Showing papers in "Forest Science in 1990"

A basal area increment model for individual conifers in the northern Rocky Mountains

Abstract: (...) The model represents the diverse ecological requirements of the various species and responds appropriately across the observed range of predictor variables. Furthermore, it is well behaved even when used for conditions found in the region but not represented in the large calibration data set (44,086 trees). In addition, it possesses desirable statistical properties such as homogeneous residual variance, minimal multicollinearity, and linear parameters. (...)

A Shelterwood Method for Regenerating Red Oak in the Southern Appalachians

Abstract: A shelterwood method is described that provides stand conditions that enhance the growth of estabhshed red oak advance reproduction, thereby improving the chances of maintaining an oak component in the next stand. Stocking of a mature, fully stocked stand is reduced to 60%, 65%, and 70% of initial stand basal area where oak site index is 70, 80, and 90 ft, respectively. The basal area reduction is accomplished from below using herbicides, leaving the main canopy essentially intact. This level and method of treatment prevents yellow-poplar, a primary competitor of red oak, from becoming established and growing prior to the final removal cut, and it eliiinates most sprout competition from shade-tolerant subcanopy species after the final removal cut. The final removal cut can be made approximately 10 years after the initial treatment. FOR. SCI. 36(4):917-929. ADDITIONAL KEY WORDS. Regeneration, prescribed fire.

Effects of annual fertilization and sustained weed control on dry matter partitioning, leaf area, and growth efficiency of juvenile loblolly and slash pine

Abstract: (...) After four growing seasons, annual fertilization and complete weed control produced similar levels of response, increasing aboveground biomass 700% for loblolly pine and 300% for slash pine. The combined treatment improved total dry matter production 1600% (from 1.9 to 32.2 Mg ha −1 ) for loblolly pine and 450% (from 4.3 to 23.6 Mg ha −1 ) for slash pine. Equally large treatment-associated increases (up to 1210%) in all-sided leaf area index were measured. Cultural treatments increased the proportional allocations of dry matter to stem wood, stem bark, and branches for both species, a consequence of accelerated stand development. (...)

Predicting Post-Harvest Performance of Advance Red Oak Reproduction in the Southern Appalachians

Abstract: Models are presented for predicting: 1) height growth of red oak advance reproduction after clearcutting, and 2) the probability of stems becoming dominants or codominants in new stands as a function of preharvest size of advance reproduction and site quality. The second model permits silviculturists to predict, prior to harvest, the contribution to a new stand of an existing population of advance red oak reproduction

Spatial and temporal variability of nitrogen cycling in northern Lower Michigan.

Abstract: La variabilite dans l'espace et dans le temps, de la mineralisation et de la nitrification de l'azote a ete etudiee dans trois ecosystemes forestiers (deux erablieres differant par le sous-etage et la vegetation herbacee, et une chenaie), afin de determiner la possibilite d'extrapoler des informations ponctuelles sur le cycle de l'azote a une region geographique. La biomasse de l'etape dominant et l'accroissement annuel sont estimes a l'aide d'equations allometriques specifiques a chaque espece. La relation entre la composition en especes et le cycle de l'azote peut-etre etendue dans l'espace et fournir un modele general de la dynamique spatiale et temporelle des transformations de l'azote

Optimizing any-aged management of mixed-species stands: II. effects of decision criteria

Abstract: The effects of maximum present value and maximum volume objectives on the efficiencies of alternative silvicultural systems are determined by solving any-aged management problems for mixed-conifer stands in the Northern Rocky Mountains. Any-aged management problems are formulated with periodic planting and harvesting controls and without constraints on the stand age or size structure over time. Optimization is performed with the Stand Prognosis Model, a single-tree simulator that has been calibrated for many forest types in the western United States. With a maximum present value objective, 1987 stumpage prices, and no logging damage, steady-state, uneven-aged management using selection cuts is the target silvicultural system for a range of stand types. Optimal transition regimes for understocked stands include clearcutting and planting western white pine (Pinus monticola Dougl. ex D. Don), a high-value, fastgrowing species. With a maximum merchantable volume objective, two types of management emerge as optimal: even-aged plantation management and an uneven-aged shelterwood system are both capable of producing the same high level of yield indefinitely. Both types of management rely on a series of thinnings to grow the most vigorous crop trees into the largest size classes. In addition, the shelterwood system ensures that adequate natural regeneration is established when the crop trees are harvested. Because the uneven-aged shelterwood system produces steady-state yields that are as high or higher than plantation management, these results call into question the widely held view that even-aged plantation management maximizes total merchantable volume production.

