Silvicultural Measures Research Articles

TreeCompR: Tree competition indices for inventory data and 3D point clouds

Abstract In times of more frequent global change‐type droughts and associated tree mortality events, competition release is one silvicultural measure discussed to have an impact on the resilience of managed forest stands. Understanding how trees compete with each other is therefore crucial, but different measurement options and competition indices (CI) leave users with a difficult choice, as no single competition index has proven universally superior. To help users with the choice and computation of appropriate indices, we present the open‐source TreeCompR package, which handles 3D point clouds and classical forest inventory data, enabling the calculation of both innovative point cloud‐based indices and traditional distance‐dependent indices. It serves as a centralized platform for exploring and comparing different CIs, allowing users to test and select the most suitable CI for their specific research questions within a common interface. To evaluate the package, we used TreeCompR to quantify the competition situation of 307 European beech trees from 13 sites in Central Europe. Based on this dataset, we discuss the interpretation, comparability and sensitivity of the different indices to their parameterization and identify possible sources of uncertainty and ways to minimize them. The compatibility of TreeCompR with different data formats and different data collection methods makes it accessible and useful for a wide range of users, specifically ecologists and foresters. Due to the flexibility in the choice of input formats as well as the emphasis on tidy, well‐structured output, our package can easily be integrated into existing data‐analysis workflows both for 3D point cloud and classical forest inventory data.

Forestal management based on acoustical values

Around and on military training areas there are usually a large number of forest stands. These primarily fulfil the special requirements of military use due to their special structure and tar-geted development. In particular, the dust, visual and noise protection functions of the forests protect the civilian environment from the undesirable effects of military training operations. The aim of forestal management measures in the forest stands is to provide and ensure these functions by selecting suitable tree species and optimising stand structures. A forest attenua-tion model has been developed in recent years, in which the acoustic attenuation of a forest stand can be deduced from forestal parameters. Furthermore, a method has been developed to predict the overall acoustic attenuation of several consecutive stands. For the planning and assessment of silvicultural measures in military functional forests with regard to their effects on noise attenuation, however, further definitions are necessary in order to be able to draw simple, comprehensible conclusions from the wealth of possible variations. The presentation introduces the models as well as the other necessary definitions and shows their application using an example.

A potential cause for extensive dieback of Acacia mearnsii plantation in highland districts of Awi zone, northwestern Ethiopia

Although Acacia mearnsii De Wild has rapidly expanded for economic and ecological purposes in the highland districts of the Awi zone, northwestern Ethiopia, recent plantations have suffered from severe defoliation, dieback, and stunted growth. We conducted this study in four districts that hold potential for A. mearnsii plantations. The study examined the identification of the causal agent, its occurrence, and local community perceptions of the plantation's significant dieback. Most respondents (75.8 %) indicated that the substantial dieback began in the rainy season of 2020 and spread rapidly. They also noted that close spacing of plantings and limited silvicultural measures exacerbated the damage. We discovered in this study that the wattle rust disease caused by the Uromycladium acacia fungus was the root cause of significant dieback for A. mearnsii plantations. The incidence and severity of this wattle rust varied significantly (p = 0.001) between districts, seasons, and plantation age groups. In Fegita-Lekuma district, the maximum disease severity was over 72 % in plantations up to two years after planting during the rainy season. The progression of the wattle rust disease caused by U. acacia has led to the loss of A. mearnsii plantations in the Awi zone, resulting in a severe economic and environmental crisis. Consequently, we should apply fungicides to seedlings at nursery sites in the short term. Eventually, however, the focus should shift towards prioritizing disease-resistant species and implementing proper forest management practices. This should be achieved through scientific initiatives that engage key stakeholders in areas where this tree species could potentially grow.

