Maximum Basal Area Research Articles

Variation in Soil and Forest Floor Characteristics Along Gradients of Ericaceous, Evergreen Shrub Cover in the Southern Appalachians

Ericaceous shrubs can influence soil properties in many ecosystems. In this study, we examined how soil and forest floor properties vary among sites with different ericaceous evergreen shrub basal area in the southern Appalachian mountains. We randomly located plots along transects that included open understories and understories with varying amounts of Rhododendron maximum (rosebay rhododendron) and Kalmia latifolia (mountain laurel) at three sites. The three sites were a mid-elevation ridge, a low-elevation cove, and a high-elevation southwest-facing slope. Basal area of R. maximum was more correlated with soil properties of the forest floor than was K. latifolia. Increasing R. maximum basal area was correlated with increasing mass of lower quality litter and humus as indicated by higher C:N ratios. Moreover, this correlation supports our prediction that understory evergreen shrubs may have considerable effect on forest floor resource heterogeneity in mature stands.

Calibrating the self-thinning frontier

Calibration of the self-thinning frontier in even-aged monocultures is hampered by scarce data and by subjective decisions about the proximity of data to the frontier. We present a simple model that applies to observations of the full trajectory of stand mean diameter across a range of densities not necessarily close to the frontier. Development of the model is based on a consideration of the slope s = ln( N t / N t−1 )/ln( D t / D t−1 ) of a log-transformed plot of stocking N t and mean stem diameter D t at time t. This avoids the need for subjective decisions about limiting density and allows the use of abundant data further from the self-thinning frontier. The model can be solved analytically and yields equations for the stocking and the stand basal area as an explicit function of stem diameter. It predicts that self-thinning may be regulated by the maximum basal area with a slope of −2. The significance of other predictor variables offers an effective test of competing self-thinning theories such Yoda's −3/2 power rule and Reineke's stand density index.

Growth and physiology of loblolly pine in response to long-term resource management: defining growth potential in the southern United States

Leaf physiology and stem growth were assessed in loblolly pine ( Pinus taeda L.) in response to 10 to 11 years of treatment with weed control (W), weed control plus irrigation (WI), weed control plus irrigation and fertigation (WIF), or weed control plus irrigation, fertigation, and pest control (WIFP) to determine whether increased resource availability can push productivity of loblolly pine closer to its biological growth potential expressed in favorable, exotic environments. Maximum basal area and stem biomass were 41 m2·ha–1 and 172 Mg·ha–1, respectively, in response to fertigation. Stemwood biomass production was positively and linearly related to basal area. Belowground woody biomass was highest in the WIF and WIFP treatments and averaged 50 Mg·ha–1, but the W and WI treatments exploited a greater area of soil with low-density coarse roots. Fertigation increased foliar nitrogen concentration and foliage biomass, but treatment had no effect on leaf physiological parameters or growth efficiency. Comparison with growth rates reported for loblolly pine in Hawaii revealed that loblolly pine grown in its native range can produce the high yields observed in exotic environments when stands are below maximum carrying capacity.

Relationship Between Maximum Basal Aarea Carrying Capacity and Maximum Size-density Rrelationships

Two important concepts in forest stand density management !a the maximum basal area carrying capacity and the maximusize-density relationship (MSDR) for individual stands !a are mathematically related. For stands with a MSDR slope lesthan 2, maximum basal area carrying capacity will occur after a stand has reached its MSDR stage of stand development, or after Reineke!?s SDI has been maximized. Maximum basal area carrying capacity and the MSDR stage of stand developmen will occur simultaneously in a stand that has a MSDR slope equal to 2. If a MSDR!?s slope is greater than 2, a stand will reac its maximum basal area carrying capacity prior to reaching its MSDR stage of stand development.

