Woodpeckers increase in abundance but maintain fecundity in response to an outbreak of mountain pine bark beetles

Many temperate woodpecker species are thought to be highly conservative in their fecundity with little response to fluctuations in availability of resources. In a 15-year field study in interior British Columbia, we evaluated responses in abundance and fecundity of six species of resident and migrant woodpeckers (downy woodpecker [Picoides pubescens], hairy woodpecker [Picoides villosus], American three-toed woodpecker [Picoides dorsalis], pileated woodpecker [Drycopus pileatus], northern flicker [Colaptes auratus], and red-naped sapsucker [Sphyrapicus nuchalis]) to a large-scale outbreak of mountain pine bark beetles that resulted in a strong positive pulse in food supply. Population densities of woodpecker species increased during outbreak years. Despite the year-round multi-annual increase in food resources, and in contrast to the strong increases in fecundity shown by nuthatches and chickadees, annual fecundity (as indicated by clutch size and number of nestlings that fledged) did not change for any woodpecker species over the study. Similarly, we found no changes in fecundity in response to selective forest harvesting despite numerical increases for woodpeckers at these sites. Our study confirms that these woodpecker species are conservative in their reproductive investment patterns even during strong multi-annual increases in food. Our findings indicate woodpecker populations are regulated numerically through variable survival and/or greater immigration rates, which can result in higher breeding densities temporarily during resource pulses.     

Planning timber harvest of residual forest stands without compromising bird and small mammal communities in boreal landscapes

Numerous efforts have been invested in designing and configuring residual forest stands in Canadian boreal forest to preserve their overall biodiversity. Now that several landscapes have been partially logged, the next issue in forest management involves the planning of residual forest stand harvesting without compromising wildlife populations. Residual stands can be cut when adjacent regeneration reaches 3 m in height according to current regulations in several Canadian provinces (e.g., Québec, Ontario, Alberta, and British-Columbia). However, little is known on whether such regenerating habitat (RE-3m) can maintain wildlife communities similar to those found in unharvested mature forest (CO). We estimated the relative abundance of small mammals and forest birds in RE-3m and CO habitats and characterized landscape and stand structures. These variables were then compared between the two contrasting successional stages and were used to build habitat use models (HUMs) for 21 species. CO and RE-3m differed with regard to several landscape characteristics and stand structure variables as a result of logging. Snowshoe Hare, Northern Flicker, Alder Flycatcher, Ruby-crowned Kinglet, White-throated Sparrow and Magnolia Warbler were more abundant in RE-3m than CO, while Red-backed Vole, Brown Creeper and Golden-crowned Kinglet exhibited lower abundances in RE-3m. No significant differences in abundance were observed for the 12 other species. Species HUMs were highly significant and explained between 64.3 and 99.1% of the total variability in abundance. Following variance partitioning, stand structure variables accounted for most of the explained variability (54.2%) while landscape characteristics accounted for only 28.7%. No difference in species richness was observed but community evenness was greater in CO than RE-3m. Our results suggest that current regulations may threaten the maintenance of 3 out of 21 censused species for which abundances were significantly lower in regenerating 3 m tall stands. As stand structure explained a large amount of variability in abundance, it should be considered during timber harvest planning in both mature and regenerating stands. Until we know more on whether the current regulations are suitable for maintaining overall biodiversity, our results suggest that some mature forest stands should be maintained within managed landscapes for a complete logging rotation period.     

