Forest Harvesting Research Papers - Academia.edu (original) (raw)

In one of the most influential studies in the recent history of forest ecology, W. W. Covington (1981) described a pattern in organic matter storage in the forest floors of northern hardwood stands as a function of date of harvest. We... more

In one of the most influential studies in the recent history of forest ecology, W. W. Covington (1981) described a pattern in organic matter storage in the forest floors of northern hardwood stands as a function of date of harvest. We review the history of the use and misuse of Covington's curve, describe the studies that tested and failed to support early interpretations of the curve, and provide some alternate interpretations. The curve suggested that forest floor organic matter declines by 50% within 20 years after harvest, and this decline was attributed to accelerated decomposition and changes in litter inputs after harvest. Subsequent studies showed that decomposition rates of surface litter generally decrease after clear-cutting, but accelerated decomposition remains possible in the Oe and Oa horizons. Changes in litter inputs are still difficult to evaluate, because the rate at which woody debris enters the forest floor is unknown. Although Covington attempted to minimize variation due to mechanical disturbance during logging, a reasonable alternative explanation for low organic matter in the forest floor of young stands is that surface material is mixed into mineral soil during harvesting operations. The pattern of forest floor organic matter in stands of different ages may be partly due to changes over time in logging technology and the intensity of biomass removal, in addition to successional effects. It is important to distinguish between mechanisms that release carbon to the atmosphere and those that transfer it to the mineral soil before making inferences about nutrient cycling and carbon sequestration.

O trabalho foi conduzido em povoamentos de eucalipto de uma empresa florestal do Estado de Goiás, com o objetivo de avaliar técnica e economicamente um sistema de colheita florestal de árvores inteiras composto de "feller-buncher",... more

O trabalho foi conduzido em povoamentos de eucalipto de uma empresa florestal do Estado de Goiás, com o objetivo de avaliar técnica e economicamente um sistema de colheita florestal de árvores inteiras composto de "feller-buncher", "skidder" e garra traçadora. Foi realizado um estudo de tempos e movimentos e determinados os custos operacionais e de produção das máquinas. Para avaliar esses valores de produtividade do "feller-buncher" e da garra traçadora, foi empregado um delineamento estatístico inteiramente casualizado com seis repetições, em esquema de parcelas subdivididas. Adotaram-se como parcelas as operações que compõem o ciclo operacional das máquinas e como subparcelas, os níveis de produtividade de floresta de 100, 200 e 300 m³ ha -1 . Os valores foram submetidos à análise de variância e ao teste de Tukey a 5% de probabilidade. Para avaliar o efeito dos tempos consumidos nas operações do ciclo operacional do "skidder" nas produtividades de floresta de 100, 200 e 300 m³ ha -1 e nas distâncias de arraste de 100, 200 e 300 m, assim como avaliar suas interações quando significativas, utilizou-se um delineamento estatístico de blocos casualizados, em esquema fatorial 6x3x3, sendo seis operações, três produtividades e três distâncias de arraste, com quatro repetições. Os valores foram submetidos à análise de variância e ao teste de Tukey a 5% de probabilidade. Concluiu-se que o "feller-buncher" registrou o maior custo de produção dentro do sistema, obtendo melhor capacidade efetiva de trabalho nas áreas de maior produtividade. O "skidder" também teve seu melhor desempenho no talhão de 300 m³ ha -1 na distância até 200 m. A garra traçadora apresentou custo de 0.97, 0.75 e 0.63 US$ m -3 para as produtividades de 100, 200 e 300 m³ ha -1 , respectivamente.

Physically based models are commonly used as an integral step in landslide hazard assessment. Geomorphic principles can be applied to a broad area, resulting in first order assessment of landslide susceptibility. New techniques are now... more

Physically based models are commonly used as an integral step in landslide hazard assessment. Geomorphic principles can be applied to a broad area, resulting in first order assessment of landslide susceptibility. New techniques are now available that may result in the increased accuracy of such models. We investigate the possibility to enhance landslide susceptibility modeling by integrating two physically-based landslide models, the Factor of Safety (FS) and the Shallow Stability model (SHALSTAB), with traditional empirical-statistical methods that utilize terrain attribute information derived from a digital elevation model and land use characteristics related to forest harvesting. The model performance is measured by the area under the receiver operating characteristic curve (AUROC) and sensitivity at 90% and 80% specificity both estimated by bootstrap resampling. Our study examines 278 landslide initiation points in the Klanawa Watershed located on Vancouver Island, British Columbia, Canada. We use a generalized additive model (GAM)and a logistic regression model (GLM) combining physical landslide models, terrain attributes and land use data, and GAMs and GLMs using only subsets of these variables.In this study, all empirical and combined physical-empirical models outperformthe physically-based models, with GAMs often performing significantly better than GLMs. The strongest predictive performance is achieved by the GAMsusing terrain attributes in combination with land use data. Variables representing physically-based models do not significantly improve the empirical models, but they may allow for a better physical interpretation of empirical models. Also, based on bootstrap variable-selection frequencies,land use data, FS, slope and plan/profile curvature are relatively the most important predictor variables.

The Kumil timber project in Papua New Guinea represents one of the earliest attempts by the State to directly involve customary landowners in large-scale timber harvesting. A unique aspect of this project was that a local landowners'... more

The Kumil timber project in Papua New Guinea represents one of the earliest attempts by the State to directly involve customary landowners in large-scale timber harvesting. A unique aspect of this project was that a local landowners' company was established to manage the logging and initiate development activities, so that customary landowners would retain a greater share of the benefits. This paper examines the experience of customary landowners with the Kumil project. The social structures applying to land tenure are examined, as well as the impact that logging has had on village stability and prosperity. Finally, the role of the landowners' company as a vehicle for meaningful villager participation in large-scale forest harvesting is assessed.

