Silvicultural Systems Research Articles

Impact of silvicultural system on natural regeneration in Western Himalayan moist temperate forests of Pakistan

Site conditions (topography, aspect, moisture availability, humus thickness, light exposure, and grazing activities) play a vital role in the germination and regeneration process. The research was conducted in the Himalayan moist temperate forest. The research site was divided based on the silvicultural system (group selection system and single-tree selection system) into 148 plots and 150 plots, respectively. The group selection system was examined on the site of 2 ha which was clear-felled under a project in the 1980's. The present study examined the impact of silvicultural systems on regeneration. The frequency table was used, and relative frequency was calculated for the species and silvicultural system, density per m2 was also calculated. Diversity indices were calculated through taxa, dominance, Simpson’s index, Shannon index, evenness, equitability, and fisher alpha. Ten taxa were found in both silvicultural systems, with individual repetition of 17 and 15 taxa, respectively. Group selection is more compact visibly as compared to the single-tree selection system. The single-tree selection system is more diversified in species composition, stand structure, moisture availability, and less humus availability. The study also highlights future predictions for the conservation of these forests, which are highly sensitive and a hotspot for wildlife and climate change phenomena. Silvicultural practices such as silvicultural system, cleaning, weeding, thinning operations are regularly practiced, which can reduce the negative impact on these productive forests.

Changes of ground vegetation after shelter wood cuttings in pine forests, the hemiboreal zone, Lithuania

Sustainable forestry plays an important role in applying forest management measures. In many forests, management is oriented towards closer natural forest processes. Silvicultural systems that retain some part of the trees in the stand, such as shelter wood cuttings have been introduced. The aim of the study was to evaluate the early changes of ground vegetation after shelter wood cuttings in sites of different soil fertility gradient in pine dominated stands on sandy soils in the European hemiboreal zone. The Scots pine stands in which first step of shelter wood cuttings was applied were investigated. The stands were selected in fresh (normal humidity) sites according to soil fertility gradient: very poor, poor and medium fertility soils. All mosses, lichens, herbaceous vegetation and dwarf shrubs were recorded, and projection cover was estimated in June - August. Ellenberg’s indicator figures were used to evaluate site conditions. In shelter wood cuttings (5-6-year-old) the number of species was higher in medium fertile sites than in very poor sites. After shelter wood cuttings the abundance of herbaceous species increased in all sites, while the abundance of mosses and lichens decreased. Within the first year after shelter wood cuttings, the abundance of Ericaceae species decreased, and abundance of Rosaceae and Poaceae species increased. Average Ellenberg’s indicator values showed that site conditions changed after shelter wood cuttings. The changes were more intensive in medium fertile sites than in poor sites. After shelter wood cuttings the richness and abundance of ground vegetation changed. The intensity of change differed in sites of certain soil fertility and was caused by alteration of site conditions, which were more homogenous in sites of the certain fertility in uncut stands than in cuttings. Key words: herbs, mosses, non-clear cuttings, vegetation

Mixedwood silviculture in North America: the science and art of managing for complex, multi-species temperate forests

Temperate mixedwoods (hardwood–softwood mixtures) in central and eastern United States and Canada can be classified into two overarching categories: those with shade-tolerant softwoods maintained by light to moderate disturbances and those with shade-intolerant to mid-tolerant softwoods maintained by moderate to severe disturbances. The former includes red spruce (Picea rubens Sarg.), balsam fir (Abies balsamea (L.) Mill.), or eastern hemlock (Tsuga canadensis (L.) Carr.) in mixture with northern hardwood species; the latter includes pine (Pinus) – oak (Quercus) mixtures. Such forests have desirable socio-economic values, wildlife habitat potential, and (or) adaptive capacity, but management is challenging because one or more softwood species in each can be limited by depleted seed sources, narrow regeneration requirements, or poor competitive ability. Appropriate silvicultural systems vary among mixedwood compositions depending on shade tolerance and severity of disturbance associated with the limiting softwoods, site quality, and level of herbivory. Sustainability of mixedwood composition requires that stand structure and composition be managed at each entry to maintain vigorous trees of species with different growth rates and longevities and to encourage development of advance reproduction or seed-producing trees of desired species. Regardless of silvicultural system, maintaining seed sources of limiting softwoods, providing suitable germination substrates, and controlling competition are critical. Here, we describe commonalities among temperate mixedwoods in central and eastern North America and present a framework for managing them.

