Timber Removals Research Articles

Performance of Skidding Operations in Low-Access and Low-Intensity Timber Removals: A Simulation of Productivity and Fuel Consumption in Mature Forests

Forest policies aiming for a greener future and decarbonization require scientific support to help in decision making on resource economy and sustainability of forest operations. Timber skidding is one of the most prevalent options in wood extraction around the world. While its operational and environmental performance is affected by several factors, of which the extraction distance, removal intensity, and machine capabilities are of first importance, there are few studies on the subject in low-access and low-intensity removals. Based on a time study which accounted for production and fuel consumption, this work modeled and quantified productivity and fuel consumption for such operational conditions. Dependence of fuel and time consumption on relevant operational factors was modeled by least square stepwise ordinary regression techniques. Then, the developed models and summary statistics were used to simulate productivity and fuel consumption for a wide range of extraction distances. The main results indicate that, for removal intensities in the range of 7 to 15 m3/ha, productivity of skidding operations in mature broadleaved forests depended heavily on the extraction distance. Taking as a reference an extraction distance of 200 m, productivity halved at 800 m, and decreased to one fourth at 2000 m. For the same conditions, fuel consumption increased linearly, being doubled at 800 m and four times higher at 2000 m. Although the unit fuel consumption increased linearly as a function of extraction distance, its magnitude of increment was much lower. The results of this study indicate that shortening the extraction distances may be the best option in increasing the operational and environmental performance of skidding operations. This may be achieved by developing further the forest road network, which, in addition to the benefits for harvesting operations, could support a more sustainable forest management.

Global forest products markets and forest sector carbon impacts of projected sea level rise

Sea level rise (SLR) is among the climate-change-related problems of greatest concern, threatening the lives and property of coastal residents and generating far-reaching economic and ecological impacts. We project that SLR will lead to an increase in the rate of new housing construction to replace destroyed structures, impact global wood products supply and demand conditions, and cause changes in global forest sector carbon mitigation potential. Findings indicate that 71 million new units will be built by 2050 to accommodate the SLR-affected global population. More than two-thirds of these new units are projected to be in Asia. The estimated extra wood products needed to build these new residential units is 1,659 million m3, assuming that all these structures would be built mainly with wood, representing a 4 % increase in total wood consumption, compared to projected reference level global wood products consumption. Increased timber removals to meet this higher construction wood demand (alternative scenario) is shown to deplete global forest carbon by 2 % by 2050 compared to the reference scenario. However, all such projected declines in forest biomass carbon could be more than offset by increased carbon sequestration in harvested wood products, avoided emissions due to substitution of wood for non-wood materials in construction, and biomass regrowth on forestland by 2050, with an estimated net emissions reduction benefit of 0.47 tCO2e/tCO2e of extra wood used in SLR-related new houses over 30 years. The global net emissions reduction benefit increased to 2.13 tCO2e/tCO2e of extra wood when price-induced changes in forest land area were included.

Evaluation of mushroom production potential by combining spatial optimization and LiDAR-based forest mapping data

High-resolution forest mapping technology is a powerful data source to assess the production capacity of forests regarding wood and non-wood ecosystem services. The study shows how to evaluate the potential benefits from forest management treatments devoted to increase mushroom supply. The study was developed in Central Spain, over a forest with important cultural and economic values attached to mushrooms. Airborne laser scanning (ALS), mushroom production models and mathematical programming as spatial optimization method are used to sequence, spatially and temporally, silviculture-oriented actions to enlarge mushroom provisioning. We present a tactical forest planning solution to incentivize mushroom yield driven by clustered silvicultural treatments applied to fine-grained segments derived from ALS data, and along a 5-year plan while embedding temporal and spatial dependencies. Mushroom yield can increase up to 18 % from current conditions if all area is treated. Our model integrates constraints to optimize the selection of segments yielding the highest benefits in terms of mushroom yield and timber removals during the treatments. The temporal sequencing was successful, so the annual interventions are scheduled aligned in space and in time to ease the actionability and realism of model outputs. The assessment of production potential is an informative, spatially and temporally explicit exercise to inform decision-makers on investment opportunities to enhance the supply of non-wood ecosystem services, tested with mushroom in this study but extendable to more non-wood ecosystem services.

