Exploring the Recruitment Dynamics of Sugar Maple and Yellow Birch Saplings into Merchantable Stems Following Harvesting in the Acadian Forest Region of New Brunswick, Canada

The recruitment of saplings in forest stands into merchantable stems is a very complex process, thus making it challenging to understand and predict. The recruitment dynamics in the Acadian Forest Region of New Brunswick are not well known or documented. Our objective was to draw an inference from existing large scale routine forest inventories as to the different dynamics behind the recruitment from the sapling layer into the commercial tree size layer in terms of density and occurrence of sugar maple (Acer saccharum Marsh.) and yellow birch (Betula alleghaniensis Britt.) following harvesting, by looking at many factors on a wide range of spatial and temporal scales using models. Results suggest that the variation in density and probability of occurrence is best explained by the intensity of silvicultural treatment, by the merchantable stem density in each plot, and by the proportion of merchantable basal area of each group of species. The number of recruits of sugar maple and yellow birch stems tend be higher when time since last treatment increases, when mid to low levels of silvicultural treatment intensity were implemented, and within plots having intermediate levels of merchantable stem density. Lastly, our modeling efforts suggest that the probability of occurrence and density of recruitment of both species tend to increase while its share of merchantable basal area increases.

Genetic Variation and the Effect of Herbicide and Fertilization Treatments on Wood Quality Traits in Loblolly Pine

The effect of silvicultural treatments (herbicide, fertilization, herbicide + fertilization) and the interactions with genetic effects were investigated for wood quality traits in a 16-year-old loblolly pine (Pinus taeda L.) genetic test established in southwest Georgia, USA. Fertilizer and herbicide treatment combinations were applied multiple times to main plots containing twenty-five open-pollinated families as sub plots. Significant differences among treatments were found for all traits. Squared acoustic velocity, used as a surrogate for wood stiffness, was higher in herbicide-only plots compared with other treatments. Wood density was considerably lower in fertilization plots. A large proportion of variance observed for wood quality traits was explained by additive genetic effects, with individual-tree heritabilities ranging from 0.78 (ring 7–16 section wood density) to 0.28 (ring 2–6 section wood density). Corresponding family-mean heritability values were well over 0.86. Genotype-by-treatment interactions were nonsignificant for all traits, indicating no need to match families to silvicultural treatments. Wood quality traits had weak genetic correlations with growth and stem quality traits (stem slenderness, sweep, and branch angle) with a range of −0.33 to 0.43, suggesting that recurrent selection on growth or stem quality traits would not adversely affect wood quality in loblolly pine. Study Implications: Silvicultural treatments of herbicide, fertilization, and their combination had significant effects on wood stiffness and wood density in a 16-year-old loblolly pine genetics-by-silviculture trial. When fertilizer was applied, wood density decreased, but the impact on stiffness was minimal. The herbicide treatment increased wood stiffness. As expected, there were large genetic differences for wood quality traits and growth and stem quality traits. Genetics-by-silvicultural treatment interactions were not significant for wood quality traits; family rankings were quite stable across cultural regimes. Families that performed well under one silvicultural treatment performed well under all treatments.

A Literature Review on Cable Extraction Practices of South Korea: 1990–2020

Cable yarding technology remains the most effective operation in steep terrain harvesting systems; however, it has limitations and challenges. Using cable yarders (tractor-, truck-, and excavator-based) to extract tree lengths and whole trees has been common since the late 20th century in South Korea, and cable yarding operations were developed in the late 1800s in the United States and Europe. Machine potential and limitations must be understood to ensure the widespread use of technology, strong cooperation, and optimal selection of machinery size. We reviewed the literature on tower yarder performances from 1990–2021 to determine the alteration of yarders and its productivity pattern and obtained 23 papers; <2 publications per year discussed the determination of cable yarding productivity. We selected independent variables (e.g., silvicultural treatment, harvesting method, and cycle log volume) for cable yarding that would likely affect productivity. Data were analyzed to compare productivities under silvicultural treatment, the harvesting method, and yarding direction and identify the interaction mechanical power (i.e., lifting capacity and machine power), yarding distance, and slope. Cable yarder productivity rates generally depended on the silvicultural treatment, harvesting method, and yarding direction, particularly in clear-cut, tree-length, and uphill yarding operation activities. The lifting capacity, machine power, and slope had no significant correlation with yarders’ productivity, particularly in thinning operations, whereas, in clear-cut productivity, it was influenced by these variables. The results contribute to improving operation activities for cable yarding systems and towards future research directions.

Effect of Thinning on Pericopsis elata (Harms) Meeuwen (Fabaceae) Found in Forest Plantations in the East and South Regions of Cameroon

This paper assesses the response of Pericopsis elata trees to silvicultural operations conducted in abandoned plantations settled between 1972 and 1975 in the East and South regions of Cameroon. Trees quality and DBH were evaluated before and 6 years after 2009 thinning. The silvicultural treatment of thinning improved the quality (physiognomy), the annual diameter increment and the stand basal area of trees. The average percentage of winding trees dropped from 82.8% in 2009 before thinning to 44.1%, six years later after thinning (2015). The most important average diameters were observed in thinned plots (27.3 &plusmn;10.4 cm - 30.5 &plusmn;10.0 cm) compared to non-thinned plots (22.9&plusmn;13.2 cm-23.3&plusmn;10.8 cm). Thinned plots gained at least 6 cm in diameter in 6 years, which is trice compared to the 2 cm observed in the non-thinned plots. The average annual diameter increment was 0.45 cm/year in thinned plots against 0.34 cm/year in non-thinned plots in the same period. Thinned plots have gain at least 6 m&sup2;/ha in the stand basal area against 1 m&sup2;/ha for non-thinned plots.

