Silvicultural Systems Research Articles

The irregular shelterwood silviculture system and managing for stand complexity from a North American perspective

The irregular shelterwood silviculture system and managing for stand complexity from a North American perspective

Planted seedling regeneration using gap-based silviculture without herbicide in a wildfire-impacted forest of the Sierra Nevada

Abstract Gap-based silviculture, which we define as the creation and maintenance of multi-aged stands through the periodic harvesting of discrete canopy gaps, provides a potential mechanism for converting previously high-graded stands into more heterogeneous, multi-aged structures. An advantage of small canopy gaps, relative to even-aged regeneration methods, is their potential to suppress shrub competition while allowing seedling growth without the use of herbicides or other means of managing shrub competition. While this idea has been proposed in principle, it has not been tested. The objective of this study was to evaluate the use of small canopy gaps, which were 0.08 ha in size with a mean ratio of gap diameter to border tree height of 1.3, as a method to regenerate four mixed-conifer tree species. Gaps were randomly treated either with or without herbicide in a Sierra Nevada mixed-conifer forest. Our hypothesis was that, if this opening size provided sufficient edge effect to control shrub competition, there would be no or little difference in seedling growth between herbicide-treated and control gaps. For all species planted, height and basal diameter growth trends over time were very similar between gaps treated with and without herbicide. The similarity in seedling growth occurred despite a substantial difference in shrub cover between untreated (43%) and treated gaps (3%). We interpret this as evidence that a gap structure such as the one tested can allow a co-occurrence of mediated shrub development and seedling recruitment and that the primary limitation on seedling growth comes from overstory trees, not shrubs. We demonstrate an example of the difference in seedling growth that can be expected between small gaps and clearcuts in order to discuss tradeoffs between these silvicultural systems. Following repeated measurements of seedlings for 7 years following planting, a wildfire burned across the study area, allowing for an additional assessment of wildfire-related seedling damage and mortality in gaps with differing levels of shrub abundance. Substantial mortality of study trees occurred following wildfire (62% mortality 1-year post-fire), but mortality was similar between treated and control gaps. This suggests that shrubs do not have a negative impact with respect to fire related mortality in small canopy gaps despite higher shrub cover. Gap-based silviculture could be a valuable tool for developing multi-aged, multi-species stands without the use of herbicide.

Taxonomic and Functional Diversity Roles of Dung Beetles (Coleoptera: Scarabaeinae) in Native Forests and Silviculture Systems in Subtropical Region of Brazil

ABSTRACTForest system simplification may be a significant driver of dung beetle diversity shifts. This study investigates the taxonomic and functional diversity of necrophagous and coprophagous beetles across native forest areas and eucalyptus plantations within a subtropical region in Brazil. Sampling was conducted at each site type (native forest vs. plantation) using baited pitfall traps (20 traps × 2 bait types × 2 sites = 80 sampling units) set 25 m apart. Coprophagous beetles were attracted using 15 g of human faeces, while necrophagous species were lured with 15 g of fish, both exposed over a 48‐h period. Native forests support higher taxonomic and functional diversity of dung beetles compared to eucalyptus plantation sites, underscoring the importance of structural complexity and habitat heterogeneity for sustaining dung beetle assemblages. Native forests foster greater functional richness and dispersion, indicative of diverse ecological strategies and functional roles. Conversely, eucalyptus plantations favour generalist species with high phenotypic plasticity, selectively filtering smaller organisms like Canthidium trinodosum (Boheman, 1858) due to altered microclimatic conditions. Additionally, eucalyptus sites favour larger‐bodied dung beetles with morphological adaptations that enhance mobility and resource use in compacted soils. These findings underscore the ecological significance of native forests in conserving biodiversity, highlighting the essential role of dung beetles for ecosystem functionality in subtropical landscapes.

