Forest carbon storage in the northeastern United States: Net effects of harvesting frequency,post-harvest retention,and wood products

Temperate forests are an important carbon sink, yet there is debate regarding the net effect of forest management practices on carbon storage. Few studies have investigated the effects of different silvicultural systems on forest carbon stocks, and the relative strength of in situ forest carbon versus wood products pools remains in question. Our research describes (1) the impact of harvesting frequency and proportion of post-harvest structural retention on carbon storage in northern hardwood-conifer forests, and (2) tests the significance of including harvested wood products in carbon accounting at the stand scale. We stratified Forest Inventory and Analysis (FIA) plots to control for environmental, forest structural and compositional variables, resulting in 32 FIA plots distributed throughout the northeastern U.S. We used the USDA Forest Service's Forest Vegetation Simulator to project stand development over a 160 year period under nine different forest management scenarios. Simulated treatments represented a gradient of increasing structural retention and decreasing harvesting frequencies, including a “no harvest” scenario. The simulations incorporated carbon flux between aboveground forest biomass (dead and live pools) and harvested wood products. Mean carbon storage over the simulation period was calculated for each silvicultural scenario. We investigated tradeoffs among scenarios using a factorial treatment design and two-way ANOVA. Mean carbon sequestration was significantly (α = 0.05) greater for “no management” compared to any of the active management scenarios. Of the harvest treatments, those favoring high levels of structural retention and decreased harvesting frequency stored the greatest amounts of carbon. Classification and regression tree analysis showed that management scenario was the strongest predictor of total carbon storage, though site-specific variables were important secondary predictors. In order to isolate the effect of in situ forest carbon storage and harvested wood products, we did not include the emissions benefits associated with substituting wood fiber for other construction materials or energy sources. Modeling results from this study show that harvesting frequency and structural retention significantly affect mean carbon storage. Our results illustrate the importance of both post-harvest forest structure and harvesting frequency in carbon storage, and are valuable to land owners interested in managing forests for carbon sequestration.     

The effect of logging on vegetation composition in Western Massachusetts

Forest harvesting is one of the most significant disturbances affecting forest plant composition and structure in eastern North American forests, yet few studies have quantified the landscape-scale effects of widespread, low-intensity harvests by non-industrial private forest owners. Using spatially explicit data on all harvests over the last 20 years, we sampled the vegetation at 126 sites throughout central and western Massachusetts, one-third of which had not been harvested, and two-thirds of which had been harvested once since 1984. Seedling and sapling densities increased with increasing harvest intensity, but decreased to levels similar to unharvested sites by year 20 for all but the most intensive harvests. The composition of understory trees appears to be only slightly changed by harvesting, and was strongly correlated with adult tree composition. Regeneration was dominated by Betula lenta followed by Pinus strobus; Quercus spp. exhibited little sapling recruitment, even in Quercus-dominated stands. Total vascular plant species richness increased substantially with harvesting on low C:N sites (i.e., rich soils), but was only slightly increased on high C:N sites. While harvesting was associated with a statistically significant change in vascular plant composition, non-metric multidimensional scaling revealed that climate (temperature, precipitation) and C:N ratios were the major correlates of composition. Overall, the compositional impacts of harvesting were minor, perhaps because of the low-intensity of harvesting. However, our results support observations from elsewhere in the northeastern U.S. of limited oak regeneration on both harvested and unharvested sites. In addition, our results suggest that increased harvest intensity may be expected to alter forest composition, particularly on rich sites where invasive species may increase as a result of harvesting.     

European forests show no carbon debt,only a long parity effect

In the past the use of woody biomass for bioenergy was considered carbon neutral. However, this changed when analyses were made of cases of land use change or old growth forest logging for bioenergy purposes. These analyses showed a significant carbon debt that could take hundreds of years to be compensated by the substitution factor of the bioenergy.Currently, carbon debt analyses are often carried out: 1) at one hectare scale, or 2) against the hypothetical case of allowing the managed forest to grow to an old-growth state, or 3) in a comparison against short term policy goals. All three are not realistic for European forests. Here we analysed carbon debt and parity of realistically increased harvesting over large forest areas in Europe. We found that under such realistic cases, a carbon debt does not occur. i.e. the large scale average stocks in the forest are not reduced. What does occur is a parity compared to the baseline harvesting levels. The parity effect was eventually also compensated for. However it took long, especially if final fellings were increased for bioenergy; which is a rather hypothetical case. In case of increased thinnings, the parity equality was often reached within 80 years compared to burning coal. Removal of harvesting residues was often compensated within 1 decade. However, parity is a theoretical comparison against a higher baseline C stock in the forest. It is not certain that this higher stocking under the baseline will be sustained, because there is an increasing chance of natural disturbances. Thus the parity may be much shorter than analysed here.     