Post-1935 changes in forest vegetation of Grand Canyon National Park, Arizona, USA: Part 1 - ponderosa pine forest

Vegetation plots originally sampled in Grand Canyon National Park (GCNP), Arizona, USA in 1935 are the earliest-known, sample-intensive, quantitative documentation of forest vegetation over a Southwest USA landscape. These historical plots were located as accurately as possible and resampled in 2004 to document multi-decadal changes in never-harvested Southwestern forests. Findings for ponderosa pine forest (PPF) differed among three forest subtypes (dry, mesic, and moist PPF), indicating that understanding the ecology of PPF subtypes is essential for development of ecologically based management practices. Dry PPF, which is transitional with pinyon-juniper vegetation at low elevation, exhibited no changes from 1935 to 2004. Mesic PPF, the core subtype of PPF, had increased densities of total trees, ponderosa pine (Pinus ponderosa), and white fir (Abies concolor) in the 10-29.9 cm diameter class from 1935 to 2004 that may have induced decreased densities of larger ponderosa pines and total tree and ponderosa pine basal areas. Moist PPF, which is transitional with mixed conifer forest at high elevation, was the most dynamic PPF subtype with decreases from 1935 to 2004 in total density and total basal area that are largely attributable to decreases in quaking aspen (Populus tremuloides). Graphical synthesis of datasets with historical and modern values for density and basal area indicates that overall PPF (all subtypes combined) increased in sapling density of all species combined and conifers with canopy potential and decreased in density of quaking aspen trees since the late 19th century. PPF of GCNP has passed through an accretion phase of forest development with increases in density and, depending on PPF subtype and variable being examined, is at or past the point of inflection to recession of density and basal area. Increases in small diameter ponderosa pine and white fir from 1935 to 2004 portend potential additional accretion, but decreases in total basal area, density and basal area of quaking aspen, basal area of ponderosa pine, and density of larger diameter ponderosa pine indicate PPF has passed the inflection point from accretion to recession. Uncertainties about 19th-century PPF structure and composition and about future ecological and societal environments lead to the conclusion that resource managers of GCNP and other natural areas should consider a change in focus from the objective of achieving desired future conditions to an objective of avoiding undesired future conditions.     

Integrating climate change into forest management in South-Central British Columbia: An assessment of landscape vulnerability and development of a climate-smart framework

The achievement of sustainable forest management requires the incorporation of risk and uncertainty into long-term planning. Climatic change will have significant impacts on natural disturbances, species and ecosystems, particularly on landscapes influenced by forest management. Understanding where vulnerabilities lie is important in managing the risks associated directly or indirectly with climatic change. The vulnerability of landscapes to natural disturbances, the resilience of ecosystems and distribution of species are all important components that need to be considered when undertaking forest planning, but climatic change is rarely factored into such planning. In this study, the vulnerability of fire potential, fire regimes, ecosystems and species to climatic change was modelled for a 145,000 ha landscape in the south-central interior of British Columbia, Canada. The results from these analyses were used to guide forest zoning, using the triad zoning framework, and for the development of a “climate-smart” management framework. The use of climate-smart management is advocated as a decision-making framework for managing forested landscapes based on an understanding of landscape vulnerability to future climatic change. From this understanding, the maintenance of ecosystem health and vitality could be achieved.     

Corrigendum to: Growth of white spruce underplanted beneath spaced and unspaced aspen stands in northeastern B.C.—10 year results

Establishing white spruce (Picea glauca (Moench) Voss) by planting it under established aspen (Populus tremuloides Michx.), stands has substantial potential as a technique for regenerating boreal mixedwood stands. The presence of an aspen overstory serves to ameliorate frost and winter injury problems and suppresses understory vegetation that may compete with white spruce. In this study we examine the growth of white spruce during the first 10 years after being planted underneath a 39-year-old stand of trembling aspen following thinning and fertilization. Results indicate successful establishment and reasonable growth rates of white spruce planted under thinned and unthinned aspen stands, even with aspen basal area of 51 m² ha⁻¹. Thinning of overstory aspen to 1000 or 2000 stems ha⁻¹ did not increase light reaching seedlings, but did result in improvements in light above the shrub layer and in diameter and height growth of the underplanted seedlings. However, these increases in growth of underplanted spruce may not justify the expense of thinnings. Fertilization of these stands prior to planting had no effect on spruce growth. Growth of spruce underplanted at this site near Fort Nelson was similar to that at two other stands near Dawson Creek, B.C.     