Direct and mediated impacts of mixed forests on Norway spruce infestation by European bark beetle Ips typographus

Climate change-induced windfalls and droughts exacerbate bark beetle outbreaks, severely impacting forest ecosystems. Despite extensive research on bark beetle infestation patterns, the question regarding the optimal spatial grid (SG) size for analyzing this phenomenon remains unresolved. The protective potential of natural forest complexity against bark beetles has been underestimated. We used remotely sensed data to fit Generalized Linear Models and structural equation models to explore the direct and environment-mediated effects of mixed forest cover (MFC) on Norway spruce forest infestation in central Europe. We assessed the effectiveness of various spatial grids (from 100 m to 1 km) for studying infestation by Ips typographus. We found a strong non-linear decline in infestation with increasing MFC across different spatial scales. The relationship between infestation and temperature was positive, while elevation had a negative effect on infestation, with higher infestation rates observed below 900 m. Direct effects of environmental predictors on infestation were significant at SGs of 100 m, 300 m, 400 m, and 500 m, but insignificant at 200 m and 1000 m SGs. Slope positively influenced infestation at 300 m and 400 m SGs. MFC exhibited significant indirect effects on infestation mediated by elevation, temperature, potential evapotranspiration, slope, and heat load index. Landscape variables played a significant role in the models at high-resolution spatial grids, whereas climate variables were influential in models at lower spatial grids of infestation data. We argue that mixed forest facilitates cooling, preserves water, enriches symbiotic fungal community, alleviating tree drought stress and mitigating infestation risk. Broad-leave trees’ non-host volatiles presumably disrupt olfactory signals, impeding beetles’ ability to locate host trees effectively. Our results underscore the potential of increasing mixed forest cover as a self-sustainable silvicultural measure for forest protection against I. typographus and for mitigating the effects of climate change.

Clear-cuts support the metapopulation of a critically endangered butterfly

Clear-cutting is believed to have a negative impact on forest biodiversity, but numerous studies have also shown its positive effects, especially in temperate and boreal regions. This phenomenon is mainly related to the creation of early successional habitats that serve as temporary meadows. Among the species that benefit the most are those associated with semi-natural grasslands, i.e. biotopes that have been disappearing from the landscape due to agricultural intensification. A good example is the Danube Clouded Yellow Colias myrmidone, one of the most endangered butterflies in Europe. Its last lowland metapopulation in the EU exists in the Knyszyn Forest (north-eastern Poland), but the species occurrence is limited to the eastern parts of this large forest complex. All currently known habitats are forest clear-cuts located mainly on former agricultural land, i.e. mostly extensively used pastures that were afforested in the 20th century. Chamaecytisus ruthenicus, the only local larval food plant of C. myrmidone, is currently found almost exclusively in first-generation forests. Logging allows the host plants to flourish, and clear-cuts are colonized by the butterfly. In 2022, intensive mark-release-recapture studies were carried out in the focal metapopulation. The estimated metapopulation size was 4643 adults, indicating a six-fold increase compared to previous studies conducted in 2017. This was plausibly mainly due to the increase in the area of potential habitats, as butterfly densities were very similar in both seasons. The improved connectivity between habitat patches resulted in a very high proportion of dispersing individuals successfully reaching other patches, which is in contrast to the dispersal mortality of ca. 50% observed five years earlier. A relatively high mobility was also observed in the case of the much smaller spring generation. To our knowledge, this is the first study to document a reversal of selection against dispersal and it demonstrates that such changes can occur relatively quickly, i.e. within a few generations. In order to ensure the long-term persistence of the viable C. myrmidone metapopulation and mitigate the negative effects of climate change, a network of stable forest-steppe-like habitats in combination with the creation of clear-cuts in forest stands with presence of C. ruthenicus would be optimal. To achieve this, we recommend leaving some selected clear-cuts without replanting to restore grasslands (through grazing and removal of excess trees, shrubs and invasive plants), while the suitability of ephemeral habitats could be improved through appropriate silvicultural measures.

Interactive effects of moose browsing and stand composition on the development of mixed species seedling stands

