Stemwood Volume Research Articles

Spatial and temporal variation in the prevalence of growth decline in red spruce populations of the northeastern United States

An analysis of the prevalence of individual-tree growth decline, based on reconstructed annual stemwood volume increment (AVI), was implemented on three data bases that have been used in past dendrochronological analyses of red spruce (Picearubens Sarg.) decline in the northeastern United States. This analysis focused on the proportion of individual trees that exhibited a decrease in periodic mean AVI, a decrease in the linear trend of AVI, and (or) a negative AVI trend during the most recent 20-year period. Various subpopulations within the data bases were identified by site location, elevation, and aspect, and tree size, age, and competitive status, and the proportion of individual trees exhibiting growth decline was compared among these subpopulations. Also, the prevalence of growth decline after 1960 was compared with historical levels of growth decline. Differences in prevalence of growth decline were found among the three data bases and among locations within data bases. The proportion of red spruce that exhibited growth decline after 1960 exceeded historical levels of decline for populations in New York, Vermont, and New Hampshire, but not in the northern Maine population. Weak positive associations were found between prevalence of growth decline and tree size (DBH) and elevation. No consistent relationship was found between growth decline and tree age, competitive status, or stand density. Contrary to a previous report, growth decline was not more common among trees that exhibited evidence of competitive release in the 1940s than among unreleased trees.

Forest production and the organization of foliage within crowns and canopies

A non-foliated area (or ‘bare inner core’) develops in the interior of tree crowns as the size of the crown increases during stand development. We examined the relationship between mean bare core volume and both stand density and mean crown volume, and its association with the production of stemwood volume for two conifer species, Pinus contorta var. latifolia and Abies lasiocarpa. Mean bare core volume decreased with absolute stand density and increased with mean crown volume for both species. As crown size increased, so did the proportion of total crown volume occupied by the bare core. Small bare core volumes were associated with small, efficient crowns, and large bare core volumes were associated with large, less efficient crowns. Mean bare core volume was negatively related to the mean ratio of crown surface area to volume but was not correlated with an index of crown slenderness, two characteristics which are assumed to be important in the development of crop tree ideotypes. The small mean bare core volume and associated increased efficiency of stemwood production at high stand densities increased per hectare productivity for both species, thereby indicating how differing density management regimes influence stand production.

Prevalence of individual-tree growth decline in red spruce populations of the southern Appalachian Mountains

The prevalence of individual-tree growth decline was determined for red spruce (Picearubens Sarg.) populations at three locations in the southern Appalachians: Mount Rogers National Recreation Area, the Black Mountains, and Great Smoky Mountain National Park. An index of annual stemwood volume increment (AVI) was computed from dendrochronological data and a site-specific DBH–height regression equation. Individual-tree AVI time series were analyzed to identify changes in 20-year periodic mean AVI and AVI trend. The proportion of red spruce that exhibited decreasing mean AVI or negative AVI trend was determined for the most recent 20-year period, and this was compared with the estimated historical prevalence of these indications of growth decline. Also, the prevalence of growth decline was compared among subpopulations that differed with regard to various tree, stand, and site characteristics. Of 263 red spruce sampled, 25% exhibited a decrease in mean AVI during the period 1967–1986, 8% exhibited a negative AVI trend without a reduction in mean AVI, and 17% exhibited a reduction in the slope of the AVI curve. The proportion of trees that exhibited decreasing or slowed growth after 1967 was substantially greater among trees growing at 1980 m than in populations at lower elevations; no relationship was found between elevation and growth decline below 1980 m. No difference was found in prevalence of growth decline between subpopulations that differed with regard to age, DBH, competitive status, stand density, slope aspect, or site exposure. The prevalence of individual-tree growth decline for the most recent 20-year period did not exceed estimated levels for historical periods of decline in the Great Smoky Mountains population.

Determinants of Stemwood Production in Pinus contorta var. Latifolia Forests: The Influence of Site Quality and Stand Structure

(1) Leaf area index of mature stands of lodgepole pine was independent of stand density. Thus, stand density did not affect total leaf area, but strongly influenced leaf area per tree. (2) Leaf area index and site index were significantly but weakly related in the lodgepole pine stands in this study. (3) While the growth of stem volume was significantly (r2 =0 45) related to leaf area index, residual variation was associated with differences in stand structure. (4) Mean tree growth increased with mean leaf area, but at a decreasing rate; this indicates the relatively low efficiency with which leaf area on large trees produces stemwood volume. (5) Reduced leaf area efficiency of large trees in low density stands was related to increased respiration requirements resulting from greater relative amounts of nonphotosynthetic to photosynthetic tissue. This explanation for differences in leaf area efficiency is supported by the observation that the ratio of foliage to total crown biomass was inversely proportional to mean crown size.