Discrepancies between Global Forest Net Primary Productivity Estimates Derived from MODIS and Forest Inventory Data and Underlying Factors

The net primary productivity (NPP) of a forest is an important indicator of its potential for the provision of ecosystem services such as timber, carbon, and biodiversity. However, accurately and consistently quantifying global forest NPP remains a challenge in practice. We converted carbon stock changes using the Global Forest Resources Assessment (FRA) data and carbon losses associated with disturbances and timber removals into an NPP equivalent measurement (FRA NPP*) and compared it with the NPP derived from the MODIS satellite data (MOD17 NPP) for the world’s forests. We found statistically significant differences between the two NPP estimates, with the FRA NPP* being lower than the MOD17 NPP; the differences were correlated with forest cover, normalized difference vegetation index (NDVI), and GDP per capita in countries, and may also stem from the NPP estimation methods and scopes. While the former explicitly accounts for carbon losses associated with timber removals and disturbances, the latter better reflects the principles of photosynthesis. The discrepancies between the two NPP estimates increase in countries with a low income or low forest cover, calling for enhancing their forest resource assessment capacity. By identifying the discrepancies and underlying factors, we also provide new insights into the relationships between the MOD17 NPP and global forest carbon stock estimates, motivating and guiding future research to improve the robustness of quantifying global forest NPP and carbon sequestration potential.

Forestry's Economic Contribution in the United States, 2016

Abstract Economic contributions of an industry sector are often vital information in the policy-making process. IMPLAN data and software were used to determine the economic contribution of forest industries to all 50 states plus Washington, D.C. Rankings of the states' contributions to employment, employee compensation, and value added were determined. National forest inventory data, rural population, and industrial energy costs were examined for correlation with total forestry contributions to each state's economies. Rankings were based on absolute contributions as well as contributions as a percentage of a state's total economy. Percentage rankings present the relative importance of forestry to a state's economy, and can differ considerably from absolute value rankings. Regional and national contributions were also calculated to model interstate and regional contribution “leakages,” or trade effects. Differences in both interstate and interregional trade flows are substantial. Industrial energy costs, rural population, and timber removals were significantly correlated with total economic contributions.

Understanding the Relationships Between American Ginseng Harvest and Hardwood Forests Inventory and Timber Harvest to Improve Co-Management of the Forests of Eastern United States

The roots of American ginseng have been harvested from the hardwood forests of the eastern United States, alongside timber, since the mid-1700s. Very little is known about this non-timber commodity relative to timber, although significant volumes of ginseng root have been harvested from the same forests along with timber. The harvest of ginseng correlated positively and significantly with hardwood forest area, hardwood growing stock volume, and timber removals. Also, it correlated with hardwood growing stock on public forestlands in the region. The annual wholesale value of American ginseng was estimated at approximately $26.9 million compared to annual stumpage value of harvested hardwood timber of just over $1.27 billion. The volume of ginseng root harvested from natural forests represents substantial extraction of biomass, and the associated value represents substantial income for people living in an economically marginalized region. Co-management of eastern hardwood forests for timber and non-timber forest products could improve local economies and better conserve the biodiversity of these forests.

Carbon Credit Possibilities and Economic Implications of Fuel Reduction Treatments

We determined the difference in carbon (C) stocks and C emissions between treated and untreated ponderosa pine stands over 100 years on the Apache and Sitgreaves National Forests, Arizona, USA, under assumed treatment scenarios, wildfire frequency, and annual percentage of area burned. Compared with the no-action scenario, total C stocks (live and dead biomass) were lower in the treatment scenarios because of timber removals from thinnings, whereas aboveground live C stocks were higher in the treatment scenarios. When total C stocks were used as the baseline, net present values (NPVs) of treatments were in the range of −$759.42 and −$722.58 ha−1 if timber and reduced requirement for C in a buffer pool were assumed to be creditable, and NPVs increased significantly if C in wood products was also eligible for C credit. When aboveground live C stocks were chosen as the baseline, NPVs ranged from −$759.42 to $2,700.44 ha−1 with revenues from timber stumpage value, reduced buffer pool, and/or C in wood products. C emissions from simulated wildfires were lower in the two treatment scenarios than in the no-action scenario. The heavier thinning treatment resulted in lower C emissions from wildfires than with the lighter thinning treatment.

