Optimal management would be different for stands where ingrowth deviates from this level. Moreover, understorey trees revive at different rates and their growth rate varies much. As a result, temporally irregular regeneration may provide a fairly constant supply of understorey trees to upper canopy layers.
The models that were used in growth simulation Pukkala et al.
Therefore, there is a possibility that the post-thinning growth was over-estimated after heavy high thinnings. The significance of this possibility was analyzed by conducting simulations in which the growth of a high-thinning spruce stand was reduced during 5 post-thinning years by decreasing the random stand effect of the diameter increment model by two standard deviations. Slower initial growth means that competition increases slower resulting in faster growth during later 5-years periods. In addition, a majority of the growth observations of this experiment represented immediate post-thinning growth.
Taking into account that spruce understoreys are usually vigorous under all canopies except a dense and pure spruce canopy, it may be concluded that the impact of thinning stress on the results of this study would remain rather small. The optimization problem was formulated so that thinning intensity was specified for three diameter classes per tree species and thinning event.
Several previous studies have also used three thinning intensities to specify and optimize the type of thinning Valsta ; Pukkala and Miina ; Vettenranta and Miina All models and optimization problems simplify reality. Realism should be added as long as it has a significant influence on the results. Those steps that were taken in the current study were all shown to be significant, having a strong impact on our comprehension about the optimal management of boreal forests. Future studies will show whether further steps towards realism are necessary. Most probably these analyses would enhance the positive effects that mixed stands and uneven-aged stand structures have on the profitability of forestry Rollin et al.
It would also be interesting to analyze the influence of market trends on optimization results. The price of spruce pulp wood has shown a decreasing trend whereas the price of small-sized birch has increased Anonym If the same trend continues, it would be profitable to increase the share of birch more than suggested in this study.
This article is published under license to BioMed Central Ltd. Research Open Access.
Continuous Cover Forestry (Managing Forest Ecosystems #23) (Hardcover)
Stand management optimization — the role of simplifications. Forest Ecosystems 1 Abstract Background Studies on optimal stand management often make simplifications or restrict the choice of treatments. Methods This study analyzed the impacts of simplifications on the optimization results for Fennoscandian boreal forests.
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Results Forced low thinning, cleaning the plantation from the natural regeneration of mixed species and ignoring advance regeneration all had a major impact on optimization results. Conclusions The results suggest that, with the current management costs and timber price level, it may be profitable to switch to continuous cover management on medium growing sites of Fennoscandian boreal forests. Plantation management Continuous cover forestry Even-aged management Mixed stands. The following set of optimizations was as conducted: 1. Otherwise the same but thinning type was not restricted to low thinning.
This suggests that financial maturity of the dominant tree layer dictates the timing of final felling instead of stand age.
Both thinnings were high thinnings since species having the largest diameters were thinned most silver birch in the first thinning, pine in the second thinning. In addition, both pines and spruces were thinned from above in the second thinning. As a consequence, the mean tree diameter decreased from Almost no spruce was removed in the first thinning since spruces were clearly smaller than pines and silver birches. Pubescent birches were removed in the first thinning although they were not larger than spruces.
This is because the growth of pubescent birch starts to decline sooner than the growth of conifers. Figure 2 Development of stand basal area and mean tree diameter dbh in a spruce plantation when a mixture of pine, spruce and birch is left in the tending of young stand optimization problem 4. We acknowledge that there is some subjectivity in such an analysis as a few studies might have been analyzed differently by other evaluators. Yet, we are confident in the general portrait that we present. This may mean that no matter the silvicultural approach used, some species will be negatively affected.
This was rarely considered in the papers we analyzed. Furthermore, scaling up from the stand to the landscape scale is often much more complex than a simple multiplication.
Nevertheless, evaluating the cumulative effects of implementing either system over a whole landscape is a difficult task, and for economic and logistical reasons has not yet been undertaken. Furthermore, both approaches encompass various silvicultural subsystems. Hence, the ecological effects observed may be quite different among the subsystems. Although this has been argued based on intuition or specific local studies, our review, based on a large range of indicators and many different taxonomic groups, clearly demonstrates that no single approach can be relied on and that both approaches are needed to ensure a greater number of positive impacts.
Our review also clearly shows the importance of maintaining protected areas as some taxonomic groups were found to be negatively affected no matter the form of management used. In the intervening matrix, a variety of silvicultural approaches will provide a gradient of conditions for less sensitive species. Factors that cause decline in some species following any type of forest management should be further studied as it may be possible to mitigate some of these effects.
For example, where soil disturbance is a factor, comparing winter versus summer harvest by silvicultural system could help mitigate some negative effects. As vernal pools and their surroundings are critical for herpetofaunal communities a group responding negatively to all silvicultural approaches , it could be worthwhile to implement study designs where the interaction between harvesting and the pools is explicitly evaluated e.
Such designs would help to disentangle the effects of multiple factors and contribute to the development of silvicultural guidelines to protect more fragile species outside conservation areas. This idea of disentangling confounding effects applies to other situations as well. In this way, several authors e. Data have not been archived because this article does not contain data. PN performed the literature review and produced all the table and figures. PN and DK led the writing of the manuscript. All authors contributed critically to the drafts and gave final approval for publication.
Ecol Evol. National Center for Biotechnology Information , U. Journal List Ecol Evol v. Philippe Nolet, Email: ac. Corresponding author. Email: ac. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. Associated Data Supplementary Materials. Abstract With an increasing pressure on forested landscapes, conservation areas may fail to maintain biodiversity if they are not supported by the surrounding managed forest matrix. Open in a separate window.
Figure 1. Figure 2. Figure 3. Table 3 Number of reviewed studies that considered timescale and spatial scale.
Forest ecosystem management: the millennium planning approach
Future research Factors that cause decline in some species following any type of forest management should be further studied as it may be possible to mitigate some of these effects. Selective felling as a potential tool for maintaining biodiversity in managed forests. Biodiversity and Conservation , 13 , — Forest Ecology and Management , , — Forestry Chronicle , 75 , 49— Natural fire regime: A guide for sustainable management of the Canadian boreal forest.
Silva Fennica , 36 , 81— Early performance of planted hybrid larch: Effects of mechanical site preparation and planting depth. New Forests , 46 , — Forest management is driving the eastern North American boreal forest outside its natural range of variability. Frontiers in Ecology and the Environment , 7 , — Plant diversity in a managed temperate deciduous forest: Understorey response to two silvicultural systems. Journal of Applied Ecology , 41 , — Can forest management based on natural disturbances maintain ecological resilience? Canadian Journal of Forest Research , 36 , — Forest Ecology and Management , , 81— The third type of silviculture was a mixture of the two systems, which in this article is called any-aged forest management Haight and Monserud Boncina has called it freestyle forest management.
Forest management under each silvicultural system was optimized from the viewpoint of the forest landowner, maximizing the economic benefit obtained from the forest. Then, it was calculated how much the forest produces other services which may not be of primary significance to the landowner but are important to the society.
The performance of different silvicultural systems in multi-objective forest management was also analyzed. The services included in the analyses are important to Finnish people, and there are numerical methods available for evaluating the amounts of the selected services. Knowing the effect of specific silvicultural methods on these services could provide scientific evidence for adjusting silvicultural policies. Since it was foreseen that a single management system is not the best in every respect, an overall efficiency analysis was conducted to find out whether some of the management systems can be classified as efficient or inefficient producers of ecosystem services.
The method used in this comparison was the data envelopment analysis Cooper et al.