Long-term impact of silviculture systems on phosphorus transformation and adsorption behaviour in semi-arid restored lands

Long-term impact of silviculture systems on phosphorus transformation and adsorption behaviour in semi-arid restored lands

Green innovations : Next-gen silvicultural strategies for managing vegetative multiplication gardens

Silvicultural operations involve implementing specific techniques to achieve desired outcomes for a stand. Various techniques can be employed to enhance the growth and quality of timber stands. These methods encompass modifications to the canopy, such as encouraging natural regeneration, as well as practices like boundary marking, planting pattern, irrigation, tending and cultural operations. Casuarina trees are woody, evergreen trees with drooping equisetoid twigs. The leaves have a scale-like connate structure, the branchlets are needle-like cladodes, and the bark has a brown, rough, fibrous texture that exfoliates in longitudinal strips. Stomata are present in cladode structures, which are responsible for the process of photosynthesis. The ability of Melia dubia to thrive in dry conditions is really quite astonishing. Flowers are characterized by the presence of both male and female reproductive components, and they are arranged in clusters at the top of the stem, next to leaves that are smaller. In this study, we will build consistent techniques for fertigation in mother gardens, develop a fertilizer schedule for clonal hedge gardens, and establish a protocol for hydroponics rooted in natural settings. Planning, pruning, thinning, fertilizing, and harvesting are some of the actions that are included in the silviculture methodology. The density, structure, and composition of tree stands are the primary focuses of these treatments at this time. By dispersing forest resources in a spatial and temporal manner, a silvicultural system makes it possible to make accessible a wide range of forest resources. Green innovations in silviculture are designed to reduce the environmental impacts of forest management by adopting sustainable, eco-friendly practices that support both biodiversity and ecosystem health. Here’s how they contribute to minimizing pesticide use and promoting biodiversity. The paper concludes with a brief overview of the main challenges likely to be faced with this integration and some strategies that may allow them to overcome these challenges. It is hoped this paper will provide a background for future case studies, and a catalyst for increasing integration between the several silvicultural strategies.

Insights in Managing Ungulates Population and Forest Sustainability in Romania

Improved forage and living conditions in certain parts of Europe over the past few decades have led to alarming levels of ungulate densities. Consequently, the overabundance of red deer, roe deer, and fallow deer in the Western Plains of Romania has begun to generate issues in the development of young oak stands. In addition to causing damage to the agricultural sector and increasing the risk of vehicle collisions, ungulates are increasing pressure on the forestry sector, mainly through the browsing of young saplings. This study quantifies the levels of ungulate browsing in oak stands using a permanent sample grid of 42 plots in both natural and artificial regeneration areas. A total of 3223 individual saplings were measured, revealing browsing intensities of 49.65% in clearcut systems and 12.8% in continuous forest cover systems. With high ungulate densities identified as the main cause, the Sustainable Population Threshold was calculated using a complex set of indices and compared to the actual numbers of ungulates, both of which were translated into stock unit equivalents. A logistic regression model was developed based on silvicultural and wildlife indices to identify other factors influencing browsing occurrence. The findings indicate that the proportion of forested areas in the hunting ground and the type of silvicultural system are significant factors in the occurrence of browsing. The problem of ungulate overabundance clearly influences forest development, and new solutions should be identified in terms of both forestry and wildlife management.

Tradeoffs in growth and fuel reduction when using prescribed fire in young mixed conifer stands

BackgroundFollowing high-severity wildfires in conifer forests that rely on wind dispersal for regeneration, reforestation practices are used to hasten the development of large, fire-resistant trees that are better able to persist through the next fire. Planted forests, however, are particularly prone to high-severity wildfire effects for the initial decades following their establishment. This vulnerability suggests the need for surface fuel reduction treatments in the early stages of stand development. Such treatments would be aligned with the disturbance regime of frequent-fire forests and could also hasten the development of multi-aged structures dominated by fire-resistant trees. Conventional treatments early in stand development include shrub competition reduction and precommercial thinning, but prescribed fire is typically avoided. To assess the potential for inclusion of prescribed fire in young stand management, we investigated how four different treatments—mastication, mastication plus herbicide, two prescribed burns, and mastication plus two burns—affected individual and stand-level growth versus fuel loads in young mixed-conifer plantations in the north-central Sierra Nevada, CA, USA.ResultsTotal surface fuel load more than doubled over 5 years in the mastication only and mastication plus herbicide treatments. Fuel accumulation was avoided in the two treatments that included prescribed fire. Stand growth was similar across the mastication only, mastication plus herbicide, and mastication plus burn treatments. Stand growth was lowest in the burn only treatment. The mastication plus herbicide treatment maximized individual tree growth, especially for white fir and incense-cedar. Individual tree growth was similar among the burn only, mastication only, and mastication plus burn treatments.ConclusionsMastication followed by repeated prescribed burning could be a viable management strategy to reduce wildfire hazard without sacrificing growth in young mixed-conifer stands that are entering a vulnerable stage of fire risk. Mastication in combination with herbicide may facilitate the growth of large, fire-resistant trees, but does not address surface fuel buildup. The use of fire alone can effectively reduce fuels, but stand growth may be somewhat low relative to mastication and herbicide. Incorporating prescribed fire is a promising approach for protecting planted stands from high-severity fire while transitioning them into multi-aged structures. Gap-based silvicultural systems that facilitate the development of multi-cohort stands can also use prescribed fire broadly in order to restore heterogeneity and low surface fuel loads.

