Biomass and nutrient removals from commercial thinning and whole-tree clearcutting of central hardwoods

The objective of this research was to evaluate the impacts of increasing product removal on biomass and nutrient content of a central hardwood forest ecosystem. Commercial thinning, currently the most common harvesting practice in southern New England, was compared with whole-tree clearcutting or maximum aboveground utilization. Using a paired-watershed approach, we studied three adjacent, first-order streams in Connecticut. During the winter of 1981–82, one was whole-tree clearcut, one was commercially thinned, and one was designated as the untreated reference. Before treatment, living and dead biomass and soil on the whole-tree clearcut site contained 578 Mg ha^–1 organic matter, 5 Mg ha^–1 nitrogen, 1 Mg ha^–1 phosphorus, 5 Mg ha^–1 potassium, 4 Mg ha^–1 calcium, and 13 Mg ha^–1 magnesium. An estimated 158 Mg ha^–1 (27% of total organic matter) were removed during the whole-tree harvest. Calcium appeared to be the nutrient most susceptible to depletion with 13% of total site Ca removed in whole-tree clearcut products. In contrast, only 4% (16 Mg ha^–1) of the total organic matter and 2% of the total nutrients were removed from the thinned site. Partial cuts appear to be a reliable management option, in general, for minimizing nutrient depletion and maximizing long-term productivity of central hardwood sites. Additional data are needed to evaluate the long-term impacts of more intensive harvests.     

In-stand scenic beauty of variable retention harvests and mature forests in the U.S. Pacific Northwest: The effects of basal area, density, retention pattern and down wood

Tensions between amenity- and timber-based economies in the U.S. and Canadian Pacific Northwest motivated a study of scenic beauty inside mature forests and timber harvests. A diverse sample of regional forests, measures of forest structure, and large, representative samples of photographs and public judges were employed to measure scenic beauty inside un-harvested mature and old-growth forests, and timber harvests. The latter varied systematically in down wood levels and retention level and pattern. Scenic beauty tended to be optimized at a basal area of 110–155 m³/ha and/or 700–900 trees/ha. Older forests and those with larger trees were perceived to be more beautiful. In harvests, greater retention levels, less down wood, and dispersed rather than aggregated retention patterns contributed to aesthetic improvements. Green-tree retention harvests offer considerable potential gains in perceived scenic beauty compared to perceived very ugly clearcuts, particularly at higher retention levels. These gains are more reliable from dispersed retention patterns. The silvicultural parameters studied change strength in affecting scenic beauty with changes in retention level. These interactions are explored in relation to a range of scenic quality objectives as an aid to planners, visual impact analysts, and silviculturists.     

EFFECTS OF BEST MANAGEMENT PRACTICES ON FOREST STREAMWATER QUALITY IN EASTERN KENTUCKY1

ABSTRACT: Forest land managers are concerned about the effects of logging on soil erosion, streamflow, and water quality and are promoting the use of Best Management Practices (BMPs) to control impacts. To compare the effects of BMP implementation on streamwater quality, two of three small watersheds in Kentucky were harvested in 1983 and 1984, one with BMPs, the other without BMPs. There was no effect of clearcutting on stream temperatures. Streamflow increased by 17.8 cm (123 percent) on the BMP watershed during the first 17 months after cutting and by 20.6 cm (138 percent) on the Non-BMP watershed. Water yields remained significantly elevated compared to the uncut watershed 8 years after harvesting. Suspended sediment flux was 14 and 30 times higher on the BMP and Non-BMP Watersheds, respectively, than on the uncut watershed during treatment, and 4 and 6.5 times higher in the 17 months after treatment was complete. Clearcutting resulted in increased concentrations of nitrate, and other nutrients compared to the uncut watershed, and concentrations were highest on the non-BMP watershed. Recovery of biotic control over nutrient losses occurred within three years of clearcutting. The streamside buffer strip was effective in reducing the impact of clearcutting on water yield and sediment flux.     

