The bottomland hardwood forest of the southern United States

Bottomland hardwood forests are valued for timber production, water storage, enhanced water quality, nutrient cycling, erosion control and wildlife habitat. However, the majority of southern bottomland stands, 90% of which are in private ownership, are occupied by a degraded mixture of tree species, caused largely by repeated, incomplete harvests. They can be naturally regenerated to a stand of favorable species composition by removing the residual stand of merchantable and non-merchantable trees. For timber production, these systems respond best to even-aged management such as clearcutting, shelterwood cutting and patch clearcutting. Plant succession under such systems allows shade intolerant species to occupy the site, followed by species of increasing shade tolerance. Uneven-aged systems, such as individual-tree selection and group selection, are also viable regeneration methods, but they require great attention to detail and frequent stand entry. In areas of high sensitivity to timber harvesting, a two-aged system such as a leave-tree is recommended. Stand disturbance, either planned or unplanned, is needed to keep southern hardwood forest stands viable.     

Financial analysis of diameter-limit cut stands in northern hardwoods

Diameter-limit cutting of stands in the US northeast is a common practice often thought to give the landowner the highest financial returns. A landowner’s decision to diameter-limit cut or use some other harvesting option on a given stand involves examining mutually exclusive investments. Previous research that compared diameter-limit cutting to other harvesting options implicitly assumed these were independent investments. This paper develops analytical models to examine a variety of harvesting options for a single stand, including diameter-limit cutting, as mutually exclusive investments, and with stand and financial parameters defined by the landowner. These models are used to examine implications of changes in the financial parameters for harvesting options. It is found that no simple guidelines can be laid down for choice of harvesting options to maximise the net present value of stands with respect to diameter-limit cutting compared to other harvesting options. The empirical examples reveal that which harvesting option has the largest net present value depends on the parameters of the landowner’s stand and the financial parameters chosen by the landowner. The analysis illustrates the importance of understanding the interrelationships between the financial and stand parameters in determining whether a diameter-limit cut is in fact the best financial option for a landowner.     

An integrated assessment approach to optimal forest bioenergy production for young Scots pine stands

Background: Bioenergy is re-shaping opportunities and imperatives of forest management. This study demonstrates,through a case study in Scots pine(Pinus sylvestris L.), how forest bioenergy policies affect stand management strategies.Methods: Optimization studies were examined for 15 Scots pine stands of different initial stand densities, site types, and temperature sum regions in Finland. Stand development was model ed using the Pipe Qual stand simulator coupled with the simulation-optimization tool Opti For Bioenergy to assess three forest bioenergy policies on energy wood harvest from early thinnings.Results: The optimal solutions maximizing bare land value indicate that conventional forest management regimes remain optimal for sparse stands. Energy harvests occurred only when profitable, led to lower financial returns. A forest bioenergy policy which included compulsory energy wood harvesting was optimal for denser stands. At a higher interest rate(4 %), increasing energy wood price postponed energy wood harvesting. In addition, our results show that early thinning somewhat reduced wood quality for stands in fertile sites. For less fertile sites, the changes were insignificant.Conclusions: A constraint of profitable energy wood harvest is not rational. It is optimal to carry out the first thinning with a flexible forest bioenergy policy depending on stand density.     

Public compensation for windstorm damage reduces incentives for risk management investments

Governments of some European countries compensate landowners for windstorm damage to forests. We analyze the impact of such programmes on non-industrial private forest owner decisions to purchase an insurance policy for windstorm coverage and other natural events and/or invest in risk-reducing forest management activities. We develop a theoretical model to predict demand for an insurance policy or risk-reducing forest management activity, and improve upon previous efforts by varying the damage losses proportional to timber stand value. We characterize the comparative static effects on risk management investments of variations in the price of insurance, landowner risk attitude, timber stand value, and presence or absence of public compensation. Then we discuss public policy implications and analyze some alternative approaches. We conclude that providing public financial assistance to non-industrial private forest owners after damage-causing events may reduce their incentive to purchase insurance or invest in protective forest management activities.     

