Irregular Shelterwood System Research Articles

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.

Mid-term results and prospects for irregular shelterwood systems in hardwood-dominated temperate rainforests in Chile

Mid-term results and prospects for irregular shelterwood systems in hardwood-dominated temperate rainforests in Chile

Implications of irregular shelterwood system on regeneration and species diversity of Sal (Shorea robusta Gaertn. f.) forest in Nepal

Silvicultural systems are essential for effective forest management and utilize the resources by conserving biodiversity, health, and valuable services forests offer to society. However, Nepal faces a significant knowledge gap due to the limited data on the effect of silvicultural systems and forest management practices on tree diversity and regeneration. Therefore, this study was conducted to assess the effects of canopy opening on natural regeneration and species diversity of Sal (Shorea robusta Gaertn. f.) forest in comparison to managed and control blocks in the southern plains of Nepal under irregular shelterwood systems. The vegetation sampling was carried out by the quadrat method (plot of 10 m* 10 m) for studying 48 plots in both managed and control forest areas. The Shannon-Wiener Index and the Simpson Index were used to measure species diversity, whereas Margalef's index was used to measure species richness. Dominant tree species in both managed and control forest areas were identified through the Important Value Index (IVI). The seedling and sapling density of Sal was found to be significantly higher (p < 0.05) in managed blocks. Seedlings of Sal from the seed origin were notably more abundant in the managed block (p < 0.01), whereas those from coppice origin exhibited higher numbers in the control block (p < 0.01). Sal was found to be dominant species in both managed block (IVI = 199.94) and control (IVI = 108.34). The species diversity and richness were significantly declining in the managed forest (p < 0.01) with higher species dominance in comparison to the control blocks. Our study found a positive correlation of canopy cover with species diversity (r = 0.69, p < 0.01) and richness (r = 0.59, p < 0.01) whereas a negative correlation with seedling (r = −0.43, p < 0.01) and sapling density (r = −0.16, p < 0.01). The application of the irregular shelterwood system in study area has effectively promoted natural Sal regeneration while concurrently reducing species diversity. To strike a balance between timber production and biodiversity conservation in these forests, further research focusing on moderating felling intensity within the irregular shelterwood system is strongly recommended.

Influence management and disturbances on the regeneration of forest stands

The renewal and sustainability of the forest stands are attained through regeneration. There are three basic methods to regenerate high forest stands: natural regeneration, direct seeding, and planting. This study reviews the factors affecting regeneration, the three methods of regeneration and the effect of stand structure on regeneration. Overall, regeneration success can be quite variable due to edaphic and climatic conditions, seed losses and/or seedling mortality. The silvicultural system is relevant to the choice of the regeneration method. Natural regeneration is used in selection and irregular shelterwood systems whereas direct seeding and planting are used in uniform shelterwood and clear-cut systems. In the former, stand stocking management is primordial to regeneration success while for the latter are species selection, seed predators and spontaneous vegetation control.

How do advance regeneration and planted seedlings of Thuja occidentalis and Picea rubens acclimate under a first irregular shelterwood cut?

Eastern white cedar ( Thuja occidentalis) and red spruce ( Picea rubens) contribute to the biodiversity and resilience of mixedwood forests. However, cuts that remove most or all the forest cover can cause the decline of these species. Among partial cutting options, the irregular shelterwood system (ISS) can create successful conditions for the development of advance regeneration and enrichment planting. We studied 6 years of ecophysiology of lower advance regeneration and planted seedlings of eastern white cedar and red spruce growing under a first ISS cut according to three cutting intensities: light cut (35% removal, 20 m2·ha−1 residual basal area), moderate cut (42%, 18 m2·ha−1), and heavy cut (52%, 15 m2·ha−1). Light-saturated photosynthesis and height growth of planted cedar and both spruce types decreased with increasing cutting intensity, in response to an increase in competing vegetation. Therefore, to limit the negative impact of competing species on cedar and spruce regeneration, we recommend protecting tall advance regeneration (2 m+) during partial cut operations and using large-sized containerized seedlings (40–50 cm height) for enrichment planting. Results also suggest that a mechanical release could help optimize the physio-morphology and growth of both regeneration types of cedar and red spruce.

