Timber production versus old-growth preservation with endogenous prices and forest age-classes

2004 ◽  
Vol 34 (6) ◽  
pp. 1296-1310 ◽  
Author(s):  
Olli Tahvonen
Keyword(s):  
Environmental Values ◽  
Timber Harvesting ◽  
Timber Production ◽  
Forest Age ◽  
Forest Land ◽  
Age Classes ◽  
Old Growth ◽  
Class Distribution ◽  
Age Class ◽  
Long Run

This study combines timber production and environmental values, applying a dynamic forest-level economic model with any number of forest age-classes. The model includes endogenous timber price or nonlinear harvesting costs and various possibilities to specify the dependence of environmental values (related e.g. to species persistence) on the forest age-class structure. The nonlinearities in the net benefits from timber production have the consequence that fluctuations in optimal timber harvesting may totally vanish or at least become smaller than in forest scheduling models without ad hoc even flow constraints. If environmental values are specified to depend on the fraction of forest land preserved as old growth, the optimal long run allocation between timber production and old growth is represented by an equilibrium continuum. Thus the optimal long run allocation depends on the initial age-class distribution. The continuum and the dependence of initial age-class distribution vanish when the rate of discount approaches zero. If the environmental values of age-classes increase smoothly with age, the long run equilibrium may simultaneously include multiple rotation periods. The model determines the optimality of producing timber and environmental values separately at different parts of the forest or at the same piece of forest land. Numerical computation suggests that the optimal solution always converges toward some optimal long run stationary age-class distribution.

The Missing Tail and Other Considerations for the Use of Fire History Models

1995 ◽  
Vol 5 (4) ◽  
pp. 197 ◽  
Author(s):  
MA Finney
Keyword(s):  
Exponential Distribution ◽  
Exponential Model ◽  
Forest Age ◽  
Age Classes ◽  
Class Distribution ◽  
Age Class ◽  
Negative Exponential Distribution ◽  
Negative Exponential Model ◽  
Negative Exponential ◽  
Tests Of Fit

This paper reviews methods used for testing the fit of the cumulative form of a negative exponential distribution to the cumulative distribution of forest age-classes. It is shown that existing methods can lead to a greater chance of falsely rejecting the fit of the negative exponential model and inferring that fire frequencies have changed through time. This results when the old-age tail of a negative exponential distribution is mathematically assumed to be present at the end of the age-class distribution. In reality, the tail is censored from sample distributions of forest age-classes. Censoring alters the shape of a cumulative age-class distribution from the straight line expected for a semi-log graph of the cumulative negative exponential model. A solution to this problem is proposed that restricts the tests-of-fit to the portion of the negative exponential distribution that overlaps with the data to be tested. The cumulative age-class distribution can then be compared directly with the cumulative of a truncated negative exponential distribution. Considerations for interpreting a poor fit are then discussed.

The timing and nature of floristic and structural changes during secondary succession in wet forests

2008 ◽  
Vol 56 (3) ◽  
pp. 220 ◽  
Author(s):  
Merrilyn Serong ◽  
Alan Lill
Keyword(s):  
Secondary Succession ◽  
Structural Changes ◽  
Timber Harvesting ◽  
Stem Density ◽  
Forest Age ◽  
Age Classes ◽  
Age Class ◽  
Mountain Ash ◽  
Wet Forests ◽  
Severe Disturbance

The timing and nature of floristic and structural changes to vegetation were documented during secondary succession in wet forests in the Victorian Central Highlands from 3 to > 100 years after severe disturbance by timber-harvesting or wildfire. A chronosequence of five forest age-classes was employed. Vegetation surveys were conducted in two 15 × 50 m sampling quadrats in each of 12 replicate sites in each forest age-class between April 2000 and June 2001. Frequencies of occurrence of 67 floristic variables (plant taxa, other vegetation elements and litter components) were used to distinguish among plant communities in the different forest age-classes. Structural comparisons were made among the age-classes using species richness, floristic variability (i.e. spatial heterogeneity), trunk diameter and stem density of Mountain Ash Eucalyptus regnans F.Muell. and heights of forest strata. Most patterns of change showed a clear unidirectional trend from the youngest to the oldest age-class. Much of the floristic change occurred within a few decades of disturbance, but some of the structural changes continued throughout succession. Vegetation changes were generally attributable to natural succession, but a few differences between young forests that regenerated after timber-harvesting and older forests that originated after wildfire were likely to be due to the different disturbance histories. The pattern of vegetation change during secondary succession in forests after severe disturbance can influence the pattern of forest use by birds. The findings of this study thus formed the foundation of an examination of the community and behavioural responses of diurnal birds to secondary succession.

