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Brazil has a vast reserve of natural forests that belong to the state; hence, the state is responsible for supplying native wood to the market. However, the management in public forests has only begun recently; thus, much research is needed to know about its profitability. This study analyzed the financial feasibility of public forest management by addressing the following aspects: state concession, federal concession, and community forest management. We used the Net Present Value, Annual Equivalent Value, and Average Cost of Production methods to assess financial feasibility and applied the Monte Carlo simulation to estimate the probability of occurrence of NPV values. Community forest management showed profitability and a low occurrence of positive NPV values. The initial subsidies and the absence of royalty payments contributed to their good financial performance. The state and federal forest concessions showed financial unfeasibility and a low probability of profitability, which were justified by a low harvested volume of forest management, a high number of hollow individuals with small dimensions, poor volume estimates, and a high occurrence of species with low commercial values. Financial viability is a critical aspect of public forest management, and the achievement of good results depends on the consideration of several factors and aspects of public forests. Characteristics such as species composition, the distance between the managed areas, and the place of consumption must be considered. Areas that are not financially viable in the current period can be considered for future management and maintenance. [ABSTRACT FROM AUTHOR]

The net primary production of tropical forests and its partitioning between long-lived carbon pools (wood) and shorter-lived pools (leaves, fine roots) are of considerable importance in the global carbon cycle. However, these terms have only been studied at a handful of field sites, and with no consistent calculation methodology. Here we calculate above-ground coarse wood carbon productivity for 104 forest plots in lowland New World humid tropical forests, using a consistent calculation methodology that incorporates corrections for spatial variations in tree-size distributions and wood density, and for census interval length. Mean wood density is found to be lower in more productive forests. We estimate that above-ground coarse wood productivity varies by more than a factor of three (between 1.5 and 5.5 Mg C ha-1a-1) across the Neotropical plots, with a mean value of 3.1 Mg C ha-a-1. There appear to be no obvious relationships between wood productivity and rainfall, dry season length or sunshine, but there is some hint of increased productivity at lower temperatures. There is, however, also strong evidence for a positive relationship between wood productivity and soil fertility. Fertile soils tend to become more common towards the Andes and at slightly higher than average elevations, so the apparent temperature/productivity relationship is probably not a direct one. Coarse wood productivity accounts for only a fraction of overall tropical forest net primary productivity, but the available data indicate that it is approximately proportional to total above-ground productivity. We speculate that the large variation in wood productivity is unlikely to directly imply an equivalent variation in gross primary production. Instead a shifting balance in carbon allocation between respiration, wood carbon and fine root production seems the more likely explanation. © 2004 Blackwell Publishing Ltd.

We conducted a study on the dominant height growth of clonal teak (Tectona grandis Linn F.) plantations in the Brazilian Amazon to assess their potential and its agreement with volumetric production. We employed two approaches, ADA (algebraic difference) and GADA (generalized algebraic difference), and analyzed data from 58 permanent plots collected over a 10 year period. To classify the sites, we developed equations and evaluated their accuracy using various criteria, including correlation coefficient, mean square of residual, Akaike's criterion, distribution of residuals, and validation through equivalence testing (TOST). We also assessed the biological realism of the constructed curves. We used cluster evaluation and dendrogram comparison to assess the agreement between site index and volumetric production for each approach. The Lundqvist–Korf baseline models (M1–ADA and M4–GADA) proved to be accurate and realistic in estimating dominant height in both approaches. Our findings indicate that the approaches utilizing dynamic equations and generating polymorphic curves effectively represent the sites and indicate the volumetric production of the plantations, with 98.3% of agreement rate. Based on our results, we recommend the use of ADA and GADA approaches for estimating the dominant height of clonal teak plantations in the Eastern Brazilian Amazon. [ABSTRACT FROM AUTHOR]