Regeneration Status and Diversity under Irregular Shelterwood System: A Study from Panchkanya Community Forest, Sunsari, Nepal

The present study is the outcome of vegetation sampling conducted in the managed and unmanaged forest patch under the irregular shelterwood system to analyze community structure and plant diversity in a degraded mixed forest in eastern Terai, Nepal. Systematic random sampling was followed by laying out 15 quadrates sized 4m2 with uniform spacing of 50 meters in both managed and unmanaged blocks, respectively. This study revealed that the first and second-year regeneration felling subsisted the Shorea robusta in the managed forest patch. There was observed a remarkable increase in regeneration but a decrease in plant diversity in the managed area in comparison to the unmanaged one. Simpson’s index of diversity was 0.760 and 0.890 and Shannon-Wiener indexes were 1.82 and 2.43 in managed and unmanaged forest blocks, respectively. Independent sample t-test showed a significant difference in the total number of regenerations between managed and unmanaged forest blocks since P-value &lt;0.05 (P=0.0166) i.e., managed blocks with opened canopy had higher regeneration but a lower diversity. This study concludes that the irregular shelterwood system is deemed pivotal for increased regeneration of Shorea robusta particularly in the eastern lowland of Nepal.

Climate and Management Factors Underlying Changes in Beech Forest Herbaceous Layer Plant Communities in the Polish Eastern Carpathians

The herbaceous vegetation and forest stand characteristics in European beech forests growing in the Polish part of the Eastern Carpathians have changed over the last 40 years. This has been influenced by many factors, including land-use change, forest management and climate change. This study investigates changes in forest cover and structure and the associated changes in herbaceous layer plant communities and seeks to elucidate whether and how beech forest herbaceous layer communities have been affected by climate change. The study used information from archival and current land cover maps, semi-permanent sampling plots, forest management plans for the Forest Districts of Brzozów, Lesko and Ustrzyki Dolne and meteorological weather station data compiled for three study periods of herbaceous vegetation (1970s, 2000s, 2010s). In the study area, the regular shelterwood system was changed to an irregular shelterwood system that produces stands with a complex overstorey structure. The results revealed the important role of light availability in shaping the species composition of the herbaceous layer in semi-natural Carpathian beech forests, which was strongly related to the course of management activities. An overall decrease in the number of species during the 2010s is linked to the ageing of beech forests, increased intensity of management activities in ageing stands, competition from understorey vegetation and lower soil moisture that can be linked to climate change. Our study partially supports the existing findings that more manipulative forest management systems can play an important role in countering the current and expected effects of climate change on the forest ecosystem because of the low degree of spatial differentiation of the stand’s structure (developmental stages). Therefore, foresters managing the structure of stands should strive to create a forest structure with high variability of developmental stages on a regional scale.

Increased levels of harvest may favour sugar maple regeneration over American beech in northern hardwoods

The increasing dominance of American beech regeneration (Fagus grandifolia Ehrh.) to the expense of sugar maple (Acer saccharum Marsh.) challenges the long-term economic viability of forest management in northern hardwoods. Based on earlier studies showing that more light in the understory favours sugar maple over beech, the irregular shelterwood system has shifted from experimental to operational over the last decade. In this paper, we evaluate the success of this shift toward irregular shelterwood for promoting sugar maple over beech by measuring the frequency, abundance of sugar maple and beech seedlings and saplings, and growth of seedlings three to six years after logging in northern hardwood forests of western Quebec, Canada. Results showed a dominance of beech regeneration regardless of the harvest intensity, particularly among tall seedlings and saplings. However, we found that the transition probability indices (projected relative combined abundance and growth) of sugar maple could be favoured, albeit to a limited extent, by an increased basal area removal, particularly where the initial occurrence of sugar maple in the advance seedling regeneration is lower than 60% and the initial beech basal area is low in the overstory (i.e. < 6 m2 ha−1). Our results highlight the importance of refining our operational management strategy to effectively limit the increasing abundance of regeneration of American beech over sugar maple in northern hardwood forests.