Effect magnitudes of operational-scale partial harvesting on residual tree growth and mortality of ten major tree species in Maine USA

Silvicultural systems based on partial harvesting (PH) have become increasingly common in areas historically dominated by clearcut-based systems in response to ecological and social concerns. Current knowledge about the effects of PH is based primarily on stand responses from controlled experiments from limited number of sites. A broader scope of inference is needed to fully understand the effects of PH when applied operationally at a landscape scale. We used 835 permanent monitoring plots from the US Forest Service Forest Inventory and Analysis network to quantify the effect magnitude (EM) of low- (5–40% basal area removal) and high-intensity (41–80% basal area removal) PH on the periodic diameter growth and mortality of residual trees of ten major tree species in Maine, USA. Our results showed that the EM and timing of statistically significant effect (p < 0.05) of the two intensities of PH varies across species. Tree diameter growth responses to high-intensity PH was rapid and prolonged for sugar maple (Acer saccharum) and American beech (Fagus grandifolia), while other species did not show significant responses for at least five years. High-intensity PH increased mortality of American beech, balsam fir (Abies balsamea), red spruce (Picea rubens), northern white cedar (Thuja occidentalis), and red maple (Acer rubrum), but not for other tree species. No relationship was found between species shade tolerance and species-specific response magnitude to PH in terms of diameter growth and tree- or stand-level (absolute or relative) mortality. This result suggests that species shade tolerance does not always determine the type or magnitude of response that a given species has to increased resource availability following PH and that other functional traits may be more important. Overall, the findings provide strong evidence that subsequent tree responses to PH are not consistent among contrasting species for at least 15 years following harvest and longer-term regional assessments are needed.

¿La combinación de clones posee alguna ventaja sobre los sistemas monoclonales?

Las plantaciones forestales han sido tradicionalmente desarrolladas a partir de material de propagación de origen seminal. Sin embargo, las principales especies plantadas en el mundo se pueden propagar vegetativamente, por lo que las posibilidades para el desarrollo de la silvicultura clonal son crecientes. El cultivo de Salicáceas se realiza con estacas o guías, por lo que las plantaciones son 100% producidas bajo un esquema de silvicultura clonal. Además, en el Delta del Río Paraná los rodales se instalan como bloques monoclonales y el clon Populus deltoides ‘Australiano 129/60’ es el más difundido, definiendo una matriz productiva con una estrecha diversidad genética. Esto determina que el sistema sea menos estable y trae aparejado un riesgo productivo ante la aparición de condiciones de estrés biótico o abiótico. En consecuencia, el modelo de silvicultura monoclonal presenta algunas desventajas no solo desde el punto de vista ecológico, sino también productivo. A partir de la posibilidad que brindan las especies forestales, que presentan una gran variabilidad tanto intra como interespecífica, es posible pensar en combinación de clones para aumentar la diversidad genética de las plantaciones. Las plantaciones clonales mixtas pueden favorecer a la disminución de los impactos de las actividades productivas en el ambiente, distribuir espacialmente la demanda de nutrientes del suelo, aumentar la diversidad genética y mejorar los índices de rendimiento del rodal. El objetivo de esta revisión es analizar los antecedentes de silvicultura clonal y plantaciones mixtas como base para la propuesta de alternativas silviculturales para las Salicáceas del Delta del Paraná.

Herbivory and leaf traits of Amazonian tree species as affected by irradiance.

Herbivory is one of the major biotic stress factors that affect the establishment of plants. However, the main factors that drive herbivory in seedlings of Amazonian tree species are still not well understood. Here we investigated whether contrasting levels of irradiance influence herbivory according to different herbivory indicators and which leaf traits are most related to interspecific variation in herbivory under contrasting irradiance conditions. We measured the leaf area lost as a result of insect herbivory in five tree species planted in a silvicultural system of secondary forest enrichment according to two indicators, herbivore damage (accumulated since plant germination) and herbivory rate (measured over time), and two irradiance conditions, understorey PPFD 2.6mol·m-2 ·day-1 ) and gap PPFD 33.1mol·m-2 ·day-1 . Furthermore, we related the interspecific variation in herbivory to a set of leaf traits: SLA, RWC, sclerophylly, phenolic compound content, tannins, condensed tannins and non-structural carbohydrates. Herbivore damage was significantly affected by light availability and species, with the highest percentage variation observed in the Meliaceae (Carapa guianensis and Swietenia macrophylla). For the herbivory rate, only the interspecific variation was significant, with Bertholletia excelsa having the lowest rates. Chemical characteristics (phenolic compounds and tannins) were most related to herbivory rates, as well as highly influenced by light conditions. Non-structural carbohydrates (starch and sucrose) were also related to the interspecific variation in herbivory. The phenolic compounds and starch, as affected by light quantity, are species dependent. Thus, the selective pressure on herbivores may be driven by species-dependent responses to light conditions.