World demand for paper has increased at an average annual rate of 4.7% over the past 40 years. Although future growth will reduce to 2-3% the existing wood resources may be inadequate to meet this growing demand for paper especially in... more

World demand for paper has increased at an average annual rate of 4.7% over the past 40 years. Although future growth will reduce to 2-3% the existing wood resources may be inadequate to meet this growing demand for paper especially in the Asia-Pacific region and Eastern Europe. In addition, logging is coming under increasing pressure from environmentalists concerned about habitat destruction and other longer-term impacts of forest harvesting. It is, therefore, necessary to consider alternative fiber sources to meet the possible shortfall of wood fiber for papermaking. Suitable nonwood fibers are abundantly available in many countries and are the major source of fiber for papermaking in some developing nations.

In this paper, we developed a mixed-integer non-linear programming model that integrates access road development and a utility theoretic spatial choice model of hunters into a strategic forest harvest-scheduling model. The model was... more

In this paper, we developed a mixed-integer non-linear programming model that integrates access road development and a utility theoretic spatial choice model of hunters into a strategic forest harvest-scheduling model. The model was applied to an operationally sized Forest Management Agreement (FMA) area in central Alberta, Canada. The resulting behavioral model had approximately 2.6 million decision variables and about 96,000 constraints, and was used to examine the impacts of timber harvesting on hunters' preference for hunting sites. We also evaluated the impacts of various levels of hunter welfare on: (i) the degree of tradeoff between timber and hunting benefits, (ii) timber harvest schedules, and (iii) the marginal costs of producing timber products. The results showed significant tradeoffs between timber and hunting benefits and a clear link between landscape characteristics and changes and behavioral responses by hunters.

Results of several long-term studies of non-woody litter decomposition in forests indicate that we need to rethink why and how we measure rates of litter decomposition. Effects on litter decomposition rates were postulated to explain some... more

Results of several long-term studies of non-woody litter decomposition in forests indicate that we need to rethink why and how we measure rates of litter decomposition. Effects on litter decomposition rates were postulated to explain some of the nutritional effects of factors such as tree species, forest harvesting and fertilization. However, the accumulated experimental evidence indicates that litter decomposition rates do not mediate these responses. Many studies have reported litter mass loss becoming extremely slow at values considerably below 100%, indicating that early decay rates may not accurately foreshadow the entire decay process. Exclusion of soil faunal activities from current measurements of decomposition rates seriously reduces the likelihood that we are properly modeling decomposition. Finally, the use of regression and correlation analyses to determine which climate or initial litter quality factors control decay rate has led to many unwarranted and potentially misleading conclusions. These concerns are illustrated with examples from a suite of litter decomposition studies in British Columbia, Canada. Insights into nutrient cycling and carbon storage in ecosystems are more likely to arise from measuring the mass and nutrient content of annual litter input and determining the maximum decomposition limit and nutrient content at that stage, than by measuring early rates of decay. Improved predictions of relative decay rates of plant litters are likely to arise from a holistic approach based on plant life attributes rather than correlations based on individual initial litter chemistry parameters. Finally, a better understanding of the fate of faecal material of soil fauna is necessary before we can accurately predict and model litter decomposition. #

A simple and relatively accurate technique for classifying time-series Landsat Thematic Mapper (TM) imagery to detect levels of forest harvest is the topic of this research. The accuracy of multidate classification of the normalized... more

A simple and relatively accurate technique for classifying time-series Landsat Thematic Mapper (TM) imagery to detect levels of forest harvest is the topic of this research. The accuracy of multidate classification of the normalized difference vegetation index (NDVI) and the normalized difference moisture index (NDMI) were compared and the effect of the number of years (1 -3, 3 -4, 5 -6 years) between image acquisition on forest change accuracy was evaluated. When Landsat image acquisitions were only 1 -3 years apart, forest clearcuts were detected with producer's accuracy ranging from 79% to 96% using the RGB-NDMI classification method. Partial harvests were detected with lower producer's accuracy (55 -80%) accuracy. The accuracy of both clearcut and partial harvests decreased as time between image acquisition increased. In all classification trials, the RGB-NDMI method produced significantly higher accuracies, compared to the RGB-NDVI. These results are interesting because the less common NDMI (using the reflected middle infrared band) outperformed the more popular NDVI. In northern Maine, industrial forest landowners have shifted from clearcutting to partial harvest systems in recent years. The RGB-NDMI change detection classification applied to Landsat TM imagery collected every 2 -3 years appears to be a promising technique for monitoring forest harvesting and other disturbances that do not remove the entire overstory canopy. D

One of timber harvesting purpose is moving wood from the forest to sawmills. Road network planning requires consideration for alternatives. This paper purposed to determine decision making in selection of alternative road network with... more

One of timber harvesting purpose is moving wood from the forest to sawmills. Road network planning requires consideration for alternatives. This paper purposed to determine decision making in selection of alternative road network with utility analysis by considering economic, ecological, and social criteria. The indicator used were the length of the road, open area, cost of road construction, felling, skidding, and empowerment of forest communities. The analysis showed that a first alternative was the best forest road network of the three alternatives designed. The results are used in decision making plan for implementation in the next rotation.

Forest harvesting can increase solar radiation in the riparian zone as well as wind speed and exposure to air advected from clearings, typically causing increases in summertime air, soil, and stream temperatures and decreases in relative... more

Forest harvesting can increase solar radiation in the riparian zone as well as wind speed and exposure to air advected from clearings, typically causing increases in summertime air, soil, and stream temperatures and decreases in relative humidity. Stream temperature increases following forest harvesting are primarily controlled by changes in insolation but also depend on stream hydrology and channel morphology. Stream temperatures recovered to pre-harvest levels within 10 years in many studies but took longer in others. Leaving riparian buffers can decrease the magnitude of stream temperature increases and changes to riparian microclimate, but substantial warming has been observed for streams within both unthinned and partial retention buffers. A range of studies has demonstrated that streams may or may not cool after flowing from clearings into shaded environments, and further research is required in relation to the factors controlling downstream cooling. Further research is also required on riparian microclimate and its responses to harvesting, the influences of surface/subsurface water exchange on stream and bed temperature regimes, biological implications of temperature changes in headwater streams (both on site and downstream), and methods for quantifying shade and its influence on radiation inputs to streams and riparian zones. (KEY TERMS: stream temperature; forestry; headwater; riparian; microclimate; water quality; watershed management; Pacific Northwest.) Moore, R. Dan, D. L. Spittlehouse, and Anthony Story, 2005. Riparian Microclimate and Stream Temperature Response to Forest Harvesting: A Review. Journal of the American Water Resources Association (JAWRA) 41(4):813-834.