物联网在林产品物流中的应用

物联网技术已广泛应用于智能交通、农业、公共安全等领域。在林产品物流领域,由于林产品涉及产品范围广泛难以标准化等原因物联网未能推广。物联网技术与林产品物流结合,让林产品携带含EPC代码的射频识标签,达到对林产品从采伐、运输、仓储、配送、销售等整个过程进行管理的目的,从而解决长期以来因为信息闭塞,产品积压等导致林产品质量等级下降,成本增高的问题。物联网在林产品物流中的实施将有利于疏通林产品的流通,大幅度提高资源利用率,对林业企业以及国家资源的合理利用都具有重要意义。     

Understory plant communities of boreal mixedwood forests in western Canada: Natural patterns and response to variable-retention harvesting

We examined patterns of variation in richness, diversity, and composition of understory vascular plant communities in mixedwood boreal forests of varying composition (broadleaf, mixedwood, conifer) in Alberta, Canada, before and for 2 years following variable-retention harvesting (clearcut, 20 and 75% dispersed green tree retention, control). Broadleaf-dominated forests differed from mixedwood or conifer-dominated forests in that they had greater canopy cover, litter depth, soil nitrogen, warmer soils, as well as greater shrub cover, herb and shrub richness and diversity (plot scale). In contrast, conifer, and to a lesser extent mixedwood, forest had greater β diversity than broadleaf forest. Overall, mixedwood and conifer forests were similar to one another, both differed from broadleaf forest. Several species were found to be significant indicators of broadleaf forest but most of these also occurred in the other forest types. Understory composition was related to canopy composition and edaphic conditions. Variable-retention harvesting had little effect on understory cover, richness, or diversity but resulted in reduced richness and β diversity at a larger scale. The clearcut and 20% treatments affected composition in all forest types. Early successional species and those common in disturbed sites were indicators of harvesting while evergreen, shade-tolerant understory herbs were indicators of the control forest and 75% retention harvest. We conclude that it is important to maintain a range of variation in canopy composition of mixedwood forests in order to conserve the associated understory communities. The presence of conifers in these forests has a particularly important influence on understory communities. The threshold for a lifeboat effect of variable-retention harvesting is between 20 and 75% retention. Examination of richness and β diversity at a variety of scales can provide interesting information on effects of harvesting on spatial reorganization and homogenization of understory plant communities.     

Sustainable production of non-timber forest products: Natural dye extraction from El Cruce Dos Aguadas,Petén,Guatemala

The traditional harvest of non-timber forest products (NTFP) in Petén, Guatemala, provides a model for integrated conservation and development programs. Conservation International and El Cruce a Dos Aguadas (El Cruce). and agricultural community in the Maya Biosphere Reserve in Northern Petén, have created a new NTFP, called Gatherings™ which is a potpourri composed of seeds, flowers and leaves. Gatherings™ is promoted on international and domestic markets as a sustainably extracted natural product whose sale provides a direct incentive for local producers to conserve their forests. The purpose of this investigation is to test the ecological sustainability of extraction of the natural dyes used to color the potpourri ingredients and to present the following eight-step method for testing the sustainability of NTFP harvesting: (1) delineate current supply area; (2) determine current supply; (3) estimate the growth and yield of target species; (4) determine the current demand; (5) compare short-term supply and demand and evaluate management options: (6) assess secondary ecological effects of harvesting; (7) repeat the process for future time periods; and (8) summarize the analysis. Using this method, we found that two of the dyes are likely to be over-harvested within 10 years, and that the harvest of the third could be increased substantially without endangering the dye-producing species. When we summarized the analysis, we found no evidence to conclude that the current production of Gatherings™ directly benefits the forests of El Cruce. However, the goodwill created by this project has contributed to a new conservation initiative; a Land Management Area which has been proposed by the community to Guatemala's National Protected Areas Council (CONAP) and which contains a 13 273 ha forest reserve.     