Effects of forest clearcutting in New England on stream macroinvertebrates and periphyton

Clearcutting may alter stream biota by changing light, temperature, nutrients, sediment particle size, or food in the stream. We sampled macroinvertebrates during late summer of 1979 in first and second order headwater streams draining both two- and three-year-old clearcuts and nearby uncut reference areas in northern New England, USA. Periphyton were sampled throughout the summer by placing microscope slides in these streams for 13–37 days. Periphyton cell densities on these slides following incubation were about six times higher in cutover than in reference streams. Green algae (Chlorophyceae) accounted for a higher proportion of total cell numbers in cutover than in reference streams, whereas diatoms (Bacillariophyceae) dominated the reference streams. The macroinvertebrate density in cutover streams was 2–4 times greater than that in the reference streams, but the number of taxa collected was similar in both cutover and reference streams. Higher numbers of mayflies (Ephemeroptera) and/or true flies (Diptera) in the cutover streams accounted for the differences. Because nutrient concentrations in the cutover streams were nearly the same as those in the reference streams, these differences in macroinvertebrate and periphyton densities were apparently caused by higher light levels and temperature in the streams in the clearcuts. Leaving buffer strips along streams will reduce changes in stream biology associated with clearcutting.Contribution from the Northeastern Forest Experiment Station, USDA Forest Service, Durham, New Hampshire 03824, USA.     

EFFECTS OF FOREST HERBICIDE APPLICATIONS ON STREAMWATER CHEMISTRY IN SOUTHWESTERN BRITISH COLUMBIA1

ABSTRACT: The herbicide glyphosate was applied to portions of two watersheds in southwestern British Columbia to kill vegetation that was competing with Pseudotsuga menziesii (Douglas-fir) plantations. This application had little significant effect on streamwater chemistry (K⁺, Na²⁺, Mg²⁺, Ca²⁺, Cl^-, NOs₃^-, NH₄⁺, PO4^3-, SO₄⁼, and SiO₂ concentrations, electrical conductivity, and pH) when vegetation cover in a watershed was reduced by 4%, but had significant (P>0.05) effects, which lasted for at least five years, when cover was reduced by 43%. In this case, most parameters increased in value following the application, with K⁺ and Mg²⁺ concentrations and pH values exhibiting the most prolonged increases and NO₃^- concentrations exhibiting the greatest percentage increases. Sulphate and dissolved SiO₂ concentrations decreased following the application. Streamwater chemical fluxes showed similar trends to concentrations except that changes in fluxes were less significant and no decreases were observed. Forest management induced losses of NO₃-N in streamwater during the first five post-treatment years in the study area decreased in the order: herbicide application (approximately 40 kg/ha) < clearcutting and slashburning (approximately 20 kg/ha) < clearcutting (approximately 10 kg/ha). In watersheds similar to those of the study area, herbicide application is likely to have a greater impact on streamwater chemistry, in general, than would clearcutting or clearcutting followed by slashburning.     

Opportunity costs of implementing forest plans

Intellectual concern with the National Forest Management Act of 1976 has followed a course emphasizing the planning aspects of the legislation associated with the development of forest plans. Once approved, however, forest plans must be implemented. Due to the complex nature of the ecological systems of interest, and the multiple and often conflicting desires of user clientele groups, the feasibility and costs of implementing forest plans require immediate investigation. For one timber sale on the Coconino National Forest in Arizona, forest plan constraints were applied and resulting resource outputs predicted using the terrestrial ecosystem analysis and modeling system (TEAMS), a computer-based decision support system developed at the School of Forestry, Northern Arizona University, With forest plan constraints for wildlife habitat, visual diversity, riparian area protection, and soil and slope harvesting restrictions, the maximum timber harvest obtainable was reduced 58% from the maximum obtainable without plan constraints.Former Graduate Student at Northern Arizona University.     

