Optimizing Stand Spatial Structure by Using Neighborhood-Based Quantitative Indicators: A Case of Boreal Forests

Background: Over the past fifty years, societies have placed increasing demands on forests, and their use has shifted gradually from wood production to the diversified benefits and functions of ecosystem services. The effects of neighborhood-based structural characteristics on regulating growth and promoting sustainability have therefore drawn much attention. However, direction for managing natural mixed forests using neighborhood-based indicators are still not clear.Methods: In this study, a tree-level harvest planning tool that considers four neighborhood-based structural parameters (species mingling, diametric differentiation, horizontal spatial pattern and crowdedness of trees) while concurrently recognizing other operational constraints, was developed using simulated annealing algorithm. The approach was applied to four 1-ha mapped stands in northeast China, namely a natural larch forest (NLF), a natural birch forest (NBF), a natural secondary forest (SEF), and a Korean pine broad-leaved forest (KBF). Results: The tree-level harvest optimization improved the objective function values by approximately 78.33% of NLF, and 134.96% of NBF, and 156.70% of SEF and 252.95%, respectively. The optimal harvest intensities for partial cutting activities varied from 22.16% (SEF) to 26.07% (NBF) of the standing volume. In evaluating the four neighborhood-based structural parameters, both species mingling and crowdedness have the highest priority to be used in structure-based forest management.Conclusions: Our results demonstrated that that the commonly used neighborhood-based structural parameters could be used to control the spatial layout of potential harvest trees, in turn may be conducive to regulate the growth and stability of forests.

The Impact of Conservation Agriculture Practice and Socio-Economic Factors on Yam Production (Dioscorea alata and Dioscorea rotundata) in Kalagoé (Lobaye, Central African Republic)

Few studies have been carried out on Yam (Dioscorea alata and Dioscorea rotundata) in relation with the conservation agriculture in CAR. Yam is cultivated in limited quantities despite its role in improving food security. In order to increase Yam production in the smallholder farms in CAR, the potential effect of crop management practices like nutrient application, mulching and minimum tillage on Yam crop yield and household financial returns, needs to be understood. A questionnaire was prepared and used as a tool for the collection of information from 100 producers of Yam without distinction of ages and sexes. In order to determinate the agronomical performance of Yam, two plots were explored. The first plot with 625m² (12.5m ×50m), known as the improved plot, is a plot on which all conservation agriculture practices were applied. The second plot, known as the traditional plot, is one on which traditional farming techniques were applied. The results of the survey show that 32% of the farmers are in favor for CA practice nevertheless 68% are not favor, which shows that a large proportion of farmers in Kalangoé are not aware of the benefits of this technique. The most widely cultivated variety is D. rotundata, because of its taste qualities. Some producers also grow both varieties at the same time. Some producers (28%) clear their plots by cutting down all the trees to leave the field bare, while a large number (72%) practice partial cutting by removing the shrubs to keep the large trees in order to protect the forest. A large number of producers (62%) also burn their plots for various reasons, including freeing up space and making it easier to move around the field because the plant debris from clearing prevents them from working properly. A small proportion of producers (26%) practice ploughing against 74% who do not practice this technique. The conservation agriculture practice applied to Yam gave interesting agronomic performances (growth and production parameters) than the farmers practices.

Six Decades of Growth and Yield and Financial Return in a Silviculture Experiment in Northern Hardwoods

The Cutting Methods Study at the Ford Forest in the Upper Peninsula of Michigan, USA, was established in 1956 and has been maintained continuously on a 10 year cycle. Methods consist of three diameter limits (DL; 13, 30, and 41 cm), single-tree selection to three residual basal area limits (STS; 11, 16, and 21 m2ha−1), and light improvement (LI) focused on improving tree grade. Long-term results show that the 41 cm DL produced the greatest managed forest value and cumulative sawlog production, followed by the STS to 11 m2ha−1 residual basal area. STS treatments and LI were uniformly superior at improving standing tree grade. In contrast, treatments that emphasize removal of large diameter trees while retaining moderate residual basal area (the 41 cm DL and 11 m2ha−1 STS) produced the largest harvest volumes of high-grade sawlogs, driving financial performance. Stand density has declined in all treatments except the 30 and 41 cm DL, where it has increased, and these two treatments have larger abundance of saplings and poles. Alternative partial cutting methods such as selection to lower residual basal areas and medium-intensity diameter-limit cuts thus may provide greater financial returns and higher average quality, and could have implications on regeneration and long-term sustainability. Study Implications: Long-term comparison of alternative partial cutting practices in northern hardwoods in the Upper Peninsula of Michigan over 60 years reveals that Arbogast-based single-tree selection is inferior using financial and volume yield criteria. Alternatives that remove more of the larger trees appear over time to increase regeneration and harvested tree quality, which in turn drives financial performance. However, treatments with extremely high volume removals perform poorly against all others, and have few, if any, redeeming financial, silvicultural, or ecological qualities.