A comparison of biodiversity values in boreal forest regeneration areas before and after forest certification

Abstract

In this study, 236 regeneration areas (mostly clear-cuts) in southern Norway were selected by random stratified selection: 118 of the study units were cut before and 118 after the introduction of forest certification in 1998. The degree of compliance with biodiversity measures established in the prevailing certification standard (ISO 14001 and the Norwegian standard “Living Forests”) was compared in a field study, and the differences were analysed. In some aspects, a clear difference could be seen, most clearly in an increasing number of green retention trees and an increasing mean width of buffer-strips left along rivers, bogs and lakes in the postcertification units compared with the precertification units. Even though there was a significant increase in the mean number of retention trees, as much as 21% of the postcertification regeneration areas still did not have sufficient retention trees to comply with the certification standard and 41% had either too few retention trees or too few spruce trees according to the standard. Concerning the management of small swamp forests, and the damage done to terrain and prelogging coarse dead wood by off-road transport, little improvement was seen. The discussion examines whether it is probable that the changes seen are a result of forest certification in Norway.     

Temporal mapping of deforestation and forest degradation in Nepal: Applications to forest conservation

Deforestation and forest degradation are associated and progressive processes resulting in the conversion of forest area into a mosaic of mature forest fragments, pasture, and degraded habitat. Monitoring of forest landscape spatial structures has been recommended to detect degenerative trends in forest conditions. GIS and remote sensing play an important role in the generation of such data to identify degraded and deforested areas as well as potential areas for conservation. In this study we analyzed forest degradation and deforestation trends in Chitwan district in Nepal, which contains key habitat elements for wildlife in the region. An artificial neural network was used to predict forest canopy density in five classes using Landsat images of the year 2001. Forest canopy density was predicted with 82% overall accuracy. Except riverine forest, forest area of all other forest types was reduced. Terai Shorea robusta forest, which has high commercial value, showed a loss of 23% between 1976 and 1989 and an overall loss of 15% forest covers between the year 1976 and 2001. Deforestation and forest degradation disproportionately reduced the sizes of the different forest types, a finding that has important management implications. The maps presented in this article could be useful to prioritize limited resources for conservation.     

From guiding principles for the conservation of forest biodiversity to on-ground practice: Lessons from tree hollow management in Tasmania

A useful theoretical approach in the literature for those trying to conserve forest biodiversity involves a number of strategies to achieve maintenance of habitat for different species across multiple spatial and temporal scales. This approach emphasises the importance of implementing measures in off-reserve areas to complement reserve systems. This contrasts with both the traditional ‘set-aside’ approach to conservation and the primary aim of production forestry. Translating this risk-spreading approach into on-ground practice is often a difficult task.     

Response of seasonal pond plant communities to upland forest harvest in northern Minnesota forests,USA

Small seasonally flooded forest ponds have received increased attention due to a growing recognition of their abundance in many landscapes, their importance as habitat for a variety of organisms, and the contributions they make to species and ecosystem diversity. There also is concern over potential negative effects of forest management in adjacent uplands on seasonal pond ecology. Several studies have examined invertebrate and songbird responses to upland harvest around seasonal ponds. Less attention has been given to examining how seasonal pond plant communities respond to adjacent forest harvesting. We studied the response of seasonal pond plant communities to adjacent upland timber harvests, assessing whether buffers around ponds (15.25 m uncut and partially cut) mitigated changes in species abundance and community composition, relative to changes in ponds that were clearcut to the pond margin. We addressed our objective using an operational-scale experiment in northern Minnesota, which included pre-harvest sampling, replicated treatments, and uncut controls. After treatment, changes in tree basal area and canopy openness in the pond basins reflected reductions in upland basal areas. Specifically, control ponds had significantly higher basal area and lower openness than ponds cut to their margins, while ponds with uncut buffers and partially cut buffers were intermediate. Changes in plant communities were evident in the ground layer and shrub/large regeneration layer. After treatment and over time, the control stands did not change significantly in ground layer structure or shrub/large regeneration layer composition. The three upland harvest treatments displayed increasingly greater deviation from their starting conditions and from the control along a gradient of increasing treatment intensity, from the buffer treatment to the partially cut buffer to the clearcut. The response in the ground layer was largely associated with increased sedge and grass cover, while the response in the shrub/large regeneration layer was associated with increases of Salix sp., Alnus incana, and Populus tremuloides. Our results indicate that adjacent upland timber harvest can lead to altered plant communities within seasonal ponds, at least temporarily. Moreover, uncut forest buffers (∼15.25 m) surrounding seasonal ponds can mitigate plant community changes to some degree. If seasonal ponds are an important resource on the management landscape and a high percentage of upland forest is in a recently cut condition at any given time, than use of harvest buffers around seasonal ponds may be an appropriate approach for mitigating short term alteration of pond plant communities.     