The moose (Alces alces L.), a common large herbivore in the boreal region, impairs forest regeneration by browsing on tree seedlings and saplings. Moose prefer deciduous species, but during winter more coniferous seedlings are used. We used meta-analyses, separately for deciduous and coniferous seedlings, for evaluating whether excluding moose browsing affected seedling density and height. In addition, we compared (1) deciduous seedling proportion, (2) stand density, (3) elapsed time from fencing and (4) estimated moose density with moose exclusion effect sizes. Fencing had a positive effect on coniferous seedling height. With more deciduous trees in a seedling stand, the fencing effect for both seedling height and density of coniferous seedlings decreased. On the other hand, the fencing effects increased with denser stands. At some point effect sizes turned to negative, and conifer species varied in their response to browsing. This implies that deciduous seedlings can protect conifers from browsing by moose up to some mixing ratio, but when deciduous seedling densities are too high, their negative effect increases, presumably through increased competition. Our results suggest that a moderate deciduous admixture in conifer-dominated mixed seedling stands can decrease moose damage but also underline the significance of timely silvicultural measures to minimize the negative effects of excessive deciduous seedlings and too dense stands. Due to differences in coniferous and deciduous species, as well as their compositions and amounts in studied experiments, more studies adjusted to local conditions are still needed to give exact measures for silvicultural recommendations.

Entomopathogens in the integrated management of forest insects: from science to practice.

The most important aim of the integrated management of forest insect pests remains the prevention of insect outbreaks, which are a consequence of the interaction of many factors in forest ecosystems, including species composition, age and health of the forest, soil type, the presence of natural enemies, and climatic factors. Integrated pest management until now has been achieved using measures aimed at shaping the functioning of stands in a changing environment. The aim of this review is to summarize research on the use of entomopathogens (microorganisms and nematodes) in the management of forest insect pests and to identify the principal knowledge gaps. We briefly describe the main research directions on the use of pathogens and nematodes to control insect pests and discuss limitations affecting their implementation. Research on entomopathogens for the biocontrol of forest insects has provided a wealth of knowledge that can be used effectively to reduce insect populations. Despite this, few entomopathogens are currently used in integrated pest management in forestry. They are applied in inoculation or inundation biocontrol strategies. While the use of entomopathogens in forest pest management shows great promise, practical implementation remains a distant goal. Consequently, sustainable reduction of forest pests, mainly native species, will be largely based on conservation biological control, which aims to modify the environment to favor the activity of natural enemies that regulate pest populations. This type of biocontrol can be supported by a range of silvicultural measures to increase the resilience of stands to insect infestations. © 2023 Society of Chemical Industry.

Geostatistical Modeling of Wildfire Occurrence Probability: The Case Study of Monte Catillo Natural Reserve in Italy

The increasing incidence of wildfires in the Mediterranean region has raised significant scientific and environmental concerns. This study focuses on a retrospective analysis of wildfire ignition and propagation within the context of the Monte Catillo Natural Reserve in Italy. After conducting a comprehensive review of the current state-of-the-art wildfire susceptibility mapping, propagation modeling, probability assessment, forest vulnerability models, and preventive silvicultural measures, we examine the regulatory framework surrounding wildfires in the national context, with a specific focus on prevention, prediction, and active firefighting measures. A geostatistical model of wildfire occurrence was developed, starting with the characterization of the area vegetation and anthropogenic factors influencing wildfire ignition. After that, wildfire observations from the period between 2010 and 2021 were included. The objective is to generate a wildfire hazard map for two distinct vegetation communities. To accomplish this, a statistical analysis was applied using the Poisson Model, assessing its goodness-of-fit by comparing observed frequencies with experimental data through the chi-square test. In conclusion, this model serves as a valuable tool for characterizing wildfire hazards, including ignition probabilities and propagation scenarios, within the Monte Catillo Natural Reserve. The research significantly contributes to enhancing our understanding of wildfire dynamics and plays a crucial role in the development of effective strategies for wildfire risk management.

DENSITAS HAMA BIBIT TANAMAN HUTAN DI PERSEMAIAN PERMANEN BPDASHL WAY SEPUTIH WAY SEKAMPUNG LAMPUNG SELATAN

The density of pest attacks in nurseries can interfere with growth and reduce seedling quality and can even cause death and cause economic losses. This study aims to analyze the density of each type of pest in the nursery. Data collection was carried out by direct observation of the sample plot at the BPDASHL Way Seputih Way Sekampung Permanent Nursery, Karang Sari Village, Ketapang District, South Lampung Regency. The sample was determined by Cluster Sampling which was based on the type of tree seed, while the placement of sample plots in each seedling bed used Systematic Sampling. The results showed that there were 19 types of pests that attack forest plant seeds in nurseries including leaf curler caterpillars, armyworms, bagworms, brown moths, wood grasshoppers, stone grasshoppers, green steamed grasshoppers, two-lane grasshoppers, small grasshoppers, dompolan lice, lamtoro lice , metallic blue beetle, red rumex beetle, sitona beetle, triple horn moth, walang sangit, koksi beetle, stem borer and snail. The highest density of pests that attack forest seedlings are wood locusts, stem borer beetles and dompolan lice. Nurseries need to monitor the development of pest populations and maintain a balance of climate and cleanliness of the area around the nursery with appropriate silvicultural measures.