Sprouting Shrub Response to Different Seasons and Fuel Consumption Levels of Prescribed Fire in Sierra Nevada Mixed Conifer Ecosystems

Abstract: Shrub survival was often dramatically different between treatments (i.e., fuel consumption level and season of burn), species, and size classes within plant species. Of the four different burn treatments, survival of the shrubs and hardwoods was as low as 12% after early fall burns (high levels of fuel consumption) and as high as 79% after early spring burn treatments (moderate levels of fuel consumption). As much as 95% of the smallest size of the small classes of shrubs (i.e., those ≤50 g dry weight biomass) were killed by prescribed fires (...)

Nematode-induced pine wilt disease: factors influencing its occurrence and distribution.

Abstract: () Pine wilt disease is expressed rarely in the northern hemisphere outside of Japan and south China The disease is expressed only where susceptible pines have been introduced into environments warmer than their natural climatic range, or where pathogenic isolates of the PWNSC have been introduced into warm climates containing susceptible tree species It is probable that the pine wilt epidemic in Japan is a result of a pathogenic form of the PWNSC being introduced around the turn of the century Pine wilt disease has not been recorded for any part of North America, Europe, or Asia where mean daily summer temperatures are 20°C or below ()

Growth and biomass partitioning of northern red oak and yellow- poplar seedlings: effects of shading and grass root competition

Abstract: (...) In all environments, shoot-root ratio and partitioning of leaf and root biomass to surface area for yellow-poplar was greater than oak. In response to competition for soil resources, both species increased biomass partitioning to the root at the expense of the shoot. In response to shading, yellow-poplar increased leaf area proportion, while oak did not. Thinner leaves and a more fibrous root system were more important in explaining yellow-poplar's higher relative growth rate under conditions of shading and root competition compared to oak than differences in shoot-root weight ratio or plasticity in biomass partitioning

A Signal Detection Framework to Evaluate Models of Tree Mortality Following Fire Damage

Abstract: (...) Receiver operating characteristic (ROC) curves show the tradeoffs that are possible by varying the decision criteria, show predictive performance with respect to chance, and show the difference between various models. Two ROC curves were generated to predict ponderosa pine mortality following fall prescribed fires in northern Idaho. One ROC curve was developed from rules of thumb using percent crown scorch. A second ROC curve was developed from a logistic mortality model using diameter at breast height and scorch height. (...)

Identifying trees in riparian areas that can provide coarse woody debris to streams.

Abstract: The natural fall of trees into mountain streams provides coarse woody debris that can improve fish habitat and influence stream morphology. Geometric and empirical equations, based on tree size and distance from the stream, were used to determine the conditional probability of a tree's adding coarse woody debris to a stream. Additional equations were developed to relate this probability to basal area factor. For conditions in the Pacific Northwest, Douglas-fir was selected to illustrate how the equations can be used for varying tree sizes and probabilities (...)

Projecting stand tables: a comparison of the Weibull diameter distribution method, a percentile-based projection method, and a basal area growth projection method.

Abstract: Trois modeles de projection de rendement differents dans leur structure mais permettant tous de faire des projections par classes de diametre ont ete compares, afin de determiner, le systeme le plus precis pour Pinus taeda. Pour la plupart des criteres consideres, le modele qui utilise l'algorithme de projection de la surface terriere, independamment de la distance, donne les meilleurs resultats

Pathogenic variability among populations of the pinewood nematode, Bursaphelenchus xylophilus.

Abstract: Virulence of populations of Bursaphelenchus spp. associated with conifers varies through-out the range of this nematode in the United States and Japan. Populations of B. xylophilus (pinewood nematode, PWN) from Japanese black and red pine in the same and distantly separated pine stands in Japan range in virulence from 0-100% and there is a tendency for the most virulent populations to be in the northernmost part of the nematode's range where establishment has been relatively recent. (...)

Genetic and environmental components of variation of site index in inland Douglas-fir.

Abstract: (...) An index to genetic variation, based on 3-year seedling height in provenance tests, accounted for approximately 40% of the variation in both 50-year and 100-year dominant height (i.e., site index) among 135 natural stands in northern Idaho and western Montana. Combining the genetic index and simple environmental variables (elevation, habitat series, latitude, longitude) accounted for nearly half the variation in site index. Path analyses estimated a strong correlation (0.76) between genotype and environment, reflecting the steep adaptive clines that are well known for this species. (...)

Relationships between site index and synoptic environmental factors in immature coastal Douglas-fir stands.