Economic assessment of transformation to continuous cover forest management in Estonia

The discussion surrounding forest management principles, particularly those related to rotation and continuous cover forestry (CCF), has gained considerable momentum in Estonia in recent years. Advocacy for the adoption of selection cuttings over clear-cutting has been prominent. Despite the longstanding practice of continuous cover forest management in Estonia, there is a noticeable absence of economic analyses on this subject. This study aims to investigate pertinent criteria and methodologies for the economic assessment of alternative silvicultural systems. Additionally, we deliberate on the factors influencing the transition from even-aged to uneven-aged forest management. The profitability of uneven-aged stand management was compared with even-aged forest management using an experimental stand that underwent recent selection cutting. To compute cash flows, stand inventory and removal data, categorised by timber assortments, were utilised to delineate changes in growing stock, timber prices and forest management costs. Net present value (NPV) was employed to assess rotation and continuous cover forest management scenarios. The calculation results indicate that, in the long term, the NPV of CCF management is relatively similar to even-aged stand management at a 1% interest rate but lower when higher interest rates are applied. Prevailing requirements currently limit the economic attractiveness of transformation from even-aged to uneven-aged stand management. Revising forest management rules is imperative to enhance the profitability of uneven-aged forest management in Estonia. Adjustments to the stand age should be made, enabling selection felling and reducing the required minimum post-cutting basal area. Keywords: continuous cover forestry; silvicultural systems; selection cutting; economics

The Interactive Role of Climatic Transfer Distance and Overstory Retention on Douglas-Fir Seedling Survival and Height Growth in Interior British Columbia.

The future climatic niche of interior Douglas-fir (Pseudotsuga menziesii var. glauca [Mirb.] Franco) is expected to have little spatial overlap with its current range due to climate change. The resulting misalignment of the climatic niche and species distribution is expected to result in many forests becoming maladapted in their current location, thus increasing vulnerability to disturbance and reducing productivity. This novel study examined the individual and interactive effects of climatic transfer distance and silviculture systems on planted 3-year-old Douglas-fir seedlings across the natural range of interior Douglas-fir in British Columbia. Several climatic transfer distance variables were considered, and the silviculture systems tested comprised the following gradients of tree retention: 0% retention (clearcut), 10% dispersed retention (seed-tree), 30% aggregate retention, and 60% aggregate retention with thinning from below. Using linear mixed effect models, we found that survival and height were positively correlated with movements of seedlings to warmer, wetter, and more humid climates. Moisture availability had a stronger influence than temperature, indicating that seedlings transferred to warmer but more arid climates would experience decreased survival and height. Where seedlings were transferred to climates with greater frost frequency or decreased humidity, greater retention of overstory trees improved survival and height. Conversely, movements to more favorable climatic conditions (warmer and wetter) resulted in improved survival and height where overstory retention was low. Our findings suggest that genetic reshuffling of populations through assisted migration could benefit from overstory retention where stressful climatic conditions due to aridity or increased frost frequency occur.