Storm damage of Douglas-fir unexpectedly high compared to Norway spruce

Since storm damage has a large impact on forest management in Central Europe, we investigated the main storm risk factors for two important conifer species, Douglas-fir (Pseudotsuga menziesii [Mirbel] Franco) and Norway spruce (Picea abies [L.] Karst.). We compared general storm damage levels of Douglas-fir and Norway spruce, the latter being known to have high storm risk among European tree species. Generalized linear mixed models and boosted regression trees were applied to recorded storm damage of individual trees from long-term experimental plots in southwest Germany. This included two major winter storm events in 1990 and 1999. Over 40 candidate predictors were tested for their explanatory power for storm damage and summarized into predictor categories for further interpretation. The two most important categories associated with storm damage were timber removals and topographic or site information, explaining between 18 and 54 % of storm damage risk, respectively. Remarkably, general damage levels were not different between Douglas-fir and Norway spruce. Under current forest management approaches, Douglas-fir may be considered a species with high storm risk in Central Europe, comparable to that of Norway spruce.

A statistical thinning model for initialising large-scale ecosystem models

Large-scale ecosystem models are important tools for carbon assessment at national scales. Many of these models are not initialised with known field data from any particular time, but simulate the growth of each stand from its estimated germination year up to the present or future. The models will overestimate current-day standing volume or biomass unless historic stand management (biomass removal due to thinning) is taken into account. The full management history of each stand is rarely known, and must be somehow estimated. One possibility is to build statistical thinning models based on data in a National Forest Inventory, which could then be integrated into the ecosystem models. If the harvesting model is constructed using only variables that are also used within the ecosystem model, then the management impacts can be included in the ecosystem model for the entire simulated life of the stand. In the case of most flux dynamics models, this precludes the use of the tree-level data that harvesting models have traditionally relied on. In this article, we develop a novel means to interrogate a subset of the Austrian National Forest Inventory based on deriving probability density functions for particular combinations of stand and site variables. We determine the parameters of a probabilistic model to estimate historic patterns of timber removals and validate it against inventory estimates. Our procedure can establish supportable estimates of historic management regimes suitable as input data for subsequent modelling of national-scale forest carbon stocks, sources and sinks.

Incorporating management history into forest growth modelling

Mechanistic modelling is an important tool for understanding the impacts of climate change and pollutants on forest growth. One of the common practical limitations of these models is a lack of specific information regarding management activities such as thinning or harvesting, which can have a very strong influence on the accuracy of results. The use of inventory data for model parameterization and calibration is also problematic, as inventories are designed to have large volumes of data amalgamated to give accurate mean results across large areas. The precision of single point estimates is often quite low.This study uses BIOME-BGC to model forest growth on 1133 sites of the Austrian National Forest Inventory, and develops a method to estimate timber removal patterns prior to the commencement of record keeping on the sites. Recognizing the poor precision of individual point estimates in the data, we do not seek to precisely calibrate the model to the data on each point. Rather, we assume that the point-wise inventory estimates will be normally distributed around the true values. We then model each site assuming no management interventions, and compare this with inventory results. Plotting the “error” between model results and NFI data shows a strong right-skew, reflecting the modelled lack of timber removals. A Box-Cox transformation of the error plot, centred on zero, would represent an unbiased model estimate of the data, thus we can determine the historic timber removals as the difference between the original error curve and its Box-Cox transformation. Calibrating the model with this information allow us to represent forest volume with greater accuracy than would otherwise be possible.