Woodland salamander population structure and body condition under irregular shelterwood systems

Ecosystem-based management aims to preserve old-growth forest attributes using techniques mimicking natural disturbances. One such technique is irregular shelterwood logging, but its impacts on forest floor organisms are poorly known. Our objective was to quantify the effects of three different treatments of irregular shelterwood on population structure and the body condition of the eastern red-backed salamander (Plethodon cinereus) 5–6 years following harvesting. A total of 64 sites in western Québec were sampled using artificial refugia and quadrat searches. Large salamanders (&gt;32 mm) were more abundant in the gap treatment than in strip, uniform, or control treatments. Small salamanders (≤32 mm) followed the same pattern, although the differences were marginal. For a given treatment, small salamanders were as abundant as large salamanders. Salamander body condition differed between the 2 years of sampling but did not differ among treatments, regardless of salamander size. We conclude that environmental conditions in irregular shelterwood treatments 5–6 years following harvesting support populations of small vertebrates on the forest floor.

Assessment of Productivity and Profitability through Scientific Forest Management in Sal (Shorea robusta) Forest of Nepal: A Case Study from Patela Community Forest, Kailali District, Nepal

Scientific forest management (SciFM) ensures improved productivity and healthy forests that are crucial for the economic development and prosperity of forest-dependent country like Nepal. This study analyzes the effects of the silvicultural intervention on the regeneration of Sal (Shorea robusta), plant species diversity, and income through the flow of forest products in the Patela Community Forest in Kailali District of Nepal, where Sal (S. robusta) forest has been managed under an Irregular Shelterwood System with 80 years of the rotation period since fiscal year 2017/18. The vegetation sampling was done by the quadrat method based on the principle of stratified random sampling from the managed and unmanaged parts of the forest. The climate based site productivity was analyzed. The profitability of scientific forest management was analyzed by income and cost incurred in managing the forest. The study revealed the promising regeneration of S. robusta in the managed areas compared to the unmanaged area. The silvicultural intervention had a significant negative effect on plant diversity showing an increase in the concentration of dominance of S. robusta. An implementation of SciFM plan generated a total net benefit of 187,000 US$ in the last 2017/18, and 2018/19 fiscal years. This study recommends existing natural forests to be managed based on sound silvicultural principles to improve the degrading nature of the productive forest that can generate revenue for the country and opportunity for community development.

Comparison of Regeneration and Yield Status between Community Forest and Collaborative Forest

The present article primarily addresses the silvicultural system (i.e., irregular shelter wood system) in Sal forest adopted in both community and collaborative forest in Kapilbastu district of Nepal. Systematic sampling with 0.5 percent sampling intensity along with statistical tools like SPSS and MS-Excel were used for resource inventory and data analysis, respectively. The result of the study shows notable increase in seedling status during the first year (2015/16) in community forest. A decrease in sapling number during the second year (2016/17) was noticed in Tilaurakot collaborative forest at its initial level of implementation. At the same time, community forest has higher yield status with a smaller number of trees felled in Tilaurakot collaborative forest under regeneration felling. The regeneration status of species varied insignificantly (p&gt;0.05) between the community forest and Tilaurakot collaborative forest. A recommendation is made for proper implementation of irregular shelter wood system for managing the existing degraded Sal forests of the Terai region of Nepal; however, its long-term effects on plant species diversity should also be further studied in detail.