Long-term influence of fire and harvesting on boreal forest age structure and forest composition in eastern Québec

In boreal forests, historical variations in the area disturbed by natural disturbances or harvesting have rarely been compared. We measured temporal and spatial variations in areas affected by severe fires and clearcutting throughout the 20th century in a 57, 332 km² section of the eastern Canadian boreal forest. We examined the effects of these disturbances on spatio-temporal variations in the abundance of forests >60 years. Natural variability for the abundance of forests >60 years was estimated from simulations of natural disturbance regimes. We also measured compositional and structural differences between three categories of stands originating from relatively recent disturbances (∼50 years; clearcutting, fires, and clearcutting followed by fires), and one category of stands that were undisturbed for at least 200 years. At the regional level, we observed that forests >60 years gradually became scarcer throughout the 20th century due to a gradual expansion of harvested areas, an effect most pronounced in the southern part of the region, where mature and old forest abundance was clearly outside the range of natural variability at the end of the studied period. At the stand level, forest composition and structure differed between stand-origin categories: clearcutting-origin stands contained more balsam fir (Abies balsamea), fire-origin stands more black spruce (Picea mariana), and fire/clearcutting-origin stands more hardwoods (Betula papyrifera and Populus tremuloides). Overall, we estimate that strict forest management targets based on natural disturbance regimes will be difficult to achieve in eastern North-American boreal forests, most notably because contemporary disturbance rates, including both clearcutting and fire, have gradually become higher than the fire rates observed during the preindustrial period.     

Nature conservation and timber production in areas with fragmented ownership patterns

Forestry has transformed the tree species composition and structure of Swedish forests. The fragmented ownership pattern in areas with non-industrial private forest ownership (NIPF), in combination with these forestry practices, have created fragmented forests with relatively low proportions of habitat types important to many species. Ecological landscape planning has been suggested and tested as a mean for integrating nature conservation and timber production in Sweden. However, ecological landscape planning concepts have been developed for areas with homogenous ownership patterns and not for areas with fragmented ownership. In this study, stands that are voluntarily set aside by individual forest owners were examined in terms of nature conservation value, and compared to randomly selected stands obtained by Monte Carlo simulation. In order to obtain rather detailed data about the set-aside stands, semi-standardized interviews were carried out directly with forest owners in three landscape areas dominated by NIPF. The interviews showed that 26 out of 29 forest owners could locate some stands where they did not have high requirements for timber yield. These stands had higher than average local and spatial nature conservation value as a result of stand structure, composition and location in the landscape. The stands did not have a random location or size, being found closer to key habitats as well as forming equally large or larger patches than other stands. These stands are suggested to form a basis for ecological landscape planning as forest owners seem to have some kind of ‘common view’ of which stands to set aside. This common view could be used to coordinate the contribution made by individual forest owners to nature conservation in areas with fragmented ownership patterns.     

An approach for examining the effects of preferential uncertainty on the contents of forest management plan at stand and holding level

A proper forest planning process includes the assessment of the decision-makers’ preferences concerning the future forest use. For some owners, it may be a difficult task to express their preferences exactly and in the form that is required for planning calculations. This study presents a new kind of approach for analyzing the effects of preferential uncertainty. The approach consists of examination of the differences in the actual decision variables in forest planning, i.e. selected treatments for stands between holding-level forest plans. In example calculations, the preferential uncertainty was examined from three different viewpoints: the uncertainty in the weights of the objective variables; the uncertainty in the partial utility function; and the combination of these two uncertainty sources. One thousand preference realizations were generated for each of these uncertainty sources. More than one treatment schedules are proposed for stands that are affected by preferential uncertainty. These stands were detected from among the resulting set of 1,000 forest plans. With this done, two potential decision-making strategies, an adaptive behavior strategy and a threshold proportion strategy, were applied as guides in decision-making for stands, which have more than one treatment alternative selected in the produced optimal forest plans. The adaptive behavior technique required that the forest owner select one treatment alternative for at least one stand that has more than one proposed treatment alternative. The treatment alternatives having frequencies exceeding the given threshold frequency were all accepted simultaneously in the threshold strategy. The main benefit of the approach is to present the effects of uncertainties in a way that can be easily understood by the actual decision-makers. It is a promising tool for practical decision-making situations because at least Finnish non-industrial private forest owners quite often focus on making stand-level forest management decisions. It is also suitable for examinations of other uncertainty sources such as timber prices or inventory data.     