The Mechanical Stability of Pure Norway Spruce Stands along an Altitudinal Gradient in the Czech Republic

Norway spruce stands are established and managed along various site conditions in central Europe. Currently, spruce often grows at locations outside of its ecological optimum, resulting in extensive damage elicited by harmful abiotic and biotic factors, which relatively shortens the time to change this adverse status in the adaptation frame by foresters. Except for the rapid change in species composition through clear-cuts, another way is possible, i.e., stabilising current (especially young) spruce stands to extend the time required to implement adaptation measures. The assumption that different site conditions will have to be respected as part of this adaptation was confirmed by our study based on NFI data of the Czech Republic. A semiparametric generalized linear model (GAM) was used to model the relationship between the height-to-diameter ratio and forest stand age, differentially considering particular forest vegetation zones. Spruce stands with lower elevations attain a lower stability (expressed by their height-to-diameter ratio; HDR) than those in the mountains. The HDR culminated in lower and middle altitudes in the first half of the rotation period, representing the most critical timing and effectivity of silvicultural measures. Contrary to previous findings, we found higher HDR values at nutrient-rich sites than those at acid ones, especially up to 50–60 years old. Therefore, more research should be devoted to the issue concerning the same thinning regime under different site conditions.

Study of Natural Regeneration of Sogdian Ash (Fraxinus Sogdiana Bunge) and Silvicultural Measures to Promote it in the Sharyn River Floodplain of Almaty Region

Study of Natural Regeneration of Sogdian Ash (Fraxinus Sogdiana Bunge) and Silvicultural Measures to Promote it in the Sharyn River Floodplain of Almaty Region

Close-to-Nature Forestry Measures in East Polissia Region of Ukraine

The article discusses close-to-nature forestry measures for the natural regeneration of pure and mixed pine forests. It is shown that successful natural regeneration of high value tree species takes place after uniformly gradual logging and progressive strip felling as final cutting operations in pure pine forests in fresh or moist oak-pine forest stands on sandy soil, resulting in the development of natural young pine forests with mixed composition. The article analyzes the state of natural regeneration after the first cycle of transformation felling operations in pure even-aged pine stands aimed at converting them into mixed pine forests of natural origin. Systems of close-to-nature silvicultural measures for restoration, development, improvement and regeneration of forest stands in the process of continuous cover forestry have been elaborated.

Silviculture in the function of sustainable development

Silviculture in the function of sustainable development

Estimasi Cadangan Karbon Dan Serapan Karbon Di Taman Maluku Kota Bandung

The availability of green open space (RTH) in urban areas is very important to mitigate the effects of global warming, especially in reducing CO2 gas levels as a result of human activities. Vegetation with chlorophyll, namely the trees in green open spaces try to absorb carbon dioxide (CO2) using sunlight, water and soil from the atmosphere through the process of photosynthesis. One form of stored photosynthetic results is biomass which makes this vegetation grow bigger and taller . In the carbon cycle and biogeochemical cycle the biomass of green open space vegetation plays an important role, all parts starting from the stems, leaves and roots store biomass. This study aims to determine the estimation of carbon stocks and absorption in Taman Maluku, Bandung City. The method used in this study is a non-destructive method (without harvesting). The research was conducted by collecting tree data and the wet weight of the understorey, then calculating the biomass to obtain estimates of carbon stocks and carbon absorption. From the research it was found that the Maluku Park in Bandung City with an area of 23,633 m2 has carbon reserves of around 179.941 tons from trees and 3.11 tons from undergrowth. Meanwhile, the estimated carbon uptake is 731,422 tonnes by trees and 11,409 tonnes by undergrowth. The high carbon stock can be influenced by several factors including: vegetation density, environment, especially sunlight, volume, specific gravity, wood constituents, water content, and silvicultural measures.