Inclusion of forest harvest legacies, forest type, and regeneration spatial patterns in updated forest maps: A comparison of mapping results

In Maine and other heavily forested states, existing land cover maps quickly become dated due to forest harvesting and land use conversion; therefore, these maps may not adequately reflect landscape properties and patterns relevant to current resource management and ecosystem studies. By updating an older land cover product (the 1993 Maine GAP map) using Landsat imagery and established forest change detection techniques, we demonstrate a practical and accurate means of providing contemporary, spatially explicit forest cover data needed to quantify landscape change. For a 1.8 million hectares study area in northern Maine, we quantify the accuracy of forest harvest classes and compare mapped harvest and regeneration area between the 2004 GAP update product and the 2004 Maine Landcover Dataset (MeLCD), a map recently developed in coordination with the 2001 National Land-Cover Database (NLCD). For the period 1995–2004, the overall harvest/non-harvest accuracy of the GAP update map is 87.5%, compared to 62.1% for the MeLCD. Producer and user accuracy for harvest detection is 92.4% and 89.7%, respectively for the GAP update, and 48.8% and 92.5% for the MeLCD. Mapped harvest area differs considerably, reflecting a systematic under-representation of recent harvest activity on the part of the MeLCD. By integrating older land cover data, the GAP update retains the forest disturbance legacies of the late 1970s through the early 1990s while simultaneously depicting 2004 forest composition for harvested and regenerating stands. In contrast, the MeLCD (and 2001 NLCD) over-represents the area and connectivity of older forest (undisturbed since the late 1970s), and provides no forest composition information for mapped forest regeneration. Systematic misclassification of forest age classes and harvest history has serious implications for studies focused on wildlife habitat modeling, forest inventory, and biomass or carbon stock estimation. We recommend the integration of older land cover data and time-series forest change detection for retention of harvest or disturbance classes when creating new forest and land cover maps.     

Floristic diversity and composition of the Biteyu forest in the Gurage mountain chain (Ethiopia): implications for forest conservation

The Afromontane forests of Ethiopia have been under a serious degradation threat. Assessment of floristic diversity and species composition in Biteyu forest of Gurage mountain chain in the central Ethiopia was conducted to examine the pattern of forest structure. Thirty plots of 30 m×30 m were used to record the vegetation and environmental data using systematic sampling technique. The local name, plant scientific names, DBH, height,species abundance and percentage canopy cover of plant species were recorded. Shannon diversity index and Sorensen's coefficients was used for comparison among communities and similar forests in the country. Threats to the forest biodiversity in Biteyu were determined by counting cattle interference and wood stumps as disturbance indicators. Relative Euclidean Distance measures by using Ward's method(linkage) was applied for cluster analysis. Environmental variables were also recorded in each plot. Woody species population structure, basal area and importance value index were analyzed using spreadsheet programs. Data on species distribution and environmental variables in the forest were analyzed by canonical correspondence analysis. A total of 190 species in 154 genera under 73 families were identified. Twenty species were found to be endemic taxa to the Flora Area. Only three plant community types were identified from the cluster analysis due to the high human influence. The Sorensen's coefficient showed the resemblance of the Biteyu forest with other Dry Evergreen Afromontane forests in the country. Moreover, altitude and slope strongly affect the species composition and structure of Biteyu forest. Given the high anthropogenic influence, high endemism, high dependence of the local community on the forest resources, forest conservation and restoration measures should be done by stakeholders.     