Balancing Multiple Objectives Using a Classification-Based Forest Management System in Changbai Mountains, China

Contemporary forest management often consists of multiple objectives, including restoration of human-impacted forested landscapes toward their range of natural variability (RNV) and sustainable levels of timber production. Balancing multiple management objectives is often challenging due to intrinsic conflicts between these objectives and a lack of reference conditions for evaluating the effectiveness of forest restoration efforts. We used a spatially explicit forest landscape model to assess how well a classification-based forest management (CFM) system could achieve multiple objectives in a Korean pine broadleaf mixed forest ecosystem at Changbai Mountain in Northeast China. The CFM system divided the forest landscape into three management areas (Commercial Forest, Special Ecological Welfare Forest, and General Ecological Welfare Forest), each with its own management objectives and prescriptions, but with an overall goal of increasing the ecological and economic sustainability of the entire landscape. The zoning approach adopted in the Chinese CFM system is very similar to the TRIAD approach that is being advocated for managing public forests in Canada. In this study, a natural disturbance scenario and seven harvest scenarios (one identical to the current harvest regime and six alternative scenarios) were simulated to examine how tree species composition, age structure, and timber production at the landscape level can be affected by different strategies under the CFM system. The results indicated that the current forest management regime would not only fail to reach the designated timber production level but also move the forest landscape far away from its RNV. In order to return the currently altered forest landscape to approach its RNV while providing a stable level of timber production over time, harvest intensities should be reduced to a level that is equivalent to the amount of timber removals that would occur under the natural disturbances; and the establishment of forest plantations is also required.

Expenditure on forestry and forest products research in Australia 2007–2008

Summary Total expenditure on forestry research and forest products research in 2007–2008 in Australia was $87.8 million. This comprised $61.0 million on forestry research and $26.8 million on forest products research and was estimated using the same methods as in the several previous assessments (Quick and Booth 1987; Lambert and Turner 1992; Turner and Lambert 1997,2005). When some peripheral expenditure such as support, administration and surveys were included, the total expenditure increased to about $105.8 million. The total expenditure represents an annual average increase of about 3% since 1982 but a slow decline (0.45% per annum) in adjusted terms (1982 dollars). About 50 organisations reported undertaking forestry and or forest products research, while other organisations provided funding for research. The expenditure was attributed to four broad sectors undertaking research—Commonwealth, state, university and private—and also to broad research areas (native forests, exotic species plantations, native species plantations and environment). Research on native forests and exotic species plantations generally declined, whereas that on surveys in native forests and native species in plantations increased from 2001–2002 to 2007–2008. Similarly, research capacity declined in traditionally strong research areas such as pests and diseases and fire behaviour, and increased in energy areas such as carbon and forest bio-energy. About 600 full-time-effective researchers and technicians were involved in research in 2007–2008, plus support and management staff. The staffing numbers of individual organisations ranged from single individuals to more than fifty. In 2007–2008, about 52% of the research funds were provided directly or indirectly by the Commonwealth Government, 28% by state governments and 20% by private companies. Total expenditure on forestry and forest products research ($87.8 million) averaged $5.78 ha−1 of managed forest. The forestry research expenditure according to forest type comprised $14.80 ha−1 on exotic species plantations, $36.90 ha−1 on native species plantations and $0.99 ha−1 on native forests (including ecological and environmental research, and hydrological studies and fauna-flora research). Additionally, there was expenditure of about $0.45 ha−1 on land-based surveys (mainly biodiversity), primarily in native forests. Total expenditure on forestry and forest products research equated to an average of $3.90 m−3 of harvested timber. This comprised $1.02 m 3 on timber removals from exotic species plantations, $7.38 m−3 from native species plantations and $1.90 m−3 from native forests.

How does silviculture affect storm damage in forests of south-western Germany? Results from empirical modeling based on long-term observations

Storms represent the most important disturbance factor in forests of Central Europe. Using data from long-term growth and yield experiments in Baden-Wuerttemberg (south-western Germany), which permit separation of storm damage from other causes of mortality for individual trees, we investigated the influence of soil, site, forest stand, and tree parameters on storm damage, especially focusing on the influence of silvicultural interventions. For this purpose, a four-step modeling approach was applied in order to extract the main risk factors for (1) the general stand-level occurrence of storm damage, (2) the occurrence of total stand damage, and (3) partial storm damage within stands. The estimated stand-level probability of storm damage obtained in step 3 was then offset in order to describe the damage potential for the individual trees within each partially damaged stand (4). Generalized linear mixed models were applied. Our results indicate that tree species and stand height are the most important storm risk factors, also for characterizing the long-term storm risk. Additionally, data on past timber removals and selective thinnings appear more important for explaining storm damage predisposition than for example stand density, soil and site conditions or topographic variables. When quantified with a weighting method (summarizing the relative weight of single predictors or groups of predictors), removals could explain up to 20% of storm risk. The stepwise modeling approach proved an important methodological feature of the analysis, since it enabled consideration of the large number of observations without damage (“zero inflation”) in a statistically correct way. These results form a reliable basis for quantifying forest management’s direct impact on the risk of storm damage.