System of Criteria and Standards for Renovation Felling in the North-Taiga Forest Region of the European Part of the Russian Federation

The main goal was to test a set of silvicultural measures that would ensure the natural regeneration of larch in areas of mature and overmature plantations with a different proportion of larch in the composition. The objects were laid in the 121st quarter of the Yemtsovsky educational and experimental forestry of the Northern Arctic Federal University (NArFU) in the Arkhangelsk region, in overmature plantations of the green moss group of forest types, the share of larch in which is from 2 to 5 units in the composition. The predominant forest types were pine forests, blueberry larch forests. The average age of larch is more than 160 years; the undergrowth of this species under the canopy was completely absent. Spruce predominates in the undergrowth, its quantity varies from 2.0 to 4.0 thousand pieces/ha. Renewal of mature and overmature plantations was successful due to spruce and pine undergrowth, but there was a settlement on all strips and deciduous species. On all lanes, the birch already has a height of 2-2.5 meters and is a strong competitor in the growth of spruce and pine, which can completely nullify the further productive development and growth of coniferous undergrowth, and especially larch. It is required to carry out care in young stands in order to form the desired target composition of conifers and the optimal density of the future young plantation. The results can be taken into account when developing a strategy for forest management and forest management, making management decisions, planning and designing activities. The obtained results of the research are the scientific basis for improving the structure of the forests of the European North, increasing their productivity, biospheric role and profitability of the forest sector of the economy.

Escape Game: Responses of Northern White Cedar (Thuja occidentalis L.) to an Extreme Reduction in White-Tailed Deer (Odocoileus virginianus Zimmerman) Population

Northern white cedar (Thuja occidentalis L.) is a species of high ecological and economic value whose abundance has been declining since the pre-industrial period. It is an important element of white-tailed deer (Odocoileus virginianus Zimmerman) habitat, but its regeneration can be compromised by excessive browsing. This situation is especially critical in deeryards, where deer concentrate during winter. In 2018 and 2019, deer culling operations were carried out by the Ministry of Forests, Wildlife and Parks of Québec over 400 km2 in response to the occurrence of chronic wasting disease cases on a red deer farm. This operation offered an opportunity to look at how variations in deer pressure influence cedar regeneration and how cedar responds to a sudden reduction in browsing. We conducted regeneration surveys within and outside mapped deeryards both in the deer reduction zone and in a control zone. We performed dendrochronological analyses of cedar seedlings and saplings to quantify radial growth response to a reduction in browsing pressure. The results show that cedar basal area influences the abundance of small seedlings but that the effect of browsing becomes dominant for seedlings taller than 50 cm. Cedar growth responds to a reduction in browsing, but a two-year period was not sufficient to translate into changes in regeneration structure. The duration of the windows of opportunity at low browsing pressure required for cedar to reach a safe height remains to be determined. However, canopy openness had a significant influence on growth, suggesting that silvicultural measures could be taken to shorten the period of vulnerability to deer browsing.

Resource-based growth models reveal opportunities to mitigate climate change effects on beech regeneration by silvicultural measures

Successful European beech (Fagus sylvatica L.) regeneration is both of great ecological and economical importance in European forest ecosystems and severely threatened by climate change impacts. To increase our knowledge of beech regeneration dynamics under climate change and the potential for controlling it through forest management, we studied interactive effects of solar radiation (PHAR), water and nutrient availability on the height growth of artificially (AR) and naturally regenerated (NR) beech seedlings. The study was conducted in the framework of experimental canopy gaps, under the influence of the 2018/19 drought and heatwaves. We measured PHAR by means of hemispherical photography, approximated water availability based on the inverse of modeled fine root density distributions of overstorey beech (BGRB) and oak (BGRO) and approximated nutrient availability based on soil fertility (SF), derived from forest site mapping. Results indicate that seedling resource availability and resulting growth responses increase with canopy gap size and vary among locations within the gap. Multiplicative non-linear mixed models suggest that AR and NR relative height growth (RI) was best explained by interactive effects of PHAR, BGRB, BGRO and SF, which reflect complementary resource use patterns of beech seedlings. At optimal resource availability, AR reached a potential RI of 174%, which is about 20% higher compared to NR. While the low light growth responses of AR and NR both reflect saturation at 5 to 15% PHAR, depending on individual size and the availability of the remaining resources, NR showed a higher RI than AR at intermediate and high PHAR levels in cases of limited BGR and SF. In contrast to AR, NR growth was affected to a lesser extent by SF and BGRB and not significantly affected by BGRO. These results suggest that overstorey oaks have a lower effect on water availability of beech seedlings than overstorey beeches. Additionally, NR showed higher tolerance to water and nutrient limitation than AR, probably due to better root system development. In conclusion, site-specific potential for mitigating the effects of climate change on beech regeneration through forest management lies in the adaptation of silvicultural systems, i.e., the creation of canopy gaps larger than 200 m2, thus significantly exceeding the average gap size of the natural disturbance regime, and the choice of the regeneration method.