Forest planners, designers and managers have to incorporate visual landscape management into their plans as part of sustainable forest management (SFM). Over the last 20 years since the ®rst``Our Visual Landscape'' conference there have... more

Forest planners, designers and managers have to incorporate visual landscape management into their plans as part of sustainable forest management (SFM). Over the last 20 years since the ®rst``Our Visual Landscape'' conference there have been numerous developments in visual management and design processes and techniques. Other developments, as part of SFM, such as ecosystem management and the need for more public participation in forestry planning, have also in¯uenced the directions of forest management. The design of forest harvest units based on emulation of landscape patterns and processes means that landscape change can be driven by non-visual issues and principles and the earlier models developed for visual landscape management are no longer necessarily valid. However, the need for public participation means that landscape perception, in a broad sense, has become very important. Communication tools, such as computer visualisations of proposed landscape change have also been developed and present valuable possibilities. In order to help managers deal with both the changing forest landscape and the changing nature of perception, an approach is suggested that links landscape patterns and their manipulation with perceptions of them in order to help the development of positive design. In order for this to progress more effectively, several lines of research and development are suggested.

Clayoquot Sound on the west coast of Vancouver Island, B.C. is an area of high-profile land-use conflict. In 1995, local scientific and management groups recognized bats as an important component of forest ecosystems. With almost no... more

Clayoquot Sound on the west coast of Vancouver Island, B.C. is an area of high-profile land-use conflict. In 1995, local scientific and management groups recognized bats as an important component of forest ecosystems. With almost no existing bat information for this area, we began studies of the bat community, with the goal of inventorying the bat community and identifying critical

Illegal logging is a major environmental and economic problem, and exceeds in some countries the amounts of legally harvested timber. In Eastern Europe and the former Soviet Union, illegal logging increased and reforestation on abandoned... more

Illegal logging is a major environmental and economic problem, and exceeds in some countries the amounts of legally harvested timber. In Eastern Europe and the former Soviet Union, illegal logging increased and reforestation on abandoned farmland was widespread after the breakdown of socialism, and the region's forest cover trends remain overall largely unclear. Our goal here was to map forest cover change and to assess the extent of illegal logging and reforestation in the Ukrainian Carpathians. We used Landsat TM/ETM+ images and Support Vector Machines (SVM) to derive forest change trajectories between 1988 and 2007 for the entire Ukrainian Carpathians. We calculated logging and reforestation rates, and compared Landsat-based forest trends to official statistics and inventory maps. Our classification resulted in reliable forest/non-forest maps (overall accuracies between 97.1%–98.01%) and high clear cut detection rates (on average 89.4%). Forest cover change was widespread in the Ukrainian Carpathians between 1988 and 2007. We found forest cover increase in peripheral areas, forest loss in the interior Carpathians, and increased logging in remote areas. Overall, our results suggest that unsustainable forest use from socialist times likely persisted in the post-socialist period, resulting in a continued loss of older forests and forest fragmentation. Landsat-based forest trends differed substantially from official forest resource statistics. Illegal logging appears to have been at least as extensive as documented logging during the early 1990s and so-called sanitary clear-cuts represent a major loophole for overharvesting and logging in restricted areas. Reforestation and illegal logging are frequently not accounted for in forest resource statistics, highlighting limitations of these data. Combating illegal logging and transitioning towards sustainable forestry requires better monitoring and up-to-date accounting of forest resources, in the Carpathians and elsewhere in Eastern Europe, and remote sensing can be a key technology to achieve these goals.

In one of the longest time series available, we present a comparison between forest inventories of 1924, 1964 and 1999 of an 800km2 forest-harvesting area in Central Guyana. Harvesting mainly targeted one species Chlorocardium rodiei... more

In one of the longest time series available, we present a comparison between forest inventories of 1924, 1964 and 1999 of an 800km2 forest-harvesting area in Central Guyana. Harvesting mainly targeted one species Chlorocardium rodiei (Greenheart), of which the population declined by 63% over the 75 years of harvesting. The decline of the population was not only detectable in the

Despite the growing concern over reptile population declines, the effects of modern industrial silviculture on reptiles have been understudied, particularly for diminutive and often overlooked species such as small-bodied snakes. We... more

Despite the growing concern over reptile population declines, the effects of modern industrial silviculture on reptiles have been understudied, particularly for diminutive and often overlooked species such as small-bodied snakes. We created 4 replicated forest-management landscapes to determine the response of small snakes to forest harvesting in the Coastal Plain of the southeastern United States. We divided the replicated landscapes into 4 treatments that represented a range of disturbed habitats: clearcut with coarse woody debris removed; clearcut with coarse woody debris retained; thinned pine stand; and control (unharvested secondgrowth planted pines). Canopy cover and ground litter were significantly reduced in clearcuts, intermediate in thinned forests, and highest in unharvested controls. Bare soil, maximum air temperatures, and understory vegetation all increased with increasing habitat disturbance. Concomitantly, we observed significantly reduced relative abundance of all 6 study species (scarletsnake [Cemophora coccinea], ring-neck snake [Diadophis punctatus], scarlet kingsnake [Lampropeltis triangulum], red-bellied snake [Storeria occipitomaculata], southeastern crowned snake [Tantilla coronata], and smooth earthsnake [Virginia valeriae]) in clearcuts compared with unharvested or thinned pine stands. In contrast, the greatest relative snake abundance occurred in thinned forest stands. Our results demonstrate that at least one form of forest harvesting is compatible with maintaining snake populations. Our results also highlight the importance of open-canopy structure and ground litter to small snakes in southeastern forests and the negative consequences of forest clearcutting for small snakes.