大兴安岭林区森林主伐方式的探讨

本文通过对大兴安岭林区森林植被结构特征,建群树种的更新特点的分析和对正在施行的各主伐方式效果的评价,认为带状间隔皆伐和二次渐伐适于本林区森林结构及更新特点,而择伐不适用,应加以限制。     

加拿大森林资源环境库兹涅茨曲线验证——基于林木生长周期的视角

利用加拿大1990—2010年林产品产量数据, 采用环境库兹涅茨曲线模型, 考察加拿大经济增长与森林资源采伐量之间的关系。与以往研究不同的是, 在回归模型中加入了代表林木生长周期的时间序列变量, 以探讨林木生长周期对森林资源采伐量的影响。结果显示, 加拿大森林资源采伐量与经济增长存在倒U型曲线关系, 且林木生长周期对曲线形状的影响显著。从研究结果得到的政策启示是, 在设置森林采伐限额时应注意林木的生长周期, 在林木初生长期应降低采伐限额来保护幼树, 从而为采伐迹地天然更新提供充足的种源和条件。     

Early responses of birds to clearfelling and its alternatives in lowland wet eucalypt forest in Tasmania,Australia

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.     

Why Is Non-Timber Forest Product Harvesting an “Issue”?

Summary

Despite an encouraging trend in North America of growing interest across a range of disciplines in non-timber forest products (e.g., this volume), NTFP harvesters' knowledge and practices continue to be poorly understood and undervalued, if not ignored, both by research scientists and forestland policy-makers and managers. This article explores why NTFP harvesting suddenly emerged in North America as an “issue” in the early 1990s. Drawing from a three-year study of chanterelle mushroom harvesters on the Olympic Peninsula Biosphere Reserve (Washington, USA), we discuss a variety of forces which intersected in this period to bring NTFP harvesting to wider attention. Unfortunately, harvesters continue to be excluded as knowledgeable actors in, if not legitimate co-managers of, temperate forest ecosystems, resulting in both passive and active harvester resistance to research and management, a devaluing of local harvesting traditions, and missed opportunities for collaboration. We reluctantly conclude that despite “New Forestry” co-management rhetoric, given existing institutional barriers and positivist scientific categories, NTFP workers will likely remain excluded from active roles in temperate forest research and management-contributing in turn to the ongoing legitimacy crisis of public and private forest management entities.     

Viability of Introducing Payments for the Collection of Wild Forest Mushrooms in Catalonia (North-East Spain)

Wild mushrooms are among the most valuable non-wood forest products in the world, and mushroom picking activities are well developed in many countries. Recent studies have demonstrated important links between forest management options and the productivity of mushrooms. Furthermore, there is evidence that the optimal forest management oriented at maximizing joint revenues from timber and mushrooms can lead to higher profits than the traditional timber-oriented management. The precondition for such management, however, is that forest owners derive benefits from mushrooms produced in their forests. In this paper, we discuss the feasibility of implementing payments for mushroom harvesting in Catalonia, North East Spain. As in many other European regions, mushroom picking in Catalonia is a long-standing tradition, which has been practiced with negligible limitations for centuries. The rising popularity of this activity in the last decades, however, has caused forest owners to voice concerns about the sustainability of this activity and about the impact it has on the private forest property. We document the results of a public opinion survey and contrast them with the issues emergent from forest owners’ interviews about the regulation of mushroom picking activities. Our results show that mushroom pickers support the idea of introducing payments for mushroom harvesting. Based on the survey and interview results, we also discuss the design aspects of payments for mushroom picking and articulate the key issues in their implementation.     

Threshold effects of variable retention harvesting on understory plant communities in the boreal mixedwood forest

We studied the effects of six levels of dispersed green-tree retention (GTR) harvesting (clearcut (0%), 10%, 20%, 50%, and 75%, and unharvested reference (100%)) on understory plant communities in the 8th growing season post-harvest in the mixedwood boreal forest in northwestern Alberta. For the partial harvest treatments (10%, 20%, 50%, 75%) sample plots were located in the partially harvested (retention) strips as well as in the intervening machine corridors used by the harvesting equipment. The understory plant community was significantly influenced by the gradient of retention level. The cover of understory vegetation, especially graminoids, increased with increasing harvesting intensity for the retention strips and overall considering both plots types. Species richness was unaffected by retention level but did decrease as tree density increased. Lower levels of retention lead to increased abundance of early successional, shade-intolerant species. The results suggest a threshold in understory response to GTR harvesting between the 10% and 20% retention treatments. In terms of understory cover and composition, machine corridors within partially harvested forests resembled clearcuts. The results suggest that retaining more than 10% during GTR harvesting could have significant benefits in terms of maintaining understory plant communities more similar to unharvested reference forest.     