An Exploratory,Post-Harvest Comparison of Ecological and Economic Characteristics of Forest Stewardship Council Certified and Uncertified Northern Hardwood Stands∗

ABSTRACT

As more forest entities worldwide consider pursuing Forest Stewardship Council (FSC) certification, a critical question remains on whether stand-level management impacts differ between certified and uncertified forests. To begin to answer this question, we measured forest structure on three FSC-certified stands, three uncertified stands, and six adjacent unharvested reference stands (12 stands total) composed primarily of sugar maple (Acer saccharum) on non-industrial private properties in central Vermont, USA. The certified and uncertified partial harvests reduced total tree biomass and live tree carbon storage by one-third compared to reconstructed pre-harvest conditions. Both treatments also contained significantly lower densities of saplings and some mid-size trees compared to non-harvested references due to similar impacts from harvesting. The net present value of merchantable sugar maple over 10 year projections was consistently lower on certified than uncertified stands, but this difference was insignificant at discount rates from 4–8%. The certified stands contained significantly greater total residual volumes of coarse woody debris (standing and downed) than uncertified stands, although the debris was smaller than that found in unmanaged mature forests. Overall, our data suggest that FSC-certified harvested stands in northern hardwood forests have similar sugar maple timber value, aboveground live tree carbon storage value, similar live tree structure, and greater residual coarse woody debris than uncertified harvested stands.     

Structure and composition of streamside management zones following reproduction cutting in shortleaf pine stands

Streamside management zones (SMZs) in the Ouachita Mountains of Arkansas and Oklahoma are frequently established along headwater ephemeral and intermittent streams to protect water quality, provide wildlife habitat, and increase landscape diversity. To better understand the function of these riparian forest corridors, we characterized the tree density and composition, forest floor mass, and downed woody debris volume within SMZs located in undisturbed, mature, upper mid-slope shortleaf pine stands and then compared these attributes to those in upland portions of these stands. In addition to evaluate the impact of upland forest harvesting on these riparian corridors, we compared the amounts and distribution of forest floor, downed woody debris (DWD), snags, and windthrows in SMZs within shortleaf pine stands that had been clearcut, had a shelterwood harvest, and had no recent management activity (uncut stands). Total tree and hardwood basal area was significantly higher (4.4 and 4.2 m² ha⁻¹) while forest floor mass was significantly lower (0.5 kg m⁻²) in the SMZs than in the upland portion of the undisturbed stands. Five years following the reproduction cuttings tree basal area, DWD volume, and forest floor mass within SMZs did not significantly differ among stands that had or had not been harvested. Snag density was significantly lower within SMZs that occurred in clearcut stands compared to those in the uncut or shelterwood stands. Harvesting activities that retain few or no residual trees appear to increase the degradation of snags. This study provided evidence that clearcutting may also increase the risk of windthrow in SMZs as well. There was little difference in the distribution of forest floor within SMZs regardless of whether the stand was harvested or the type of harvesting that occurred in the stand. However, DWD amounts were higher near the SMZs edge than in the interior of the SMZs with the greatest differences in distributions in stands that were clearcut.     