Meeting visual quality objectives with operational radial-strip partial cutting in coastal British Columbia: A post-harvest assessment

The spectacular aesthetic quality of British Columbia's coastal forests has long been an issue for forest managers who must often meet government-imposed visual quality objectives. The result of such objectives within traditional clearcutting silvicultural systems has often been large reductions in otherwise allowable timber removals. In this document we present the results of a post-harvest analysis of an operational trial using radial-strip partial harvesting in a highly visually sensitive area of coastal British Columbia. The analysis confirmed that this innovative form of partial harvesting successfully met visual quality requirements, while concurrently permitting significantly more timber extraction, in an operationally feasible manner, than would have been available under a traditional clearcutting system. We attribute the visual success of this harvest method in a highly visually sensitive area primarily to: (1) the radial pattern of linear clearings where it is not possible to see more than a few cleared strips from any one vantage point; (2) the avoidance of a regular series of parallel geometric clearings; (3) the narrow clearing width, which maximises bare ground screening; (4) feathered edges, which avoided highly contrasting edges of the strips; and (5) green tree retention across age classes. Faller and management experience with this method is expected to result in higher productivity and lower costs in the future. This harvesting technique appears to present a viable alternative to clearcutting for forest managers working in visually sensitive areas. Future work should focus on understanding and determining impacts on other factors such as ecological values and silvicultural goals. Key words: aesthetics, partial-cutting, simulation, VIA, visual impact assessment, VQO, visual quality objective

Impacts of Rotation Age Changes on Growth/Removals Ratios

Abstract When forest managers and policymakers wish to assess the ability of a given forest resource to support a sustainable level of timber harvests, they frequently use growth/removals ratios (G/R) developed from forest inventory data. Recently published inventory data for forests of the southern United States have documented numerous states in which softwood harvests exceed softwood growth, raising concern over the sustainability of this critical resource. At the same time, forest managers in the South have been investing in a wide range of practices that have dramatically increased the growth rates for softwood plantations. As these growth increases are verified in the field, forest managers respond accordingly with adjustments to management regimes, including shortening of rotation lengths. This, in turn, means that the area of forest harvested annually must increase in a given forest estate to approach a regulated forest condition. The Timber Inventory, Growth, and Removals model (TIGR) is a spreadsheet model developed to evaluate the impact of shortening rotation length on the growth/removals ratios for managed forests. The model demonstrates that a temporary imbalance of removals over growth results when the rotation age is shortened. Hence, managers and policymakers should use caution when making inferences or public claims about sustainable harvest levels from growth/removals ratios alone. If the public has been convinced that G/R ratios greater than 1.0 imply sustainable harvests, then difficult explanations will be required when the G/R ratio drops below 1.0. South. J. Appl. For. 26(2):72–77.