Management options for the conversion of allochthonous coniferous forest patches towards more natural species composition in the Vorpommersche Boddenlandschaft National Park, NE Germany

The conversion of coniferous tree plantations towards natural self-regenerating forests is one of the targets of forestry in Europe and particularly desirable in national parks. The aim of this study was to evaluate the effectiveness of different conversion approaches (conducted once) on natural forest development in man-made spruce plantations. We studied the effects of three distinct management options (partial-cutting [PC], clear-cutting with timber removal [CC] and clear-cutting with timber remaining [CCr]) six years after application on tree regeneration (sapling identity, abundance, height, browsing intensity) and understorey species composition in former spruce plantations within the Vorpommersche Boddenlandschaft National Park in Northeastern Germany. An unmanaged spruce [M] and near-natural beech [N] stands were considered as local references. The sites differed significantly in tree regeneration and understorey species composition. The abundance of native tree saplings was highest at site CCr, their height did not differ among sites, while browsing intensity was most pronounced at site CC. Understorey species composition of all management options was equally dissimilar to site N. However, site CCr contained more species that are typically abundant in local beech forests. Clear-cutting of spruce plantations with dead wood remaining on site favoured the natural regeneration of native trees and understorey vegetation compared to clear-cutting with timber removal, partial-cutting and no management. Herbivore browsing detrimentally affected tree regeneration independent of the treatment. Clear-cutting with timber removal promoted the dominance of competitive herbaceous species that may hamper long-term forest regeneration. We conclude that progression of site CCr appears to proceed fastest towards natural forest conditions. Further long-term data is required to derive clear trends regarding time and direction of forest regeneration. Keywords: forest conversion, spruce plantations, beech forest, natural tree regeneration, understorey species composition, deer browsing

Exploring the various parameters of CO2 laser in the cutting of paper

The revolution in the printing industry started by digital printing has resulted in the introduction of personalised production of small runs, fast job changes and short deadlines. By introducing digital printing into mainstream and production focus, even for the largest printing machine manufacturers, a new era of the graphic industry has just begun. After these significant changes in the printing process, the following process of graphic production – post-press needs to be digitalised. The initial goal is to back up the possibilities of digital printing and enable it to be applied as widely as possible to its full potential. Postpress has become a bottleneck in the digital world. One of the analogous processes, which is the focus of improvement, is the cutting of graphic materials in irregular shapes in the process of creating packaging. The use of lasers enables the digitisation of the die-cut or partial cutting post-press process. Cutting of different shapes is obtained when the laser touches the substrate and where it evaporates at that moment. A thermal process accompanies this evaporation, that to a greater or lesser extent affects the substrate to be cut. The parameters that govern laser are the subject of this paper. The development of laser cutting technology has opened various possibilities for innovations in the graphic and printing industry. Since this is still considered as new technology, extensive researches on its options are essential to reach the full potential of this technology. This paper is going to analyse the overall characteristics and use of laser technology in the graphic industry by focusing on the processing of paper materials. Indispensible to mention are the advantages and disadvantages of this technology. There are a lot of comparisons among existing technologies developed for cutting graphic materials and paper. The importance of this topic is concerning all production phases of the graphic product – from processing the raw material to cutting the final product such as packaging. Regarding that, the scope of the laser processing of the graphic materials is reviewed. The paper gives suggestions for further research and experiments regarding this topic.

Wind damage over 21 years across different levels of tree removal in natural-origin mixed forests of northwestern British Columbia

In many regions, forestry practices are shifting to partial harvesting approaches that seek to maintain species and structural diversity in managed forests. We monitored windthrow for 21 years following partial cutting treatments with 0%, 30%, and 60% removal in a large, replicated experiment located in mixed-species mature and old-growth forests of fire origin. There was no evidence that wind damage to merchantable trees (≥17.5 cm) varied among the three removal treatments. We found no evidence of a short-term spike in susceptibility to windthrow after partial cutting during the initial years following treatment. Over 21 years, a total basal area of 2.4 m2·ha–1 was damaged, which was 5.9% of the original standing basal area at the start of the experiment. We found clear differences in susceptibility to windthrow among the different tree species. The percentage of original standing trees that were windthrown varied from 0% to 23.7%. Eight of nine species had ≤10% damage over the monitoring period. Foresters should be aware of differences among tree species in risk of wind damage but should not use a general concern about susceptibility to windthrow as a reason to avoid partial cutting systems (that can achieve a diversity of management objectives) in structurally diverse, multispecies forests.

Natural Regeneration Following Partial and Clear-Cut Harvesting in Mature Aspen-Jack Pine Stands in Eastern Canada

Over the last three decades, the ecological basis for the generalized use of even-aged silviculture in boreal forests has been increasingly challenged. In boreal mixed-wood landscapes, the diminishing proportion of conifers, to the benefit of intolerant hardwoods, has been a primary concern, coupled with the general rarefication of old-growth conifer-dominated stands. In this context, partial cutting, extended rotations and forest renewal techniques that eliminate or reduce regenerating hardwoods have been proposed as means of regaining greater conifer cover. As a result, experimentation and industrial application of various forms of both variable retention and partial harvesting are occurring across the commercial Canadian boreal forest. In this study, we compared the effects of two harvesting intensities, clearcutting and low-intensity partial cutting (removal of 25–31% of tree basal area), on hardwood and conifer regeneration levels 7–19 years following treatments in aspen (Populus tremuloides)-dominated stands and verified whether regeneration differences existed between micro-sites on and off machinery trails. The abundance of aspen regeneration increased with percent basal area removal and was positively correlated to the abundance of mature aspen prior to harvesting. The abundance of fir (Abies balsamea) regeneration after partial cutting was similar to controls and higher than after clear-cutting and was positively correlated with ground cover of mixed litter (i.e., mixture of needles and leaves) and negatively correlated with ground cover of broadleaf litter. These results suggest that it is possible in boreal mixed-woods to control aspen abundance and promote or maintain conifer regeneration through silvicultural treatments that limit canopy opening and promote mixed forest floor litter.