Effects of deforestation on microbial diversity in a Siberian larch(Larix sibirica) stand in Mongolia

For evaluating microbial community changes in a Siberian larch stand disturbed by forest fire or clearcutting,357 clones were randomly selected and sequenced using a culture-independent approach and 16S rRNA sequencing to characterize the bacterial composition and diversity from the different disturbed Siberian larch stands.Interestingly,the burned larch stand had an increase in the relative amounts of b-proteobacteria and Firmicutes and a decrease in Acidobacteria,while Gemmatimonadetes increased Verrucomicrobia decreased in the harvested larch stand.Microbial diversity and richness were higher in the undisturbed larch stand than the disturbed(burned or clear-cut)larch stands,and the influence of clear-cutting was more negative than that of the forest fire.This study indicates that evaluating the microbial diversity of undisturbed,burned,and clear-cutting Siberian larch stands provides information about the impact of forest disturbances on soil microbial communities,which may be helpful for understanding and evaluating soil health and devising reafforestation strategies for larch.     

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.     

Effects of harvesting intensity on carbon stocks in eastern Canadian red spruce (Picea rubens) forests: An exploratory analysis using the CBM-CFS3 simulation model

Carbon stocks and stock changes in a chronosequence of 24 red spruce (Picea rubens Sarg.) dominated stands in Nova Scotia, Canada, were compared against predictions from the Carbon Budget Model of the Canadian Forest Sector (CBM-CFS3). Regression analysis of the observed versus simulated total ecosystem C stocks indicates the model's predictions accounted for 81.1% of the variation in the observed biomass data and for 63.2% of the variation in total ecosystem C data; however, the simultaneous F-test for bias was significant. Discrepancy between the observed and simulated total ecosystem C data was primarily caused by differences in dead organic matter C pool estimates, with the model consistently predicting higher soil C throughout stand development. Changes to model parameters were not warranted however, as the field data measured only a portion of the mineral soil profile represented in the model.

Clear-cut and partial-cut harvesting scenarios for red spruce stands were simulated to examine the impacts of clear-cut and partial-cut harvesting on C stocks. Total ecosystem C increased in the partial-cut stand throughout the 240-year simulation from 308.9 to 327.3 Mg C ha⁻¹, while it decreased in the clear-cut stand to 305.8 Mg C ha⁻¹. Enhanced C sequestration in the partial-cut stand was a consequence of the residual standing biomass providing a continuous source of litterfall and reducing decomposition rates of the forest floor. Choice of harvest system clearly affects forest ecosystem C stocks, but also affects the amount of C removed from forests to meet society's needs. Over the period of the simulation, partial cutting provided 115.6 Mg C ha⁻¹ of merchantable timber, while clear-cutting provided 132.4 Mg C ha⁻¹. Strategies aimed at using forest management to mitigate atmospheric C increases need to assess both the direct impacts on the forest ecosystem and the indirect impacts through product and energy substitution associated with the use and storage of harvested biomass.     

海南霸王岭陆均松类热带山地雨林伐后林结构与物种多样性研究

霸王岭林区是海南岛最典型的热带山地雨林分布区.在该区,现存分布面积最广、资源数量最大的是热带山地雨林的各种伐后林.以霸王岭分布最广的以陆均松(Dacridium pierrii)为主的山地雨林的伐后林为对象,研究了其组成、径级、高度结构和物种多样性特征,对比分析了伐后林与原始林以及伐后林不同类型之间的异同.结果表明:原始热带山地雨林经采伐后中小乔木和灌木的优势度增大,而大乔木树种的优势度则明显下降.阳性树种的种类、数量和相对重要性随采伐破坏的程度而增加.伐后林中矮、小树木在林分中比例随采伐破坏的程度增加,而高、大树木,特别是进入主林层树木的比例则随采伐破坏的程度明显下降.从林分测树因子的变化来看,采育择伐和径级择伐的林分要优于大强度择伐和皆伐的林分.原始林的物种丰富度大于伐后林,但其多样性指数和均匀度指数大都小于伐后林.组成上与原始林相似性较大的伐后林是各种择伐后的林分,而皆伐后的林分与原始林在组成上已有很大差别.     