We developed state and transition models (STMs) to evaluate the effects of natural disturbances and land-use practices on aquatic and riparian habitats. The STMs consisted of discrete states defined by channel morphology and riparian... more

We developed state and transition models (STMs) to evaluate the effects of natural disturbances and land-use practices on aquatic and riparian habitats. The STMs consisted of discrete states defined by channel morphology and riparian vegetation. Transitions between states resulted from plant succession and from natural and anthropogenic disturbances. Channel conditions and habitat suitability for anadromous salmonids were ranked by using a qualitative four-factor scale for each state in the STMs. Disturbance probabilities were varied to define both historical and current disturbance regimes. Models were run for 120 years with the current disturbance regime to illustrate changes associated with Euro-American settlement, and then run for an additional 50 years under the historical disturbance regime to illustrate the potential for passive recovery. Results suggested that Euro-American settlement dramatically changed riparian vegetation and channel conditions, which resulted in substantial declines in habitat quality. Passive recovery of channel conditions and habitat suitability was qulck in some stream types, but slow in others. Overall, our results underestimate the effects of human land uses on streams and overestimate the rate of recovery under passive restoration because the models do not yet include the effects of many management activities, especially those resulting from forest harvest and roads. O ( S . M . Wondzell), mhemstromG3fs.fed.us (M.A. Hemstrom), pbissonG3fs.fed.u~ (P.A. Bisson).

The way to plan and carry out forest harvesting operations is based on statistical methods for estimating the volume of wood to be processed. Trying to account for natural reality creates practical problems that seem to be underrated at... more

The way to plan and carry out forest harvesting operations is based on statistical methods for estimating the volume of wood to be processed. Trying to account for natural reality creates practical problems that seem to be underrated at present and which may cause a general negative perception of the forestry activity, especially for non-specialists. On the other hand, there is a risk that positive errors (above the tolerance limit), involuntary or not, remain unnoticed and be speculated by those who use the volume of wood obtained. This editorial draws attention to only a few of these issues in an attempt to eliminate certain "inconsistencies" in their practical approach.

We investigated the recovery of sediment characteristics in four moraine, headwater streams in north-central Minnesota after forest harvest. We examined changes in fine sediment levels from 1997 (preharvest) to 2007 (10 years postharvest)... more

We investigated the recovery of sediment characteristics in four moraine, headwater streams in north-central Minnesota after forest harvest. We examined changes in fine sediment levels from 1997 (preharvest) to 2007 (10 years postharvest) at study plots with upland clear felling and riparian thinning, using canopy cover, proportion of unstable banks, surficial fine substrates, residual pool depth, and streambed depth of refusal as response variables. Basin-scale year effects were significant (p < 0.001) for all responses when evaluated by repeated-measures ANOVAs. Throughout the study area, unstable banks increased for several years postharvest, coinciding with an increase in windthrow and fine sediment. Increased unstable banks may have been caused by forest harvest equipment, increased windthrow and exposure of rootwads, or increased discharge and bank scour. Fine sediment in the channels did not recover by summer 2007, even though canopy cover and unstable banks had returned to 1997 levels. After several storm events in fall 2007, 10 years after the initial sediment input, fine sediment was flushed from the channels and returned to 1997 levels. Although our study design did not discern the source of the initial sediment inputs (e.g., forest harvest, road crossings, other natural causes), we have shown that moraine, headwater streams can require an extended period (up to 10 years) and enabling event (e.g., high storm flows) to recover from large inputs of fine sediment.

This analysis examines the impacts of forest harvesting and other angling site attributes on anglers' willingness-to-pay for trips to Ontario's fly-in fishing sites. A hedonic model that relates the prices charged by fly-in remote tourism... more

This analysis examines the impacts of forest harvesting and other angling site attributes on anglers' willingness-to-pay for trips to Ontario's fly-in fishing sites. A hedonic model that relates the prices charged by fly-in remote tourism enterprises to the attributes at and surrounding fishing lakes forms the empirical application. Important attributes examined are forest harvesting, forest fires, angling quality, and camp improvements. The hedonic model employed a spatial simultaneous autoregressive model that corrects for spatial lagged dependency in the data. This correction was found to have a significant impact on the marginal prices of the attributes examined. The analysis shows that forest harvesting has a negative albeit weak relationship on the prices charged by tourism operators for remote fishing trips. D

Forest harvesting involves the creation of roads and cutblocks, both of which can influence animal habitat use. We evaluated the cumulative effects of forestry on habitat selection by six packs of gray wolf (Canis lupus) widely... more

Forest harvesting involves the creation of roads and cutblocks, both of which can influence animal habitat use. We evaluated the cumulative effects of forestry on habitat selection by six packs of gray wolf (Canis lupus) widely distributed in Quebec's boreal forest. Resource selection functions were used to evaluate cumulative effects at two levels. First, we studied how the response of wolves to roads and cutblocks varied within their home range (HR level) as a function of the local abundance of these habitat features. Second, we assessed whether differences in the response to roads and cutblocks observed among packs (inter-HR level) could be explained by variations in their average abundance among individual home ranges. At the HR level, we found that cumulative effects shaped habitat selection of wolves, and the nature of the effects varied during the year. For example, we detected a decrease in the selection of roads following an increase in local road density during the rendez-vous and the nomadic periods, but not during the denning period. At the inter-HR level, we found a functional response to logging activity only during the denning period. Packs with home ranges characterized by a larger proportion of recent cutblocks selected these cutblocks more strongly. We conclude that cumulative effects of logging activities occur at multiple levels, and these effects can have profound effects on habitat use by wolves, thereby influencing spatial predator-prey dynamics. Wildlife conservation and management in boreal ecosystems should thus account for cumulative impacts of anthropogenic features on animal distribution.

Habitat alteration caused by forest harvesting seems to contribute to the decline of forest-dwelling caribou, an ecotype of woodland caribou (Rangifer tarandus caribou) inhabiting the boreal ecosystem. To serve as basework to the... more

Habitat alteration caused by forest harvesting seems to contribute to the decline of forest-dwelling caribou, an ecotype of woodland caribou (Rangifer tarandus caribou) inhabiting the boreal ecosystem. To serve as basework to the establishment of conservation measures for the species, we have studied the hierarchical habitat selection of forest-dwelling caribou in a boreal landscape of Québec strongly impacted by logging.