Seedling recruitment in response to artificial gaps: predicting the ecological consequence of forest disturbance

Artificial gaps are widely created for forest management. However, the interactive effects of gap sizes and within-gap locations on seedling regeneration are rarely tested. Therefore, whether there are lower and upper size limits for artificial gaps remains controversial. Here, we aimed to test the hypothesis that the effects of within-gap positions on seedling regeneration are dependent on gap sizes. Newly germinated wild seedlings of shade-intolerant Quercus mongolica scattered in different positions within artificially created gaps of different sizes were surveyed to test our hypothesis. Large gaps promoted seedling growth more than medium and small gaps. The increase in Q. mongolica seedling growth in large gaps can be largely attributed to the dormancy breaking of the apical buds and increased net photosynthetic rates. More importantly, we showed that the effects of within-gap position were prominent only in medium gaps, i.e., the effect of within-gap position appears to be dependent on gap size. We show an integrative effect of gap size and within-gap location on seedling performance of shade-intolerant oaks, suggesting future studies should evaluate the influence of within-gap location in conjunction with the role of gap size. We therefore suggest that gap creation in silvicultural systems should highlight the lower and upper size limits of forest gaps, which will vary with the species and regions studied.

Natural dynamics of temperate mountain beech-dominated primary forests in Central Europe

Natural disturbances are key factors in the formation of forest ecosystem structure. Evaluation of the spatial and temporal extent of disturbance regimes is critical for understanding forest dynamics, forest structural heterogeneity, and biodiversity habitats. Quantifying disturbance regimes is therefore imperative for appropriate management of forests and protected areas. However, natural disturbance regimes have rarely been assessed using dendrochronological methods on a regional scale across primary mixed beech-fir forest stands - one of the dominant forest vegetation types in Europe. To study the natural disturbance regimes of beech-dominated mixed-forest stands, we established 42 permanent study plots with an area of 0.1 ha across three primary forest stands in the Western Carpathians, a region that still contains large areas of primary forest. We reconstructed each stand-level disturbance history using a tree-ring based approach. The temporal synchronicity of disturbance events was then evaluated by delineating stand-level disturbance events using a kernel density function, and through the detection of plot-level disturbances with severities greater than 10 percent. The results obtained from the chronologies showed substantial variability in time and space, especially in the mid-19th century. Low- and moderate-severity plot-level disturbance events were most common, but high- and extremely high-severity plot-level disturbance events also occurred. The observed spatial and temporal variability suggests that the beech-dominated forests were primarily driven by mixed-severity disturbance regimes, with windstorms as the main disturbance agent.This reconstruction of the disturbance regime provided unique insight into the scale of mortality processes in these beech-dominated mixed forests. This information can help guide ecological forestry in areas where both wood production and biodiversity preservation are simultaneous goals, such as by employing more spatiotemporally-complex silvicultural systems that resemble natural disturbance patterns and facilitate heterogeneous forest structures.