scholarly journals Stand damage when harvesting timber using a tractor for extraction

2013 ◽  
Vol 74 (1) ◽  
pp. 27-33 ◽  
Author(s):  
Zbigniew Karaszewski ◽  
Dieter F. Giefing ◽  
Piotr S. Mederski ◽  
Mariusz Bembenek ◽  
Anita Dobek ◽  
...  
Keyword(s):  
Statistical Difference ◽  
Timber Harvesting ◽  
Age Classes ◽  
Substantial Impact ◽  
Age Class ◽  
Thinning Operations ◽  
Stand Damage ◽  
Agricultural Tractor ◽  
Timber Extraction

Abstract Damage to the remaining stand is an unavoidable consequence of thinning operations. The different machines used for timber extraction differ in the level of damage of trees they cause, mainly through wounds to the bark and cambium which can make a substantial impact on the remaining trees. Three different methods of timber harvesting with a chainsaw were analyzed: the short wood system (SWS), the long wood system (LWS) and the full tree system (FTS) in which an agricultural tractor is used for timber extracting. All systems were analyzed in stands containing three different age classes: 2nd (21-40 years), 3rd (41-60 years) and 4th (61-80 years). The level of damage to the remaining stand was assessed considering the percentage of trees exhibiting wounds (scratched bark and/or damage to the cambium) to calculate an index of stand damage (WDI) which incorporated the volume of harvested timber per hectare. The SWS produced the lowest damage to trees in stands of all age classes: average 5%, with the less damage in the oldest stand. After using the LWS, 9% of trees were wounded; in this method there was no statistical difference in frequency of wounding across all the analyzed stands. The highest level of damage was incurred after the FTS, causing 11% of trees to be injured. In stands of the 2nd age class, the method of timber harvesting had no statistically significant effect on the amount of wounding endured. The WDI was lowest in SWS: 0.08, higher in LWS: 0.15 and the highest, 0.23, when FTS was applied.

Species richness, abundance, and composition of hypogeous and epigeous ectomycorrhizal fungal sporocarps in young, rotation-age, and old-growth stands of Douglas-fir (Pseudotsuga menziesii) in the Cascade Range of Oregon, U.S.A.

2002 ◽  
Vol 80 (2) ◽  
pp. 186-204 ◽  
Author(s):  
J E Smith ◽  
R Molina ◽  
M MP Huso ◽  
D L Luoma ◽  
D McKay ◽  
...  
Keyword(s):  
Pseudotsuga Menziesii ◽  
Ectomycorrhizal Fungi ◽  
Forest Succession ◽  
Fungal Species ◽  
Tsuga Heterophylla ◽  
Douglas Fir ◽  
Forest Age ◽  
Age Classes ◽  
Old Growth ◽  
Rotation Age