Modelling forest succession in two southeastern Canadian mixedwood ecosystem types using the ZELIG model

The gap model ZELIG was validated for red spruce–balsam fir–yellow birch and yellow birch–sugar maple–balsam fir forest types in southern Quebec, Canada. Long-term historical data originating from the Lake Edward Experimental Forest, La Mauricie National Park, were used. The effect of the variation in plot size, representing the space within which trees uptake site resources, was also examined. Several species were included in both forest types: red spruce ( Picea rubens Sarg.), balsam fir ( Abies balsamea (L.) Mill.), yellow birch ( Betula alleghaniensis Britton), white birch ( Betula papyrifera Marsh.), red maple ( Acer rubrum L.), sugar maple ( Acer saccharum Marsh.), American beech ( Fagus grandifolia Ehrh.), eastern hemlock ( Tsuga canadensis (L.) Carr.) and northern white cedar ( Thuja occidentalis L.). The pattern of change in basal area growth varied among species, ranging from a steady increase to a more or less rapid decline. There was a good agreement between observations and predictions for yellow birch, red spruce, red maple, sugar maple, balsam fir and northern white cedar. Plot size had a significant impact on the dynamics of the different species. Depending on the species, the decline was accelerated, the amplitude of the fluctuations varied, or the maximum basal area reached changed. Predicted regeneration varied among species and the number of seedlings generally increased with increase in plot size. The pattern of development for most species was related to their life characteristics. The results highlighted the fact that there is a critical lack of knowledge and data on the dynamics of regeneration from the seedling to the sapling stages for the two forest types studied, which resulted in poor predictions for some species. As the life characteristics varied among species, the use of only one plot size for all species may not be realistic.

Calculation of uneven-aged stand structures with the negative exponential diameter distribution and Sterba's modified competition density rule

Depending on Sterba's modified Competition Density Rule [Sterba, H., 1975. Assmann's theorie der grundflächenhaltung die “Competition Density Rule” det Japaner Kira, Ando und Tadaki. Cbl. f.d. ges. Forstw. 92, 46–62], the maximum basal area ( G max), quadratic mean diameter ( d G max ), and stem numbers ( N G max ), for uneven-aged stands of Abies nordmanniana in the Black Sea Region in Turkey were calculated. Then, an exponential diameter distribution as a function of dominant height for these stands was obtained by solving nonlinear system of equations, which uses the maximum basal area ( G max) and the stem numbers ( N G max ) as input values, and gives diminution coefficient ( q) and the number of stems in the largest diameter class ( N 1) as outputs. The results are in accordance to Sterba and Monserud's findings [Sterba, H., Monserud, R.A., 1993. The maximum density concept applied to uneven-aged mixed species stands. For. Sci. 39 (3), 432–452] on the slope of the maximum density line, and with Susmel's [Susmel, L., 1956. Laws and the variation of the parameters in uneven-aged normal forests. L’Italia Forestale e Montana XI (3), 3–14] concept of decreasing q with increasing dominant height.

Carbon limitation leads to suppression of first year oak seedlings beneath evergreen understory shrubs in Southern Appalachian hardwood forests

Inhibition of canopy tree recruitment beneath thickets of the evergreen shrubs Rhododendron maximum L. and Kalmia latifolia L. has long been observed in Southern Appalachian forests, yet the mechanisms of this process remain unresolved. We present a first-year account of suppression of oak seedlings in relation to Rhododendron and Kalmia basal area, light and resource availability, seedling performance and the rates of seedling damage i.e., herbivory. We found no evidence of first-year seedling suppression or significant resource deficiencies beneath thickets of K. latifolia in mature mixed hardwood stands. Suppression beneath R. maximum was apparent during the first growing season. We found that seedling biomass, light availability prior to canopy closure, and seedling tissue C:N ratios were negatively correlated with R. maximum basal area. Basal area of R. maximum was positively correlated with seedling mortality rates, soil Al, and early-growing season leaf herbivory rates. Seedling growth was positively correlated with light and tissue C:N, while negatively correlated with soil Al. Overall, our results support the inhibition model of shade-mediated carbon limitation beneath dense understory shrubs and indicate the potential importance of herbivory and aluminum toxicity as components of a suppression mechanism beneath R. maximum thickets. We present a causal model of first year inhibition beneath R. maximum in the context of our findings and the results of prior studies.

