Abstract. A mechanistic understanding of how tropical-tree mortality responds to climate variation is urgently needed to predict how tropical-forest carbon pools will respond to anthropogenic global change, which is altering the frequency and intensity of storms, droughts, and other climate extremes in tropical forests. We used 5 years of approximately monthly drone-acquired RGB (red–green–blue) imagery for 50 ha of mature tropical forest on Barro Colorado Island, Panama, to quantify spatial structure; temporal variation; and climate correlates of canopy disturbances, i.e., sudden and major drops in canopy height due to treefalls, branchfalls, or the collapse of standing dead trees. Canopy disturbance rates varied strongly over time and were higher in the wet season, even though wind speeds were lower in the wet season. The strongest correlate of monthly variation in canopy disturbance rates was the frequency of extreme rainfall events. The size distribution of canopy disturbances was best fit by a Weibull function and was close to a power function for sizes above 25 m2. Treefalls accounted for 74 % of the total area and 52 % of the total number of canopy disturbances in treefalls and branchfalls combined. We hypothesize that extremely high rainfall is a good predictor because it is an indicator of storms having high wind speeds, as well as saturated soils that increase uprooting risk. These results demonstrate the utility of repeat drone-acquired data for quantifying forest canopy disturbance rates at fine temporal and spatial resolutions over large areas, thereby enabling robust tests of how temporal variation in disturbance relates to climate drivers. Further insights could be gained by integrating these canopy observations with high-frequency measurements of wind speed and soil moisture in mechanistic models to better evaluate proximate drivers and with focal tree observations to quantify the links to tree mortality and woody turnover.

In mid‐January 2005 a convective squall line traversed 4.5 × 106 km2 of Amazonia from southwest to northeast. As seen in Landsat images, this atypical convective storm left blowdown imprints with diffuse geometry, unlike the fan‐shaped wind disturbance of much more frequent east‐to‐west propagating squall lines. Previous work reported 0.2% of the forest area damaged by this one relatively rare event within one Landsat image and assumed similar disturbance across the entire traverse. We mapped convective wind damage impact to the region in 2005 by identifying large‐scale (>4 ha) blowdown imprints in 30 Landsat images. The diffuse‐type imprints associated with this single squall line contributed up to 60–72% of total 2005 wind‐disturbed area detected across the region, but damage was highly concentrated in central Amazonia. Consequently, the distribution of large wind damage patches in 2005 across Amazonia was very different from long‐term average. Regional distribution of wind‐driven tree mortality for smaller patch sizes remains unknown.

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.

Abstract. A mechanistic understanding of how tropical tree mortality responds to climate variation is urgently needed to predict how tropical forest carbon pools will respond to anthropogenic global change, which is altering the frequency and intensity of storms, droughts, and other climate extremes in tropical forests. We used five years of approximately monthly drone-acquired RGB imagery for 50 ha of mature tropical forest on Barro Colorado Island, Panama, to quantify spatial structure, temporal variation, and climate correlates of canopy disturbances, i.e., sudden and major drops in canopy height due to treefalls, branchfalls, or collapse of standing dead trees. Treefalls accounted for 77 % of the total area and 60 % of the total number of canopy disturbances in treefalls and branchfalls combined. The size distribution of canopy disturbances was close to a power function for sizes above 25 m2, and best fit by a Weibull function overall. Canopy disturbance rates varied strongly over time and were higher in the wet season, even though windspeeds were lower in the wet season.  The strongest correlate of temporal variation in canopy disturbance rates was the frequency of 1-hour rainfall events above the 99.4th percentile (here 35.7 mm hour−1, r = 0.67). We hypothesize that extreme high rainfall is associated with both saturated soils, increasing risk of uprooting, and with gusts having high horizontal and vertical windspeeds that increase stresses on tree crowns. These results demonstrate the utility of repeat drone-acquired data for quantifying forest canopy disturbance rates over large spatial scales at fine temporal and spatial resolution, thereby enabling strong tests of linkages to drivers. Future studies should include high frequency measurements of vertical and horizontal windspeeds and soil moisture to better capture proximate drivers, and incorporate additional image analyses to quantify standing dead trees in addition to treefalls.