Harvesting Criteria Application as a Technical and Financial Alternative for Management of Degraded Tropical Forests: A Case Study from Brazilian Amazon

This article addresses a case study on the application of criteria for harvesting, aiming at restoration and profitability in a degraded tropical forest in the Amazon. The objective is to provide technical and economic information to promote a truly sustainable silvicultural management system in forests with this profile and turn them into a desirable financial asset for conservation and social development. In the forest census, 85.907 trees ha−1 (100.8566 m3 ha−1) were inventoried with diameter at breast height (dbh) ≥ 25 cm, belonging to 106 commercial species. When applying the harvest criteria, 19.923 trees ha−1 (29.99 m3 ha−1), referring to 53 species, were destined for harvest. Some trees were selected by more than one criterion, totalizing 17.985 trees ha−1 by density, 1.831 trees ha−1 by compromised health, 0.212 trees ha−1 by maximum dbh, 18.933 trees ha−1 by minimum dbh, 1.385 trees ha−1 by tree stem (quality 3), and 0.080 trees ha−1 by species conservation. In all scenarios, the application of criteria for harvesting proved to be profitable with excellent cost–benefit ratios. The selection of trees with a minimum cutting diameter of 25 cm in shorter cycles tends to allow the promotion of new commercial species. The set of actions presented has the potential to favor the maintenance of biodiversity and expansion of low-density populations, health and the potential increment of the forest productivity. In addition, it is more feasible for the supply of forest products in a shorter time than provided for in Brazilian regulations; however, they must respect the specificities of the species and also of the site.

Regeneration responses in black ash (Fraxinus nigra) wetlands: implications for forest diversification to address emerald ash borer (Agrilus planipennis)

Emerald ash borer (EAB) (Agrilus planipennis) has had an extensive impact across North America. It is currently present in Minnesota, USA but has not been observed in northern portions of the state where the vast majority of black ash (Fraxinus nigra) trees are located. Unlike other ash forest communities, the black ash forest type occurs in wetlands and is dominated by black ash with few associate species. Because of this, the loss of black ash can result in changes to the hydrological regime and species composition. The goal of this study was to quantify the structure and composition of regeneration 5 to 11 years post-harvest in three silvicultural systems (group selection, clearcut, and diameter-limit harvesting) to evaluate the potential for establishment of other tree species. Overall, regeneration post-harvest was high but variable across all systems. Across silvicultural systems, there was no significant relationships between residual overstory trees (> 10 cm dbh) basal area and non-ash regeneration TPH, indicating flexibility in designing treatments for diversification. Populus sapling (2.54–10 cm) density was significantly negatively correlated to the depth of the soil muck layer. In contrast, a positive relationship was observed between depth of the soil muck and black ash saplings. These findings indicate that specific silvicultural systems in combination with site quality (e.g., clearcuts on high-quality sites with shallow muck layers) may help to promote non-ash species in black ash forests that are threatened with EAB.

Fine-scale analysis reveals a potential influence of forest management on the spatial genetic structure of Eremanthus erythropappus

Forest management may have significant effects on forest connectivity and natural population sizes. Harvesting old-growth single trees may also change natural patterns of genetic variation and spatial genetic structure. This study evaluated the impacts of forest management using a silvicultural system of seed trees on the genetic diversity and spatial genetic structure of Eremanthus erythropappus (DC.) MacLeish. A complete survey of 275 trees on four plots was undertaken out to compare the genetic variation of a managed stand with an unmanaged stand. We genotyped all adult and juvenile individuals 60 months after the management and compared the genetic diversity and the spatial genetic structure parameters. Genetic diversity was considered high because of an efficient gene flow between stands. There were no genetic differences between stands and no evidence of inbreeding. Genetic clustering identified a single population (K = 1), indicating no genetic differentiation between managed and unmanaged stands. Adult and juvenile individuals of the unmanaged stand were more geographically structured than individuals from the managed one. There was a tendency of coancestry among juveniles at the first class of distance of the managed stand, suggesting a drift of genetic structure possibly caused by management. Understanding early responses to management on genetic diversity and stand structure is a first step to ensuring the effectiveness of conservation practices of tree species. The sustainability of forest management of E. erythropappus on genetic diversity, and more accurately, on spatial genetic structure needs evaluation over time to promote effective conservation of the population size and genetic variability.

HUBUNGAN ANTARA UKURAN RUMPANG DAN PERTUMBUHAN DIAMETER TANAMAN ULIN (Eusideroxylon zwageri Teijsm &amp; Binn.) DI KHDTK KINTAP KECAMATAN KINTAP KALIMANTAN SELATAN

Deforestation and degradation of natural forests and plants reached 1.6-2.0 million ha. Forestry Research and Development Agencies throughout Indonesia have begun to develop various silvicultural techniques of ulin so that the extinction of the plant can be prevented. One of the silvicultural systems that began to be developed was a gap system. The purpose of this study was to determine the growth of ulin (Eusideroxylon zwageri Teijsm &amp; Binn.), and the influence of the size of the gaps on the growth of ulin plants in Kintap KHDTK. The results obtained were the average growth of the lowest ironwood plants from the value of diameter (1.27 cm) that was at without gap treatment, while the highest growth was the best diameter (5.01 cm), which was at the gap with diameter of 12 m. The optimal diameter of ironwood growth is in the size of a 12 m. Treatment of overlays of 12 m gives a good growth effect for ironwod plants.

