bluuebunny/crossref_metadata_2025 huggingface dataset:
Alterations of growth and shikimic acid levels by sublethal glyphosate applications on pin cherry and trembling aspen
Authors: Stasiak M. A. , Hofstra G. , Payne N. J. , Prasad R. , Fletcher R. A.
Published: July 2007

Field experiments were conducted to evaluate the effect of low doses of glyphosate (0.04–0.5 kg/ha) on pin cherry (Prunuspensylvanica L.f.) and trembling aspen (Populustremuloides Michx.) trees in conifer plantations. Applications were repeated twice over a 2-year period, with treatments applied in late July and growth assessments made 1 and 2 years later. Growth and vigour of these species, measured as percent mortality, visual injury, and leaf and stem lengths, continued to be affected 2 years after treatment even with the lowest rate of glyphosate. Shikimic acid levels were substantially increased within 2 days after herbicide application and could be used to assess glyphosate damage in the field before visual symptoms become apparent.
Natural selection for ozone tolerance in Populustremuloides: an evaluation of nationwide trends
Authors: Berrang P. , Karnosky D. F. , Bennett J. P.
Published: July 2007

Relative ozone sensitivity was evaluated among populations of Populustremuloides Michx. from 15 locations, mostly in national parks, that spanned the United States. Seven to 15 clones were selected from each population, greenhouse grown, fumigated with 150 ppb ozone for 6 h, and evaluated for visible injury. Differences among populations were statistically significant, with the most tolerant populations being obtained from the West Coast, the northeast, and the industrialized portions of the Great Lakes. Populations sampled from areas that failed to achieve the National Ambient Air Quality Standard for ozone had significantly less injury than populations from areas that achieved this standard. There was a significant negative correlation between the amount of injury and maximum daily ozone averages at localities where the populations were collected. There were also significant correlations between the amount of injury and two climatic variables, annual precipitation and minimum temperature. Differences among clones within populations were highly significant, and clonal variance was negatively correlated with maximum daily ozone average for the area where the populations were collected. These findings support our hypothesis that ambient levels of ozone may be eliminating ozone-sensitive clones from natural populations of this species, but indicate that climatic variables play a role as well.
Testing a mechanistic carbon balance model against observed tree growth
Authors: Korol R. L. , Running S. W. , Milner K. S. , Hunt Jr. E. R.
Published: July 2007

A forest ecosystem model, FOREST-BGC (Biogeochemical cycles), was used to simulate the 5-year growth increments of 177 interior Douglas-fir (Pseudotsugamenziesii var. glauca (Beissn.) Franco) trees growing in uneven-aged stands. It was neither practical nor possible to develop a complete carbon balance for each tree on first principles, owing to both the cost and difficulty in obtaining carbon balance data for individual trees. Therefore, to calibrate the model carbon allocation parameters, maintenance respiration coefficients of the stems and roots, and the stomatal and mesophyll conductances, were used to maximize the fit between predicted and measured growth for one young, vigorous open-grown tree. The remaining 176 trees were simulated without additional calibration. These parameters were believed to be species specific and were found to be appropriate for a range of sites, tree sizes, and stand densities. A competition factor was added to modify the microclimate of each tree by reducing two driving variables (precipitation and radiation) proportionally to changes in their canopy interception due to the leaf area of the neighboring trees. This method enabled FOREST-BGC to reliably simulate actual growth in uneven-aged stands (R2 = 0.95). Although the model parameters remained constant, the simulated carbon balances were dynamic, with the total maintenance respiration increasing with an increase in tree size and (or) competitive stress.
Simple, flexible, trigonometric taper equations
Authors: Thomas Charles E. , Parresol Bernard R.
Published: July 2007

There have been numerous approaches to modeling stem form in recent decades. The majority have concentrated on the simpler coniferous bole form and have become increasingly complex mathematical expressions. Use of trigonometric equations provides a simple expression of taper that is flexible enough to fit both coniferous and hardwood bole forms. As an illustration, we applied trigonometric taper equations to examples from thinned and unthinned slash pine (PinuselliottiiEngelm. var. elliottii), willow oak (Quercusphellos L.), and sweet gum (Liquidambarstyraciflua L.). Comparison of new trigonometric models with a segmented-polynomial approach developed in 1976 indicates that equations based on trigonometric functions perform equally well and have real advantages in terms of parsimony.
Sugar maple seed production and nitrogen in litterfall
Authors: Pregitzer Kurt S. , Burton Andrew J.
Published: July 2007