Determining equations to estimate with precision the volume of commercial trees is relevant for decision taking on the use of the forest and on the establishment of public policies for the monitoring and control of natural resources, their valorization and investments. Current paper develops volume equations for the Dense Ombrophilous Forest in Ipixuna, northeastern region of the state of Pará, Brazil. The real volume of 296 sample trees was determined according to the Smalian method. Forty-six trees were selected for a database for the validation of the equations. Twelve mathematic models were tested, of which six had simple entrance and six had a double entrance. Simple entrance models proved to have the best adjustment quality for the Hohenald & Krenn model, with equation v = 5.29918-0.1374d+0.00010d² (R²aj. = 0.84, Sy.x% = 19.81; DMP% = -3.63). In the case of double entrance, the best was Schumacher & Hall model, with equation Logv = -3.7657+1.9242.logd+0.7540.logh, (R²aj. = 0.96, Sy.xr% = 10.46, DMP% = -0.34). After validation of selected equations, the Schumacher & Hall was recommended to estimate the volume of commercial trees in the municipality of Ipixuna due to high precision adjustment. [ABSTRACT FROM AUTHOR]

Sustainable production of timber from commercial species across felling cycles is a core challenge for tropical silviculture. In this study, we analysed how the intensity and type (harvesting and thinning) of silvicultural interventions affect: (a) recruitment of small stems (5 cm ⩽ DBH < 15 cm), (b) increment of future crop trees (15 cm ⩽ DBH < 50 cm) and (c) recovery of harvestable growing stocks (DBH ⩾ 50 cm) of 52 commercial timber species in the Tapajós National Forest, Brazil. Intervention intensities comprised logging (on average 61 m 3 ha −1 ) and associated damage to remaining trees (1982) and thinning (refinement) to reduce basal area at the stand level (1993/1994). These interventions together resulted in a gradient of reduction in basal-area from 19 to 53% relative to pre-logging stocks. Trees (DBH ⩾ 5 cm) were measured on eight occasions in 41 permanent sample plots of 0.25 ha each. The dynamics were analysed at the stand level over 30 years and compared among treatments (including unlogged forest) and to pre-logging stands. Recruitment and growth temporarily increased following interventions and recovery of harvestable growing stock decreased with intervention intensity. Harvesting substantially increased recruitment of small stems relative to the unlogged forest, but recruitment rates decreased over time and did not increase following thinning. Gross increment of future crop trees was higher in logged than in unlogged forest and increased over time with high intensity of follow-up thinning, where it remained significantly higher than in control plots over time. Increased recruitment rates and volume increments were mainly driven by long-lived pioneer species, changing the composition of the growing stock. In 2012, recovery of harvestable growing stock of the 22 species harvested in 1982 varied between 19% and 57% in logged treatments relative to pre-logging levels. When considering an additional group of 30 species that were not harvested in the permanent sample plots but are now potentially commercial, relative recovery increased enough to support a second harvest under the present regulations (maximum harvest of 30 m 3 ha −1 ), except for treatment with high thinning intensity where stocks were still less than 30% relative to pre-harvest levels. In contrast, light and medium thinning intensity promoted recovery of harvestable growing stock. These findings indicate that intensive thinning should be avoided and silvicultural interventions oriented towards future crop trees of target species should be adopted. This may enhance recovery and reduce unintended changes in composition of the commercial growing stock. [ABSTRACT FROM AUTHOR]

Managed forests are important landscape components in tropical regions and may contribute to biodiversity conservation. Yet, managing tropical forests sustainably requires an understanding of ecosystem responses to silvicultural interventions. We investigated how silvicultural intervention intensity affects tree species composition and diversity over 30 years in the Brazilian Amazon by comparing them to pre-logging conditions and to an unlogged control. The interventions comprised logging in 1982 and thinning in 1993–1994 and ranged in intensity from 19 to 53% reduction in the original basal area (BA). Trees with a diameter at breast height (DBH) ≥ 5 cm were measured on eight occasions in 41 permanent sample plots of 0.25 ha each. Silvicultural intervention intensity influenced both tree species composition and its trajectory within 30 years. In contrast, tree species diversity was not impaired. High intervention intensities (with BA reduction > 6.6 m 2 ha − 1 ) had a substantial influence on the community of trees (DBH ≥ 10 cm), which did not show signs of return to pre-logging species composition. The reduction of BA through harvesting damage and thinning had a stronger effect on species composition than logging of mature trees itself. Thus, damage should be kept to a minimal level and strong thinning interventions should be avoided. This may enhance ecosystem recovery and maintenance of biodiversity at other trophic levels. Since current permitted harvesting intensities in the Brazilian Amazon are lower than the lowest intensity examined in our study, legal harvesting practices are unlikely to cause substantial, long-term changes in tree species composition. [ABSTRACT FROM AUTHOR]