Advances in Forestry Science

Yield and economic feasibility of Eucalyptus dunnii stands under different management regimes

Tue, 02 Jul 2024 00:00:00 +0000

The aim of this study was to analyze volume yield, number of logs per assortment and economic feasibility of Eucalyptus dunnii stands under different management regimes. The stands are located in Fernandes Pinheiro, Paraná State, Brazil and cover a total area of 2.26 hectares, fragmented into three strata (treatments): A (8 years after coppicing regime), B (9-year old stand after two thinnings), and C (7-year old stand after one thinning). Diameters at breast height (d) of all trees and heights of 110 trees were obtained. The total height of the other trees was estimated by a hypsometric relationship. Tree volume was obtained through a taper function. For the economic analysis comparing the three strata, the periodic equivalent value (PEV) and the internal return rate (IRR) were evaluated considering an interest rate of 8%. The commercial volumetric estimates ranged from 156.61 to 375.53 m³ ha⁻¹. The stratum A yielded more logs, mostly for energy; stratum B yielded larger logs, and stratum C yielded similar number and volume of logs from all assortment classes. For economic analysis, PEV ranged from R$ 196.16 to R$ 1,255.79 ha year⁻¹, and IRR ranged from 12.73% per year (stratum A) to 21.35% per year (stratum C), based on a interest rate of 8%. It was concluded that the management condition of stratum C resulted in higher economic returns, with its product primarily destined for Sawmill 1.

Comparative Study of Water Quality Across Different Seasons in the Gregório River Watershed, São Paulo, Brazil

Danielly de Oliveira Fornaziero, João Ânderson Fulan, Jhony Vendruscolo — Tue, 02 Jul 2024 00:00:00 +0000

The goal of this study was to monitor the water quality in the Gregório river, São Carlos, São Paulo during the dry and rainy seasons using traditional methods such as physical and chemical analysis of the water and biological indicators. Six sampling points were monitored, ranging from the nearest location to the source of the river to its confluence with the Monjolinho river. Physical and chemical parameters of water (water surface temperature, dissolved oxygen, pH, and conductivity) were measured using a multiparameter probe. The distance between the points was determined according to the access to the site: from P1 to P2 (1328 m), from P2 to P3 (1278 m), from P3 to P4 (201 m), from P4 to P5 (820 m), and finally from P5 to P6 (1814 m). The biotic index used in conjunction with the environmental variables was the Biological Monitoring Working Party (BMWP), a qualitative index that utilizes benthic macroinvertebrates to classify water quality. Ceratopogonidae, Chironomidae, Chironomus, Enchytraeidae, Hirudinea, and Naididae were recorded at sites P1, P2, and P6 during both the dry and rainy seasons. This study, particularly at P6, it was observed that despite the higher concentration of dissolved oxygen compared to the other analyzed sites, which would indicate good water quality, the BMWP indicated that the location had a strongly polluted water quality, suggesting that environmental factors must be associated with biological indicators. It was concluded that the use of biological indicators along with environmental data provided a more reliable understanding of water quality.

Estimating the annual diametric increment in a natural Rainforest in south Brazil

Tue, 02 Jul 2024 00:00:00 +0000

Diametric increment is a complex variable to be estimated in natural forests, especially given species composition and slow tree growth. In these situations, some studies have turned their attention to the use of individual tree growth models combined with strategies for grouping trees or species. This work aimed to estimate the diametric increment of trees in a natural remnant of a natural Rainforest in south Brazil, aiming to investigate methodologies for forming groups of individuals that favor the estimation of individual diametric increment. The groups were formed based on a two-stage methodology, based on relative diameter, diametric increment, and competition indexes. The diametric increment was estimated based on a ratio estimator used to reconcile the grouping strategy. The grouping method satisfactorily classified the individuals, in which the competition indexes were relevant for this classification. The estimation error of the diametric increment was 0.0599 cm.year-1 for the training data and 0.0765 cm.year-1 for the validation data. The estimate of the future diameter had an average error of 4.52%. The combination of a two-stage stratification and ratio estimator was satisfactory for accurately estimating the diameter increments of all tree species.