EFFECTS OF GROUP-SELECTION OPENING SIZE ON BREEDING BIRD HABITAT USE IN A BOTTOMLAND FOREST

An increase in timber removals from southern bottomland forests of the United States has been predicted, warranting investigations of the effects of silvicultural alternatives on avian breeding habitat. We studied the effects of creating group-selection openings (man-made canopy gaps) of various sizes on breeding bird habitat use in a bottomland hardwood forest in the Upper Coastal Plain of South Carolina, USA. We used spot mapping and mist netting to estimate bird abundance at 0.06-, 0.13-, 0.26-, and 0.5-ha gaps and at uncut control areas during the 1996, 1997, and 1998 breeding seasons (1 May–1 August). There were significant increases in the number of species mapped (P = 0.0001) and netted (P = 0.0001) with successive increases in gap size. The greatest number of total spot-map detections (P = 0.0002) and mist net captures (P = 0.0004) also occurred in and around the large gaps. These patterns were the result of increased use of larger gaps by field-edge species, primarily Brown-headed Cowbird (Molothrus ater), Common Yellowthroat (Geothlypis trichas), and Indigo Bunting (Passerina cyanea), and some forest-edge species, such as White-eyed Vireo (Vireo griseus) and Northern Parula (Parula americana). Conversely, Acadian Flycatcher (Empidonax virescens) was less abundant in and adjacent to gaps. Because there were few differences in vegetation among gaps of different sizes, it is likely that birds that were detected more frequently in and adjacent to larger gaps selected those gaps based on other factors correlated with size. Creation of 0.5-ha group-selection openings in southern bottomland forests should provide breeding habitat for some field-edge species in gaps and habitat for forest-interior species and canopy-dwelling forest-edge species between gaps, provided that sufficient mature forest is maintained.

THE FORESTER'S LEVER: INDUSTRIAL ECOLOGY & WOOD PRODUCTS

Abstract Despite increases in the nation's population, affluence, and timber removals, US forest area has remained constant and timber inventory has risen 30 percent since 1952. Industrial ecology, which analyzes the flow of timber through systems of production and consumption, seeks to explain how that happened; it also shows the leverage that consumers, millers, and foresters have to reduce harvested area and continue the rebirth of the American forest. Changes in demand by consumers, wood utilization by millers, and management by foresters can help conserve forests for uses other than timber. Of the three actors, however, foresters can exert the most leverage—by increasing the growth rate of trees.

A timber harvesting model for Austria

Between 1981 and 1985 the Austrian National Forest Inventory (ANF) established a set of 5500 clusters, each with four permanent plots covering all Austrian forests. After the first remeasurement between 1986 and 1990 models were developed to predict tree growth, mortality and the behavior of forest owners in harvesting timber. A set of logistic equations describes the probability for a given stand to exhibit intermediate harvesting, single-tree selection or final clear cutting. Independent variables were either continuous or categorical, describing: (i) regional units such as provinces, (ii) types of ownership (groups of ownership sizes), (iii) site factors (elevation and slope), and (iv) stand characteristics (species mixture, density, mean diameter). Timber removals on the plots are recorded by five relative diameter at breast height (dbh)-classes. Removal percentages differ by elevation, harvesting categories, and tree species groups. Timber harvest forecasts and their spatial arrangement over Austria in the following four 5-year periods were made available to the public using computer software. In 1997 data of the second inventory remeasurements were available and thus the forecasts for this period could be evaluated. When forecast units are large enough, deviations from the model are either small or can be explained by a different timber market scenario and/or a general socio-economical scenario.

Sustainability in forest management: An evolving concept

Sustainability in forest management is both a biological and socioeconomic concept. Originating in 18th century Europe with the aim of avoiding social and economic disruptions associated with timber shortages, sustained-yield forest management evolved to a highly technical process of modeling growth, mortality, and risk in order to set timber removals at a level that theoretically could be maintained in perpetuity. Changing scientific understanding of the ecological functioning of forest ecosystems has challenged the notion that a sustained yield of timber is equivalent to sustaining all the components and natural processes necessary to maintain the long-term health and productivity of these ecosystems. Continuing uncertainty over what is socially and economically acceptable, as well as ecologically sustainable, will make optimality in forest management a much more difficult objective than in the past.

Carbon fluxes resulting from U.S. private timberland management

A carbon budget model was developed to examine the effects of forest management practices on carbon storage in U.S. private timberlands. The model explicitly incorporates the demand for wood products and its impact on harvesting and other management decisions. Forest carbon is divided into four components: carbon stored in trees, soils, forest litter, and understory vegetation. Changes in the forest carbon inventory result from tree growth and management activities, in particular harvesting. Harvesting of timber for wood products is determined by demand and supply forces. The model then tracks carbon in timber removals through primary and secondary processing and disposal stages. Harvesting also has effects on carbon in soils, forest litter, and understory vegetation. A base-run scenario projects increases in carbon storage in U.S. private timberlands by 2040; however, this increase is offset by carbon emissions resulting from harvesting.