The influence of seed production on litterfall was studied for 2 years at five northern hardwood sites located across the Great Lakes region. Flower and seed litter contributed > 1 Mg•ha−1 dry matter in several instances, accounting for as much as 34% of total litter deposition. Significant differences between years were measured for both foliar and reproductive litter inputs at the sites. Production of reproductive litter and foliar litter were negatively correlated at the stand level (r = 0.99, P < 0.001), suggesting a direct trade-off between leaf biomass and reproductive biomass. Bumper seed crops had a large impact on total aboveground N litterfall. Reproductive N flux was as high as 41 kg•ha−1•year−1. Averaged across both years and all sites, reproductive litter accounted for 36% of total N in aboveground litterfall (range = 14–61%). When compared with the amount of N returned in foliage, reproductive litter averaged 67% (range = 18–174%). Nitrogen uptake and return in litterfall can be underestimated, especially during periods of heavy seed production, if flowers and seeds are ignored. Periodic life-history events like seed production can play an important role in ecosystem-level processes like N cycling.
The use of a 32P root bioassay to indicate the phosphorus status of forest trees. 2. Spatial variation
Authors: McDonald M. A. , Malcolm D. C. , Harrison A. F.
Published: July 2007

A bioassay based on the rate of uptake of 32P by forest tree roots was developed as a predictor of phosphorus fertiliser requirements for mature forest stands. Seasonal variation is known to be significant, and this paper reports on a study that examines the implications of spatial variation on the interpretation of bioassay results. Sampling stands growing on spaced-furrow ploughing indicated that positional or microsite differences interact with season of sampling. The ridges created by this kind of site preparation appeared to be nutritionally impoverished with respect to the flats and furrows, and this effect was most marked in summer. A greenhouse split-root experiment with conifer seedlings indicated that within-plant variability is of less consequence than the spatial variability of the forest floor. Sampling positions are suggested for standardizing sampling procedure.
Incidence of anthracnose and twig canker in two Mississippi sycamore plantations
Authors: Ammon Vernon , Vann Stephen , McCracken Francis
Published: July 2007

One lowland and one upland sycamore (Platanusoccidentalis L.) plantation containing trees from eight sycamore seed sources were sampled for the incidence (occurrence and abundance) of causal organisms of sycamore anthracnose and sycamore twig canker during four growing seasons. Considerable variation in incidence of sycamore anthracnose, caused by Apiognomoniaveneta (Sacc. & Speg.) Hohn., was detected among seed sources at both locations. There were no significant differences among seed sources in the incidence of sycamore twig canker, caused by Diaporthearctii (Lasch) Nitschke, at either plantation. Incidence of both pathogens was higher in the lowland plantation than in the upland plantation.
Effects of nitrogen fertilization on young jack pine (Pinus banksiana) and on its suitability as a host for jack pine budworm (Choristoneura pinus pinus) (Lepidoptera: Tortricidae)
Authors: McCullough Deborah G. , Kulman Herbert M.
Published: July 2007

Effects of nitrogen fertilization on growth, foliar nitrogen concentration, and monoterpenes were determined on 7- to 11-year-old jack pine (Pinusbanksiana Lamb.) on two sites in northwestern Wisconsin. One site established after wildfire; the other after clear-cutting. Jack pine budworm (Choristoneurapinuspinus Free.) larvae were caged on fertilized and unfertilized trees on each site. Relations among foliar nitrogen, monoterpenes, larval survival, and adult budworm weight were examined. Foliar nitrogen concentration, needle weight, shoot and diameter growth, and monoterpene production were lower on wildfire site trees than on clear-cut site trees, and were significantly increased on both sites by fertilization. Fertilization increased production of staminate cones on the wildfire site. Height growth differed between sites but was unaffected by fertilization. Contrary to expectations based on the resource availability theory, foliar nitrogen and monoterpene levels were positively related. Survival of jack pine budworm larvae was greater on clear-cut than on wildfire site trees, but was not significantly affected by fertilization. Larvae on low-nitrogen trees on the wildfire site clipped more foliage than those on the clear-cut site, suggesting compensatory feeding. Adult female weight was higher for larvae on wildfire than clear-cut site trees. Two monoterpene compounds and site-related differences were the best predictors of adult female weight based on regression.
An image analysis system for determining densitometric and ring-width time series
Authors: Thetford Roy D. , D'Arrigo Rosanne D. , Jacoby Gordon C.
Published: July 2007

A new interactive image analysis method for determining tree-ring density and width data for dendrochronological studies is described. The method employs the Prism Image Analysis System (from Dapple Systems, Inc.) for Apple Macintosh microcomputers and uses additional FORTRAN software (program MACDRUID) developed for tree-ring applications. The principal advantages of this system are (i) interactive image analysis, which substitutes computer software for the complex scanning densitometer operations used in previous systems and (ii) high resolution, which is necessary for processing the narrow-ringed, stressed trees often sampled in dendroclimatology. Other advantages are real-time editing, ease of adjustment for angle variation of ring boundaries, and the ability to append individual frame data into homogeneous time series. Comparisons of ring-width and density data determined by this image analysis system with similar measurements derived from other methods indicate that the image analysis data are of equal precision and quality for use in dendrochronological studies. In addition to applications in the fields of dendrochronology and wood science, this image analysis method is applicable for analyzing variations in cyclical banding in other types of geological samples, such as sediment laminae (e.g., varves) and corals.
Spatial variability and collector requirements for sampling throughfall volume and chemistry under a mixed-hardwood canopy
Authors: Puckett Larry J.
Published: July 2007