Retention of large, old trees in alternatives to clearcutting with a comparison of ground- and helicopter-based assessments

Habitat trees (mature live and dead trees with hollows) are a keystone habitat in Australian eucalypt forests where tree hollows typically occur in large, old trees. These trees provide potential habitat for hollow-using birds, bats and arboreal marsupials, including many threatened species. Habitat trees may be felled during forest harvesting and can also be negatively affected by wildfires. Shortages of habitat trees in harvesting landscapes can be a limiting factor for populations of hollow-using vertebrates. Retention forestry systems are expected to retain a greater number of habitat trees within sites than traditional clearcutting silviculture, but there is a need to quantify how the pattern of retention (dispersed trees vs. retained clumps) will affect the numbers and types of trees retained. The method of assessment (ground-based vs. aerial surveys) may influence the estimated numbers of habitat trees. We investigated habitat tree retention at the Warra Silvicultural Systems Trial in Southern Tasmania, Australia. This trial was instrumental in developing alternatives to clearcutting in tall, wet, old-growth eucalypt forests. Our research has two objectives. Objective 1 is to assess the numbers of habitat trees retained in various alternatives to clearcutting by comparing: unlogged control areas, 0.5–1 ha clumps retained within a harvested matrix (aggregated retention), trees scattered throughout the harvested area (dispersed retention), and small ~0.08 ha machinery exclusion zones where trees were retained if they were not of commercial value (clearcutting with understorey islands). Objective 2 is to compare ground-based to aerial, helicopter-based, assessment of large live and dead trees. Although low replication of harvest treatments precluded statistical comparison of silvicultural systems, the results, based on 1,260 trees, were clear. Of the various alternatives to clearcutting, aggregated retention retained the greatest proportion of all classes of habitat trees, primarily because of higher retention targets, but possibly also because of greater survival with reduced wind exposure in aggregates. Substantially fewer habitat trees were retained with dispersed retention, and virtually none with understorey islands in clearcutting. Aerial and ground-based assessment methods provided similar estimates of numbers of trees with visible hollows in aggregates and understorey islands (R2 = 0.95). Choice of method for future studies should consider available resources and objectives, since there were advantages and disadvantages of each approach. In conclusion, aggregated retention was found to be the preferred silvicultural system for retaining habitat trees within sites for hollow-using vertebrates, and helicopter surveys provide a rapid alternative to traditional ground-based assessment.

Silvicultural options for the transformation of even-aged Rhizophora apiculata stands to irregular and diverse mangroves – A simulation experiment

Mangrove rehabilitation efforts regularly intend to re-establish the former canopy cover quickly by establishing even-aged monocultures. However, there are concerns that these stands are less resilient to disturbances than structurally diverse forests and cannot provide ecosystem services as effectively. The objective of this study was to identify silvicultural systems for the transformation of even-aged Rhizophora apiculata stands to more irregular and species-diverse stands.The individual-based forest model KiWi was used to simulate the dynamics of a 1-ha sized Rhizophora apiculata stand under (1) passive management without intervention, (2) stand clearcutting, (3) group clearcutting, (4) expanding-gap shelterwood, and (5) crown thinning. As observed in the field, seedlings of the less shade-tolerant tree species Avicennia marina regenerated naturally under the canopy of R. apiculata. The transformation process was considered complete at the onset of the steady state characterized by a multi-layered forest structure as well as a stable basal area and stem size distribution.Without intervention, stands entered a steady state, on average, after 226 years under poor site conditions, or 179 years under good conditions. Silvicultural systems that required multiple entries, specifically expanding-gap shelterwood and crown thinning, halved this time by creating multi-layered stand structures while retaining a partial canopy cover. Moreover, continuous crown thinnings were necessary to maintain a species-diverse upper canopy. In contrast, small group clearcuts developed into two-layered stands and were ineffective. The removal of the upperstory through a stand clearcut or a large group clearcut reversed the initial planting arrangement but could develop into irregular stand structure only if propagules were supplied uninterruptedly. Intense forest operations were necessary to accelerate the transformation of even-aged mangrove stands. Forest managers should consider the potential future costs of transformation when planting even-aged stands instead of assisting the natural regeneration of former mangrove sites. Silvicultural field trials are proposed for the development of detailed guidelines.