Can community forestry contribute to household income and sustainable forestry practices in rural area? A case study from Tshapey and Zariphensum in Bhutan

Community forestry is an emerging success model of state–community partnership for forest management and poverty reduction. Bhutan's initial experience of forest management by user group is promising, but merits further study on how community forests have experienced with harvesting and income generation consistent with national forest policy. This study quantifies whether community forestry contribute to household income with equitable products and income distribution and gender inclusive participation; and community forests are managed applying the principles of sustainable harvest without compromising regeneration and productivity. We applied a combination of social and ecological methods using household interview and forest sampling plots. Our findings revealed that community forestry contributes to household income through harvesting and marketing of large trees, and non-wood forest products where markets are accessible. Household income, however, vary widely between rich and poor households with former capitalizing on commercial and latter on subsistence products. Timber harvesting is consistent with the principles of sustainable harvest without altering species composition, regeneration and productivity. To narrow income inequality, pro-poor approach to community forestry needs to target poor households with income diversification activities and market accessibility. The promising results are context-driven and warrant consolidation from other community forests experiencing harvest in Bhutan.     

To what extent do forest herbs recover after clearcutting in beech forest?

We studied the occurrence of 22 plant functional groups and the distribution patterns of 12 forest herbs in four clear-felled areas of different ages, and across ecotones between the forest and clearcuts in a 4383 ha beech forest in central Belgium. The main goal was to improve our knowledge on the clearcut harvesting system and its possible influence on herb vegetation. Within each study site, the herbaceous vegetation was sampled along a north–south and an east–west transect with points at 20 or at 10 m intervals. We studied a total of 82 vegetation relevés (4 m²) on 18 transects according to the Braun–Blanquet method. Around the study sites, the abundance of each species present was noted according to a grid-map with cells of 50 m × 50 m, up to a distance of 150 m from the clearcut edges. Differences in species’ cover percentage and frequency between the clearcuts and the surrounding matrix were tested. The colonisation rate for each species was calculated and possible effect of clearcut age on the plant composition was examined. Results of this study show that plant functional groups with a high conservation value, such as ancient-forest species, stress-tolerant species and autochorous species showed a progressive decrease in time after clearcutting. Most of the studied forest herbs had a lower frequency and/or cover in the clearcut areas than in the surrounding forest matrix. For some of these species, we found a progressive abundance decrease along a 150 m-gradient within the forest towards the clearcut (e.g. Dryopteris dilatata, Luzula pilosa, L. sylvatica, Oxalis acetosella). Others, such as Anemone nemorosa and Circaea lutetiana, are characterised by a regular cover in the forest which suddenly drops at the edge and sustains a very low level throughout the clearcut. If some forest herbs recover better than others, data collected so far indicate that most of the studied species are not able to recover such disturbed sites within a few years. We conclude that silvicultural systems should be adapted to the dispersal and recruitment limitations of forest herbs in order to enable their long-term conservation. To achieve this goal, management without large clear fellings and harvesting methods that never leave the ground completely bare are proposed as alternatives to the clearcutting system.     

Nutrient status of managed and natural forest fragments of Fagus sylvatica in southern Europe

Beech forests located in the southwestern limit of Europe have been affected by severe deforestation and long-term fragmentation. Some of these forests have been subjected to partial cutting, whereas others have been maintained with little or no active management. It has previously been shown that past management has led to substantial changes in tree structure, diversity and plant species. These perturbations, through their influence on the litterfall and forest floor, may affect nutrient cycling and the nutritional status of such fragile ecosystems. Mineral nutrition was investigated in 53 forest fragments by analysis of data corresponding to nutrient concentrations in forest floor, mineral soils and foliage. In comparison with other beech forests in Central Europe subjected to higher levels of air pollution, the stands showed fewer incidences of nutrient deficiencies and lower foliar concentrations of S and heavy metals. Partial cuts carried out in recent decades have reduced the forest floor mass proportional to the intensity of the harvesting. The effect was probably due to the lower litter input and the increased decomposition of litter as a consequence of the environmental changes in forest gaps. The partially cut stands displayed higher foliar levels of K and Mg, which could be attributed to the greater release of these elements as a consequence of the increased decomposition of litter. However, past management has brought about lower foliar concentrations of P and N. Both effects were found to be proportional to basal area and the forest floor mass, which suggests that they are related to the intensity of harvesting. Although the causes are uncertain, this negative effect may be due to a reduction in forest floor thickness, which implies the loss of preferred rooting space for trees.     

