共查询到20条相似文献，搜索用时 437 毫秒
1.
2.
Z. Villegas M. Peña-Claros B. Mostacedo A. Alarcón J.C.Licona C. Leaño W. Pariona U. Choque 《Forest Ecology and Management》2009
Silvicultural treatments are often needed in selectively logged tropical forest to enhance the growth rates of many commercial tree species and, consequently, for recovering a larger proportion of the initial volume harvested over the next cutting cycle. The available data in the literature suggest, however, that the effect of silvicultural treatments on tree growth is smaller in dry forests than in humid forest tree species. In this study, we analyze the effect of logging and application of additional silvicultural treatments (liana cutting and girdling of competing trees) on the growth rates of future crop trees (FCTs; i.e., trees of current and potentially commercial timber species with adequate form and apparent growth potential). The study was carried out in a tropical dry forest in Bolivia where a set of 21.25-ha plots were monitored for 4 years post-logging. Plots received one of four treatments that varied in intensity of both logging and silvicultural treatments as follows: normal (reduced-impact) logging; normal logging and low-intensity silviculture; increased logging intensity and high-intensity silviculture; and, unlogged controls. The silvicultural treatments applied to FCTs involved liberation from lianas and overtopping trees. Results showed that rates of FCT stem diameter growth increased with light availability, logging intensity, and intensity of silvicultural treatments, and decrease with liana infestation degree. Growth rate increment was larger in the light and intensive silvicultural treatment (22–27%). Long-lived pioneer species showed the strongest response to intensive silviculture (50% increase) followed by total shade-tolerant species (24%) and partial shade-tolerant species (10%). While reduced-impact logging is often not sufficient to guarantee the sustainability of timber yields, application of silvicultural treatments that substantially enhanced the growth rates of FCTs will help move the management of these forests closer to the goal of sustained yield. 相似文献
3.
4.
The economic problems of private forestry are intimately boundup with those of the State and the supporting industries. With the aim of becoming 25 per cent self-supporting, and tocreate a U.K. industry with overall efficiency, competitiveby world standards, a national forest is proposed of 7 millionacres with a minimum annual planting programme of 120,000 acres.This could be achieved 60 per cent by the State and 40 per centby private interests. Eight full-scale fully integrated sawmills, pulp, paper, andparticle board mills will be required for each 1 million acresof coniferous forests. The industries should be situated locallyto the forests, to draw timber supplies from a radius of notmore than 30 miles, and with the provision of adequate internaland external roads. To maintain confidence in a long-term industry there is theneed for continued Government support. If the private sectoris to play its part there must be no change in the grant aidsystem and the helpful tax structure. For efficiency in the forest there must be careful investmentplanning and choice of site, improved management, silviculture,harvesting and marketing techniques, increased specializationof men and machines, and a proper integration of forestry, agriculture,sporting, fishing, and public amenity. 相似文献
5.
The impacts on bird assemblages of silvicultural alternatives to clearfelling in lowland wet eucalypt forest were studied over a decade at Warra, Tasmania. Using a multiple-visit point-count procedure and a before-after-control-impact design, indices of relative incidence were derived for the 44 bird species recorded at 177 survey-points, and used in both univariate and multivariate analyses. The majority of species had strong associations with either mature forest or young regeneration post-harvest, with very few more generalist species present. Bird assemblages in the unharvested mature forest were not static over this period, but this could not readily be explained by the expansion of forest harvesting in the surrounding landscape. However, the shift was subtle compared to the responses to harvesting, which induced a fundamental change in assemblage composition irrespective of the silvicultural system applied. The ability of the different systems to retain elements of the original mature forest avifauna varied markedly. Dispersed retention silviculture was no better than clearfelling, with or without unharvested understorey islands in the latter system. By contrast, both the unharvested parts of coupes subjected to stripfelling, and the retained aggregates in coupes subjected to aggregated retention silviculture, maintained mature forest bird assemblages. The long-term value of stripfelling for mature forest avifauna is compromised because the unharvested strips will be harvested mid-rotation. Aggregated retention silviculture, however, is designed for long-term retention of mature forest in aggregates, and our results suggest that this system may offer a means of sustaining mature forest bird assemblages at the coupe-level. However, individual mature forest species varied in their degree of tolerance, and we suggest that no system is completely resilient to harvesting effects. 相似文献
6.
关于加强森林培育学理论研究的探讨 总被引：1，自引：0，他引：1
随着科学发展和社会对森林需求的增加, 加强森林培育学理论研究显得十分必要, 但是如何通过开展理论研究, 以便最终形成能够有效指导森林培育技术的理论体系, 目前尚缺乏广泛讨论和研究。为此, 文中提出以系统科学的思想和方法为指导, 从森林系统的起源、立地条件与森林生长的相互作用关系、森林系统的功能及其实现基础、森林系统的动态变化规律及森林培育技术对森林最终目标的影响等方面开展研究。随着研究在深度和广度的展开, 森林培育学的理论体系定会逐渐形成和完善。 相似文献
7.