Application of silvicultural system, yield regulation and thinning practices in natural forests: case study from western Terai

Harvesting of mature forest crop, regenerating the harvested area and tending of young crop are major silvicultural operations in forest management. Silvicultural system provides a framework for carrying out these silvicultural operations in a systematic manner. Yield is the annual amount of produce that can be realized sustainably. Similarly, thinning is the principal tending operation carried out in immature crop, is more often complicated in natural forest. This paper attempts to review silvicultural system applied in Terai region of Nepal under scientific forest management in order to regulate yield and to suggest new methods of thinning in natural forests. The study was conducted in Buddha Shanti Collaborative Forest in Nawalparasi district, western Terai Nepal. Data related to implementation status of CFM Plan were collected through field observation. Harvesting data were collected during harvesting operation. The collected harvesting data were analyzed for yield regulation. Irregular shelter-wood system was applied in Buddha Shanti CFM. The applied method of yield regulation is combination of area and stem control. Area control is applied for regeneration period. Annual harvest is controlled by number of stems. Tree harvesting area is fixed for ten years and annual harvesting amount is fixed by number of tree. In this method annual numbers of trees for harvesting are fixed. Total enumeration method was applied for thinning to find out the most frequent size of pole in selected sub compartment. During the enumeration process; distance between the every stem and fore bearing was also recorded with the help of laser distance meter and compass. A stem map was prepared with the help of Arc-GIS and the grid distance was fixed based on the most frequent size of stem. Then, one stem from each grid was selected for retaining after harvesting and remaining stems were cut down. This method provides appropriate guideline for implementing it objectively by reducing subjective judgment and provide more systematic method for thinning. The field practices of application of silvicultural system and yield regulation were found in accordance to the scientific forest management Procedures 2014 in Buddha Shanti CFM. The method for thinning applied in the CFM was found applicable to other similar type of forests. Banko JanakariA Journal of Forestry Information for Nepal Special Issue No. 4, 2018, Page: 92-97

The irregular shelterwood system as an alternative to clearcutting to achieve compositional and structural objectives in temperate mixedwood stands

Even-aged systems including clearcutting and its variants have been used for decades in North America for managing conifer-dominated stands with the goal to achieve sustainable wood production. Although clearcutting has been successfully applied in conifer-dominated stands of the boreal forest, it has proved maladapted in the temperate mixedwood forest where hardwood and shrub competition is more intense. Over time, regulated even-aged management has simplified the structure and composition of the temperate mixedwood forest which used to be dominated by late-successional stands with high conifer proportions. This study assesses alternative silvicultural systems inspired by natural dynamics for balsam fir (Abies balsamea [L.] Mill.) – yellow birch (Betula alleghaniensis Britton) stands growing in Québec, Eastern Canada. In absence of stand-replacing disturbances, spruce budworm outbreaks (Choristoneura fumiferana [Clem.]) and windthrow trigger regeneration phases through gap dynamics that result in multi-cohort, irregular stand structures. Here, we assess irregular shelterwood systems aiming at regenerating red spruce (Picea rubens Sarg.), balsam fir and yellow birch. In 2009, we established an experiment made of four randomized blocks comparing a gradient of treatments of increased cutting intensity: (i) uncut control (0% removal, 30m2/ha); (ii) continuous cover irregular shelterwood (19m2/ha of residual basal area [RBA] at the first cut, 25–30years intervals without final cut), (iii) extended irregular shelterwood (RBA 17m2/ha, final cut at year 30), (iv) uniform regular shelterwood (RBA 15m2/ha, final cut at year 10) and (v) clearcut (harvest of merchantable trees >9cmDBH). We monitored light transmission, seedbed quality and lower vegetation (<3m) during the first 5years postcut. Shelterwood treatments diversified both understory light and seedbed conditions, thereby increasing the array of available regeneration niches. Shade-tolerant red spruce and balsam fir established more successfully in the less intense irregular shelterwood treatment (continuous cover) and with a higher spruce: fir proportion. All cutting treatments increased seedling density >30cm of mid-tolerant yellow birch. Interspecific competition dominated by pin cherry (Prunus pensylvanica L.f.) and red maple (Acer rubrum L.) was the main factor limiting conifer establishment and was more abundant in the clearcut. Maintaining a partial cover in shelterwood treatments successfully limited competition expansion while regenerating target species. Even if relatively short term, results show that irregular shelterwood systems could be a sound alternative to clearcutting for regenerating and maintaining the structure of late-successional balsam fir-yellow birch stands.