Abstract: Indirect synoptic measures of climate, soil moisture, and soil nutrients are used to characterize site quality in the biogeoclimatic ecosystem classification. To assess relationships of these measures to potential forest productivity, environmental and site index data from 133 sample plots established in immature coastal Douglas-fir stands were utilized. The stands were distributed across three climatic regimes (biogeoclimatic units), five soil moisture regimes, and five soil nutrient regimes. These regimes were used as categorical variables in stratification of the data and regression analysis (...)

Growth and photosynthetic responses to a range of light environments in Chinese tallowtree and Carolina ash seedlings.

Abstract: (...) Growth and dry mass partitioning at all light levels, differences between leaf photosynthetic systems developed at 20% and 100% light, and crown profiles of net photosynthesis (P N ) in 53% of full sunlight were measured. Tallowtree dry mass peaked at 100%, light while ash dry mass peaked at 53% light. Expressed as a proportion of peak dry mass within species, growth of tallowtre exceeded that of ash at all light levels except 53% of full sunlight. In all but 100% light, tallowtree partitioned more dry mass to leaves than did Carolina ash. (...)

Ecophysiological responses in mesic versus xeric hardwood species to an early-season drought in central Pennsylvania

Abstract: Field and laboratory studies were used to evaluate net photosynthesis and plant and tissue water relations in saplings of co-occurring xeric (Quercus prinus and Q. ilicifolia) versus mesic (Q. rubra and Castanea dentata) hardwood species during a droughty summer. Mean daily net photosynthesis, leaf conductance, leaf water potential, and water use efficiency were reduced in all four species during the peak drought period. Throughout the study, net photosynthesis and leaf conductance were on average high in Q. ilicifolia and Q. prinus, intermediate in Q. rubra, and low in C. dentata. (...)

Winter injury susceptibility and cold tolerance of current and year-old needles of red spruce trees from several provenances.

Abstract: (...) Winter injury was found exclusively on current-year needles (i. e., buds and twigs were vitually uninjured), and 34% to 68% of trees were injured each year. Laboratory assessments of cold tolerance of curret and year-old needles of trees representing four red spruce and four balsam fir (Arabies balsamea [L.] Mill.) provenances indicated that current-year needles of red spruce, but not balsam fir, were 8° to 12°C less cold tolerant than year-old needles in late autumn and early winter. (...)

Feedback thinning policies for uneven-aged stand management with stochastic prices.

Abstract: (...) Numerical results are presented using a stage-structured model for unevenaged stands of California white fir (Abies concolor). Stumpage price is the sum of a deterministic constant and a normally distributed random error. With these assumptions, optimal feedback thinning policies have significantly higher expected present values than do thinning policies that ignore price fluctuations. However, feedback policies have greater volatility in harvest revenue over time. Sensitivity analysis shows that the expected present value of optimal feedback management increases as the level of price risk increases

Effects of phosphorus and ectomycorrhizas on the carbon balance of loblolly pine seedlings

Abstract: () Both phosphorus fertilization and mycorrhizal development caused a substantial increase in the net rate of photosynthesis and dry matter accumulation, but neither treatment resulted in significant changes in shoot-root allocation of dry matter or shoot dark respiration At low and medium levels of mycorrhizal development, the net photosynthetic response to mycorrhizal formation appeared to be due to enhanced P nutrition However, at high levels of mycorrhizal development, as much as 17% of the total increase in the net photosynthetic rate that resulted from mycorrhizal development, may be attributed to mechanisms other than enhanced phosphorus nutrition ()

Relationships among humus forms, forest floor nutrient properties, and understory vegetation.

Abstract: Examination of these relationships was accomplished in this study by a numerical analysis of forest floor and vegetation data that were obtained from 151 cool mesothermal forest ecosystems of southern British Columbia and stratified into seven humus form groups. Four forest floor nutrient properties (pH, C/N ratio, total N, and sum of exchangeable Ca, Mg, and K) and nine diagnostic combinations of species differentiated the groups. pH and mineralizable-N consistently increased, and C/N ratio consistently decreased from Lignomors to Hemimors, Humimors, Mormoders, Leptomoders, and to Vermimulls, indicating the presence of a regional decomposition gradient

A variable-form taper function for Pinus oocarpa Schiede in central Honduras.

Abstract: (...) The model predicts tree profile as a function of total height, diameter at breast height, and relative height with a continuous function using a changing exponent to compensate for the form of different tree sections. The proposed five parameter model predicts underbark diameters with a standard error of 1.4 cm. The point where the taper curve changes from neiloid to paraboloid form, the inflection point, was assumed to occur at 25% of total height. For the data used, no changes in the predictive ability of the model were observed with different locations of the inflection point

Dating decline and mortality of Chamaecyparis nootkatensis in southeast Alaska.