A utilização de sistemas de informação geográfica (SIG) no planejamento florestal possibilita a análise e o reconhecimento de padrões espaciais das espécies florestais em perfil bidimensional e tridimensional. O objetivo deste estudo foi demonstrar a eficiência do método de coordenadas cartesianas e espaciais (MCCE), método de correção da localização das coordenadas UTM das árvores em concordância com a localização de campo ou cartesianas (X,Y), aliado ao cálculo do índice do vizinho natural (ANND) no reconhecimento e análise de padrões espaciais de quatro espécies comerciais madeireiras em área de manejo florestal em Caracaraí, RR, Brasil. O ANND pressupõe completa aleatoriedade espacial.Simulações foram realizadas em 9 ha, subdivididos em 100 subparcelas de 100 m2 cada. Foram coletados: o diâmetro (DAP > 10 cm), alturas comercial e total, volume comercial e as coordenadas cartesianas (X,Y) e espaciais (UTM). Foram observados padrões espaciais aleatórios para Eschweilera bracteosa e Manilkara huberi. Os padrões espaciais dispersos e raros foram mais observados em Cedrelinga cateniformis e Dinizia excelsa. O MCCE demonstrou ser um método eficiente para o reconhecimento e análise de padrões espaciais de espécies nativas da floresta tropical amazônica, facilitando o planejamento florestal mediante simulações 2D e 3D da floresta.Spatial pattern of Amazonian timber species using cartesian and spatial coordinates methodGeographic information system (GIS) applied to forest analysis permit the recognition and analysis of spatial patterns of species in two and three dimensional. The aim of this study to demonstrate the efficiency of cartesian and spatial coordinates method (MCCE), method of correcting UTM coordinates of trees location in accordance with the location of field or Cartesian (X ,Y), combined with natural neighbor index (ANND) in recognition and analysis of spatial distribution patterns of four commercial timber species in forest management in Caracaraí, Roraima State, Brazil. Simulations were performed on 9 ha, divided into 100 plots of 100 m2 each. Collected data were DBH > 10 cm, commercial and total heights, cartesian coordinates (X,Y) and spatial coordinates (UTM). Random spatial patterns were observed in Eschweilera bracteosa and Manilkara huberi. The dispersed and rare spatial patterns were observed in Dinizia excelsa and Cedrelinga cateniformis. MCCE proved to be an efficient method in the recognition and analysis of spatial patterns of native species from Amazon rain forest, as forest planning becomes easier by 2D and 3D simulations.Index terms: Geographic information system; Forest management; Natural neighbor index