Light response of Fagus sylvatica L. and Abies alba Mill. in different categories of forest edge – Vertical abundance in two silvicultural systems

In managed Dinaric montane fir (Abies alba Mill.) and European beech (Fagus sylvatica L.) forests, the light response of young beech and fir in gap microsites was studied during three consecutive growing periods (2009, 2010, and 2011) under controlled environmental conditions in stands of single-tree and irregular shelterwood silvicultural system. According to maximal quantum yield, the different response between species in microsite light categories was evidenced for silver fir on microsites with predominating diffuse light and for beech on microsites with predominating direct light, respectively.Abundance and change of share in microsite light categories was compared over different elevation belts on comparable sites between two silvicultural systems. The share of forest edge area was bigger in the irregular shelterwood system. Change in width of forest edge (20, 30 and 40m) did not affect the proportion and share of the microsite in both regions of different silvicultural system. Separation of microsite areas between both silvicultural systems, evident in lower elevation belts was not evident in the most conflict and highest elevation zone, while the absolute values of all categories above 700m in both systems were almost identical, indicating the same, small-scale irregular shelterwood system, known also as the freestyle silvicultural approach.

Dynamics of ecosystem services in Pinus sylvestris stands under different managements and site quality classes

Timber and biodiversity are considered two antagonistic ecosystem services (ES), largely influenced by silviculture and site ecological conditions. In order to address the trade-offs between these two ES over time, we performed a retrospective study at compartment level in the Pinus sylvestris forests of the Spanish Central Mountain System. Archival data from Management Plans for eight forests with contrasting silvicultural systems (uniform shelterwood system, group shelterwood system, irregular shelterwood system,) and three different site quality classes were analysed. Timber production was assessed through stand volume, harvested timber volume and a stand volume index. Biodiversity was examined through structural diversity (Gini index, Shannon tree size diversity index, Simpson’s reciprocal index and evenness index, all applied to diameter classes) and the abundance of large living trees. For all silvicultural systems investigated, stand volume and harvested timber volume have grown since the beginning of the management plans (beginning of the twentieth century in some forests). The largest yields of timber corresponded to the best quality sites with more intensive silvicultural treatments (uniform and group shelterwood systems). The uniform shelterwood system showed lower figures for structural diversity, though not always significant. The best site qualities maintained notable structural diversity values, even under the most intensive management system. The application of the different management systems over decades has revealed a synergy between timber production and structural diversity, particularly in those systems maintaining more than one age class, although results are conditioned by forest harvesting history. The interaction between historical silvicultural treatment and site quality has been identified as an important source of information to understand forest dynamics and functioning of ES provision.

Does scientific forest management promote plant species diversity and regeneration in Sal (Shorea robusta) forest? A case study from Lumbini collaborative forest, Rupandehi, Nepal

Scientific forest management is an emerging need for managing existing natural forests of Nepal on the basis of silvicultural intervention. The study was carried out in Lumbini Collaborative Forest at Rupandehi District of Nepal, where Sal (Shorea robusta) forests are being managed under Irregular Shelterwood System with eighty years of cutting cycle since 2011–2012. The study was purposed to find out the intial effects of silvicultural intervention on plant species diversity and regeneration of Sal forest. The vegetative sampling was done using quadrate method based on the principle of simple random sampling both in the managed as well as the unmanaged parts of forest. The study found out remarkable increase in regeneration as well as decrease in plant diversity in the managed first and second-year stands (Block I and Block II respectively) as compared to the unmanaged stand (Block III) at its initial level of implementation. The mean value of diversity, richness, evenness, dominance index and regeneration of S. robusta varied significantly (p?0.05) between the managed blocks (stands). The seedling density of S. robusta was found higher in the managed blocks (Block I and Block II) as compared to the unmanaged one (Block III) in terms of height class. The study recommends implementation of Irregular Shelterwood System for managing the existing degraded Sal forests of the Terai region of Nepal, however, its long term effects on plant species diversity should be further studied in detail.Banko Janakari, A Journal of Forestry Information for NepalVol. 25, No. 1Page: 20-29