Environmentally sensitive plot-scale timber harvesting: impacts on suspended sediment, bedload and bank erosion dynamics

The impact on sediment pollution of environmentally sensitive harvesting of a 15 ha plot (20% of the catchment area) of mature coniferous plantation forest in the 0.89 km2 Afon Tanllwyth catchment, Plynlimon, was investigated for 12 months before harvesting began and a further 18 months after. The results revealed: (a) a steepening of the suspended sediment concentration vs. discharge rating curve resulting in a 39% increase in suspended sediment yield (as compared to the adjacent forested Hafren catchment) during the year in which the harvesting operations took place; (b) a statistically significant increase in main channel bank erosion rates, as compared with the nearby Afon Cyff; main channel banks are estimated to have contributed around 80% of the total catchment suspended sediment yield during the two year period (1995-1996), and (c) no significant change in bedload yields over the duration of the study, though a longer post-harvesting time series of bedload data will be required to properly assess the impact of the harvesting operation upon bedload yields. Forest management implications of these findings are discussed in detail with respect to the existing Forest and Water guidelines.     

STORMFLOW AND SEDIMENT LOSS FROM INTENSIVELY MANAGED FOREST WATERSHEDS IN EAST TEXAS1

ABSTRACT: Five small (4 ha) forested watersheds in East Texas were instrumented in December 1980 to determine the effect of forest harvesting, mechanical site preparation, and livestock grazing on stormflow, peak discharge rate, and sediment loss. After three pretreatment years, four of the watersheds were treated as follows: (1) clearcutting followed by roller chopping; (2) clearcutting following by shearing and windrowing; (3) clearcutting following by shearing, windrowing, and continuous grazing; and (4) clearcutting followed by shearing, windrowing, and rotational grazing. Clearcut harvesting and all site preparation treatments significantly increased stormflow, peak discharge, and sediment losses over the undisturbed condition. Roller chopping and shearing/windrowing had little impact on sediment loss from these watersheds and appears to be a sound forest conservation practice for gently sloping watersheds (> 8 percent). As applied, livestock grazing had minimal impact on stormflow and peak discharge. The moderately stocked continuously grazed treatment had little impact on sediment loss, but the high stocking density of the rotational grazing treatment increased sediment losses over the undisturbed condition. Sediment losses from these intensively managed forest watersheds, even though significantly greater than from undisturbed conditions, were within the range of sediment losses from undisturbed watersheds in the Southeast, below the range of losses from mechanically prepared watersheds elsewhere, and well below potential losses from pasture and cropland.     

Is motion more important than it sounds?: The medium of presentation in environment perception research

This study assessed the incremental validity of different media for representing landscapes with significant dynamic elements. The experimental design independently varied the presence of motion and sound in different representations of a wild and scenic river in order to evaluate the adequacy or sufficiency of the surrogate to reflect physical changes in the landscape. Three representational conditions were identified: (1) video/sound, (2) video/no sound, and (3) static/no sound. A pilot study assessed the ability of the static images to represent river flow levels per se, and confirmed comparability with prior results (Brown & Daniel, 1989, Journal of Environmental Psychology, 7, 233–250). Scenic beauty judgments were then collected within each representational condition. Multiple regression analyses were used to determine the relationship of flow level to perceived scenic beauty for each representation condition. The results demonstrated that motion and sound, individually and conjointly, influenced judgements of scenic beauty for a landscape with a significant dynamic element.     

Perceptions of Prescribed Burning in a Local Forest Community in Victoria, Australia

The general perceptions of prescribed burning were elicited from forest users for an area that has been subject to this form of land management for at least 20 years. The largest group consisted of local residents living in and around the Wombat State Forest with two smaller groups of students from a nearby university campus and local professional land managers. A questionnaire was given to each participant in order to explore how the forest was used, to determine the level of knowledge of burning in the targeted forest and Victoria and the perception of the appearance, effectiveness of protection, and accessibility to the forest after prescribed burning. Generally all groups had similar responses with community members having stronger views on the effectiveness and practicalities of prescribed burning, whereas students were more neutral in their opinions. All participants claimed knowledge of prescribed burning activities within Victoria, but fewer had experience of planned fires in the Wombat State Forest. All groups agreed that areas that had not been recently burned had a better appearance than those that had, but this result may have included a range of value judgments. Land managers had a greater understanding of the ecological importance of season and timing of burning; however, some students and community members were equally knowledgeable. Prescribed burning did not impede access to the forest, nor did smoke from prescribed burns pose any great problem. The majority of the participants felt that the amount of prescribed burning done in the forest was adequate for engendering a feeling of protection to life and property, yet many were still suspicious of this management practice. These initial findings indicate several areas in which further research would be useful including the efficacy of education programs for community members and improved communication of burn plans by land managers.     