Knowledge of the community structure of ectomycorrhizal fungi among successional forest age-classes is critical for conserving fungal species diversity. Hypogeous and epigeous sporocarps were collected from three replicate stands in each of three forest age-classes (young, rotation-age, and old-growth) of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) dominated stands with mesic plant association groups. Over four fall and three spring seasons, 48 hypogeous and 215 epigeous species or species groups were collected from sample areas of 6300 and 43 700 m2, respectively. Cumulative richness of hypogeous and epigeous species was similar among age-classes but differed between seasons. Thirty-six percent of the species were unique to an age-class: 50 species to old-growth, 19 to rotation-age, and 25 to young stands. Seventeen species (eight hypogeous and nine epigeous) accounted for 79% of the total sporocarp biomass; two hypogeous species, Gautieria monticola Harkn., and Hysterangium crassirhachis Zeller and Dodge, accounted for 41%. Average sporocarp biomass in young and rotation-age stands compared with old-growth stands was about three times greater for hypogeous sporocarps and six times greater for epigeous sporocarps. Average hypogeous sporocarp biomass was about 2.4 times greater in spring compared with fall and for epigeous sporocarps about 146 times greater in fall compared with spring. Results demonstrated differences in ectomycorrhizal fungal sporocarp abundance and species composition among successional forest age-classes.Key words: ectomycorrhizal fungi, sporocarp production, forest succession, Pseudotsuga menziesii, Tsuga heterophylla zone, biodiversity.

Forest taxation in multiple-stand forestry with amenity preferences

2008 ◽  
Vol 38 (4) ◽  
pp. 806-820 ◽  
Author(s):  
Jussi Uusivuori ◽  
Jari Kuuluvainen
Keyword(s):  
Substitution Effect ◽  
Timber Harvesting ◽  
Forest Owner ◽  
Age Class ◽  
Lump Sum ◽  
Amenity Values ◽  
Long Run ◽  
Sales Taxation ◽  
Short Run ◽  
The Impact

This paper investigates the impacts of forest taxes within an age-class forest model where the landowner derives utility from both consumption and the amenity values of standing forest. The model generalizes the existing models used to analyze forestry taxes. It is shown how the age-class model enables a more detailed analysis of the substitution and income effects of various taxes. These effects are shown to be linked to the properties of the utility function and to the distribution of the landowner’s assets between forests and nonforest assets. The results indicate that for most utility functions, income effect is unlikely to dominate the substitution effect of taxes on forest owner timber harvesting decisions. Numerical examples are used to demonstrate how the tax impacts can differ in the short run and long run. The results imply that higher consumption levels combined with profit or sales taxation applied in forestry will effectively reinforce each other in increasing optimal rotations. On the other hand, a lump-sum tax may be used to counteract the impact of increasing consumption levels.

scholarly journals Managing forest harvesting to maintain old growth in boreal and sub-boreal forests

1999 ◽  
Vol 75 (4) ◽  
pp. 623-631 ◽  
Author(s):  
Philip J. Burton ◽  
Daniel D. Kneeshaw ◽  
K. David Coates
Keyword(s):  
Basal Area ◽  
Timber Harvest ◽  
Forest Harvesting ◽  
Stand Age ◽  
Forest Age ◽  
Old Growth ◽  
Partial Cutting ◽  
Growth Status ◽  
Age Class ◽  
Old Growth Forest

Old-growth stands can be rare in northern coniferous forests, and hence are worthy of protection and special management. We describe some quantitative guidelines for recognizing old-growth stands and options for maintaining a long-term supply of old-growth values in landscapes managed for timber production. In the Sub-Boreal Spruce forests of central British Columbia, attributes most indicative of old-growth status include stand age, the density of large (> 1.0 m3) snags and downed logs, stand basal area and volume. It is suggested that partial cutting could occur in some old-growth stands, while still maintaining their structural and functional attributes, if large logs, snags and trees are retained at the threshold densities necessary to recognise old-growth status. At the landscape level, the use of extended timber crop rotations is advocated. Planning for a tapered forest age class distribution (with decreasing areas of forest allowed to persist to successively older ages) is suggested as a means of sustainably generating true old-growth, and as an alternative to the use of partial cutting and patch retention. Arithmetic formulas are developed which provide guidelines for the proportion of the forest land base to be kept in each successive age class. This model for regulating human disturbance in commercial forests holds promise as a mechanism for allowing continued timber harvest and even-aged stand management while retaining a near-natural proportion of old-growth forest in northern landscapes. Key words: disturbance regime, even-aged management, extended rotations, forest age class structure, forest management, old-growth attributes, rotation length, silvicultural systems, sub-boreal spruce zone, timber supply planning.