Habitat loss is a leading cause of global amphibian declines. Forest removal is a particularly significant threat because an estimated 82% of amphibians rely on forests for part of their lives. 2. Biphasic amphibians rely on suitable... more

Habitat loss is a leading cause of global amphibian declines. Forest removal is a particularly significant threat because an estimated 82% of amphibians rely on forests for part of their lives. 2. Biphasic amphibians rely on suitable terrestrial habitat to support their post-metamorphic growth and survival and also to maintain appropriate habitat and landscape connectivity. 3. We created 4 replicate, 16-ha experimental arrays in the southeastern USA to examine the effects of forest removal on migratory movements of adult biphasic amphibians. Each array contained four forest-harvesting treatments that included an unharvested control, a partially harvested stand, a clearcut with coarse woody debris retained, and a clearcut with coarse woody debris removed. 4. Some amphibian species emigrated from wetlands in significantly greater numbers through forest controls compared with harvested treatments. Also, salamanders were generally more sensitive to forest removal than were frogs, with a significantly greater proportion of salamanders migrating through forested habitat compared to frogs. 5. For several species, individuals were significantly more likely to avoid clearcuts when emigrating compared to immigrating. Individuals that emigrated into clearcut treatments were more likely to reverse direction and return to wetlands in some species. 6. Synthesis and applications . Our study identifies one mechanism by which forest removal shapes the abundance and distribution of amphibians in terrestrial habitat. To promote the persistence of amphibian populations, conservation efforts should focus on preserving forest habitat adjacent to reproduction sites. Such measures are especially important where forest habitat connects local populations or where it links reproduction sites to other habitat features necessary for amphibian growth, survival, or overwintering.

''Close-to-nature forest stands'' are one central key in the project ''Future oriented Forest Management'' financially supported by the German Ministry for Science and Research (BMBF). The determination of ecological as well as economical... more

''Close-to-nature forest stands'' are one central key in the project ''Future oriented Forest Management'' financially supported by the German Ministry for Science and Research (BMBF). The determination of ecological as well as economical consequences of mechanized harvesting procedures during the transformation from pure spruce stands to close-to-nature mixed forest stands is one part of the ''Southern Black Forest research cooperation''. Mechanical operations of several typical forest harvesting vehicles were analysed to examine the actual soil stresses and displacements in soil profiles and to reveal the changes in soil physical properties of the forest soils. Soil compaction stresses were determined by Stress State Transducer (SST) and displacement transducer system (DTS) at two depths: 20 and 40 cm. Complete harvesting and trunk logging processes accomplished during brief 9-min operations were observed at time resolutions of 20 readings per second. Maximum vertical stresses for all experiments always exceeded 200 kPa and at soil depths of 20 cm for some vehicles and sequences of harvesting operations approached !500 kPa. To evaluate the impacts of soil stresses on soil structure, internal soil strengths were determined by measuring precompression stresses. Precompression stress values of forest soils at the field sites ranged from 20 to 50 kPa at soil depths of 20 cm depth and from 25 to 60 kPa at soil depths of 40 cm, at a pore water pressure of À60 hPa. Data obtained for these measured soil stresses and their natural bearing capacities proved that sustainable wheeling is impossible, irrespective of the vehicle type and the working process. Re-occurring top and subsoil compaction, increases in precompression stress values in the various soil horizons, deep rut depths, vertical and horizontal soil displacements associated with shearing stresses, all affected the mechanical strengths of forest soils. In order to sustain naturally ''unwheeled'' soil areas with minimal compaction, it is recommended that smaller machines, having less mass, be used to complete forest harvesting in order to prevent or at least to maintain currently minimal-compacted forest soils. Additionally, if larger machines are required, permanent wheel and skid tracks must be established with the goal of their maximum usefulness for future forest operations. A first step towards accomplishing these permanent pathways requires comprehensive planning with the Federal State Baden-Württemberg. The new guideline for final opening with skid tracks (Landesforstverwaltung Baden-Württemberg, 2003) proposes a permanent skid track system with a width of 20-40 m.

A survey of timber harvesting experts revealed a consensus that smaller equipment minimized capital investment, but with a sacrifice of productivity. However, under certain conditions smaller equipment can be more efficient than large,... more

A survey of timber harvesting experts revealed a consensus that smaller equipment minimized capital investment, but with a sacrifice of productivity. However, under certain conditions smaller equipment can be more efficient than large, less maneuverable machines. While a majority of respondents thought that future changes in the forest industry would favor increased use of small-scale equipment, they considered the relatively low productivity of such equipment to be a major obstacle to its adoption.

In Ethiopia, plantation forestry for the purpose of soil conservation and wood production is established mainly on degraded mountain slopes. These forests with a rotation age of 12-34 years consist of mainly exotic tree species; and have... more

In Ethiopia, plantation forestry for the purpose of soil conservation and wood production is established mainly on degraded mountain slopes. These forests with a rotation age of 12-34 years consist of mainly exotic tree species; and have great potential to provide maximum wood production and economic incentives at the age of 8-20 years. 15 N natural abundance in soils under a 25-year-old forest on Mt. Yegof has been used to determine if the short rotation forests result in significant inputs of N to soils and improve the degraded soils before harvest at the rotation age of 12-34 years. Since I have previously described the fractional contributions of the present forest vegetation to the build-up of soil organic matter (SOM) on Mt. Yegof, patterns of d 15 N and d 13 C values were compared to determine if shifts in soil 15 N are related to vegetation shifts by afforestation. On Mt. Yegof, soil d 15 N values were 0.9-3.9% in soil at 0-5 cm and >6% in soil at 30-50 cm. Plant d 15 N values ranged from À4.6 to À0.7%. Despite the negative d 15 N values of the vegetation cover, the high d 15 N values in the topsoil indicate that return of N to soils by litter-fall is minimal on Mt. Yegof and, hence, the present forests do not change very much the soil 15 N signals at the surface layer. At this site, the high d 13 C values throughout the soil profiles is clear evidence of a long phase of C 4 grass dominance or cultivation of C 4 crops along the entire elevation gradient. The slight shift towards lower d 15 N values in soil at 0-5 cm indicate only a trend of 15 N depleted SOM build-up through litter-fall from the present forest vegetation. This and previous studies show that the planted forests on Mt. Yegof did not result in significant changes in the inputs of C, N and SOM, and hence, cannot signify the improvement of degraded soil conditions during a 25-year forest growth. Thus, these forests made need a rotation period much longer than 25-year period to signify ecological rehabilitation and to establish a sustainable forest ecosystem with less N losses on the fairly steep slopes at Mt. Yegof. From the points of view of soil conservation and soil fertility management, it could be suggested that forest harvest at the time of maximum wood production may not necessary be considered if ecologically sustainable forests are to be managed on highly degraded mountain slopes in the Ethiopian highlands.