Minimum distance boundary method: maximum size-density lines for unthinned Acacia mangium plantations in South Sumatra, Indonesia

A minimum-distance boundary method that will minimize the sum of distances between measured points and a fitted self-thinning lines on log-log coordinates of stand density and quadratic mean diameter was proposed in order to estimate the maximum size density line: an upper boundary of self-thinning line. The lines for A. mangium were inferred with this method using data in two areas of unthinned plantations in South Sumatra, Indonesia. Slopes of the lines were deduced as −1.63 and −1.67 within the range of 10–21 cm of quadratic mean dbh. The intensity of self-thinning was examined as a rate of reduction of density in relation to dbh increment. The rates were found to be higher than the slopes in the range close to the maximum line; hence the lines inferred in this study were likely existent. Maximum basal area deduced from the size-density line was 28–30 m2/ha at 12cm of dbh and then it increased up to 34–37 m2/ha at 20 cm of dbh.

Individual tree basal-area growth parameter estimates for four models

Four sigmoid growth models are fit to basal-area data derived from increment cores and disks taken at breast height from oak trees. Models are rated on their ability to fit growth data from five datasets that are obtained from 10 locations along a longitudinal gradient across the states of Delaware, Pennsylvania, West Virginia, and Ohio in the USA. We examine and compare the estimated parameters for the four models across a range of sample sites and tree ages. We then examine the differences among these models. The Chapman–Richards model is recognized as the best regarding minimum Mean Square Error (MSE) and gives reasonable estimates of maximum basal-area growth for old-age trees. The Weibull model is shown to be the poorest in terms of ability to fit the data. The apparent reason for this lack of fit is discussed. The Richards model ranked third in terms of meeting the MSE criteria but did best in terms of meeting the SAS stop criteria. The von Bertalanffy model is shown to have problems meeting the stop criteria of the SAS non-linear fit algorithm but ranks second in terms of samples meeting the MSE criteria. The von Bertalanffy model also tends to underestimate the long-term maximum value or asymptote of basal area over time.

Production dynamics of intensively managed loblolly pine stands in the southern United States: a synthesis of seven long-term experiments

Results from seven long-term experiments in the southern US were summarized to understand production dynamics of intensively managed loblolly pine plantations. Replicated studies that spanned a wide range of soil and climatic conditions were established (North Carolina—NC; Georgia—GA (three sites); Florida—FL; Louisiana—LA; Oklahoma—OK). All experiments received some combination of silvicultural treatments, including fertilizer application, understory competition control, irrigation, and thinning. Accumulation of stemwood biomass at age 15 years varied among sites and ranged from 70 Mg ha −1 (NC) to 180 Mg ha −1 (GA). All sites that received fertilizer and weed control applications were responsive to treatments, and growth responses ranged from about 2-fold (GA) to 3.5-fold (FL) at age 15 years. Variation in fertilizer responses among sites reflected differences in soil types, inherent site quality, and stages of stand development. Site carrying capacity, expressed as maximum basal area attained in closed canopy stands, was surprisingly consistent among sites and climatic conditions, reaching 45–48 m 2 ha −1 under the most intensive silvicultural treatments. Across studies, competition-related mortality was initiated as stand basal areas approached 30–35 m 2 ha −1, and annual stemwood biomass increment peaked as basal areas reached about 20–35 m 2 ha −1. These data suggest that a regional maximum in stand density occurs for loblolly pine when regular fertilizer additions are made or inherent soil nutrient supply is high. Periodic density management will be required to minimize reductions in individual tree and net stand growth. Wood specific gravity at a standard ring age of 10–11 years varied both among sites and by treatment within sites, and ranged from approximately 0.45 (OK site) to 0.56 (GA sites). Maximum leaf area index (LAI) among sites varied from about 2.5 to 6.5. The relationship between stemwood biomass increment and LAI across sites was strong at LAI levels <3.0, but was considerably more variable at higher LAIs. Variation in stemwood increment at higher LAIs was substantially reduced, however, when extreme data points were removed; a logistic function explained 75% of the variation in stemwood increment across all sites. Differences in productivity among sites were not strongly related to site water balance. Taken together, these results support other work which suggests that soil nutrient availability is the dominant driver of loblolly pine productivity across its natural range. Future research should seek to better understand the mechanisms of nutrient demand, uptake and utilization efficiency in developing stands, as well as the factors controlling intraspecific tree competition.