scholarly journals Conserving woodland caribou habitat while maintaining timber yield: a graph theory approach

2016 ◽  
Vol 46 (7) ◽  
pp. 914-923 ◽  
Author(s):  
Jonathan L.W. Ruppert ◽  
Marie-Josée Fortin ◽  
Eldon A. Gunn ◽  
David L. Martell
Keyword(s):  
Graph Theory ◽  
Rangifer Tarandus ◽  
High Volume ◽  
Timber Harvesting ◽  
Optimization Approach ◽  
Theory Approach ◽  
Heuristic Procedure ◽  
Woodland Caribou ◽  
Old Growth ◽  
Old Growth Forest

The fragmentation and loss of old-growth forest has led to the decline of many forest-dwelling species that depend on old-growth forest as habitat. Emblematic of this issue in many areas of the managed boreal forest in Canada is the threatened woodland caribou (Rangifer tarandus caribou (Gmelin, 1788)). We develop a methodology to help determine when and how timber can be harvested to best satisfy both industrial timber supply and woodland caribou habitat requirements. To start, we use least-cost paths based on graph theory to determine the configuration of woodland caribou preferred habitat patches. We then developed a heuristic procedure to schedule timber harvesting based on a trade-off between merchantable wood volume and the remaining amount of habitat and its connectivity during a planning cycle. Our heuristic can attain 84% of the potential woodland caribou habitat that would be available in the absence of harvesting at the end of a 100 year planning horizon. Interestingly, this is more than that which is attained by the current plan (50%) and a harvesting plan that targets high volume stands (32%). Our results indicate that our heuristic procedure (i.e., an ecologically tuned optimization approach) may better direct industrial activities to improve old-growth habitat while maintaining specified timber production levels.

scholarly journals Slenderness of trees in black locust stands

2018 ◽  
Vol 79 (2) ◽  
pp. 113-117
Author(s):  
Szymon Bijak ◽  
Katarzyna Orzoł
Keyword(s):  
Standard Deviation ◽  
Black Locust ◽  
Robinia Pseudoacacia ◽  
Habitat Type ◽  
Stand Age ◽  
Age Classes ◽  
Breast Height ◽  
Age Class ◽  
Crown Length ◽  
Research Material

Abstract This paper investigates the slenderness of black locust (Robinia pseudoacacia) trees in relation to the biosocial status of the trees, stand age class, crown parameters and habitat type. The research material was collected on 35 research plots in the Sława Śląska, Sulechów and Głogów forest districts in western Poland and comprises 1058 trees. For each tree, we measured height (h) as well as diameter at breast height (d) and determined its biosocial status (Kraft class), crown length (CL) and relative crown length (rCL). The age class and habitat type were assessed at the plot level. Because the obtained values for slenderness (s=h/d) diverged significantly from the normal distribution, we used Kruskal-Wallis and Mann-Whitney tests to investigate the influence of the above-mentioned parameters on the h/d ratio. Black locust slenderness ranged from 0.31 to 1.95 with an average of 0.91 (standard deviation 0.24). It furthermore differed significantly between Kraft classes (the higher the biosocial status, the lower the slenderness) and age classes (the older the trees, the lower their slenderness). We also found a significant effect of the habitat type (in oligotrophic sites trees formed more slender trunks than in mesotrophic sites) and crown parameters on the h/d ratio (decreasing with increasing crown length and relative crown length). The obtained results suggest that the slenderness of black locust does not differ substantially from native broadleaved trees in Poland.

