and aquatic ecosystems' structure, key for biodiversity studies. However, the practical use of these observations globally faces practical challenges. Firstly, available 3D data are geographical biased, with significant gaps in the tropics. Secondly, no data source provides, by itself, global coverage at a suitable temporal recurrence. Thus, global monitoring initiatives, such as assessment of essential biodiversity variables (EBVs), will necessarily have to involve the combination of disparate datasets. We propose a standardised framework of ecosystem morphological traitsheight, cover and structural complexitythat could enable monitoring of globally-consistent EBVs at regional scales, by flexibly integrating different information sourcessatellites, aircrafts, drones or ground data -, allowing global biodiversity targets relating to ecosystem structure to be monitored and regularly reported.

Monoammonium phosphate (MAP), triple superphosphate (TSP), and phosphoric acid (H3PO4), with and without the addition of magnesium oxide (MgO), were mixed with poultry litter (PL) to produce biochar-based fertilizers (BBFs). This is a novel approach aiming to add value to PL residue and to increase P use efficiency in acidic tropical soils. Samples of BBFs were assessed by P-release kinetics in water, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and a bioassay with maize in a greenhouse using a clayey Oxisol. Addition of MgO reduced the kinetics of P released from BBFs impregnated with all P sources. XRD analysis showed the formation of low-solubility Ca2P2O7 and Mg2P207 compounds, which is supported by POP or PO stretching observed in the FTIR spectra. The MgO-treated BBFs increased shoot dry matter production compared to the control, but were inferior when compared to TSP in the short term. The slow release of P and the alkaline reaction of the BBFs show great potential for these materials to be used as enhanced P fertilizers in tropical soils.

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