国外森林采伐技术的现状

近30年来,国外森林采伐技术发生了巨大的变化,已经开始实现全盘机械化。文章阐述了国外森林采伐工艺和设备的发展状况,概括地介绍了自行式采伐机械,并对工业发达国家森林采伐全盘机械化的起因做了初步探讨。最后,作者针对当前我国的情况,提出了不应该机械地照搬外国先进技术的意见。     

Carbon balance of forest stands,wood products and their utilization in South Korea

Forests provide wood products and feedstock for bioenergy and bio-based products that can mitigate climate change by reducing carbon emissions. In order to assess the effects of forest products on reducing carbon emissions, we analyzed the carbon balance for individual carbon pools across the forest supply chain over a long period of time. We simulated particular forest supply chain activities pertaining to even-aged management of pine stands in South Korea to demonstrate our methods. Two different rotation scenarios (i.e., 40 and 70 years) were assessed over the 280-year time horizon in terms of temporal changes in carbon stock in each carbon pool along the supply chain, carbon transfer between carbon pools, substitution effects, and delayed carbon release by wood products. We found that the average carbon stock level was higher for the 70-year rotation scenario, but the total amount of gain in carbon was higher for the 40-year rotation at the end of the time horizon. This study confirms that forest products and energy feedstock can both reduce carbon emissions and increase carbon storage. However, the complexity of carbon accounting along the supply chain warrants a thorough evaluation from diverse perspectives when it is used to assess forest carbon management options.     

新西兰森林采伐管理制度与借鉴

森林采伐管理是森林资源管理的核心内容之一。在计划经济条件下制定的中国森林采伐管理制度对于森林资源保护起到了重要作用。但是, 随着市场经济不断完善、集体林权制度改革不断深入, 这种管理制度已经不适应现代林业发展的需要, 亟待完善。分析了新西兰在森林采伐方面实施的分类采伐管理、森林可持续经营计划、森林可持续经营许可证、年度采伐计划等管理措施, 期望能为完善中国森林采伐管理制度提供参考模式和经验借鉴。     

Modeling Forest Owner Harvesting Behaviour and Future Intentions in Tasmania

Our ability to design public policies that effectively promote the efficient use of privately owned forest resources is underpinned by an understanding of the way in which forest production and investment decisions are made, and of how forest owners respond to changes in social, economic, and institutional conditions. A model of non-industrial private forest owners (NIPF) past harvesting behaviour and future harvesting intentions using a logit approach is presented. A Tobit model, which investigates harvesting intensity, is also developed. The responses to a survey of 386 NIPF owners in Tasmania are used to construct the data set consisting of socio-economic characteristics of NIPF owners, their forest ownership objectives, and property characteristics. The current study is innovative in that the role of NIPF owner objectives and attitudes is assessed in three econometric models exploring past harvesting behaviour, harvesting intensity, and future harvesting intentions. A series of observations can be made from comparing the results of the three models. For example, higher pulp prices are unlikely to affect NIPF owners harvesting intentions but are likely to increase harvesting intensity. The financial characteristics of the NIPF owner contribute most to predicting future harvesting intentions, with financial security being a disincentive to future harvesting. Landowner objectives and attitudes are important in explaining past harvesting activities and future intentions but do not significantly affect harvesting intensity. Furthermore, there are significant differences between different types of landowners in terms of the incentives that are likely to make them change their mind about participating in native forest harvesting.     

亚太地区非木材林产品生产和利用现状及前景

本文概述了在亚太地区日益受到重视的非木材林产品的资源、生产及利用现状, 重点对中国、菲律宾、泰国、印度、马来西亚和印度尼西亚做了介绍, 并对非木材林产品的发展前景进行了描述。