Timber Growth Research Articles

Earthworms as bio-indicators of forest site quality

The effectiveness of earthworm species as bio-indicators of forest site quality was tested by a dataset of 180 plots in temperate lowland forest (Flanders, Belgium). In these plots, earthworm samples were taken together with vegetation surveys and additional site quality parameters. Vegetation surveys were used to calculate mean humidity, acidity and nitrification indices and to display sites in a humus quality-soil humidity-ecogram. In this ecogram, the earthworm biomass per species, per ecological category and in total was related with timber growth indices for ash ( Fraxinus excelsior) and beech ( Fagus sylvatica). The observed parallels and discrepancies are discussed.

Simulated financial returns and selected environmental impacts from four alternative silvicultural prescriptions applied in the neotropics: a case study of the Chimanes Forest, Bolivia

The objective of this study was to compare the financial returns and selected environmental impacts from four alternative silvicultural prescriptions when applied to a sample area in the Chimanes Forest of Bolivia. Timber growth and yield and residual tree damage were estimated by simulating application of the prescriptions over a 50 year planning horizon using a diameter class model. Financial returns from the four prescriptions were estimated using discounted cashflow analysis. The annual net cashflows were computed as the product of the yields of each of three classes of timber and the corresponding weighted average net tree value for the class computed from production cost and product price data taken from the literature. In the Chimanes Forest, silvicultural prescriptions based on highly selective cutting of single species are substantially more profitable than prescriptions involving cutting across a broad range of species given current relative prices among commercial species and prevailing interest rates. All prescriptions were shown to be highly profitable yielding a rate of return in excess of the average real rate of return from commercial activities in Bolivia over the past 8 years. Impact on woody vegetation including both damage and commercial removals was shown to be highest for the prescription involving the most intensive management. Road construction and total area disturbed were highest for the two prescriptions based on highly selective cutting. Independent of the prescription chosen, forest practices must be monitored and controlled by some organization independent of the concessionaires to prevent degradation of production forests.

The Economics of Logging High Conservation Value Native Forests

AbstractThis paper analyses various aspects of the economics of logging high conservation value native forests. After outlining the multiple uses of these forests, evidence is reviewed that suggests that subsidisation of logging is extensive. Next the paper reviews work that indicates that when account is taken of the environmental values lost due to logging (including the value of water with alternative uses) there are net social costs from logging high conservation native forests. Finally, changes to the structure of the wood products industry are analysed and it is argued that the growth of plantation timber, although rapid, has been constrained by subsidisation of native forests logging. Despite this, the data show that plantation-sourced wood will capture most of the market for sawn timber and pulp within a decade. There is thus the opportunity for Australia to have its timber needs met without the environmental costs associated with logging of native forests.

SQUIRREL STRATEGY

Summary The Timber Growers Association (TGA) has drawn up an action list which it intends to pursue vigorously on behalf of its members in order to obtain a Squirrel Strategy. 1. Press for urgent action to be taken by Government to resolve the confused and contradictory legal framework covering grey squirrel control2. Press for the swift approval and introduction of known technological advances.3. Encourage and exhort Scottish Natural Heritage and English Nature to accept the critical position of the remaining red squirrel populations and to formulate appropriate strategies4. Maintain the pressure for research into alternative control methods to be accorded appropriate priority.

Forest Sector Impacts from Changes in Forest Productivity Under Climate Change

The consequences of elevated carbon dioxide and climate change on forest systems and the role that economics could play in timber harvest and vegetation change have not been addressed together. A framework was developed to link climate change scenarios, an ecosystem model, a forest sector model and a carbon accounting model. Four climate scenarios were used to estimate net primary productivity (NPP) for forests in the United States. Changes in NPP were estimated using TEM, the Terrestrial Ecosystem Model which uses spatially referenced information on climate, soils and vegetation to estimate important carbon and nitrogen fluxes and pool sizes within ecosystems at the continental scale. Changes in NPP under climate change were used to modify timber growth within the Aggregate Timberland Assessment Model (ATLAS), which is a part of the forest sector model (TAMMATLAS) used by the Forest Service to examine timber policy questions. The changes in timber inventories were then translated into changes in the amount of carbon stored on private timberlands using a national carbon model (FORCARB). Regional changes in productivity filter through the forest sector and result in changes in land use and timber consumption. Long-term changes in carbon storage indicate that these private timberlands will be a source of carbon dioxide for all but the most optimistic climate change scenario.

