1,721,010 research outputs found
Dendrometric characterization of Cupressus lusitanica mill. planted under Pinus taeda L. shelter in southern Brazil
No full textBackground: We analyzed if C. lusitanica can be planted in a shelterwood system with P. taeda as theshelter stratum. The study was conducted in a 13-yr-old C. lusitanica stand under P. taeda canopy inSouthern Brazil. Samples of these trees were measured in terms of diameter at breast height (DBH), totalheight, individual volume, and crown projection area. The species ́ growing space efficiency (GSE) wasalso analyzed. A 10-meters distance criterion from P. taeda trees was applied to check their influence onC. lusitanica growth behavior through correlation.Results: The 36-yr-old P. taeda trees showed expressive means in the dendrometric variables, compatiblewith its age (mean DBH of 58 cm, total height 30 m, individual volume of 3.7 m³, and crown projectionarea of 128 m²). There was a statistically significant effect (p>0.05) of P. taeda cover on C. lusitanicadiameter (mean of ~13 cm). Although not significant, an effect of P. taeda canopy was also observed onC. lusitanica height. The two species summed a basal area of 36.5 m² ha-1 and a crown projection area of34,209.2 m² ha-1. A tendency of increasing GSE with increasing diameter was observed for both species.Conclusion: These results show that a shelterwood with C. lusitanica under P. taeda is possible, butfurther investigations with longer production cycles and with silvicultural treatments (i.e. thinnings andshelter removal) should be conducted for a better understanding of shelterwood systems with thesespecies in southern Brazil in terms of growth performance and soil use sustainability
Biomass quantification of Pinus taeda L. from remote optical sensor data
No full textThis research aimed to estimate the biomass trunk of a Pinus taeda L. stand from vegetation indices from Landsat-8/OLI and Sentinel-2/M SI op tical remote sensors. In order to obtain the biomass, a forest inventory was carried out with the installation of 33 circular p lots of 400 m², in which all the individuals had the diameter at breast height (cm) and the total height (m) measured. Then, 30 trees were scaled by the Smalian method. The individual tree volume was estimated by the M ey er regression volumetric equation, which showed the best p erformance for the analy zed data set. The biomass was obtained through the p roduct of the individual tree volume by the wood basic density . Subsequently , aerial biomass was obtained p er p lot. The p rocessed orbital images were gathered from the Landsat-8/OLI and Sentinel-2/M SI sensors. We derived 19 vegetation indices for both images, which were correlated with the biomass p er p lot. The indexes with the best correlation with the biomass were considered as regression variables to develop models by the Step wise technique (Backward and Forward). The correlation was significant among the variables and the best model was derived from the Landsat-8 data, which estimated the biomass p er p lot with an error of 8.75% and an adjusted coefficient of determination of 0.8173. Nevertheless, the statistical analy sis revealed that there was no significant difference between the biomass estimated by the inventory and by the remotely located data
Avaliação da sobrevivência e modelagem do desenvolvimento inicial de árvores para restauração da Mata Atlântica
Get PDFEcological restoration has become an important complementary practice to protect natural resources and preserve biodiversity.
However, native species may be used in restoration programs in ways that do not optimize their performance. This research evaluated the
survival and to model the initial growth of 15 native tree species planted in “filling” and “diversity” lines in the post-planting phase of a
restoration experiment in the subtropics of the Brazilian Atlantic Forest. We measured survival rate (%) one year after planting and collar
diameter (mm), total height (m), crown projection area (m²) and crown volume (m³) in the first 48 months after planting. Growth modeling for
each variable and species was based on the non-linear mathematical Logistic, Gompertz, and Chapman-Richards models. Model selection for
each variable/species was supported by the Akaike Information Criterion, standard error of the estimate, and coefficient of determination. The
highest survival rates were reported for Cordia americana, Gochnatia polymorpha, Inga uruguensis, Peltophorum dubium, Prunus sellowii e
Zanthoxylum rhoifolium (91.7%) and for Solanum mauritianum (90.3%). The species with faster growth were, by increasing order, Mimosa
scabrella, Trema micrantha, Solanum mauritianum and Croton urucurana. With a better understanding of the initial developmental potential of
tree species, it is possible to increase the species and functional diversity of the filling group. There was no single model capable of describing
the variables analyzed and different models were needed to describe different characteristics and species.A restauração ecológica tornou-se uma importante atividade complementar para proteger os recursos naturais e conservar a
biodiversidade. No entanto, as espécies nativas podem estar a ser utilizadas em programas de restauração de formas que não otimizam as suas
características. O objetivo deste trabalho foi avaliar a sobrevivência e modelar o desenvolvimento inicial de 15 espécies arbóreas nativas plantadas
em linhas de “preenchimento” e “diversidade” na fase de pós-plantio numa experiência de restauração nos subtrópicos da Mata Atlântica Brasileira.