Acacia canopy structure and carbon stock in Ba Vi, Vietnam

Forest structure is a key component of its management and assessment in every forest ecosystem. In the study, 23 plots were established to obtain data on the acacia forest community based on tree size. Results from the study indicated that the acacia community could be broadly divided into two groups based on tree-size variables. The diameter and height frequency distributions of Group 1 were right-skewed, while those of Group 2 were more complicated. In both groups, there were positive correlations between tree-size variables, nonetheless the relationship between diameter at breast height and total height was best described using the cubic equation. Further, the Weibull and Sinh-Arcsinh (SHASH) best simulated the diameter and height frequency distribution. High-quality trees were found in a large diameter (> 30 cm) and height groups (> 22 m). In contrast, low-quality plants often concentrated on the smallest sizes. Therefore, trees with a diameter of 2–10 cm and a height lower than 8 m should receive attention to tend. Carbon stock in the two groups was 61.48 Mg·ha–1 and 64.21 Mg·ha–1, respectively. Tending solutions and measurements should be carried out regularly to promptly propose silvicultural measures and improve forest quality in future.

Silviculture in deteriorated stand conditions and complex societal demands in the area of National Park "Fruska Gora"

The application of silviculture measures on contemporary, rationalized basis in order to sustain and improve forests in the area of the National park ?Fruska Gora?, is the most im?portant segment of forest management, having in mind their anthropogenically deteriorated conditions and their purpose. For the improvement of stand conditions, intensive silvicultural tending measures are necessary in certain phases of development of the stands which is con?trary to the passive protection. The main reasons for the application of these measures are in the coppice origin of the stands on over 82% of the area of National park and the silver lime dominance compared to other edificators (oaks and beech). On the basis of the ecosystem approach in forest management, and especially in conditions of more pronounced climate change, the silvicultural measures need to be rationally synchronized with biological-ecological demands of the main species and dominant processes in forest ecosystems. In other words, there is a need to implement the elements of close-to-nature forest management. This paper points toward the most important determinations of silviculture in order to achieve the goals of special-purpose forests in the National park.

NEAREST NEIGHBOR PATTERNS OF DOMINANT TREE SPECIES IN TROPICAL FORESTS, PHOU KHAO KHOUAY NATIONAL PARK, LAOS

Target-tree management is a silviculture technique that aims to achieve sustainable forest management by considering the spatial structure of forests. In this study, a new quantitative method was used to analyze the spatial structure of natural forest stands in the Phou Khao Khouay national park in Laos. The method involved mapping and measuring all individual trees with a diameter at breast height (DBH) greater than or equal to 5 cm in 32 permanent plots of 50 m × 50 m. The analysis focused on four spatial structural parameters: uniform angle index, species mingling, height dominance, and crowding. The results showed that (1) the dominant species in the three forest types had a species mingling degree ranging from medium to complete mixture; (2) the target trees were found to have a dominant height compared to their nearest neighbors; (3) the distribution patterns of trees in the stands varied from regular to clumped; and (4) the crowding index indicated a distribution density of trees from sparse to dense. Dispersal limitation and competition among neighboring trees were the main mechanisms driving the forest's spatial structure in the study area. The findings of the present study provide valuable information for proposing silvicultural measures that promote sustainable forest management in Phou Khao Khouay National Park. By understanding the spatial structure of forests, target-tree management can be used to improve forest health, increase biodiversity, and enhance the ecosystem services provided by forests.