Stand growth scenarios for Bombacopsis quinata plantations in Costa Rica

In total 60 plots of approximately 80 trees each (including missing trees) were measured, with ages between 1 and 26 years. The main objective of this study was to develop intensive management scenarios for B. quinata plantations in Costa Rica to ensure high yielding of timber wood. The scenarios were based on a fitted curve for the relationship of DBH, and total height with age. A criterion of maximum basal area (18, 20, 22 and 24 m 2 ha −1) was used to simulate different site qualities. Plantation density was modeled as a function of the crown area occupation of the standing trees. The scenarios consist of rotation periods between 23 and 30 years, final densities of 100–120 trees ha −1, mean DBH between 46 and 56 cm, and mean total heights of 30–35 m. The productivity at the end of the rotation varies between 9.6 and 11.3 m 3 ha −1 per year, yielding a total volume at the end of the rotation of 220–340 m 3 ha −1. The scenarios presented here may provide farmers and private companies with useful and realistic growth projections for B. quinata plantations in Costa Rica.

Determinação de regimes de desbaste para povoamentos de &lt;i&gt;Pinus elliottii&lt;/i&gt; E. do Planalto Ocidental no estado de Santa Catarina.

O presente trabalho teve como objetivo estudar, para povoamentos de Pinus elliottii E., o desenvolvimento de parâmetros dendrométricos em função da altura dominante e fator de área basal, expresso pela razão da área basal remanescente e a área basal máxima de uma testemunha sem desbaste. A produção máxima, dos regimes de desbaste determinados, foi obtida com uma fator de área basal de 0,65, significando que se pode desbastar um povoamento em até 35% de sua área basal, em relação a uma testemunha sem desbaste. A produção máxima obtida foi de 877 e 933 m³ com casca por hectare, para rotações de 20 e 22 anos, respectivamente, para um número inicial de 2400 árvores por hectare, no sítio médio da região de estudo, com altura dominante de 23,7 metros, aos 20 anos. Os regimes de desbaste para um fator de área basal de 0,55, com redução de até 45% da área basal, em relação a uma testemunha sem desbaste, permitiu obter produções totais com perdas de, aproximadamente, -10%, mas com ganhos significativos de incremento diamétrico.

Analytical estimation of branchwood volume in sugar maple, linked to branchiness

An analytical link is proposed between branchwood volume and branchiness. A segmented linear model with one parameter is used to describe the branch basal area density along the tree bole and integrated to find a function describing the cumulative branch basal area. It appears that the bases of insertion of the branches defining the base of the light crown correspond to the maximum branch basal area density along the bole. This function is then used together with an individual branch volume equation to find a model that estimates branchwood volume. This model is calibrated with data gathered in 15 stands dominated by sugar maple (Acer saccharum Marsh.) in southern Quebec. A comparison is made with other models of branchwood volume found in the literature.