Optimising the management of even-aged Pinus sylvestris L. stands in Galicia, north-western Spain

The study developed management instructions for even-aged Pinus sylvestris stands in Galicia (north-western Spain). Although these stands are highly productive, no silvicultural management schedules have been proposed so far for them on the basis of systematic analyses. This study used data from 2160 optimisation runs to develop the management instructions. Land expectation value was used as the objective function. Different prices of timber assortments were considered and the discounting rate was varied from 0.5 to 5%. The method employed to find the optimal management schedules of stands was the combination of a stand simulator and an optimisation algorithm. The simulator uses an earlier growth and yield model for Pinus sylvestris in Galicia to predict the future development of the stand with a given management schedule while the optimisation algorithm seeks the best management schedule among all the possible alternatives. The results show that optimal rotation lengths vary widely between 42 and 170 years, high discounting rates and good site quality resulting in the shortest rotations. Four thinnings were found to be suitable for all sites and discounting rates. With discounting rates higher than 1% the commercial thinnings should gradually decrease the stand basal area towards the end of the rotation.     

Spatially explicit assessment of carbon stocks of a managed forest area in eastern Germany

The Kyoto-protocol permits the accounting of changes in forest carbon stocks due to forestry. Therefore, forest owners are interested in a reproducible quantification of carbon stocks at the level of forest management units and the impact of management to these stocks or their changes. We calculated the carbon stocks in tree biomass and the organic layer including their uncertainties for several forest management units (Tharandt forest, Eastern Germany, 5,500 ha) spatially explicit at the scale of individual stands by using standard forest data sources. Additionally, soil carbon stocks along a catena were quantified. Finally, carbon stocks of spruce and beech dominated stands were compared and effects of thinning intensity and site conditions were assessed. We combined forest inventory and data of site conditions by using the spatial unions of the shapes (i.e., polygons) in the stand map and the site map. Area weighted means of carbon (C) stocks reached 10.0 kg/m2 in tree biomass, 3.0 kg/m2 in the organic layer and 7.3 kg/m2 in mineral soil. Spatially explicit error propagation yielded a precision of the relative error of carbon stocks at the total studied area of 1% for tree biomass, 45% for the organic layer, and 20% for mineral soil. Mature beech dominated stands at the Tharandt forest had higher tree biomass carbon stocks (13.4 kg/m2) and lower organic layer carbon stocks (1.8 kg/m2) compared to stands dominated by spruce (11.6, 3.0 kg/m2). The difference of tree biomass stocks was mainly due to differences in thinning intensity. The additional effect of site conditions on tree carbon stocks was very small. We conclude that the spatially explicit combination of stand scale inventory data with data on site conditions is suited to quantify carbon stocks in tree biomass and organic layer at operational scale.     

Nutrient cycling and biomass flows in a low-quality forest stand improvement system in the Lesser Khingan Range of China

The material flow and bulk internal flow analyses were used to establish a material accumulation and cycling model for a low-quality forest stand improvement system and a series of processes were considered. The model was applied in a one-hectare low-quality forest plot in the Lesser Khingan Range of China. Results showed that during 1997–2007, the stands absorbed 270.19 kg of N, 74.28 kg of P, and 124.39 kg of K from soils, 51.82 kg of N and 2.38 kg of P were directly absorbed by foliage, and 16.25 kg of K was released to soils by eluviation. Until 2007, the accumulated nutrients in the stands included 236.91 kg of N, 65.28 kg of P, and 108.55 kg of K. When horizontal strip clearcutting was applied in 2007, 50% accumulated nutrients in the stands were shifted due to harvesting operations, and 212.74 kg of N, 26.97 kg of P, and 98.88 kg of K were accumulated in soils, declining by 9.47% for N, 3.68% for P, and 17.60% for K, respectively, compared with year 1997. 94.61 t per hectare of biomass was generated, of which the biomass in stands accounted for 87.36%. The felled tree biomass was 36.89 t per hectare, of which 84.90% and 10.03% of biomass were utilized in terms of logs and other means, and the rest was left on site.     