Potential for developing Porang (Amorphopallus oncophyllus Prain) in logged over area forest TPTI system as a buffer area for IKN East Kalimantan Province

Abstract The tropical rainforest landscape in East Kalimantan province has proven to be a pivotal driver of the regional and national economy. Spanning 6,055,793 hectares of production forest, a majority of which is under the management of 106 active forest utilization permit holders (PBPH), the region employs the Indonesian Planting Select Logging (TPTI) silviculture system to manage and enhance the value of logged over forest areas. This experiment aims to determine the growth rate of Porang plants in logged over areas forest under the TPTI system using a complete randomized design with six replicates and three treatment levels: without organic fertilizer/control (P0), application of 1000g/plant manure (P1), and biochar + 1000g/plant manure (P2). The data obtained were then subjected to ANOVA test. The test results revealed that the application of biochar + manure 1000g/plant (P2) significantly influenced average growth rate the plant height of 11.34 cm/month, Leave number of 6.17 sheet/month, and fresh tuber yield of 58.7 g. Whereas the control treatment only gave average results plant height of 9.09 cm/month, Leave number of 4.83 sheet/month, and fresh tuber yield of 22.2 g. These findings underscore the potential of Porang as a viable interstitial crop within production forest lands, emphasizing the feasibility of integrating it into agroforestry systems.

Silvicultural Systems and Their Practices in Terai Forests of Nepal: A Review

It is more than eight decades that Nepalese foresters initiated appropriate silvicultural systems to obtain goods and services from forest, in perpetuity. Several forest management plans were prepared in the past. Unfortunately, these forest management plans were not implemented until 2012 AD. Government of Nepal had introduced a silviculture-based forest management procedure, known as Scientific Forest Management (SciFM) in 2014. One of the objectives of this procedure was to provide management guidelines for Community Forests (CFs) and government managed forests. It has been more than a decade that SciFM was implemented in Terai forests (CF and government managed forests) but how far the procedure supported in achieving its goal is not well documented. This paper examined the forest management system that was implemented in Terai districts of Nepal, irrespective of its management regime. For the study, field visits were carried out in five Terai districts (Morang, Kapilvastu, Dang, Kailali and Kanchanpur) during March and October 2021 to examine the procedure followed in managing the forests and observe the outcomes aimed by the procedure. Both published and unpublished literature on silviculture, silvicultural systems, and forest management, especially devoted to Nepalese context were reviewed. Operational Forest Management Plans (OFMPs) developed by government entities and Community Forests User Groups implemented “irregular shelter-wood system” of forest management in their respective forests, retaining some mother trees for shelter and obtaining quality seeds, based on 80 years of rotation period for Sal (Shorea robusta) although the basis of fixing the rotation is not very clear. The review indicates that, in most sites of Terai parts of Nepal, it may not be necessary to retain mother trees, for ensuring Sal regeneration. There is some possibility of estimating Sal rotation due to appearance of hollowness in the trees, which may help decide the harvestable age of Sal trees in future.

Influence of irregular shelterwood treatments on intensity and severity after a large wildfire in lodgepole pine stands: A case study from the interior British Columbia.

Climate change has significantly impacted the wildfire regimes in lodgepole pine forests, resulting in prolonged fire seasons and altered fire behaviour. In North America, fire patterns have shifted towards more frequent and severe wildfires after a century of fire suppression. In response, silviculture practices in fire-prone areas should aim to restore diverse forest structures that are resistant or resilient to wildfires. In Western Canada, where forestry is a key industry, interest in seeking silvicultural solutions for promoting forest resilience to wildfires has increased following the devastating wildfire seasons between 2017 and 2023. Irregular shelterwood, a silvicultural system with a relatively short history of implementation in British Columbia, has been deployed in ecologically sensitive areas to promote structural heterogeneity and meet management goals for biodiversity and wildlife values. Although the impacts of irregular shelterwood on wildlife habitat and abundance have been well studied, the interaction between wildfire and the stand structure created by irregular shelterwood remains poorly understood. To understand the effectiveness of the irregular shelterwood in building wildfire resilience, we present a study of a lodgepole pine stand that was treated with irregular shelterwood and partially burned in a wildfire in 2017. This study collected ground fuel, canopy fuel, and tree data from four stand types (irregular shelterwood treated-burnt, treated-unburnt, untreated-burnt, and untreated-unburnt) and analyzed the difference in char height and fire-induced mortality between burnt and unburnt conditions, with irregular shelterwood treatment being a variable. The results demonstrated reduced wildfire effect in the irregular shelterwood stand in this region of British Columbia. This observation was made at a stage where the openings have not been colonized by regeneration. This case study provides valuable insights into the effectiveness of irregular shelterwood in mitigating wildfire risk, and proposes a potential silviculture solution to promote forest resilience to wildfire.