Variation in Potential Volume Yield of Loblolly Pine Plantations

Abstract Variation in the potential volume at a given site index, which is a result of differences in the maximum basal area, was investigated using data from permanent plots in loblolly pine plantations across the southern United States. The data were stratified into three physiographic regions--Atlantic Coastal Plain, Piedmont, and Gulf Coastal Plain--and the maximum stand density index (SDImax) value (Reineke 1933) was estimated for each stand by applying Sterba's (1975) extension of the competition density rule of Kira et al. (1953). The Gulf Coastal Plain exhibited the lowest density potential and differs significantly from each of the other two regions. Between the Atlantic Coastal Plain and the Piedmont, no significant differences in the density potential exist. Significant differences mean different maximum basal areas and therefore differences in the total yield within the same site index; these differences in yield cannot be detected using the site index method only. Data from the control plots, which represent the stand development without any thinning influences, showed that the variation between the regions was mainly due to differences in the potential of supporting trees/ha. This result was confirmed by calculating the mean relative space (Hart 1928) for each region. The relationship between top height and volume/ha for the unthinned control plots showed different volume production potential under comparable conditions at a given top height among the regions. The volume development figures follow the same order by region as the SDImax values. The highest potential (volume/ha at a given top height) is represented by the Atlantic Coastal Plain, followed by the Piedmont, followed by the Gulf Coastal Plain. For. Sci. 40(1):162-176.

The Maximum Density Concept Applied to Uneven-Aged Mixed-Species Stands

Abstract In even-aged pure stands, the relationship between density and quadratic mean diameter of different stands can be described by a hyperbola, the coefficients of which depend allometrically on dominant height (Sterba's modified Competition Density Rule). From the equations describing these relationships the slope of Reineke's maximum density line can be calculated and (for a given data set) tested against the hypothesis that this slope is - 1.605. Data from 134 even- and uneven-aged mixed species stands in northern Idaho and northwestern Montana showed that this slope depended on the skewness of the dbh1.5 distribution, which in turn was correlated with structural stand characteristics like "unevenagedness" and species mixture. The parameters of the extended Competition Density Rule were simultaneously estimated by nonlinear regression under an assumption relating asymptotic dominant height and maximum basal area by habitat type. Results demonstrated that both the maximum basal area at a given dominant height are higher in even-aged pure stands (with smaller skewness of the dbh1.5 distribution) than in uneven-aged mixed stands. Furthermore, the differences in maximum stem number and maximum basal area resulting from differing skewness decrease with increasing dominant height. Large differences in maximum basal area can be shown between different habitat types and any given site index, thus demonstrating that habitat types can be used to distinguish yield levels sensu Assmann. For. Sci. 39(3):432-452.

Crown and basal area relationships of open-grown southern pines for modeling competition and growth

Data were collected on open-grown loblolly pine (Pinustaeda L.), longleaf pine (Pinuspalustris Mill.), and shortleaf pine (Pinusechinata Mill.) and analyzed to provide predictive equations of crown width and maximum potential basal area growth for crown competition and growth and yield models. The measurements were taken on 115 open-grown loblolly pine trees and 76 shortleaf pines in southeastern Arkansas. The longleaf pine data consisted of 81 open-grown trees from southern Alabama, Georgia, and Florida. A circle and an ellipse were tested as geometric models of the vertically projected crown. No significant differences between the tree shapes were found based on analyses of length and azimuth of the largest crown diameter, and the circle was chosen as an appropriate model. This indicated that only the distance between trees, not their orientation to one another, need be included in models of crown competition based on crown contact. Predictive equations of mean crown width based on diameter at breast height were fitted for each species for use in models of crown competition. A Chapman–Richards growth rate function with an intercept term was fit to periodic annual inside-bark basal area growth based on initial inside-bark basal area to provide empirical estimates of maximum basal area growth rates for growth and yield modeling of the given species. Additionally, equations to predict double bark thickness as a function of diameter at breast height were fit for each species to facilitate the use of the equations with outside-bark measurements of diameter.

Response of Eastern White Pine to Nitrogen Fertilization

Abstract Plots were established in nine eastern white pine stands; six on outwash soils and three on till soils. Nitrogen was applied to the plots at rates of 0, 50, 100, and 200 lb/ac. Four-year growth response functions for basal area/ac and merchantable cubic ft volume/ac were developed. Basal area growth was 9.2 ft²/ac greater and volume growth was 235 ft³/ac greater on the till soils compared with the outwash soils, regardless of application rate Both basal area and volume growth increased as basal area/ac increased. Maximum basal area response, 5.7 ft²/ac, and maximum volume response, 198 ft³/ac, was estimated to occur at an application rate of approximately 160 lb of nitrogen/ac, with incremental response being greater at lower application rates. Fertilization at a rate of approximately 100 lb of nitrogen/ac appears to be a cost effective practice for many white pine stands. North. J. Appl. For. 8(2):83-85.