Modelling air temperature gradients across managed small streams in western Washington

Leaving riparian strips on both sides of a stream is widely accepted to be an effective management approach in sustaining the valuable functions of stream and riparian ecosystems. The authors' overall objective is to provide microclimatic information for assessing the effectiveness of these strips. During the summer of 1993 and 1994, air temperatures were collected across 20 small, buffered streams in western Washington, USA, including five streams sampled before and after harvesting of the forest. These data were statistically analysed to examine the effects of adjacent harvesting with preservation of 16–72 m riparian forest strips. Regression models were developed to predict air temperatures at the stream and buffer edges, the difference between two locations, and seasonal changes. The authors found: (1) clearcutting in winter 1993/94 increased air temperature on the stream by up to 4°C, and changes in temperature variability from the stream to the upland, measured by coefficient of variation (CV), were significantly higher after harvesting; (2) forest buffers provided minimal protection for stream air temperature during the middle of summer (July) but were more effective early and late in the season; (3) buffer width was not a significant variable in predicting stream air temperature, suggesting that even a 72 m buffer was not sufficient to maintain a stream environment because of greater depth of edge influences.1998 Academic Press     

Forest Restoration and Forest Communities: Have Local Communities Benefited from Forest Service Contracting of Ecosystem Management?

Conservation-based development programs have sought to create economic opportunities for people negatively impacted by biological diversity protection. The USDA Forest Service, for example, developed policies and programs to create contracting opportunities for local communities to restore public lands to replace jobs lost from reduced timber harvest. This article examines 12 years of Forest Service land management contracting in western Oregon, Washington, and northern California to evaluate if contractors located in communities near national forests have been awarded more land management contracts and contract value over time. We find that land management contracting spending has declined dramatically and, once we control for intervening factors, we find that local contractors have received a smaller proportion of land management contracts over time.     

Timber harvest calculations on a National Forest: A case study

Harvest calculations determine sawtimber flows from public lands and are closely scruntinized by a wide spectrum of forest users. This study examines the reliability of harvest calculations on a single national forest in New Mexico Forest Service determinations of an array of variables were reviewed and evaluated. The study revealed a lack of precision in Forest Service adherence to self-imposed procedural standards governing the calculation process. Timber sales have taken place on lands where such standards prohibit harvesting and these lands have been included in annual harvest calculations. Assumptions required by a mathematical model used by the Forest Service in calculating the harvest were not followed in the subsequent implementation of the harvest level. These factors suggest that the Forest Service could have significantly over-stated annual harvest rate for the first decade. Opportunities exist to improve the calculation, and benefits realized may greatly exceed additional costs of implementation     

Monitoring Forest Carbon Sequestration with Remote Sensing and Carbon Cycle Modeling

Sources and sinks of carbon associated with forests depend strongly on the management regime and spatial patterns in potential productivity. Satellite remote sensing can provide spatially explicit information on land cover, stand-age class, and harvesting. Carbon-cycle process models coupled to regional climate databases can provide information on potential rates of production and related rates of decomposition. The integration of remote sensing and modeling thus produces spatially explicit information on carbon storage and flux. This integrated approach was employed to compare carbon flux for the period 1992–1997 over two 165-km² areas in western Oregon. The Coast Range study area was predominately private land managed for timber production, whereas the West Cascades study area was predominantly public land that was less productive but experienced little harvesting in the 1990s. In the Coast Range area, 17% of the land base was harvested between 1991 and 2000. Much of the area was in relatively young, productive-age classes that simulations indicate are a carbon sink. Mean annual harvest removals from the Coast Range were greater than mean annual net ecosystem production. On the West Cascades study area, a relatively small proportion (< 1%) of the land was harvested and the area as a whole was accumulating carbon. The spatially and temporally explicit nature of this approach permits identification of mechanisms underlying land base carbon flux. Published online     