Information Needs of Non-industrial Private Forest Owners After Logging Operations in Finland: A Case Study

In this study, the information needs of non-industrial private forest owners in Finland, after logging operations, were investigated. The study was carried out as an online survey in 2017. The survey was targeted at non-industrial private forest owners who had sold their timber during the previous 10 years (2008–2017) and whose email addresses were in the customer relationship management system of a large wood procurement company in Finland. A response link for the survey was successfully sent to 31,988 forest owners, of whom 3323 replied (response rate: 10.4%). The final study data included 3284 non-industrial private forest owners. The results of the study, which need to be interpreted cautiously due to the low response rate, showed that the forest owners want better-quality reporting after logging operations. Furthermore, the results suggested that gender, age, education, occupational status, place of living, size of, and access to, forest property, and length of, and objectives for, forest ownership have a significant effect on their information needs. Younger, highly-educated, female, urban-living and multi-objective forest owners with larger forest holdings and short forest ownership tenures desired more information. Particularly, the respondents conveyed that they would like more and better information about thinning harvesting result. The results also indicated that when different groups of forest owners call for certain information, there is a need for producing different types of reports after logging operations for different forest owner segments.

     

An analysis of a silvopastoral system for the marginal land in the Southeast United States

Almost 20 million acres of non-forest cropland in the South can be classified as marginal. Demand projections for forest products call for a 40 percent increase by year 2030. Recent regenerated tree acres lag behind harvested acres. Multiple land use practices combining trees and grazing adjust cash flows forward mitigating negative flow period associated with conventional forest production. Profit opportunities for private, non-industrial landowners can be increased by ranking inputs in order of changes to net present value(NPV). A sensitivity analysis of an agroforestry scenario, including trees, beef cattle, and pasture, allows producers to concentrate management efforts where returns are greatest. Model results show greatest returns to NPV was realized from improvement to Chip-N-Saw income. The least increase in NPV came when the cost of control burns was changed.     

闽西北人工林经济效益动态分析

为比较人工林的不同林分在不同林龄下的经济效益,依据与当地林业生产企业的资料和数据,采用净现值法、内部收益率法等经济分析方法,分别对不同龄级的杉木、马尾松和桉树人工林的动态收益进行分析,并对工资水平、成本、税费、木材产量和价格进行敏感性分析。研究结果表明：各种林分和龄级人工林的净现值均大于零;桉树林的内部收益率最高,木材产量和价格对经济效益的影响最为明显。     

Model-based investigation on the effects of spatial evenness,and size selection in thinning of Picea abies stands

Size and spatial distribution of trees are important for forest stand growth, but the extent to which it matters in thinning operations, in terms of wood production and stand economy, has rarely been documented. Here we investigate how the choice of spatial evenness and tree-size distribution of residual trees impacts wood production and stand economy. A spatially explicit individual-based growth model was used, in conjunction with empirical cost functions for harvesting and forwarding, to calculate net production and net present value for different thinning operations in Norway spruce stands in Northern Sweden. The in silico thinning operations were defined by three variables: (1) spatial evenness after thinning, (2) tree size preference for harvesting, and (3) basal area reduction. We found that thinning that increases spatial evenness increases net production and net present value by around 2.0%, compared to the worst case. When changing the spatial evenness in conjunction with size preference we could observe an improvement of the net production and net present value up to 8.0%. The magnitude of impact differed greatly between the stands (from 1.7% to 8.0%) and was highest in the stand with the lowest stem density.