Estimation of the maximum basal area at each growth stage

Estimation of the maximum basal area at each growth stage

Predicting Potential Stand Composition From Site Characteristics in the Shawnee Hills Forest of Illinois

An approach to predicting future stand composition using standard ecological methods and multiple regression analysis is presented. A composition index value for each of 54 undisturbed, compositionally stable, mature stands was obtained by multiplying the importance value (relative basal area) of a species by its adaptation value and summing for all species in a stand. Adaptation values ranging from 1-10 were assigned based on the position of species maximum basal area values along a stand basal area gradient. Three multiple linear regression models were developed for predicting stand CI from effective soil depth, percent stone, available soil water, slope position, aspect and distance to the opposing slope. The models, which accounted for 90-97 % of the variation, were validated using data from seven compositionally stable stands not used in model development. The models closely predicted compositional change in a disturbed stand for which 48 years of permanent plot data were available. Successional trends were examined in six additional stands disturbed 50-70 years ago. In most stands, predicted stand composition closely coincided with the presence of established understory stems. The most substantial changes were found on N slopes and stream terraces where Quercus alba and Q rubra stands are being replaced by Acer saccharum and other mesophytic hardwoods. When applied to broad ridges that were once farmed, the models predicted that under presettlement site conditions (i.e., uneroded forest soil), stands were dominated primarily by Q. alba with small amounts of Q. stellata and Q. velutina. On sites where erosion has reduced soil depth to 25 and 15 cm, it was projected that stands would be dominated by Q stellata and Q. marilandica, and by Juniperus virginiana, respectively. A biological interpretation of the site-vegetation relationships, identified by the models is based on soil water storage and the influence of topographic factors on evapotranspiration loss. INTRODUCTION The successional process has been investigated for many years, yet there is no currently acceptable method for predicting potential forest composition given specific site conditions. Succession is defined here as the systematic temporal replacement of a forest community composed of relatively shade-intolerant species by one in which more shade-tolerant species dominate to form a compositionally stable community. Usually stands of early successional species develop after moderate to severe cutting, fire, wind, disease or insect attack which removes the overstory canopy and permits more lightdemanding species to invade and dominate sites where they normally are excluded. Considerable research has concentrated on community dynamics with a view toward predicting the species mix in compositionally stable (climax) forest. Stephens and Waggoner (1970, 1980) developed transition probability values that permitted anticipation of species change in forest composition, whereas Leak (1970) predicted successional change by birth and death simulation. In both studies, predictions were based upon systematic sampling over a long period. Stout et al. (1975) constructed multispecies models that indicated trends toward certain forest species (e.g, Acer saccharum). Goff (1968), Goff and Zedler (1972), Zedler and Goff (1973) and Auclair and Goff (1974) used several size association and stratification analyses to determine species succession vectors, replacement potential and forest trends. Botkin et al. (1972a, 1972b) developed a computer-generated model JABOWA) which simulated forest composition changes using Monte Carlo techniques to decide births and deaths over any selected period; this

Estimating Potential Density from Thinning Experiments and Inventory Data

Abstract By combining and modifying the Competition Density Rule of Kira et al. (1953), Reineke's concept of stand density index (Reineke 1933), and Assmann's theory of maximum basal area, a method to estimate potential density of sites has been developed. From the data of 11 thinning experiments it has been shown that the maximum stand density index, estimated in this way, is well correlated with the gross volume yield at a given height and thinning regime. Data from an inventory show that with this method of estimating and characterizing maximum stand density it is possible to evaluate differences of gross volume yield that would never have been detected if only yield tables had been used. For. Sci. 33(4):1022-1034.