《Forest Policy and Economics》2000,1(1):71-79
This paper examines factors determining the payment schemes for silvicultural workers when activities are performed in-house rather than contracted out. The payment schemes examined include piece rates, hourly wages and salaries (monthly or bi-weekly). The research is based on data from a 1997 survey of British Columbia forest companies. Results of our analysis indicate that firms choose silvicultural payment schemes to synchronize the attributes of activities with the firms’ characteristics for the purpose of economizing on transaction costs. Generally, larger companies rely more on wages, and especially salaries, than do smaller companies. The latter are more likely to opt for piece-rate payment schemes. The more workers that a company hires directly, the more likely that a piece-rate system is adopted. However, as the length of silvicultural season increases, the greater the chance that the forest companies rely on salaries. 相似文献
8.
9.
我国森林培育学发展的战略研究 总被引：6，自引：0，他引：6
本文通过对世界近几十年来森林培育学在理论和技术方面的进展，以及我国森林培育学的现状和存在的问题的论述，提出了森林培育学科的发展战略，并强调了今后人工林的培育应在景观水平上进行生态系统经营。 相似文献
10.
《Journal of Sustainable Forestry》2013,32(3-4):353-387
Changes in old growth structural features as well as susceptibilities to disturbances were projected in stands typical of the eastern Washington Cascades. Projected changes with and without silvicultural operations were made. Doing no silvicultural activities in these stands will not rapidly increase old growth structural features and will allow the stands to become very susceptible to insects and wind breakage, followed by fires. Specifically designed silvicultural operations can maintain or rapidly increase old growth structural features and reduce susceptibilities to most disturbances. Unless some trees killed in the silvicultural operations are removed, the treated stands will become very susceptible to fires. Removing some of the thinned trees can also offset the costs of doing the operations. A landscape approach of treating various stands with different silvicultural regimes will probably best maintain a dynamic balance of structural features, a reduced susceptibility to various disturbances, and a steady flow of wood for manufacturing. 相似文献
11.
介绍了营林、集材拖拉机的特点及我国营林、集材拖拉机的基本现状及其发展历史;分析了营林、集材拖拉机目前的需求状况及市场前景;提出了在林权改革新形势下保留和发展营林、集材拖拉机的必要性和重大意义. 相似文献
12.
M. Peña-Claros T.S. Fredericksen A. Alarcón G.M. Blate U. Choque C. Leaño J.C. Licona B. Mostacedo W. Pariona Z. Villegas F.E. Putz 《Forest Ecology and Management》2008
Use of reduced-impact logging (RIL) techniques has repeatedly been shown to reduce damage caused by logging. Unfortunately, these techniques do not necessarily ameliorate the low growth rates of many commercial species or otherwise assure recovery of the initial volume harvested during the next cutting cycle. In this study, we analyze the effect of logging and application of additional silvicultural treatments (liana cutting and girdling of competing trees) on the growth rates on trees in general and on of future crop trees (FCTs) of 24 commercial timber species. The study was carried out in a moist tropical forest in Bolivia, where we monitored twelve 27-ha plots for 4 years. Plots received one of four treatments in which logging intensity and silvicultural treatments were varied: control (no logging); normal (reduced-impact) logging; normal logging and low-intensity silviculture; and, increased logging intensity and high-intensity silviculture. Tree growth rates increased with intensity of logging and silvicultural treatments. The growth rates of FCTs of commercial species were 50–60% higher in plots that received silvicultural treatments than in the normal logging and control plots. Responses to silvicultural treatments varied among functional groups. The largest increase in growth rates was observed in FCTs belonging to the partially shade-tolerant and the shade-tolerant groups. These results indicate that silvicultural treatments, in addition to the use of RIL techniques, are more likely to result in a higher percentage of timber volume being recovered after the first cutting cycle than RIL alone. 相似文献
13.
14.
通过对香椿林分进行调查，井进行不同抚育方式、施肥和造林密度试验．结果表明，实行椿油（菜）间种是香椿幼林抚育的最佳方式；合理施肥显著促进林木生长，并以单施尿素4．5km／100m2或过磷酸钙7．5kg／100m2，15kg／100m2和22．5kg／100m2．以及混施尿素3kg／100m2加过磷酸钙15kg／100m2增多效果更为显著；若以培育香椿中小径级用材为目标，造林密度以1667～2615株／hm2为宜．并根据这些结果，提出了香椿优化栽培技术组合． 相似文献
15.
16.