Post-1935 changes in forest vegetation of Grand Canyon National Park, Arizona, USA: Part 2—Mixed conifer, spruce-fir, and quaking aspen forests

This study examined changes in never-harvested mixed conifer (MCF), spruce-fir (SFF), and quaking aspen forests (QAF) in Grand Canyon National Park (GCNP), Arizona, USA based on repeat sampling of two sets of vegetation study plots, one originally sampled in 1935 and the other in 1984. The 1935 plots are the earliest-known, sample-intensive, quantitative documentation of forest vegetation over a Southwest USA landscape. Findings documented that previously described increases in densities and basal areas attributed to fire exclusion were followed by decreases in 1935-2004 and 1984-2005. Decreases in MCF were attributable primarily to quaking aspen (Populus tremuloides) and white fir (Abies concolor), but there were differences between dry-mesic and moist-mesic MCF subtypes. Decreases in SFF were attributable to quaking aspen, spruce (Picea engelmannii + Picea pungens), and subalpine fir (Abies lasiocarpa). Decreases in QAF resulted from the loss of quaking aspen during succession. Changes in ponderosa pine forest (PPF) are described in a parallel paper (Vankat, J.L., 2011. Post-1935 changes in forest vegetation of Grand Canyon National Park, Arizona, USA: part 1 - ponderosa pine forest. Forest Ecology and Management 261, 309-325). Graphical synthesis of historical and modern MCF data sets for GCNP indicated tree densities and basal areas increased from the late 19th to the mid 20th century and then decreased to the 21st century. Changes began earlier, occurred more rapidly, and/or were larger at higher elevation. Plot data showed that basal area decreased earlier and/or more rapidly than density and that decreases from 1935 to 2004 resulted in convergence among MCF, SFF, and PPF. If GCNP coniferous forests are trending toward conditions present before fire exclusion, this implies density and basal area were more similar among these forests in the late 19th century than in 1935. Changes in MCF and SFF can be placed in a general framework of forest accretion, inflection, and recession in which increases in tree density and basal area are followed by an inflection point and decreases. Accretion was triggered by the exogenous factor of fire exclusion, and inflection and recession apparently were driven by the endogenous factor of density-dependent mortality combined with exogenous factors such as climate. Although the decreases in density and basal area could be unique to GCNP, it is likely that the historical study plots provided a unique opportunity to quantitatively determine forest trends since 1935. This documentation of post-1935 decreases in MCF and SFF densities and basal areas indicates a shift in perspective on Southwestern forests is needed.     

Small mammals and retention islands: An experimental study of animal response to alternative logging practices

The integration of forest biodiversity conservation with wood production is a key part of ecologically sustainable forest management. This can be a particular challenge at the stand-level when high-intensity silvicultural systems like clearfelling are employed. Alternative logging practices to clearfelling that result in partial stand retention are being widely promoted in many parts of the world. We present new findings from a replicated block experiment designed to examine the responses of small terrestrial mammals to the retention of islands of forest within otherwise clearfelled harvest units. Our experiment was conducted in the Mountain Ash (Eucalyptus regnans F. Muell) forests of the Central Highlands of Victoria, south-eastern Australia. We quantified the effects of four treatments on small terrestrial mammal abundance: (1) an uncut (‘control’) area of forest; (2) a 1.5 ha retained island within an otherwise clearfelled area; (3) three 0.5 ha retained ‘islands’ within an otherwise clearfelled area; and (4) a traditionally clearfelled area of forest, over the different stages of harvesting operations from pre-cut to post-cut to post-burn.     