Eleventh-Year Results of Fertilization, Herbaceous, and Woody Plant Control in a Loblolly Pine Plantation

Abstract Through 11 years, fertilization at planting significantly increased the stemwood volume (outside bark) per loblolly pine (Pinus taeda L.) on an intensively prepared moderately well-drained fine sandy loam site in northern Louisiana. Four years of herbaceous plant control significantly increased pine survival, and because herbaceous plant control increased survival, it resulted in a significant increase in total stand volume. Woody plant control no longer produced significant results by age 11. South. J. Appl. For. 14(4):173-177.

Red spruce decline on Whiteface Mountain, New York. I. Relationships with elevation, tree age, and competition

Detailed stem analysis and stand structure and history analyses are used to evaluate relationships between growth decline in populations of red spruce (Picearubens Sarg.) on Whiteface Mountain and elevation, tree age and size, and stand dynamics. The study sites are virgin, uneven-aged spruce-fir forests at 900 and 1100 m elevation. Most red spruce sampled exhibited substantial decreases in annual stem wood volume increment from 1964 to 1984, particularly large trees and trees from higher elevation. While larger trees exhibited more severe growth decline, there is no evidence of a direct causal link between tree age and decline. Inverse relationships between growth and competition indices are evident for periods prior to the onset of decline, but these relationships degrade during the period of growth decline; competition is not causally linked to decline. There is some indication that the decline-inciting stress was particularly severe for canopy-emergent and exposed red spruce, suggesting the action of an atmospheric stress.

Biomass of picea abies (L.) Karst. in midwestern bohemia

he distribution of tree biomass was investigated in 3 even‐aged Norway spruce (Picea abies L. Karst.) stands aged 57, 78 and 106 years in midwestern Bohemia. The results of sample tree analyses were used to derive prediction equations for tree biomass components using the allometric model Y=A1 x XA2 , where Y is mass, and X is the measure of tree size (diameter at breast height, height, crown length) or stem sapwood area at breast height. The distribution of needle mass according to age, and the relationship between dry matter of foliage and annual current stem wood volume increment were investigated. The total amounts of stand biomass components were calculated using the diameter and height distribution, and tree biomass prediction equations. The results were compared with data of several authors.

Productivity of New England hemlock/hardwood stands as affected by species composition and canopy structure

Canopy structure, yield, and current productivity of two even-aged stands (of ages 44 and 87 years) composed of hemlock ( Tsuga canadensis (L.) Carr.) and hardwoods (primarily Quercus rubra L. and Acer rubrum L.) were compared with that of adjacent hardwood stands of the same age, site conditions, and hardwood species composition, but which lacked hemlock. In the hemlock/hardwood mixtures, hemlock formed a dense understory beneath the hardwood overstory, while hardwood stands lacked comparably dense understories of any species. The mixed stands were found to have significantly greater yields and current production rates in total stand basal area than adjacent hardwood stands. Basal area yield and production of the hardwood component of the mixed stands were not significantly different from that of the adjacent hardwood stands, indicating that the hemlock growth was largely additive to that of the hardwood overstory. Similar patterns were observed when data were converted to stemwood volume or above-ground biomass measures, although not all differences were statistically significant. Published yield tables for hemlock indicate that basal area and biomass yield of pure hemlock stands of similar age and site conditions was also exceeded by that of the hemlock/hardwood mixtures in the present study. A review of plantation studies comparing mixed stands with adjacent pure stands of the component species indicates consistency with the results of the present study in the pattern of mixed stands with stratified canopies having greater yield than pure stands of the overstory species. There is some evidence to indicate that mixtures have greater yields than pure stands of the understory component as well, although fewer data exist for this comparison.

Leaf Area, Stemwood Growth, and Nutrition Relationships in Loblolly Pine

Abstract The relationships among loblolly pine (Pinus taeda L.) stand leaf area index (LAD, stemwood volume growth (m3/ha/yr), and growth efficiency (m3stemwood/ha/yr/LAI) were examined in three nitrogen (N) by phosphorus (P) fertilization field trials. Prior to fertilization, stockinglevels and nitrogen limitations varied for the three stands. LAI increased significantly (up to 60%) following N fertilization on the two N deficient stands. Phosphorus additions did not affect LAI. Stemwood growth was positively and linearly related to LAI across treatments and stands. Variationsin LAI across stands reflected the differences in stocking and N availability. On average, a unit of LAI produced 7.3 m3stemwood/ha/yr. Growth efficiency was not affected by fertilization on two of the three stands. A decrease in growth efficiency at a projected LAI above 3.5 resultedfrom an asymptotic relationship between stemwood growth and LAI on a stand that was fully stocked and highly responsive to N fertilization. The use of LAI as an index of stocking is proposed because LAI integrates tree size, stand density, and site resource supply. In addition, it is proposedthat the deviation of a stand's current LAI from the maximum supportable LAI based on fixed site factors (e.g., water, temperature) may provide a good measure of a stand's potential responsiveness to fertilization. For. Sci. 34(3):547-563.