Avaliou-se a taxa de sobrevivência (%) um ano após o plantio e o diâmetro do colo (mm), a altura total (m), a área de projeção de copa (m²) e o
volume de copa (m³) nos primeiros 48 meses após o plantio. A modelagem de crescimento para cada variável e espécie foi baseada nos modelos
matemáticos não lineares: Logístico, Gompertz e Chapman-Richards. A seleção do modelo para cada variável/espécie teve como base o Critério
de Informação de Akaike, erro padrão da estimativa e coeficiente de determinação. Os percentuais de sobrevivência mais altos foram para Cordia
americana, Gochnatia polymorpha, Inga uruguensis, Peltophorum dubium, Prunus sellowii e Zanthoxylum rhoifolium (91,7%) e para Solanum
mauritianum (90,3%). As espécies de crescimento mais rápido, por ordem crescente, foram: Mimosa scabrella, Trema micrantha, Solanum
mauritianum e Croton urucurana. Com o conhecimento do potencial de desenvolvimento inicial das espécies, é possível aumentar a diversidade
de espécies e funcional do grupo de preenchimento. Não houve um modelo único capaz de descrever todas as variáveis de desenvolvimento
analisadas. Foram necessários diferentes modelos para descrever as diferentes características e as diferentes espécies.We thank the Conselho Nacional de Desenvolvimento
Científico e Tecnológico – CNPq – (National Council for Scientific
and Technological Development) Brazil for financial support
(Process 575081/2008-2).info:eu-repo/semantics/publishedVersio
Estimation of leaf area index of Pinus taeda L. and Cupressus lusitanica Mill. by vegetation indices
No full textThis research aimed to quantify the leaf area index (LAI) of a forest of Pinus taeda L. and Cupressus lusitanica Mill. using optical data from the Landsat-8/OLI and Sentinel-2/MSI sensors. For that, 50 circular plots of 500m 2 in the area were allocated, in which LAI readings were performed using the LAI-2200 equipment. The remotely located data comprised images of the Landsat-8/OLI and Sentinel-2/MSI orbital sensors. After digital processing, 15 vegetation indexes were calculated for each image used. These data were correlated with LAI by plot. With the best indexes correlated with the LAI variable, regression models were constructed using the Stepwise technique (Backward and Forward). The best model was determined based on the adjusted coefficient of determination (R 2 adjusted), standard error of estimate (Syx%), Akaike Information Criterion (AIC), Bayesian Information Criterion (BIC) and Root Mean Squared Error (RMSE). The results showed that there was a significant correlation among the average rates per plot and the LAI per plot. The fitted models developed with the indexes derived from Sentinel-2 had superior performance to the models built with the Landsat-8 data. The best estimate was the LAI per plot with 4.75% of error and adjusted R 2 of 0.9134. There was no significant difference between the LAI obtained from the field campaign and the LAI estimated by the spectral data (Landsat-8/OLI and Sentinel-2/MSI). However, it is recommended to test this methodology using sensors of high spatial resolution and with other species of the genera Pinus and Cupressus
Mimosa scabrella Benth. planted for forest restoration in southern Brazil
No full textTropical trees planting resurgent in a global warming scenario, and this activity relies on information about forest species ecology and its different functional traits. we evaluated the initial performance of Mimosa scabrella using the Generalized Linear Models (GLM) technique to fit mathematical models for collar diameter growth x height, and for crown projection area x collar diameter in a forest restoration planting. The following variables were obtained in the first four years after planting: collar diameter (mm), total height (m), crown projection area (m²) and crown volume (m³). The models fitting was performed by GLM on Gamma, Normal and Poisson distribution, identity and logarithmical join function, and they were analyzed based on Akaike and Bayesian Information Criteria, standard deviation of the estimate and determination coefficient. M. scabrella showed an excelled performance on the 48 months of age, with average increment of 200.28 mm in collar diameter, 6.88 m in total height, 2.95 m² in crown projection area and 83.41 m³ in crown volume. Its growth reduced only on periods of frost occurrence, but it restarted after these climatic events. The species growth, as well as its high survival rates and resprouting, allow its recommendation as a shady species of fast canopy fulfillment in forest restoration projects
Comparison of Forwarder Productivity and Optimal Road Density in Thinning and Clearcutting of Pine Plantation in Southern Brazil