The carbon budget of the Spanish forests

A model for the calculation of anthropogenic CO2 emissions from perturbed forests (‘extraordinary emissions’) is described. Timber production as well as wildfire statistics are used, and relevant physicochemical parameters are derived from the literature, to calculate the annual amounts of perturbed biomass and extraordinary emissions to the atmosphere from the Spanish forests — including soils — in the years 1960–1990; these emissions increased from 5.3 106 t (metric tons) of carbon in 1970 to 10.6 106 t C in 1990. A sensitivity analysis of the results has been performed to identify the most critical parameters. Contributions of observed timber growth and natural vegetal detritus and soil organic matter to the net forest carbon flux have been estimated to calculate the carbon budget in the Spanish forests between 1966 and 1974, which represents a net gain of carbon, ranging from 9.2 to 18 millions t. Finally, the methods used to calculate biospheric carbon balance and their results are compared and discussed.

The Effect of Competition on Timber Growth in a Mixed Evergreen Forest Stand

SYNOPSIS Competition among trees of the southern Cape forests was determined by calculating the distances among all trees on a 2,86 ha forest stand and correlating the distance between two neighbouring trees with the growth rate of the smaller one of the pair. Both inter- and intraspecific competition was evident between most of the chosen species combinations. The apparent more pioneer-like species, such as Olea capensis subsp. macrocarpa, Ocotea bullata and Apodytes dimidiata, showed weaker competitive abilities than later successional species such as Podocarpus latifolius, Curtisia dentata andPterocelastrus tricuspidatus. Most of the southern Cape forest trees are shade-tolerant and can grow in close proximity to other trees, but the growth rate of various species is retarded by competition. It was concluded that the harvesting of the weaker competitors strictly according to the numerical proportions by which they occur in the forest is unnecessary, that the more valuable timber species profit from the advanced development stage of the forest in that they are better late-successional competitors, that the role of the dominant forest tree, Olea capensis subsp. macrocarpa, is not fully understood and that the present management approach of harvesting trees that will most likely die, is sound.

Evaluation of six site classifications for modelling timber yield of regrowth karri (Eucalyptus diversicolor F. Muell.)

The utility of five indirect and one direct classification of site for stratifying the productivity of regrowth karri stands in southwest Western Australia was evaluated. The indirect classifications comprised separate edaphic, climatic and vegetative classifications derived previously using hierarchical cluster analysis on a range of soil, meteorological and floristic attributes measured on 214 permanent sample plots (PSPs). Two other classifications based on landform and the composition of overstorey species had been mapped at a regional scale. Stand site index (height at age 50 years of the tallest 25 stems ha−1) provided a direct classification of site. The productivity of stands of maximum density selected from the same PSP database was compared between strata (levels) for each classification. The classifications were evaluated on their ability to assist in stratifying stand volume (V), basal area (G) and stocking density (N) and interpreting stand-level dynamics including the rate of mortality and the rate of segregation into dominance classes. None of the indirect classifications were satisfactory. In contrast, classification by site index of the stands of maximum density enabled them to be stratified into differing (P<0.05) volume and stocking productivity classes, within which the correlated dynamics of stand development could be consistently interpreted. Site index is recommended for the primary stratification of the mensurational database when modelling the growth and yield of timber within regrowth karri forests.

Effect of lignin derived phenols and their methylated derivatives on the growth of Lentinus spp.

The effect of several lignin related phenols and the corresponding 4-methoxylated derivatives on the growth of edible and timber degrading Lentinus spp. was investigated. Methoxylated derivatives were generally more inhibitory, findings which conflict with previous speculation that fungal mediated 40-methylation of phenolics represented a general detoxification mechanism

Lumber Production and Marketing Changes by Sawmills in Massachusetts, 1957-1989

Abstract Studies of Massachusettś sawmill lumber production and marketing practices for the years 1957 and 1989 indicate there are fewer mills currently but that volume production has remained nearly constant at 112 mmbf. Hardwoods have become a larger proportion of production (47 vs. 32%) during the 32-year period Market outlets have changed, thereby modifying the extent of lumber seasoning and grading for both hardwood and softwood lumber marketed by sawmills. Markets for byproducts of sawmills have developed during the period, increasing revenues and solving the residue disposal problem. The Massachusetts sawmill industry has the potential to become larger based on growth of timber in the state, but social, environmental, and institutional constraints are likely to preclude this from occurring. North. J. Appl. For. 9(2):67-69.