Abstract: The dates of death for individual snags of Alaska yellow-cedar were determined by counting annual rings on 73 western and mountain hemlock trees growing beneath larger, dead Alaska yellow-cedars, and in live callus strips on 46 Alaska yellow-cedars with partial bole death. Average time since death was 4, 14, 26, 51, and 81 years for snags in class I (foliage retained), class II (twigs retained), class III (secondary branches retained), class IV (primary branches retained), and class V (bole intact but no primary branches retained), respectively

Multicriteria nonlinear programming for optimal spatial allocation of stands.

Abstract: The forest planning problem is formulated using stand level variables for each management unit It is shown that harvests can be spatially allocated to stands to meet nonadjacency requirements by using a nonlinear programming formulation A penalty function form of the mathematical program is used to find solutions This study represents a first attempt at a possibly robust technique It appears to be applicable to small forest areas For larger forest areas containing many stands (>200) the method is predicted to converge too slowly for practical use

Considerations on modeling the market for softwood lumber in the United States.

Abstract: This paper uses the Granger causality test to determine whether the demand for softwood lumber affects price in the current period or subsequent periods, or whether price is exogenous. This test is run for each of four geographically distinct regions in the United States. Further statistical tests are then used to detect the geographical extent of the softwood lumber market. The results indicate that demand is indeed strongly connected to prices, and that there is a national market for softwood lumber

Alternate expressions for the economic theory of forest fire management.

Abstract: Two traditional economic efficiency criteria, minimization of cost plus net value change versus profit maximization, are compared in terms of the insights provided into fire management decisions. The historic rationale for favoring minimization over maximization is examined and questioned. Advantages of formulating the problem in terms of profit maximization include explicit attention to production relations obscured by previous graphical representations of the minimization criterion (...)

Growth and Biomass Partitioning Response of Northern Red Oak Genotypes to Shading and Grass Root Competition

Abstract: First-year biomass, biomass relative growth rate, and biomass partitioning among organs were compared among eight open-pollinated families of northern red oak (Quercus rubra L.) under crossed levels of light intensity (100% and 37% full sun) and grass root competition (presence and absence of grass roots (Poa pratensis L.)). Onto- genetic patterns of biomass partitioning during the first year of seedling development were characterized by coefficients of the allometric equation Y = aX b. Grass root competition reduced seedling biomass at both levels of light intensity. Shading reduced seedling biomass in the absence of grass but had no effect in its presence. Total biomass and biomass relative growth rate differed among families, and family x environment interaction variance was negligible compared to family variance. Results suggest that families with superior juvenile growth rate under competition-free conditions will also have superior growth rate under at least some conditions of shading and root competi- tion. Biomass partitioning to leaf area, and to shoot weight relative to root weight declined during seedling development. Both shoot-root ratio and leaf area ratio were greater in shaded compared to full sun environments, while the presence of grass root competition had an opposite effect on both ratios. Families differed in shoot-root ratio, and shoot-root ratios of families responded differently to grass root competition. How- ever, family differences in biomass partitioning were not consistently related to family differences in growth rate in any environment. FOR. ScI. 36(2):293-303.

Classification of forest vegetation in north-central Minnesota using Landsat multispectral scanner and thematic mapper data.

Abstract: L'objectif est de determiner comment les caracteristiques des forets et des capteurs (resolution spectrale et spatiale) affectent la precision de la classification en types de couverts forestiers, dans le Parc d'etat d'Itasca. Les cartes issues de la classification Landsat sont comparees pixel par pixel a une carte numerique de reference, afin d'etablir les differences statistiquement significatives. La precision de la classification varie de 26 a 86% selon le capteur, le nombre de classes et la mesure de performance. La resolution spectrale et radiometrique accrue Thematic Mapper entraine une augmentation de 7-15% de la precision par rapport au radiometre multispectral a balayage. La meilleure combinaison spectrale est constituee d'une bande dans le visible, une dans l'infrarouge proche, une dans l'infrarouge moyen

Growth-competition relationships in young hardwood stands on two contrasting sites in southwestern Wisconsin.

Abstract: Crown-based competition measures were used to assess the relationships between growth and competition for trees in young mixed-hardwood stands on two ecosystems with contrasting site conditions. The two southwestern Wisconsin ecosystems compared were gently sloping summits with deep loessal soils and steeply sloping southwesterly backslopes with loam soils. (...) The two best predictors of height growth are the height of a tree relative to the average height of dominants and codominants, and the cross-sectional area of the exposed portion of the crown at its widest point. (...)