Silvicultural systems and estimated profitability of Nothofagus dombeyi plantations: an option for forestry diversification in Chile

Silvicultural systems and estimated profitability of Nothofagus dombeyi plantations: an option for forestry diversification in Chile

A case study on the impact of coppicing on small mammal diversity: First evidence from the high Agri Valley in the Basilicata Region, Italy

A case study on the impact of coppicing on small mammal diversity: First evidence from the high Agri Valley in the Basilicata Region, Italy

Effect of the irregular shelterwood system on soil organic carbon stock and soil quality of Shorea robusta Gaertn. f. forest in Nepal

The effective management of forests relies on the crucial role played bysilvicultural systems. However there exist a significant knowledge gap regarding impact of these systems in Nepalese forests. Therefore, this research was conducted to assess the effects of the forest management activities under irregular shelterwood system on soil organic carbon (SOC) stock and the overall soil quality of Sal (Shorea robusta Gaertn. f.) forests in Terai region of Nepal. Stratified random sampling method with 1.67 % sampling intensity was adopted in this study where management of stands was used as basis of strata. A total of 30 composite soil samples (15 each from managed and unmanaged forest stands) were collected from a depth of 0–30 cm, taken from the four corners and the center of each plot. Soil quality index (SQI) method was used for soil quality assessment using indicators on the basis of prior studies conducted in Nepal. Our study found significant difference in soil parameters except organic carbon, pH, silt, and clay among the managed and unmanaged forest stands (p < 0.05). SOC stock of unmanaged forest stands (48.87 ± 1.34 ton ha−1) was significantly greater than managed forest stands (27.76 ± 1.27 ton ha−1). Similarly, unmanaged forest stands demonstrated better soil quality with higher SQI value (0.66) than managed forest stands (0.50). This negative impact of irregular shelterwood silviculture system highlights the necessity for management interventions to enhance SOC stock and overall soil quality. To establish a robust conclusion, further replication of similar studies at different soil depths and in other management regimes, along with longitudinal studies, is essential.

The Expanding Thread of Ungulate Browsing—A Review of Forest Ecosystem Effects and Management Approaches in Europe

In recent decades, ungulates have expanded in number and range in Europe. This review aims to analyze the impact of ungulate browsing in different forest ecosystems and identify the main driving factors and trends. In total, 155 studies were analyzed in preparing this review, across 19 European countries. In Europe, the main browsers are represented by roe deer (Capreolus capreolus L.), red deer (Cervus elaphus L.), moose (Alces alces L.), chamois (Rupicapra rupicapra L.), and fallow deer (Dama dama L.). Regarding browsing severity, they frequently exceeded 50%, meaning that over half of the saplings were browsed. Ungulate density was the main driving factor of browsing severity, with areas exhibiting high browsing pressure often having more than ten individuals per square kilometer. The type of silvicultural system used played a vital role in the severity of browsing, and trends in foraging for preferred tree species were identified. Fencing was the most common non-harmful protection method used, while hunting management was the most efficient method for controlling deer numbers and browsing intensity. Large carnivores were missing in most study areas, but in the areas where they were present, they played a significant role in creating a chain reaction of ecological impacts. Considering the significant impact of ungulate browsing on forest ecosystems, there is a pressing need for more research to comprehend and effectively mitigate the effects of deer presence comprehensively.