IMPROVING AQUATIC HABITAT CONDITIONS OVER TIME WHILE PRODUCING WOOD PRODUCTS: AN EXAMINATION OF OPTIONS1

ABSTRACT: A land management activity scheduling model that can perform a multi-period, simultaneous evaluation of aquatic habitat quality and commodity production goals was used to identify alternatives which would allow the improvement of aquatic habitat conditions over time, while producing wood products. The scheduling model has the ability to use stream sediment index levels, stream temperature index levels, and equivalent clearcut acres (ECA) levels as primary goals. A secondary goal imbedded in the model is the achievement of an even-flow of timber harvest volume, and a tertiary goal is the achievement of maximum efficiency (maximum net present value). The scheduling model utilizes a heuristic programming technique (Tabu search) to guide the selection of timber harvests and road standards. A 14,643 acre case study watershed in eastern Oregon is used to illustrate several policy scenarios. Activities considered include: clearcutting and partial cutting; cable, skyline, ground-based, and helicopter logging; road obliteration; requiring lower truck tire pressures on forest roads; and tree planting in riparian areas. The scheduling model produced land management plans which were spatially and temporally feasible over ten ten-year time periods. Stream temperature was shown to be dramatically reduced if tree planting is performed in all riparian areas, regardless of whether harvesting activities occurred, and including meadows and forested areas where shade density is low. Timber harvest volume levels decreased 31 to 43 percent, and net present value levels decreased 36 to 46 percent, from an unconstrained case, when any of the following occurred: ECA was constrained to 15 percent, sediment index levels were required to decrease by 1 percent per decade, or temperature levels were constrained to “no harvest” levels. The use of a heuristic programming technique is a departure from traditional techniques that are commonly used in management plan development. Yet the heuristic technique allows the inclusion of complex management goals, many of which may be prohibited when using more traditional mathematical programming techniques. In addition, decision variables which require spatial information, requiring them to take on integer or non-linear representations, can be accounted for without realizing the limitations of the traditional techniques.     

Large-Scale Effects of Timber Harvesting on Stream Systems in the Ouachita Mountains, Arkansas, USA

Using Basin Area Stream Survey (BASS) data from the United States Forest Service, we evaluated how timber harvesting influenced patterns of variation in physical stream features and regional fish and macroinvertebrate assemblages. Data were collected for three years (1990–1992) from six hydrologically variable streams in the Ouachita Mountains, Arkansas, USA that were paired by management regime within three drainage basins. Specifically, we used multivariate techniques to partition variability in assemblage structure (taxonomic and trophic) that could be explained by timber harvesting, drainage basin differences, year-to-year variability, and their shared variance components. Most of the variation in fish assemblages was explained by drainage basin differences, and both basin and year-of-sampling influenced macroinvertebrate assemblages. All three factors modeled, including interactions between drainage basins and timber harvesting, influenced variability in physical stream features. Interactions between timber harvesting and drainage basins indicated that differences in physical stream features were important in determining the effects of logging within a basin. The lack of a logging effect on the biota contradicts predictions for these small, hydrologically variable streams. We believe this pattern is related to the large scale of this study and the high levels of natural variability in the streams. Alternatively, there may be time-specific effects we were unable to detect with our sampling design and analyses.     

Simulating Spatial and Temporal Context of Forest Management Using Hypothetical Landscapes