Tendencias minimalistas en la gestión de los bosques tropicales mexicanos: motivaciones y experiencias

2021 ◽  
Vol 348 ◽  
pp. 29-36
Author(s):  
Martin Alfonso MENDOZA B. ◽  
Angélica NAVARRO-MARTÍNEZ ◽  
Carl W. MIZE ◽  
Gerson Daniel ALDUCIN CHÁVEZ ◽  
Patricia NEGREROS-CASTILLO
Keyword(s):  
Forest Management ◽  
Performance Indicator ◽  
Timber Harvesting ◽  
Land Value ◽  
Tropical Regions ◽  
Slash And Burn ◽  
Tropical Timber ◽  
Long Run ◽  
Residual Stock ◽  
Rational Management

Tropical timber regions across the world share common problems such as degradation and poor regeneration after timber harvesting. Traditional Mayan land management through slash and burn is now recognized as an effective way of renewing forest stands in multispecies tropical forests. The practice of slash and burn for forest management in Mexico has led to area regulation, which has made land value a convenient means of assessing alternative forest plans. The use of expected land value as a performance indicator shifts the manager's attention from managing a species mix to balancing financial tradeoffs between liquidation or retention of the standing biomass. Since the forest-wide residual stock is so large, land value overrides the importance of revenue from timber sales. Several forest management methods along these lines have appeared in tropical regions of Mexico over a thirty-year time span and represent a patrimonial system of forest management (PS). The gradual innovation generated by PS is described here, as well as examples of PS practices. PS methods today provide stewardship for a total of 155,814 ha in different parts of Mexico. PS performance will become evident in the long run; in the meantime, the embrace of PS by private landowners and regulatory institutions is equated with a positive, independent opinion about PS design. The Mexican experience suggests pathways for rational management of all types of forests. PS features that are worth replicating are, for instance, the inclusion of disturbance patterns as factors in decision making, as well as the use of specific silvicultural regimes for roads, woodlands, closed forests, hilltops, swamps, riparian zones, clearings and forest edges.

scholarly journals FURTHER INVESTIGATIONS ON THE ORIGIN OF TUMORS IN MICE

1915 ◽  
Vol 22 (6) ◽  
pp. 713-731 ◽  
Author(s):  
A. E. C. Lathrop ◽  
Leo Loeb
Keyword(s):  
Tumor Incidence ◽  
Age Classes ◽  
Age Class ◽  
The Difference ◽  
Different Strains

1. In crossing strains known to diner in their tumor rates, the hybrids show in a considerable number of cases a tumor rate corresponding to the parent with a high tumor incidence; in some cases the offspring have the tumor rate of the parent with the low tumor incidence; in certain cases the tumor rate of the offspring is intermediate between those of the parents. That these results are not accidental follows from the fact that we could show in some cases that two sisters crossed with the same strains or with the same male give similar offspring, and in other cases we could show that the same individual crossed successively with two strains that behave similarly produces hybrids with a similar tumor incidence. 2. There exists some evidence for the conclusion that different strains in being crossed with other strains differ in their power to impress their tumor rate upon the crosses. Thus the English strain and the I and II daughters of No. 10 have the tendency to transmit to the offspring a high tumor rate, while Cream, Silver, and some European other than 151 have a tendency to transmit a low tumor rate. While crosses of these daughters of No. 10 with European 151 or with No. 8½ show the high tumor rate of the mothers, the crosses of one of the same females with Cream or Silver show an intermediate tumor rate. 3. We find further evidence for our conclusion previously stated that age class, of the tumors and tumor rate are not dependent on the same factor. The age class enters into the crosses as a factor independent of the tumor rate. Thus we find in the crosses between the first daughter of No. 10 and Cream, and in the crosses between the same female and English Silver a similar tumor rate, but the age classes differ in conformity with the difference in the age classes of the parents. We find, furthermore, that while in some cases a tumor rate and an age class that correspond to each other (high tumor rate, early tumors—low tumor rate, late tumors) are transmitted to the offspring, in other cases tumor rate and age class transmitted to the crosses diverge. 4. It seems that certain strains with very late tumors if mated with strains with earlier tumors have a tendency to transmit to the offspring their own tendency to very late tumors. With a certain strain lateness of the tumors seems to be dominant, while a low tumor rate is not necessarily dominant in the same crosses. This was noticeable in the crosses into which the strain European ± 102 or 103 entered as one of the parents. 5. If both parents have a similar tumor rate the offspring have usually a similar tumor rate. There was, however, one exception to this rule in the case of the German ± Carter mice, in which the offspring showed a much lower tumor rate and higher age class than either of the parent strains.

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