Canopy Opening and Site Preparation Effects on Conifer and Understory Establishment and Growth after an Uneven-Aged Free Selection Regeneration Harvest in the Northern Rocky Mountains, USA

Research Highlights: Forest management is trending toward creating multi-aged forest structures and diverse vegetative compositions. The challenge is successfully designing and implementing treatments that create these diverse forests. Regeneration establishment is the most important step when applying a silvicultural system because it determines future treatments and optimizes management options. This study provided the minimum canopy openings that favor the establishment of shade-tolerant and shade-intolerant tree species to inform the implementation of uneven-aged management. Background and Objectives: A replicated study was implemented in 2007 in moist mixed-conifer forests to design, apply, and test two silvicultural concepts, canopy opening size and site preparation. Our objective in 2015 was to evaluate tree regeneration establishment and growth and understory vegetation in relation to these two silvicultural concepts. Materials and Methods: Canopy opening sizes as measured by lidar ranged from 15% to 100%; and through the application of prescribed fire, mastication, pile and burn, or no site preparation, different combinations of forest floor substrates were created. We stratified our study area into five canopy opening classes and four site preparation treatments. Using this stratified sampling scheme, we located 65 plots and measured tree species, abundance, 5-year height growth, and vegetative lifeforms. Results: The pile and burn site preparation favored the establishment of all six tree species. The canopy opening size of 55% to 92% favored the regeneration of both shade-tolerant and shade-intolerant species. Grand-fir 5-year height growth was significantly influenced by site preparation and canopy opening, and western white pine 5-year height growth was only influenced by canopy opening. Treatments did not influence vegetative richness. Conclusions: This study provided key treatment parameters in designing the regeneration step for uneven-aged management strategies with the goal of creating vegetative diversity and establishing shade-intolerant tree species in moist mixed-conifer forests.

Effective determination of biomass in oak coppices

The diameter at breast height of the largest sprout per coppiced stool proved to be accurate for the total sprout biomass estimates at stand level. Traditional coppicing is one of the oldest silvicultural systems for biomass production. However, a quick and simple biomass estimate methodology across the entire growth period is lacking. The objective of this study was to find the sprout parameters that need to be measured for accurate sprout estimates as well as to find a necessary minimum number of sprouts for these estimates. Using data from 20 sample Turkey oak multi-stem trees, we modelled sprout biomass as a function of an increasing number of sprouts in interaction with different sprout parameters in a later post-resprouting period. Results showed that the DBH of only two of the largest sprouts per stump proved to be accurate estimators of the total sprout biomass of the individual stool. For sprout biomass estimates at stand level, we recommend measuring the DBH of the largest sprout within each stool in a plot and then calculating and summing the estimated sprout biomasses of the individual stools. This study illustrates that the biomass can simply be estimated by easily measured parameters of sprouts; therefore, the multi-stemmed trees can be easily included into the yield or ecosystem studies of woody vegetation with less time-consuming measurements.

Adoption of new silvicultural methods in Mediterranean forests: the influence of educational background and sociodemographic factors on marker decisions

The adoption of new silvicultural methods and approaches requires an understanding of the differences between those and “old” or “conventional” approaches, along with extensive training to break previous knowledge bias. Forestry is in transition towards ecosystem-based management, and new silvicultural approaches are appearing worldwide. However, the adoption of an alternative silvicultural approach is difficult in practice. We analyzed the effect of forestry background and demographic variables (gender and age) of 24 raters on the application of the systemic approach (SA) and the conventional approach (CA) in the Northern Apennines (Italy) and compared this with tree marking performed by experts. Data were analyzed as raters’ departures from experts’ selections at the stand and the individual tree level. The probability of tree selection was also calculated. At the stand level, raters with forestry background performed the SA as if they were marking for crown thinning, whereas the CA was less intense than experts’ crown thinning. Non-foresters differentiated poorly between the SA and the CA. At the individual tree level, background and gender affected tree selection. The adoption of the SA as a silvicultural system may be conditioned by previous knowledge. The difference between SA and CA remains unclear when it comes to non-foresters. Gender was a more important variable than age in selecting which trees would be harvested.