A quantitative relationship between forest growth rates and Thematic Mapper reflectance measurements

Abstract Effective forest management requires reliable forecasts of timber growth. In New Brunswick, the growth of spruce-fir stands is greatly affected by annual and cumulative defoliation caused by the spruce budworm. This study was designed to determine whether the Thematic Mapper (TM) could detect defoliation in a way which was correlated with stand growth well enough to be used as a predictive tool. Regression analysis was used to explore relationships between stand reflectance in the Thematic Mapper bands and stand volume and growth measured in permanent sample plots. Good (R 2>0.8) relationships were found between net annual spruce-fir volume change and vegetation condition indices incorporating TM near-infrared and shortwave infrared reflectances. Good relationships were also found between live spruce-fir volume and TM band 4 (near-infrared) reflectance. These results have encouraged us to plan a province-wide calibration and measurement programme aimed at improved stand development forecasts for the 1992 New Brunswick timber inventory and allocation.

Design and development of agroforestry systems for Illinois, USA: silvicultural and economic considerations

Recommended managerial inputs and associated outputs expected from practicing agroforestry on marginal farm lands in the central USA are discussed. Modeled management combinations are based on five timber species, three sites indices, three timber growth rates, five agricultural crops, all common crop rotations, and three tillage systems. Black walnut (Juglans nigra L.), combined with row crop production, is used to illustrate a specific multicropping alternative. Based on net present value, modeled agroforestry systems incorporating black walnut performed better on the better sites and at the medium to high timber growth rates whereas management systems using red oak (Quercus rubra L.) with row crops performed better on the poorer sites and at the lower growth rates. For agroforestry to be competitive with traditional agriculture, medium to high timber growth rates were necessary. Also, lower interest rates and the existing U.S. income tax structure favored agroforestry versus traditional agriculture. Substantial increases in net income may be possible through incorporating other income producing activities such as nut production within the agroforestry system.

Market Assessment and Economic Potential of the Red Pine Utility Pole Industry in Wisconsin

Abstract Minnesota, Iowa, Illinois, Michigan, and Wisconsin electric and telephone utilities use an estimated 278,000 distribution poles annually, of which 180,000-245,000 are 35 or 40 ft long and in pole Class 1, 2 or 3. Most poles are southern pine, Douglas-fir or western red cedar. Red pine's current market share is only 7%. Most utilities surveyed expressed a willingness to use red pine poles if they could be purchased at the same or at a slightly lower price than they currently pay for southern pine poles. A local pole production facility would benefit from Wisconsin's lower stumpage prices and transportation costs relative to those in the Pacific Northwest and the South. Wages are somewhat higher in Wisconsin than in competing regions, but on balance Wisconsin producers should initially enjoy a net cost advantage of $18-$38 per pole. As pole production expands, some of this cost advantage is expected to be passed on to timber growers in the form of higher stumpage prices. A single pole-treatment facility could treat 10,000-15,000 poles annually, and retain an additional one to two million dollars per year in the state economy. The regional demand appears to be sufficient to support several such plants. Whether sufficient pole material supply would be forthcoming from Wisconsin forests to support such plants is a crucial question that remains to be addressed. North. J. Appl. For. 7:189-193, December 1990.

Influence of Mechanical Site Preparation on Deer Forage in the Georgia Piedmont

Abstract Seasonal standing crops of white-tailed deer (Odocoileus virginianus) forage were compared among five types of mechanical site preparation in a 6-year-old loblolly pine (Pinus taeda L.) plantation. Treatments were: unharvested control (C); harvest only (H); chainsaw residuals (CR); shear and chop (SC); and shear, rake, burn, and disk (SRBD). Diferences among treatments were compared within species and within forage groups (vines, forbs, grasses, woody). The CR and SC treatments, which consistently produced more forage biomass in all categories, also exhibited average or above-average timber growth relative to the other treatments. South. J. Appl. For. 14(2):77-80.