Using sensitivity and uncertainty analyses to improve predictions of broad-scale forest development

The FORET model of forest development can be used to estimate influences of natural and anthropogenic disturbances on forest dynamics. Interpreting the effects of these disturbances requires an understanding of sources of error in the model; however, error analysis of a complex model is not straightforward. The method of applying sensitivity and uncertainty analyses in this paper takes advantage of the modular structure of the FORET code to examine errors that occur as a result of parameter variability or inadequate representation of the natural variability of the system. The FORET model can be broken down into factors affecting tree birth, death and growth, and the growth module is composed of an equation for optimal growth that is modified by effects of prevailing environmental conditions. Both the analytical and Monte Carlo sensitivity analyses show that optimal tree growth is most sensitive to the maximum diameter of a species (a parameter obtained from field measures). The uncertainty analysis focuses on spatial heterogeneity as a source of errors due to inadequate representation of the natural variability. Errors that occur as a result of extrapolating from a few plots to a region have greater impact on projections of above-ground stem-wood volume for those forest types which have the highest projected volume per area and the greatest land area covered. Measured and projected forest volume for the state of Vermont compare well. Improvements in the comparison depend on reducing the variability in measured volume, particularly for the maple-beech-birch forest type. These results demonstrate procedures of sensitivity and uncertainty analyses of complex simulation models that are useful for interpretation of model projections for large regions.

The Hubbard Brook Ecosystem Study: Forest Biomass and Production

A small watershed in the White Mountains of New Hampshire bearing mesophytic, cool—temperate, broadleaf—deciduous forests was studied. Acer saccharum, Betula lutea, and Fagus grandifolia are dominant, but toward higher elevations Picea rubens and Abies balsamea also occur and indicate the transition toward subalpine climate. The stands are young (following cutting in 1909—17) but contain older trees; stand composition is thought reasonably representative of the climax. For application of the Brookhaven system of forest dimension analysis, 93 sample trees of major species were cut and roots excavated. Mean dimensions of sample trees, and the constants for the system of logarithmic regressions relating volume, surface, mass, and growth to diameter at breast height and other independent variables, show decrease in tree sizes and height/diameter ratios toward higher elevations. Stand characteristics, based on application of the regressions to forest samples, show trends of decrease for the elevation belts from low to high: stem basal area 26.3, 23.7, and 22.0 m2/ha, weighted mean tree height 16.9, 16.7, and 10.8 m, weighted mean age 124, 95, and 83 yr, stem wood volume 176, 155, and 103 m3/ha, aboveground biomass (dry matter) 162, 152, and 102 t/ha, estimated volume increment 379, 365, and 223 cm3/m2/yr, aboveground net primary productivity (1956—60) 1127, 1041, and 790 g/m2/yr, and leaf area ratio 6.2, 5.7, and 5.5 m2/m2. Biomass (and, presumably, production) of root systems is 18%—21% of that aboveground. Different estimations suggest that a mean climax biomass for the watershed may be around 350 t/ha, aboveground. Net ecosystem production (i.e., addition to the pool of woody biomass in the community) is estimated as 350 g/m2/yr aboveground and 85 belowground for 1956—60, 238 and 52 g/m2/yr for 1961—65. Analysis of stem wood volume increments reveals an abrupt and striking (18%) decrease in volume growth and productivity from 1956—60 to 1961—65. The net primary productivity of the former period, with a weighted mean for the watershed of 1110 g/m2/yr above and below the ground, is thought more nearly normal for the forest. Both drought and effects of increasing air pollution (notably increasing acidity of rainfall) may be responsible for the recent decrease in productivity.

Factors Influencing the Weight of Black Spruce and Balsam Fir Stems

The factors influencing green weight of black spruce and balsam fir stems were investigated. It was found that for black spruce stems, moisture content and sapwood content could be predicted by the age and height of the tree. For balsam fir, however, it was difficult to establish meaningful correlations. Stem bark volume was well correlated for both species with diameter at breast height. Regression equations for stem green density with different combinations of independent variables estimated at breast height were developed; it was found that breast height specific gravity and moisture content were the most important variables in predicting stem green density. Stem wood volume was very well correlated with stem weight immediately after felling.