Get PDFThe prescription of forest management determines the number of trees to be cut and, consequently, the harvested wood volume, which directly influences the forest operations dynamic. The objectives of this paper were (i) to analyze the effect of process factors on wood extraction performance with forwarder in first thinning and clearcutting of Pinus taeda L. plantations; and (ii) to economically determine the optimal road density to manage these plantations. Time and motion studies at the cycle element level were conducted to quantify and model the time consumption, productivity, and operational costs of the extraction. The optimal road density (ORD) for both operation types (OT) was determined based on the transport geometry model, considering the minimization of the sum of unitary costs with construction and maintenance of roads, loss of productive area, and wood extraction. The extraction distance (ED), slope (SL), average log volume (LV), and OT had a significant effect on the time consumed in travels, and therefore, on productivity (PPMH). In clearcutting, the average PPMH was 12.17 m3ob PMH0-1, while, in thinning, it was 10.94 m3ob PMH0-1; however, as the ED increased, the difference of PPMH and the cost of extraction between the operations decreased, which highlighted a greater effect of this factor on forwarder’s work in clearcutting. For this reason, the ORD for clearcutting (37.76 m ha-1) was higher than for thinning (27.84 m ha-1). Therefore, we demonstrated in this study that the type of operation and forest management regime, as well as their interaction with process factors, affect the sizing of the number of roads per unit area, and also the costs of the forest activity
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Initial growth perfomance of valuable timber species in Southern Brazil: Araucaria angustifolia, Balfourodendron riedelianum, and Parapiptadenia rigida
No full textThe initial growth of three Brazilian native timber species in the city of Dois Vizinhos-PR, Brazil, was described - Araucaria angustifolia, Balfourodendron riedelianum, and Parapiptadenia rigida, using four non-linear mathematical models (Gompertz, Logistic, Logistic 4P, and Chapman-Richards). In the first 4 years after planting, information about collar diameter (mm), total height (m), crown height (m), and crown diameter (m) was obtained twice a year for 12 individuals per species. Crown area (m²) and crown volume (m³) were estimated. The growth in these four variables (collar diameter, total height, crown area, and crown volume) was projected using the models, and their fitting was assessed based on the values of the Akaike Information Criterion, the Bayesian Information Criterion, the standard error of estimate, and the coefficient of determination. The models generated excellent statistics for all parameters in all variables, with better statistics for collar diameter (coefficient of determination higher than 0.65 and standard error lower than 30%) and total height (coefficients of determination higher than 0.72 and standard error lower than 37%). Considering the three species, Parapiptadenia rigida showed the fastest growth in all variables (median of 70.97 mm for collar diameter, median of 4.475 m for total height, median of 10.35 m² for crown area, and median of 15.30 m³ for crown volume at 48 months). Longer monitoring periods in this and other experiments are recommended to characterize the growth of these three Brazilian native timber species to adequately describe their performance in timber and forest restoration projects
Desempenho de Guazuma ulmifolia Lam. na restauração florestal subtropical
Get PDFWe evaluated the initial development of Guazuma ulmifolia Lam. in a reforestation experiment in the southwestern region of Parana State, Southern Brazil. In a 70 native tree species plantation (3x2 m spacing) data were collected biannually, up to 48 months, from 72 individuals of Guazuma ulmifolia. The species performance was evaluated regarding its survival (96%), root collar diameter (6.79 cm), total height (12.84 m), crown projection area (14.36 m2) and crown volume (49.86 m3). The species growth at the age of 48 months, associated to its high survival and sprouting rates, tells of excellent behavior in the region, and it could be highly recommended as a shading species for fast canopy fulfillment in forest restoration projects, especially in regions with frost occurrence.O objetivo deste estudo foi avaliar o desenvolvimento inicial de Guazuma ulmifolia Lam. em um plantio de restauração ecológica na região sudoeste do estado do Paraná, sul do Brasil. Em um plantio realizado com 70 espécies arbóreas nativas, sob espaçamento 3 x 2 m, coletaram-se dados semestrais, até os 48 meses, de 72 indivíduos da espécie Guazuma ulmifolia. O desempenho das plantas foi avaliado quanto à sobrevivência, diâmetro do colo, altura total, área de projeção de copa e volume de copa. A espécie apresentou excelente performance aos 4 anos de idade: sobrevivência (96%), diâmetro de colo (6,79 cm), altura total (12,84 m), área de projeção de copa (14,36 m2) e volume de copa (49,86 m3). O crescimento da espécie aos 48 meses de idade associada à sua alta taxa de sobrevivência e rebrota, confere excelente performance na região, podendo ser altamente recomendada para utilização como espécie sombreadora para rápido preenchimento de dossel em projetos de restauração florestal, especialmente em regiões com ocorrência de geadas.Conselho Nacional de Desenvolvimento Científico e Tecnológico – CNPq (Process 575081/2008-2).info:eu-repo/semantics/publishedVersio
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