Susceptibility of ponderosa pine, Pinus ponderosa (Dougl. ex Laws.), to mountain pine beetle, Dendroctonus ponderosae Hopkins,attack in uneven-aged stands in the Black Hills of South Dakota and Wyoming USA

Mountain pine beetle, Dendroctonus ponderosae Hopkins can cause extensive tree mortality in ponderosa pine, Pinus ponderosa Dougl. ex Laws., forests in the Black Hills of South Dakota and Wyoming. Most studies that have examined stand susceptibility to mountain pine beetle have been conducted in even-aged stands. Land managers increasingly practice uneven-aged management. We established 84 clusters of four plots, one where bark beetle-caused mortality was present and three uninfested plots. For all plot trees we recorded species, tree diameter, and crown position and for ponderosa pine whether they were killed or infested by mountain pine beetle. Elevation, slope, and aspect were also recorded. We used classification trees to model the likelihood of bark beetle attack based on plot and site variables. The probability of individual tree attack within the infested plots was estimated using logistic regression. Basal area of ponderosa pine in trees ≥25.4 cm in diameter at breast height (dbh) and ponderosa pine stand density index were correlated with mountain pine beetle attack. Regression trees and linear regression indicated that the amount of observed tree mortality was associated with initial ponderosa pine basal area and ponderosa pine stand density index. Infested stands had higher total and ponderosa pine basal area, total and ponderosa pine stand density index, and ponderosa pine basal area in trees ≥25.4 cm dbh. The probability of individual tree attack within infested plots was positively correlated with tree diameter with ponderosa pine stand density index modifying the relationship. A tree of a given size was more likely to be attacked in a denser stand. We conclude that stands with higher ponderosa pine basal area in trees >25.4 cm and ponderosa pine stand density index are correlated with an increased likelihood of mountain pine beetle bark beetle attack. Information form this study will help forest managers in the identification of uneven-aged stands with a higher likelihood of bark beetle attack and expected levels of tree mortality.     

Use of forest resources,traditional forest-related knowledge and livelihood of forest dependent communities: Cases in South Korea

The patterns of forest resource use in South Korea have been overviewed along with the forest resource availability to the forest users and in relation to the socio-economic conditions of local people. In South Korea, forest income arises more from non-timber forest products (NTFPs) and forest ecosystems services than from timber. The relationship between availability of forest resources and income of residents in mountainous villages was addressed with statistical analysis of results of household surveys conducted in Gangwon-do Province. The result indicates that the mere existence of forest resources and related cultural heritages is not enough for local communities to obtain income from forest land. Proper arrangements for local communities in accessing the forest resources and knowledge of making use of the resources is required to make the relationship constructive for people's livelihood. Joint management agreement between forest communities and the forest owner serves both parties for sustainable forest management in Korea as seen in the case of maple sap collection within Seoul National University Forests. The traditional knowledge held by local residents is of value for income generation for forest dependent communities and is considered as an integral part of sustainable forest management as seen in the case of native honey bee keeping near protected forest areas managed by the national forest authority. However, traditional cultural values may be positive or negative for ecologically sound forest management as seen in the pest management policy of the Korean government formulated based on cultural value rather than considerations of ecosystem health.     

Influence of variable retention harvests on forest ecosystems: Plant and mammal responses up to 8 years post-harvest

Green-tree retention systems are an important management component of variable retention harvests in temperate zone coniferous forests. Residual live trees (“legacy trees”) provide mature forest habitat, increase structural diversity, and provide continuity in the regenerating stand. This study was designed to test the hypotheses that, at up to 8 years after harvest, abundance and species diversity of communities of (i) understory plants and (ii) forest-floor small mammals, and (iii) relative habitat use by mule deer (Odocoileus hemionus), will decline with decreasing levels of tree retention. Communities of plants and forest floor small mammals were sampled in replicated clearcut, single seed-tree, group seed-tree, patch cut, and uncut forest sites in mixed Douglas-fir (Pseudotsuga menziesii)—lodgepole pine (Pinus contorta) forest in southern British Columbia, Canada from 2000 to 2003 (5–8 years post-harvest). Habitat use by mule deer was measured during summer and winter periods each year from 1999 to 2003 in these same sites.     