Human inhabitance and agriculture have fundamentally altered global pattern of biodiversity and ecosystem processes. Therefore, integration of community-based approach is an effective conservation strategy. Community forestry is an... more

Human inhabitance and agriculture have fundamentally altered global pattern of biodiversity and ecosystem processes. Therefore, integration of community-based approach is an effective conservation strategy. Community forestry is an important community-based approach, which can help in conserving local ecological assets in a sustainable manner. Lichens are known to be more sensitive indicators of ecosystem functions and disturbances than any other cryptogam and vascular plant community. Present study reports a preliminary assessment of epiphytic lichens in a community forest in Dadeldhura district, west Nepal, in order to identify potential indicator of forest health and land-use pattern. Epiphytic (corticolous) lichens were sampled from ten land-use units (LUU), using narrow frequency grids of 10 cm × 50 cm, each divided into five sampling units of 10 cm × 10 cm, on the bark of selected tree species. Quercus leucotrichophora was the dominant phorophyte followed by Pinus roxburghii, Rhododendron arboreum and Myrica esculenta. Foliose parmeloid (Parmotrema spp., Heterodermia spp., Hypotrachyna spp., Bulbothrix spp., Canoparmelia spp., Canomaculina spp.) was the most abundant lichen group, found inhabiting all the phorophytes followed by crustose, fruticose and dimorphic growth forms. Maximum diversity of parmeloid lichens was recorded on older stand of Quercus while younger stands usually harbored crustose lichens (e.g., Lecanora spp., Basidia spp.). Though the lichen diversity increased from outer fringes of the forest to the core, the vegetation stand age was not distributed in any consistent pattern suggesting unconstrained harvesting of the forest. Lichen diversity was found constrained by phorophyte determinants (stand age, aspect, and bark properties) and community harvesting of the forest.

Este trabalho objetivou avaliar o desempenho de um trator florestal "feller-buncher" Prentice Blount (modelo Hydro AX-611E) na colheita de madeira de um povoamento de Eucalyptus saligna Smith, de seis anos, durante as operações de corte,... more

Este trabalho objetivou avaliar o desempenho de um trator florestal "feller-buncher" Prentice Blount (modelo Hydro AX-611E) na colheita de madeira de um povoamento de Eucalyptus saligna Smith, de seis anos, durante as operações de corte, amontoamento, derrubada direcionada e rebaixamento de tocos. A metodologia baseou-se na determinação de tempos e movimentos de máquina em operação de colheita comercial e a respectiva produção de madeira sob a forma de árvores inteiras, utilizando-se a técnica de amostragem rápida. Os resultados indicam que o ciclo operacional completo de colheita de madeira atingiu a média de 60,02  13,11 segundos, com a produção respectiva de 4,41  0,90 fustes. Não houve correspondência funcional entre o tempo operacional efetivo do ciclo de operações de colheita e o número de árvores colhidas. Esse resultado demonstra que vários fatores associados atuaram no processo de colheita, como as condições da área de trabalho, povoamento florestal, máquina florestal e operador.

Reduced-impact logging is a type of selective logging that incorporates a variety of techniques aimed at lowering levels of damage to the residual stand. In a Bolivian subtropical humid forest we studied differences in gap size,... more

Reduced-impact logging is a type of selective logging that incorporates a variety of techniques aimed at lowering levels of damage to the residual stand. In a Bolivian subtropical humid forest we studied differences in gap size, vegetation structure, regeneration and phenology between anthropogenic and natural gaps in a reduced-impact logged and unlogged forest. Harvesting took place between 1 and 4 years previously. Logging gaps were significantly larger than natural gaps (d.f. 1, variance ratio (vr.) 6.38, p = 0.014) and had significantly lower coverage of lianas (d.f. 1, vr. 8.64, p < 0.01). Seedlings were more prevalent in logging gaps than in natural tree-fall gaps (d.f. 1, vr. 13.97, p < 0.001), as were members of the herbaceous genus Heliconia (d.f. 4, vr. 3.05, p = 0.023). In larger gaps microclimatic conditions favour the regeneration of non-commercial pioneer species. We propose that ground disturbance during bole removal causes higher rates of mortality to shade-tolerant species in advanced stages of regeneration. This removes the competitive height advantage needed by shade-tolerant species to compete within gaps, and thus further promotes the opportunity for pioneer species to dominate gap regeneration. These observed differences between anthropogenic and natural tree-fall gaps are of direct importance to forest managers attempting to understand how disturbance associated with reduced-impact logging influences the regeneration of commercial tree species in Bolivian forestry concessions. We discuss the ecological and silvicultural implications of these results. #

... In the Rawdon area (Fig. 4), to the east, differential erosion is responsible for the development of an Appalachian-type relief (Ritchot, 1964b). ... Fig. 4. Appalachian-type relief in the Rawdon area, Canadian Shield, Québec... more

... In the Rawdon area (Fig. 4), to the east, differential erosion is responsible for the development of an Appalachian-type relief (Ritchot, 1964b). ... Fig. 4. Appalachian-type relief in the Rawdon area, Canadian Shield, Québec (Ritchot, 1964b). View Within Article. ...