/ Spatially explicit models that combine remote sensing with geographic information systems (GIS) offer great promise to land managers because they consider the arrangement of landscape elements in time and space. Their visual and geographic nature facilitate the comparison of alternative landscape designs. Among various activities associated with forest management, none cause greater concern than the impacts of timber harvesting on the composition, structure, and function of landscape ecosystems. A timber harvest allocation model (HARVEST) was used to simulate different intensities of timber harvest on 23,592-ha hypothetical landscapes with varying sizes of timber production areas and different initial stand age distributions. Our objectives were to: (1) determine the relative effects of the size of timber production areas, harvest intensity, method used to extract timber, and past timber harvest activity on the production of forest interior and edge; and (2) evaluate how past management (in the form of different initial stand age distributions) constrains future timber production options. Our simulations indicated that the total area of forest interior and the amount of forest edge were primarily influenced by the intensity of timber harvest and the size of openings created by harvest. The size of the largest block of interior forest was influenced most by the size of timber harvests, but the intensity of harvest was also significant, and the size of nontimber production areas was important when harvests were numerous and widely dispersed within timber management areas, as is often the case in managed forests. Stand age-class distributions produced by past harvest activity limited the amount of timber production primarily when group selection was used, but also limited clear-cutting when recent harvest levels were high.KEY WORDS: Simulation modeling; Timber harvest; Historical context; Spatial context; Landscape pattern; Forest interior; Forest edge     

Slash fire hazard analysis on the Siskiyou National Forest

Potential increase in fire hazard as a result of timber harvesting is a concern of forest managers throughout the United States. Treating fuels can help reduce unacceptable fire hazards. To evaluate alternative fuel treatments, managers need to know their effects on fire hazard. A decision analysis approach to estimating fire hazard in terms of expected burned area was applied to a watershed in the Siskiyou National Forest (Oregon). Three treatment alternatives (do nothing and two levels of yarding unmerchantable material) were evaluated, and the effects of the treatments were projected over a 90-yr period. Initially, the effects of applying a treatment are small. After 50 years of treatment, the most intense alternative can be expected to show almost a 50% reduction in burned area compared to no treatment. The procedure also estimates burned are by fire size and fire intensity classes. Managers may find this useful for estimating expected fire effects associated with a particular fuel treatment regime.     

Linking GIS-based models to value ecosystem services in an Alpine region

Planning frequently fails to include the valuation of public goods and services. This can have long-term negative economic consequences for a region. This is especially the case in mountainous regions such as the Alps, which depend on tourism and where land-use changes can negatively impact key ecosystem services and hence the economy. In this study, we develop a semi-automatic procedure to value ecosystem goods and services. Several existing process-based models linked to economic valuation methods are integrated into a geographic information system (GIS) platform. The model requires the input of a digital elevation model, a land-cover map, and a spatially explicit temperature dataset. These datasets are available for most regions in Europe. We illustrate the approach by valuing four ecosystem services: avalanche protection, timber production, scenic beauty, and habitat, which are supplied by the “Landschaft Davos”, an administrative district in the Swiss Alps. We compare the impacts of a human development scenario and a climate scenario on the value of these ecosystem services. Urban expansion and tourist infrastructure developments have a negative impact on scenic beauty and habitats. These impacts outweigh the benefits of the developments in the long-term. Forest expansion, predictable under a climate change scenario, favours natural avalanche protection and habitats. In general, such non-marketed benefits provided by the case-study region more than compensate for the costs of forest maintenance. Finally, we discuss the advantages and disadvantages of the approach. Despite its limitations, we show how this approach could well help decision-makers balance the impacts of different planning options on the economic accounting of a region, and guide them in selecting sustainable and economically feasible development strategies.     

Effects of nano-SiO(2) and different ash particle sizes on sludge ash-cement mortar

The effects of nano-SiO₂ on three ash particle sizes in mortar were studied by replacing a portion of the cement with incinerated sewage sludge ash. Results indicate that the amount of water needed at standard consistency increased as more nano-SiO₂ was added. Moreover, a reduction in setting time became noticeable for smaller ash particle sizes. The compressive strength of the ash–cement mortar increased as more nano-SiO₂ was added. Additionally, with 2% nano-SiO₂ added and a cure length of 7 days, the compressive strength of the ash–cement mortar with 1 μm ash particle size was about 1.5 times better that of 75 μm particle size. Further, nano-SiO₂ functioned to fill pores for ash–cement mortar with different ash particle sizes. However, the effects of this pore-filling varied with ash particle size. Higher amounts of nano-SiO₂ better influenced the ash–cement mortar with larger ash particle sizes.