Canopy microclimate response to pattern and density of thinning in a Sierra Nevada forest

Restoring Sierra Nevada mixed-conifer forests after a century of fire suppression has become an important management priority as fuel reduction thinning has been mandated by the Healthy Forests Restoration Act. However, in mechanically thinned stands there is little information on the effects of different patterns and densities of live-tree retention on forest canopy microclimate. This study compared gradients of air temperature and vapor pressure deficit (VPD) through the vertical forest profile among an overstory-thin, an understory-thin, an un-thinned control, and a riparian environment in a Sierra Nevada mixed-conifer forest. Temperature and humidity were recorded for a year by 60 data loggers arrayed in 12 trees at 5, 15, 25, 35, and 45 m above the forest floor. Both thinning treatments had significantly more extreme summer daily ranges of temperature and VPD than the control across heights. The overstory-thin resulted in the greatest maximum temperatures, VPDs, and VPD range among all sensors at 5 m, and significantly higher summer maximum temperatures and VPDs than the control in lower strata (≤15 m). The understory-thin also had significantly higher summer maximum temperatures than the control (≤15 m), but these too were significantly less than in the overstory-thin nearest the surface at 5 m. Understory thinning did not alter the mean or range of microclimate as much as overstory thinning. Riparian microclimate had significantly lower minimums and means, and greater daily ranges of temperatures and VPDs than the control. Results suggest that thinning canopy cover significantly increases the extremes and variability of understory microclimate compared to thinning from below and no-thin treatments.     

Beetles, trees, and people: Regional economic impact sensitivity and policy considerations related to the mountain pine beetle infestation in British Columbia, Canada

This article investigates the regional economic impact sensitivity to the current mountain pine beetle infestation in five study areas of British Columbia, Canada, using a computable general equilibrium framework. Baseline general equilibrium economic databases are constructed for each region using a hybrid data collection approach involving primary and secondary sources. A computable general equilibrium model is constructed for each region and used to simulate the sensitivity of a suite of economic indicators to changes in forestry sector exports resulting from the impacts of mountain pine beetle on the available timber supply. The computable general equilibrium models constructed for each region provides an indication of economic vulnerability to the infestation and can assist decision-makers with the identification of policy considerations and priority areas for mitigation planning in response to the anticipated fluctuations in timber supply.     

Potential use of a spatially constrained harvest scheduling model for biodiversity concerns: Exclusion periods to create heterogeneity in forest structure

The objective of this paper is to investigate potential use of a spatially constrained harvest scheduling model for biodiversity concerns. Change in the degree of biodiversity is represented only by spatial characteristics of harvesting patterns of forest stands with different exclusion periods applied to adjacent forest stands. A spatially constrained harvest scheduling model called SSMART (Scheduling System of Management Alternatives foR Timber-harvest) is used for the analysis. It is one of the heuristics to solve a spatially constrained harvest scheduling problem by using the partitioning heuristic. The algorithm incorporated into SSMART is designed to seek a solution for a multicriteria problem with present net value maximum, meeting spatial feasibility and minimizing period-to-period harvest flow fluctuation, approximating even-flow constraints within the 0–1 integer programming framework. Our experimental analysis shows that the longer exclusion period, the less the harvest flow level and the total present net value are derived and the more heterogeneous the forest structure becomes in terms of the forest stand age distribution. It is also shown that the three exclusion period results in a stable forest stand age distribution over the time horizon for our experimental forest. This research supported by the Grants-in-Aid for Scientific Research (No. 09041071) from the Ministry of Education, Science, Sports, and Culture of Japan.