Activities associated with timber harvesting have occurred within floodplain forests in the southern United States for nearly two hundred years. However, it is only in the last ten years that any information has become available about the... more

Activities associated with timber harvesting have occurred within floodplain forests in the southern United States for nearly two hundred years. However, it is only in the last ten years that any information has become available about the effects of harvesting on the ecological functions of this valuable resource. Hydrology is the driving influence behind all ecological processes in floodplains, and

The search for decreasing in production costs led forestry companies to seek ever cheaper lands to implement their activities. The use of areas with steep slopes comes with this demand. Among the forestry operations in mountainous... more

The search for decreasing in production costs led forestry companies to seek ever cheaper lands to implement their activities. The use of areas with steep slopes comes with this demand. Among the forestry operations in mountainous terrain, forest harvesting is one of those that offer more risks to human health and that are enhanced by the relief factor. Light of the lack of studies and risk prevention in the forest crop, this study aims to analyze the risks of forest harvesting by overhead cables, tree length system in mountainous terrain for all partial movements and occupations involved in the cut (chainsaw) and forest extraction (cable car). An analysis of all movements of partial harvesting and occupations involved, based on the guidelines of the Brazilian regulation number 9 was performed. Were quantitatively measured noise and temperature, and the ergonomic factors were analyzed with the aid of photographs and Ergolândia 5.0 software for OWAS (Ovako Working Posture Analysis System) and RULA (Rapid Upper Limb Assessment) methods analisis. The other types of risks were determined based on the literature and information collected in the study area. This study concluded that the risk analysis by means of the partial motions for each class of occupation were sufficient to determine the risks involved in cutting and mountain forest extraction activities. The chainsaw operator was the occupation that offered greater risks in quantity and severity for these conditions. Among the evaluated partial movements, showed the highest risks were: tree cutting, cutting and rising carrier-car. Finally, the condition of mountainous terrain increased the amount and severity of the risks involved in this activity, which demonstrates the need for further risk analysis of forest harvesting for various conditions.

Forested buffer strips are left along water bodies after forest harvesting to protect water quality and fish stocks, but little is known about their utility as reserves for forest species in managed landscapes. We report on changes in... more

Forested buffer strips are left along water bodies after forest harvesting to protect water quality and fish stocks, but little is known about their utility as reserves for forest species in managed landscapes. We report on changes in terrestrial vertebrate communities from pre-to post-harvest in experimentally created buffer strips (20, 100, 200, and 800 m wide) in a boreal mixedwood forest in Alberta, Canada. We trapped anuran amphibians and small mammals and spot-mapped bird territories around 12 lakes (4 treatment levels, 3 replicates) before and after harvesting. Changes in small mammal or amphibian abundance were not detected for any treatment relative to controls; however, these species are habitat generalists that used and even bred in clearcuts. Total bird abundance did not change after harvesting, with the exception of crowding in 20-m buffers 1 year post-harvest. Species composition did not change for amphibians and small mammals after harvest, but forest-dependent bird species declined as buffer width narrowed from 200 to 100 m and narrower. We concluded that 20-100 m buffers would not serve as reserves for forest songbirds in managed landscapes, but that 200 m wide strips conserved the pre-harvest passerine bird community, at least up to 3 years post-harvest.

We examined factors that affect site selection by female American black bears (Ursus americanus) in coastal British Columbia, Canada, 1992-95. We monitored 9 radiocollared females and compared sites that were selected within their home... more

We examined factors that affect site selection by female American black bears (Ursus americanus) in coastal British Columbia, Canada, 1992-95. We monitored 9 radiocollared females and compared sites that were selected within their home ranges to those that were not selected using 1-1 matched logistic regression procedures. We used information-theoretic inference to assess the effect of 19 habitat, temporal, and spatial variables in 27 candidate models to explain selection of sites within home ranges. The model that best explained site selection was 50 times more likely to be the best model, given the data, than the second-best model. The best model suggested that the probability that a site would be used by female black bears increased with increasing values of phenologically adjusted berry value interacting with light levels, phenologically adjusted succulent forage value, and forest harvesting. Probability of use decreased with increasing distance from streams dependent upon salmon (Oncorhynchus spp.) availability and increasing distance from low-traffic roads. Although the best model included horizontal visibility and distance to high-traffic roads as variables, these factors had undetermined effects on the probability of use (95% confidence interval of odds ratio encompassed 1). Including phenological adjustments for abundance of berries and succulent foods greatly increased the support for the models by the data, compared to models based on cover of food plants alone. These results confirm that bears are cognizant of both temporal and spatial differences in food availability and that they modify their selection of sites based on these differences. Our results imply that site selection by female black bears involved a complex set of decisions about not only food availability, but also disturbance by humans. To increase the compatibility of timber production with conservation of black bear habitat, managers need to consider the spatial and temporal effects of the creation of food-rich openings and different types of roads on the suitability and effectiveness of habitats to support black bears.

A sustainable forest management system requires that a balance must be reached between ecosystem nutrient losses and gains in the course of a rotation. In order to determine the influence of stand characteristics (species composition,... more

A sustainable forest management system requires that a balance must be reached between ecosystem nutrient losses and gains in the course of a rotation. In order to determine the influence of stand characteristics (species composition, density, site potential productivity), method of forest harvesting (stem-only versus whole-tree) as well as rotation length on nutrient losses induced by biomass harvesting, a geochemical balance (nutrient inputs minus outputs) was computed from published information and forest inventory databases for the southern portion of the boreal forest of Quebec. Losses were compared with potential nutrient gains that varied according to soil types. We provided a tool for assessing the risk of having a negative nutrient budget (outputs > inputs) that forest managers can use with information that is already available to them. This exercise was conducted for five commercial tree species, namely paper birch (Betula papyrifera Marsh.), aspen (Populus tremuloides Michx.), balsam fir (Abies balsamea (L.) Mill.), jack pine (Pinus banksiana Lamb.), and black spruce (Picea mariana (Mill.) B.S.P.), grouped into four site indexes and three stand density classes. Strong differences in nutrient exportation in biomass appeared between stands of different compositions as well as between stands of the same species but of different classes of productivity or density. The most nutrient-demanding tree species were trembling aspen and balsam fir. As expected, whole-tree harvesting caused a greater drain on nutrient reserves than stem-only harvesting, but this effect varied strongly with tree species and was greatest for balsam fir and lowest for jack pine. Harvesting the forest before or after the age of financial maturity, which might be desirable under some circumstances, generally created a lesser nutrient drain but this was at the expense of biomass production. Aspen was an exception to this rule showing a greater nutrient drain for stands harvested prior to the age of financial maturity. Implications for the development of indicators of sustainable forestry and for future research are discussed.