Effects of shelterwood and single-tree cutting systems on topsoil quality and functions in northern Iranian forests

Foresters always emphasize the understanding of soil properties in evaluating site capacity to support productive forests. In order to conserve and improve soil quality and functions, sophisticated forest management systems are of particular importance. Hyrcanian forests of Iran have been harvested under different silvicultural operations such as shelterwood and selective cutting systems. So far, no studies have been conducted to explore the effects of forest management systems on soil properties in this ecosystem. Consequently, the present study aimed to investigate the impact of shelterwood and single-tree cutting systems on soil quality and functions (i.e. organic matter fractions, biota and microbial/enzyme activities), 10 and 20 years after employing these systems in Hyrcanian beech stands, compared to intact forests (control areas). A total of 60 soil samples (30 × 30 × 10 cm) including 30 samples in August 2008 and 30 samples in August 2018 from each site (i.e. control areas, shelterwood and single-tree systems) were transferred to the laboratory. In addition, topsoil water content, temperature and biological dynamics (August 2008, November 2008, August 2013, November 2013, August 2018 and November 2018) were monitored across the different forest management systems. Based on our data, the studied forest sites and soil properties could be separated by PCA output. The first and second axes, respectively, accounted for 38.59 and 10.95% of the explained variance. The control areas enhanced soil organic matter fractions, biota and microbial/enzyme activities. Between different silvicultural operations, the single-tree system, which is considered as a close-to-nature system, has provided better conditions for soil quality and functions as compared to the shelterwood management system. The understanding of ecological changes within widespread forest management systems can be helpful in forest management and plays a significant role in evaluating silvicultural systems.

Joint production of wood, resin, and carbon from pine plantation forest in Java

Pine (Pinus merkusii) plantation forest has been developed in Java Island under Perhutani management with clear-cutting and artificial regeneration silviculture system. The main products of pine plantation forests are wood and resin. Although the Indonesian government has committed to reduce the greenhouse gases (GHGs) emission for 26% by 2020 with voluntary efforts, pine plantation forest may contribute to reduce GHGs emission through enhancing carbon stock. The additional income from carbon sales might or might not change the optimal rotation of the pine forest. This study aims to analyze the effects of additional income from resin and carbon benefits on the optimal rotation of pine plantation forest in Java. The modified Faustmann model is used to determine the optimal rotation. The results of this study show that (1) the inclusion of resin benefits may lengthen the optimal rotation age, (2) the optimal rotation of timber and resin production of pine forest in Java for size class III, IV, V, and VI are 34, 33 32, and 30 years respectively, (3) additional income from carbon sales may increase carbon stock by 8%, and lengthen optimal rotation for 3 years. Perhutani may change the optimal rotation due to additional benefits from resin and carbon.

The Decline of the Clearcut: 26 Years of Change in Silvicultural Practices and Implications in Minnesota

AbstractSilvicultural decisions and forest-management practices in Minnesota represent the collaboration and partnership between forest managers from multiple organizations and forest researchers. To better understand current practices, trends, needs, and opportunities, Minnesota has invested in the collection of quantitative data on the application of silvicultural systems and forest-management activities in 1991, 1996, 2008, and 2017. Drawing on those data, the goal of our study is to summarize 26 years of data to characterize and quantify trends in forest-management practices. During this period of time, timberland ownership (acres) has increased, whereas harvested volume has decreased (cords). Across state, federal, county, forest industry, and tribal forest lands, which collectively represent the majority of timberlands in Minnesota, the clearcut system decreased from 91% of the harvested area in 1991 to 72 percent in 2017. In contrast, the proportion of total harvested area as part of shelterwood, seed tree, selection, and thinning treatments all more than doubled from 1991 to 2017. Factors influencing the changes relate to forest health and diseases, shifts in ownership structure, and shifts in organizational policy and/or goals. The factors identified mirror many of the trends forest managers are experiencing in other regions, nationally and internationally.