Insignificant effect of management using irregular shelterwood system on the genetic diversity of European beech (Fagussylvatica L.): A case study of managed stand and old growth forest in Slovenia

In the presented case study, we aim to understand the impact of an irregular shelterwood system (ISS) on the genetic diversity of European beech (Fagus sylvatica L.) firstly by comparing managed stand to old growth beech forest and secondly by comparing two successive generations in both managed and old growth stands. Studies on European beech to date have not yet investigated the effect of ISS on its genetic diversity and have rarely addressed the effect of management on the genetic diversity of successive generations.The study was conducted in two mixed beech stands in Slovenia; the unmanaged Rajhenavski Rog old-growth European beech forest reserve and beech forest in Osankarica, managed according to ISS. All 140 sampled adult trees and saplings were genotyped at 16 nuclear microsatellite loci.ISS mimics genetic processes of the old growth rather well in the studied managed stand. The comparisons of diversity measures between managed and old growth stands did not reveal any significant differences between the two for any of the cohorts; the differences between the cohorts from the same stand were not significant. The observed significant shift in allele frequencies at four loci between successive generations could not be unambiguously attributed to management. Cohorts from the same stand had similar genetic structure, but six individuals from the managed stand formed a unique cluster.No convincing evidence of the effect of ISS on genetic diversity of the studied managed beech stand was found.

Managing Heterogeneous Stands Using a Multiple-Treatment Irregular Shelterwood Method

In eastern Canada, past diameter-limit cutting left a legacy of low-density and heterogeneous hardwood stands. The complex stand structure and variable density hinders the application of uniform treatments for stand regeneration and rehabilitation. This article describes an innovative approach called the “multiple-treatment irregular shelterwood system.” Two variants of the method are presented to achieve extended irregular shelterwood and continuous cover irregular shelterwood. The silvicultural prescription recognizes microstands that are grouped into microtypes based mainly on sapling stocking and tree canopy closure. For each microstand, harvesting of mature trees is allowed if the understory has sufficient stocking of saplings. If not, partial cutting and/or soil scarification is prescribed to promote regeneration. The design of the trail system and the sequence of entries are adapted for each irregular shelterwood variant. Results from two field trials show that this method is operationally feasible. Existing advance regeneration was adequately protected, and favorable microsite conditions were created when sufficient regeneration was lacking. Half of the volume of wood was harvested from test sites with no high grading of species composition or tree quality, while maintaining a high degree of structural heterogeneity.

History, current status and future prospects of uneven-aged forest management in the Dinaric region: an overview

Summary The development of uneven-aged forest management in the Dinaric region (north-west Balkans) is reviewed. Unevenaged silviculture has been the major silvicultural system in the region since regular forest management began in the second half of the nineteenth century. Regular forest management in former virgin forest areas began as selection forest management mainly because of the awareness of the importance of multilayered continuous forest cover for preventing soil erosion on carbonate substrate. The observed period of more than 100 years has seen several changes to unevenaged forest management ranging from the complete domination of rigid selection forest management to the gradual acceptance and eventual domination of the irregular shelterwood system and finally to the acceptance of freestyle forest management, which is presently practiced in the Slovenian part of the Dinaric region. Freestyle silviculture combines practices of different silvicultural systems. By using this system, consideration for site conditions and heterogeneous stand dynamics at small spatial scales is possible. In the observed period, some stand parameters of Dinaric forests have changed substantially. Growing stock has increased significantly, the number of large-diameter trees has increased and alternation of the main tree species (silver fir and European beech) has occurred. The development of uneven-aged forest management is described and its prospects are discussed.

Comparison of various cutting systems affecting those morphological features that determine stability in the Pilsko high mountain spruce forest

Charakterystyka wybranych cech morfologicznych świerków wpływających na ich stabilność, ukształtowanych w wyniku stosowania różnych rębni w borze górnoreglowym na Pilsku