Mathilde Redon Sandra Luque Frédéric Gosselin Thomas Cordonnier 《Annals of Forest Science》2014,71(7):751-760
Context
Uneven-aged management systems based on selection silviculture have become popular in European mountain forests and progressively replace other silvicultural practices. In time, this trend could lead to a homogenisation of the forest mosaic with consequences on structural indices recognised as beneficial to forest biodiversity.Aims
This study was conducted to investigate the potential effects of a generalisation of the selection silvicultural system on structural diversity in the forest landscape with consequences for forest biodiversity conservation.Methods
We compared four structural indices (tree species richness, diameter heterogeneity, deadwood volume and basal area of mature trees) in five different stand types typical of the northern French Alps, using forest plot data in the Vercors mountain range. Through virtual landscape simulations, we then calculated predicted mean proportions of stand types under two different conservation strategies: (i) maximising mean index values at the landscape level and (ii) maximising the number of plots in the landscape with index values above given thresholds.Results
Multi-staged forests did not maximise all indices, the best solution being to combine the five stand types in uneven proportions to improve biodiversity conservation.Conclusion
The expansion of selection silviculture in European heterogeneous forest landscapes could enhance biodiversity conservation if other stand types with complementary structural characteristics are maintained. 相似文献17.
《Journal of Sustainable Forestry》2013,32(1):17-28
Abstract Mexican forestry science has been affected by its relationship with the Mexican state, and by the history of state forestry institutions. Conflicts between conservationists and politicians engaged in land reform resulted in loss of power for conservationists in the forest department in the 1940s. More recent political struggles for control of the forests color the interpretations which forest communities and foresters place upon forest management practices, and may lead to present day debates over specific silvicultural practices. If foresters are to apply silvicultural techniques, they need to be aware of the political experience of the landowners they work for, and the political implications of their own technical knowledge. 相似文献
18.
The purpose of this study was to predict the likely amounts of carbon sequestration on a national scale for Japan in the Article-3.4
private planted forests of the Kyoto Protocol during the first commitment period. We regarded the planted forests that had
undergone silvicultural practices such as weeding, pruning, and thinning since 1990 as Article-3.4 planted forests in accordance
with the definition given by the Forestry Agency of Japan. Regression models were developed to predict the forest areas that
had undergone silvicultural practices, employing silvicultural subsidies and forest workers' wages as predictor variables.
Then the time series changes in the predictor variables were provided by extending their recent trends, with the result being
that the forest areas that have undergone silvicultural practices were predicted on the basis of the three scenarios of the
variables. Thus, the Article-3.4 forest area was calculated considering overlaps of silvicultural practices over fixed stands,
and the area was converted into the amount of carbon sequestration by multiplying it by coefficients such as a volume table,
biomass expansion factor, and others. The result implied that Article-3.4 private planted forests were expected to sequester
8.16–8.87 Mt-C year−1 during the first commitment period. These amounts cover 63%–68% of the carbon sequestration goal by land-use change and forestry
activities capped under the Marrakesh Accords. To realize this prediction, it is important to provide a sufficient silvicultural
subsidy to last until the end of the first commitment period and to implement silvicultural practices on the forest stands
that have not undergone such practices since 1990. 相似文献
19.
John A. Stanturf Robert C. Kellison F. S. Broerman Stephen B. Jones 《Forest Policy and Economics》2003,5(4):407
The history of forest management in the southern United States has been a process of intensification and the pine forests of the Coastal Plain can be regarded as in the early stage of crop domestication. Silviculture research into tree improvement and other aspects of plantation establishment and management has been critical to the domestication process, which began in the early 1950s with the paradigm shift from natural stand management to plantation forestry. Advances were incremental innovations that relied heavily on basic knowledge gained in other disciplines and from formal university–industry silviculture research cooperatives. These cooperatives played a critical role in the domestication process, especially as they disseminated technological innovations. Sixteen major pulp and paper companies were examined in terms of participation in research cooperatives, expenditures on research and implementation of innovations. Despite a lack of relationship between company size (gross sales) and expenditures on forestry research, implementation of innovations was significantly related to research expenditures, timberland owned and total sales. Adjusting for timberland ownership or annual sales, the companies that spent the most on forestry research did the best job implementing research results. Emerging trends in industry structure and support for research may indicate a new role for public research institutions in the South, and call into question the need for silviculture research cooperatives. 相似文献
20.
《Forest Ecology and Management》1997,95(2):141-152
This paper reports the results of a case study in the characterization of economics benefits of forestry research. An ex ante perspective is adopted given most of the impacts will occur well into the future. Improved methods of anticipating the benefits of research and technological change in forestry are needed given the increasing scarcity of research resources in the sector. The approach employed in this paper attempts to reflect the role of time lags in research, development and adoption, as well as the adoption costs, uncertainty and policy change. Both deterministic and stochastic cost-benefit algorithms were employed to calculate the benefits of silvicultural research on black spruce (Picea mariana [Mill.] B.S.P.), a relatively slow growing boreal tree species. Despite preconceptions that such research is not economically viable, the results suggest that silvicultural research on slow growing species may be a worthwhile investment. To be worthwhile from a wood growing perspective real stumpage values must increase through time. A priori justification of this particular silviculture and hence the research project also included improved wildlife habitat conditions. However, these benefits are ill-defined and probably should not be used as a rationale for either the research or the silvicultural practice itself without further study. 相似文献