A Simulation/Linear Programming Approach to Timber Supply Modeling

Abstract A growth and yield simulator was combined with a forest inventory processor and a linear programming model to analyze and project timber inventory, growth and harvest for industrial and nonindustrial lands in each of five regions in California. Harvest priorities for each stand type were chosen by maximization of conifer output over alternative periods of time subject to volume, species, and inventory constraints. Results indicated that timber harvest from forest industry land would decline in the next several decades, but that this decline would be offset by increased output from nonindustrial holdings. A substantial buildup of hardwood inventories on small private ownerships is anticipated. West. J. Appl. For. 4(3):80-84, July 1989.

A growth model for north Queensland rainforests

A model to predict the growth of commercial timber in north Queensland's rainforests is described. More than 100 commercial species and several hundred other tree species are aggregated into about 20 species groups based on growth habit, volume relationships and commercial criteria. Trees are grouped according to species group and tree size into cohorts, which form the basis for simulation. Equations for predicting increment, mortality and recruitment are presented. The implications of the model on rainforest management for timber production are examined. The model has been used in setting the timber harvest from these rainforests, and should provide an objective basis for investigating the impact of rainforest management strategies. The approach should be applicable to other indigenous forests.

A Dynamic Forest Sector Model with a Swedish Case

Abstract Forest management and new plant investments are long-term decisions. Consequently, strategic planning is vital for the companies involved and has been one of the most important functions of management. In the future this could be even more important. Many forest companies are facing slow market growth along with, cyclical fluctuations in demand, high interest rates and high investment requirements to increase or replace capacity. This paper presents an instrument to aid managers in their strategic planning. A mathematical description of the instrument, a long-term forest sector model, is presented followed by an example of its use in a Swedish case. The model was developed to analyze the impact of cost competitiveness on the structural change of the Swedish forest sector in a 15-25 year perspective. The model is used now by managers in Sweden to produce scenarios for the Swedish forest industry. The output from the model is also used as input for specific enterprise models. The model consists of two symmetric, competing forest sectors--one for the domestic forest sector and one for the competing forest sectors of other countries. Each forest sector covers all activities, ranging from timber growth to the consumption of forest industry products such as paper, sawn wood, and panels. At the end of this paper an application of the model is illustrated by the Swedish forest sector. One conclusion drawn is that since the Swedish forest sector is competing in a world market the development of its profit level compared with competitors is extremely important. Forest Sci. 32:377-397.

Effects of Landslide Erosion on Subsequent Douglas‐fir Growth and Stocking Levels in the Western Cascades, Oregon

AbstractShallow, rapid landslides are common events in steep terrain of the Pacific Northwest. The effect of landslides on timber growth potential of forest land was estimated by examining a 30‐yr history of clearcutting and landsliding in the western Oregon Cascades. The height growth of Douglas‐fir [Pseudotsuga menziesii (Mirb.) Franco] and stocking level of all commercial conifer species on naturally regenerated landslides were compared with the height growth and stocking level on nearby, artificially regenerated clearcut units of similar aspect, elevation, ages, and slope position. Average height growth of Douglas‐fir trees 5 to 18 years old on the landslides was reduced 62% compared to trees on clearcuts, and the average stocking level was reduced 25% from the clearcut level. One‐third of the landslide area was estimated to be nonstockable because of unstable or impenetrable substrate.

Wildscape: forestry, scenery and wildlife

Philip Nicholl's paper was concerned with the specialist field of how to grow two cubic metres of timber where only one grew before. Lord Dulverton, a practising forester, now places timber growing into a wider context: landscape evolution and habitats for wildlife. Lord Dulverton is well known for his integrated view of rural land uses through his practical activities, writings, broadcasting and speeches in the House of Lords. Among his many forms of public service are his presidencies of the Timber Growers Organisation (1976–8), and the British Deer Society (1973), his chairmanship of the Forestry Committee of Great Britain (1978–80), his trusteeship of the World Wildlife Fund (UK) and his membership of the Scottish Advisory Committee to the Nature Conservancy Council (Guest Editor's introduction).

Forest Research in Florida

Abstract Florida is experiencing serious land-use conflicts due to dramatic increases in population and economic activity. Forest managers have increased timber growth despite these conflicts. Many groups are cooperating in diverse research efforts to provide the basis for continued productivity of the state's 15 million acres of commercial forestland.