Functional Diversity Changes after Selective Thinning in a Tropical Mountain Forest in Southern Ecuador

Background: The impact of selective thinning on forest diversity has been extensively studied in temperate and boreal regions. However, in the tropics, knowledge is still poor regarding the impacts of this silvicultural treatment on functional diversity, especially in tropical mountain forests, which are considered to be highly biodiverse ecosystems and also endangered by human activities. By evaluating the changes on functional diversity by using different indicators, hypothesizing that selective thinning significantly affects (directly or indirectly) tropical mountain forests, this work promotes sustainable ecosystem use. Methods: A total of 52 permanent plots of 2500 m2 each were installed in a primary mountain forest in the San Francisco Biological Reserve to assess the impact of this silvicultural treatment. Selective thinning can be defined as a controlled process, in which trees that compete with ecologically and/or valuable timber species are progressively removed to stimulate the development of profitable ones, called potential crop trees (PCT). In doing so, the best specimens remain in the forest stand until their final harvest. After PCT selection, 30 plots were chosen for the intervention, while 22 plots served as control plots. The thinning intensity fluctuated between 4 and 56 trees ha−1 (average 18.8 ± 12.1 stems ha−1). Functional Diversity (FD) indices, including the community weighted mean (CWM), were determined based on six traits using the FD package implemented in R software. The difference between initial and final conditions of functional richness (FRic), functional divergence (FDiv), functional evenness (FEve), functional dispersion (FDis), and Rao quadratic entropy (RaoQ) was modeled using linear mixed models (LMM). As fixed factors, we used all the predictors inherent to structural and ecological forest conditions before and after the selective thinning and as a random variable, we used the membership to nested sampling units. Results: Functional Richness (FRic) showed significant changes after selective thinning, the other indexes (FEve, FDis, FDiv, RaoQ) were only influenced by predictors related to ecological conditions and characteristics of the community.

Soil Disturbance and Recovery after Coppicing a Mediterranean Oak Stand: The Effects of Silviculture and Technology

Traditional coppice management system is one of the most debated topics in the Mediterranean area, as it is a forest management system that accounts for over 23 million hectares. Coppicing is considered the oldest form of sustainable forest management. Its past and current widespread popularity is mainly due to its capacity to positively contribute to the rural economy and ecosystem services. This research aimed at assessing the effect of coppicing on soil characteristics, understanding a possible treatment return time, and evaluating the implementation of proper sustainable forest operations (SFOs) in order to have a better understanding of the disturbance caused by silvicultural treatment and forest operations with two different harvesting techniques. The results demonstrated that physical, chemical, and biological soil features were partially disturbed by the coppicing. Both silvicultural treatment and forest operations influenced soil disturbance. The least impactful technique was extraction by winch, while forwarding resulted in heavier alterations of soil characteristics. It took about five years for the soil to recover its original pre-harvest conditions when the disturbance was caused by the silvicultural treatment alone (non-trafficked areas) and about eight to nine years when the disturbance was the cumulated effect of silvicultural treatment and logging activity (trafficked areas).

Assessment on the growth performance of planted Dryobalanops beccarii at reforestation sites after implementation of selective girdling

Wasli ME, Ambun DB, Kalu M, Sidi M, Nahrawi H, Elias H. 2020. Assessment on the growth performance of planted Dryobalanops beccarii at reforestation sites after implementation of selective girdling. Biodiversitas 21: 1880-1889. This study was conducted to evaluate the growth performance of planted Dryobalanops beccarii Dyer at reforestation sites after silvicultural practices in Gunung Apeng National Park (GANP), Sarawak. The assessed area was planted with D. beccarii in 2005 and undergo silvicultural treatment by understory clearing which implemented annually. Due to the suppressed growth rate of the planted trees, an additional silvicultural treatment, the selective girdling on selected pioneer species, was implemented once, in 2012. In this study, study plots with two treatments were established: T1: understory clearing only (control plot), and T2: additional selective girdling of existing pioneer species in addition to the understory clearing practice applied in T1. The growth performance of the planted D. beccarii in terms of DBH, height, survival and mean annual increments in diameter (MaiD) and height (MaiH) were assessed and monitored at the initial stage when the selective girdling treatment was applied and 4, 24, 36, 48, 60 and 72 months after girdling. Our findings showed that the survival rates of planted trees at 72 months under treatments T1 and T2 were 82.9% and 79.2%, respectively. The average tree DBH in T2 was significantly higher than that in T1, and the average tree DBH values for T1 and T2 were 7.5 cm and 9.4 cm, respectively. The average tree heights for T1 and T2 were 8.3 m and 9.2 m, respectively. In terms of the mean annual increments in height (MaiH) and diameter (MaiD), those in T2 were significantly higher than those in T1. Our findings indicated that T2 started to show better growth performance than T1 after a period of 36 months. In conclusion, the additional silvicultural treatment by selective girdling at the reforestation site had a long-term, progressive effect on the growth performance of the planted trees.