Historický vývoj výberkového spôsobu hospodárenia v Európe: review

Presented literature review summarizes the knowledge about the issue of historical development of selection silvicultural system in Europe. It describes the selection system as a way to manage the forests that was connected until the first half of the 19th century mainly with not regulated tree harvesting and the overexploitation of forests. Only in some mountain regions with higher proportion of fir, the selection systém was appplied in a sustainable way with the single tree selection. Especially the forests in these regions became in following period the model for the foundation of selection silvicultural system on scientific basis. The largest expansion of selection system was recorded in the first half of the 20th century. After World War II, the interest in this silvicultural system gradually started to decrease, except the traditional regions of its origin. Currently we can observe the increasing popularity of selection forests that in the changing environmental conditions are assumed to be ecologically and economically more stable alternative to even-aged monoculture stands.

Enhancing productivity and sustainability of ravine lands through horti-silviculture and soil moisture conservation: A pathway to land degradation neutrality

Enhancing productivity and sustainability of ravine lands through horti-silviculture and soil moisture conservation: A pathway to land degradation neutrality

Modelling Diameter at Breast Height Distribution for Eight Commercial Species in Natural-Origin Mixed Forests of Ontario, Canada

Diameter at breast height (DBH) is a unique attribute used to characterize forest growth and development for forest management planning and to understand forest ecology. Forest managers require an array of DBHs of forest stands, which can be reconstructed using selected probability distribution functions (PDFs). However, there is a lack of practices that fit PDFs of sub-dominating species grown in natural mixed forests. This study aimed to fit PDFs and develop predictive models for PDF parameters, so that the predicted distribution would represent dynamic forest structures and compositions in mixed forest stands. We fitted three of the simplest forms of PDFs, log-normal, gamma, and Weibull, for the DBH of eight tree species, namely balsam fir (Abies balsamea [L.] Mill.), eastern white pine (Pinus strobus L.), paper birch (Betula papyrifera Marshall), red maple (Acer rubrum L.), red pine (Pinus resinosa Aiton), sugar maple (Acer saccharum Marshall), trembling aspen (Populus tremuloides Michx), and white spruce (Picea glauca [Moench] Voss), all grown in natural-origin mixed forests in Ontario province, Canada. We estimated the parameters of the PDFs as a function of DBH mean and standard deviation for these species. Our results showed that log-normal fit the best among the three PDFs. We demonstrated that the predictive model could estimate the recovered parameters unbiasedly for all species, which can be used to reconstruct the DBH distributions of these tree species. In addition to prediction, the cross-validated R2 for the DBH mean ranged between 0.76 for red maple and 0.92 for red pine. However, the R2 for the regression of the standard deviation ranged between 0.00 for red pine and 0.69 for sugar maple, although it produced unbiased predictions and a small mean absolute bias. As these mean and standard deviations are regressed with dynamic covariates (such as stem density and stand basal area), in addition to climate and static geographic variables, the predicted DBH distribution can reflect change over time in response to management or any type of disturbance in the regime of the given geography. The predictive model-based DBH distributions can be applied to the design of appropriate silviculture systems for forest management planning.

Age and growth reductions increase the proportion of dark heartwood in sugar maple at the northern limit of its range

Abstract The wood of sugar maple (Acer saccharum Marsh.) in the northernmost part of the species range often exhibits high proportions of discoloured wood at the centre of the stems, which is referred to as dark heartwood. This defect significantly decreases the wood market value of the species, which, in turn, challenges the implementation of state-of-the art silvicultural treatments. The causes of dark heartwood are associated with trauma and the colder climate of the northern regions. In this study, we investigate factors influencing the occurrence of dark heartwood in sugar maple’s northern populations, considering tree age, vigour, stem growth, and local climate. We also aimed to determine whether the proportion of dark heartwood is higher in northern stands compared to more southern ones. We collected samples from 302 sugar maple stems at 16 sites within two bioclimatic domains of Quebec, Canada, i.e. the balsam fir–yellow birch domain (representing the northern limit of the sugar maple range) and the sugar maple–yellow birch domain (representing a more southern location within the range). Our results indicate a positive relationship between dark heartwood proportions and stem age, as well as with the amplitude of the maximum growth reduction throughout the tree’s lifespan and the length of the longest suppression period. We also observed significantly higher dark heartwood proportion for a given tree age in northern stands. The results suggest that silvicultural systems aiming to release suppressed crop trees through group selection using a cut-to-length system could favour the development of high quality timber.