Neste estudo foram analisadas variáveis biofísicas para definir áreas potenciais para o plantio de espécies florestais tradicionais no território do Distrito Federal. As espécies testadas foram Pinus caribaea Morelet var. caribaea, P. caribaea Morelet var. hondurensis (Sénécl.) W. H. G. Barrett & Golfari, P. caribaea Morelet var. bahamensis (Griseb.) W. H. G. Barrett & Golfari, P. elliottii Engelm. var. elliottii, Eucalyptus camaldulensis Dehnh., E. urophylla S. T. Blake, E. grandis W. Hill, Corymbia citriodora (Hook.) K. D. Hill & L. A. S. Johnson (ex Eucalyptus citriodora), C. torelliana (F. Muell.) K. D. Hill & L. A. S. Johnson (ex Eucalyptus torelliana), Hevea brasiliensis (Willd. ex A. Juss.) Müll. Arg.e Tectona grandis L. f. Para identificar as áreas aptas para a implantação dos povoamentos florestais, foi realizada a sobreposição de variáveis do meio físico do Distrito Federal com variáveis relacionadas às exigências adaptativas de cada espécie estudada. Com base nos resultados desta pesquisa, as espécies que apresentaram potencial para cultivo nas condições físicas do Distrito Federal foram as três variedades de Pinus caribaea, P. elliottii var. elliottii, Eucalyptus camaldulensis, E. urophylla, E. grandis e Corymbia citriodora. As espécies Corymbia torelliana, Hevea brasiliensis e Tectona grandis não apresentaram potencial para o cultivo.Palavras-chave:Silvicultura; sistema de informação geográfica. AbstractSmall scale ecological zoning of Distrito Federal, Brazil, for traditional forest species. This study evaluated biophysical variables to identify suitable areas of the Distrito Federal for planting traditional tree species. The studied tree species included Pinus caribaea Morelet var. caribaea, P. caribaea Morelet var. hondurensis (Sénécl.) W. H. G. Barrett & Golfari, P. caribaea Morelet var. bahamensis (Griseb.) W. H. G. Barrett & Golfari, P. elliottii Engelm. var. elliottii, Eucalyptus camaldulensis Dehnh., E. urophylla S. T. Blake,  E. grandis W. Hill, Corymbia citriodora (Hook.) K. D. Hill & L. A. S. Johnson (ex Eucalyptus citriodora), C. torelliana (F. Muell.) K. D. Hill & L. A. S. Johnson (ex Eucalyptus torelliana), Hevea brasiliensis (Willd. ex A. Juss.) Müll. Arg. and Tectona grandis L. f.Suitable areas for the studied tree species were identified by overlapping biophysical variables of the Distrito Federal, wich included adaptive tree requirements and site characteristics.Based on this research results, the territory of the study area is suitable for cultivation of three varieties of Pinus caribaea, P. elliottii var. elliottii, Eucalyptus camaldulensis, E. urophylla, E. grandis and Corymbia citriodora. There were no suitable areas for cultivation of Corymbia torelliana, Hevea brasiliensis and Tectona grandis.Keywords: Silviculture; geographic information system.

Tomato fruits are highly perishable. In this sense, adopting techniques to maintain and extend its shelf life is essential. Recent studies have used microalgae as an edible coating for fruit, as it is a nutrient-rich alternative and reduces fruit mass loss and respiration, delaying senescence. The aim of this study was to evaluate the application of microalgae-based coatings with or without the use of modified atmosphere packaging, polyvinyl chloride (PVC), in post-harvest tomato conservation. The design used was completely randomized, in a 4x2 factorial arrangement, with four coatings (no coating, coating composed of Spirulina platensis sp., Chlorella sp. and Scenedesmus sp.) and two conditions (with and without PVC), totalizing 8 treatments, with four replicates, consisting of one fruit each. Stored for 7 days at 10±2ºC and 55±5% UR and evaluated at harvest and on the last day of storage. The fruits coated with Chlorella sp. without PVC and Scenedesmus sp. associated with PVC, showed the lowest mass losses, representing a reduction of 73.79% and 78.47%, respectively, in relation to the control. In addition to mass loss, the levels of ascorbic acid (18.91 and 16.97 mg/100 g), citric acid (4.02 and 4.01), respectively, and the SS/AT ratio also stood out. The microalgae Chlorella sp. and Scenedesmus sp. can be used in coating ‘Santa Clara’ tomato fruits to maintain their physicochemical characteristics over 7 days of storage. The use of PVC film coating helped maintain these characteristics, reducing the perishability of the fruits.

Buttresses and other natural structures modify the shape of stems in Amazonia and change the diameter at breast height (DBH) measured at 1.3 m at ground level. The lack of adequate measurement techniques affects negatively forest dynamics analyses and biomass estimating. The study evaluated an indirect method of measuring diameters in trees with DBH > 40 cm using principles of digital photogrammetry. The results obtained with two cameras (smartphone and Sony) were compared with direct measurements using diametric tape and a ladder. The technique is adequate to measure the diameters of trees with measurement point above 2 m of ground, with a confidence interval of ±1cm. The use of photogrammetry as a supplementary tool to the diametric tape (IC ± 0.24 cm) is recommended, helping to measure trees with diameter above the reach of the technician in forest inventories.