Land management associated with forest practices in British Columbia (BC) over the last three decades has led to the development of terrain stability hazard mapping. Terrain stability mapping (TSM) in BC originated in the early 1970s,... more

Land management associated with forest practices in British Columbia (BC) over the last three decades has led to the development of terrain stability hazard mapping. Terrain stability mapping (TSM) in BC originated in the early 1970s, when forest harvesting was progressing from valley bottoms onto steep, unstable terrain, which led to an increase in harvesting-and road-related landslides. Since then TSM methods have been evolved. Beginning in the early 1970s, terrain hazards were incorporated into the forest inventory classification system to delineate environmentally sensitive areas for land-use planning. By 1974, operational terrain stability maps were introduced by the MacMillan Bloedel forest company on the Queen Charlotte Islands. In the 1980s, this method was adopted by other forest companies and government agencies along the BC coast and then extended to the BC interior in the 1990s. The system was refined over time, based on new knowledge and on the introduction of mapping standards, including standards for capture and presentation of digital maps. In 1995, reconnaissance terrain stability mapping and detailed terrain stability mapping were formalized with three and five hazard classes, respectively. More recently, qualitative and semi-quantitative approaches to predict landslide occurrence based on terrain and landslide inventories have been incorporated into the techniques for TSM.

Non-timber forest products are the major source of income for mountainous countries like Nepal. This article attempts to explore a case of traded non-timber forest products (NTFPs) in Jajarkot district and its contribution to the economy.... more

Non-timber forest products are the major source of income for mountainous countries like Nepal. This article attempts to explore a case of traded non-timber forest products (NTFPs) in Jajarkot district and its contribution to the economy. Collection of medicinal and aromatic plants (MAPs) and resin tapping are some of the major sources of employment for a large number of rural people. 53 different types of NTFPs are traded from the Jajarkot district. Local people collect these NTFPs from the forest and export them within and outside the district mainly to India and China. Jajarkot district on average exported 1,590,681.72 kg NTFPs worth NRs. 3,819,271.6 (equivalent to USD 32,081.88) from the year 2015 to 2020 to the national economy through royalty. NRs. 2,246,719.4 (equivalent to USD 18,872.44) per year came from MAPs and NRs. 1,572,552.2 (equivalent to USD 13,209.4) from resin during the years 2015 to 2020. If this district could produce all the commonly available NTFPs in a large scale, then there would be a high possibility of transforming the current unviable economy into a practical and vibrant economy. A proper inventory, identification and sustainable harvesting, are essential to promote and conserve these NTFPs.

... Our analysis found that threshold conditions for potential forest impacts from Al stress are indicated by four successive measurement endpoints: (i) soil base saturation less than 15% of effective CEC; (ii) soil solution Ca/Al molar... more

... Our analysis found that threshold conditions for potential forest impacts from Al stress are indicated by four successive measurement endpoints: (i) soil base saturation less than 15% of effective CEC; (ii) soil solution Ca/Al molar ratio ≤1.0 (for 50% risk); (iii) line root tissue Ca/Al ...

Unmanaged cedar (Thuja plicata)-hemlock (Tsuga heterophylla) forests of the northern Interior Wetbelt of British Columbia support standing and dead trees with a variety of structural features that provide habitat for wildlife. We describe... more

Unmanaged cedar (Thuja plicata)-hemlock (Tsuga heterophylla) forests of the northern Interior Wetbelt of British Columbia support standing and dead trees with a variety of structural features that provide habitat for wildlife. We describe the pre-harvest abundance and characteristics of wildlife trees (standing trees with special characteristics that provide habitat for wildlife) and coarse woody debris (CWD) at three silvicultural systems trials in cedar-dominated stands, and the short-term effects of forest harvesting on the abundance and attributes of CWD. The treatments were clearcut, group retention (70% volume removal), group selection (30% volume removal), and unlogged control. We measured standing trees in 75 0.125-ha plots and CWD along 225 24-m transects, using a functional classification system to characterize habitat attributes of trees and logs. CWD assessments were repeated on the same transects after the harvest. The relationship between tree size and occurrence of habitat features was strong for both standing trees and logs. Each of the four major tree species in the study area was associated with specific habitat features that occurred more often in that species than in any other. Large concealed spaces at the bases of trees, providing den sites and escape cover, were associated with hybrid white spruce (Picea engelmannii  glauca). We suggest that these trees had originated on nurse logs that subsequently rotted away; if that supposition is correct, there may be shortages of these structures in future stands that originate from plantations. Forest harvesting had little effect on the volume of CWD, but did affect the decay class distribution, reduce the proportion of pieces having structural habitat attributes, and reduce piece lengths; these effects were generally proportional to the level of harvest removal. Partial-cut silvicultural systems have the potential to mitigate anticipated deficits in large wildlife trees and logs in managed stands, if components of the stand are managed on longer rotations than those planned for timber production alone. a Goat river wet cool ICH . b Slim very wet cool ICH .

This study relaxes the assumption of perfect capital markets in the classical Faustmann forest rotation model. A constraint on borrowing changes all the basic properties of optimal forest harvesting. Instead of a constant rotation period,... more

This study relaxes the assumption of perfect capital markets in the classical Faustmann forest rotation model. A constraint on borrowing changes all the basic properties of optimal forest harvesting. Instead of a constant rotation period, an in"nite chain of rotations is determined by a nonlinear di!erence equation. The rotation period evolves over time and approaches a stationary rotation in "nite or in"nite time. The length of optimal rotation, timber supply and the value of forest land depend on forest-ownerspeci"c factors that are normally nonexistent in rotation problems. The model explains several empirical "ndings that cause problems for the classical versions of the Faustmann model. ." (O. Tahvonen).