Throughfall was intensively sampled during five storms in August, September, and November 1988, July 1989, and January 1990. For each storm, 50 collector bottles with funnels were positioned at random on a 0.1-ha plot under a mixed-hardwood forest canopy in northern Virginia. Concentrations and net inputs of H+, NH4+, Na+, K+, Ca2+, Mg2+, Mn2+, Cl−, NO3−, and SO42− and throughfall volume were evaluated for spatial variability both within and among storms and were used to estimate the number of collectors necessary for throughfall collection. Ion concentrations were generally less variable within storms compared with net ion input data. Concentrations and net inputs of some ions were consistently less variable than others; for example, Ca2+, NO3−, and SO42− were less variable than NH4+ and K+. These patterns of variability were consistent in comparisons both within and among storms. The relatively low variability of NO3− and SO42− is probably due to dry deposition of these ions as anthropogenic pollutants, while the low variability of Ca2+ is the result of deposition in windblown soil particles. The high variability of NH4+ and K+ is probably the result of biological processes. Ammonium is strongly retained by the canopy, and K+ is readily leached from it. Retention by, and leaching from, the canopy can induce spatial variability as a result of spatial heterogeneity in the biota. Throughfall volume also displayed low variability within and among events, requiring an average of 11 collectors to estimate the mean within 10% at the 95% confidence level.
Annual rates and elemental concentrations of litter fall in thinned and fertilized Douglas-fir
Authors: Trofymow J. A. , Barclay H. J. , McCullough K. M.
Published: July 2007

Overstory litter fall, primarily needles, was collected for 15 years within control and treated plots in a stand of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) located near Shawnigan Lake, British Columbia. Treated plots were thinned or fertilized, or both; thinned plots had two-thirds of their basal area removed, fertilized plots were treated with 448 kg N•ha−1 of either urea or ammonium nitrate, and half the fertilized plots were refertifized at the same rate 9 years later. The annual rate of litter fall in control plots averaged 1890 kg•ha−1. In control plots significant yearly variations were observed in litter-fall mass and concentrations of K, Mg, and Ca but not N or P. Thinning decreased rates of litter fall by 80%, but rates returned to control-plot levels after 13–15 years in unfertilized plots and after 8–10 years in fertilized plots. Fertilization without thinning depressed litter fall in the year of treatment but increased the rate by 20–80% in subsequent years. Litter-fall N concentrations increased by 40–80% the year of fertilization and then began declining 3–6 years later. Nitrogen fertilization reduced litter-fall P, K, and Mg concentrations for 8, 4, and 1 year(s), respectively, following fertilization. The effects were greater in ammonium nitrate plots than in urea plots. Rates of litter fall correlated poorly with stand density but well with basal area and stemwood increment. Correlations with the latter two variables varied with time and treatment.
Leaf temperature effects on net photosynthesis, dark respiration, and photorespiration of seedlings of black locust families with contrasting growth rates
Authors: Mebrahtu Tesfai , Hanover James W. , Layne Desmond R. , Flore James A.
Published: July 2007

Rates of net photosynthesis, dark respiration, and photorespiration of six half-sib families of black locust (Robiniapseudoacacia L.) were measured at leaf temperatures ranging from 10 to 40 °C. Rates of dark respiration increased with increasing leaf temperature in all families and reached as high as 67% of gross photosynthesis at 40 °C in one family. Dark respiration of foliage accounted for 12.5 to 59% of the reduction in net photosynthesis at temperatures higher than those optimum for net photosynthesis. Rates of photorespiration peaked at 10 to 20 °C, exhibiting the same pattern as net photosynthesis, and did not contribute to the decline in net photosynthesis at high temperatures. The families with high rates of net photosynthesis also had high rates of photorespiration. Rates of dark respiration were significantly different among the families, and the slow-growing families had the highest rates of dark respiration. A significant interaction between half-sib families and leaf temperatures was noted for dark respiration. The data indicated the possibility of improving the growth of black locust by selection and breeding for large leaf area, high rates of net photosynthesis and low rates of dark respiration.
A critical look at multiple criteria decision making techniques with reference to forestry applications
Authors: Howard Andrew F.
Published: July 2007

Solution techniques for multiple criteria decision making are procedures and mathematical algorithms for aiding decision making when multiple criteria are considered. Multiple criteria decision making methods are well suited for ill-structured problems that encompass many of the more vexing problems facing forestry today. A brief review of multiple criteria decision making is presented to serve as background to the present study and to introduce interested readers to the vast multiple criteria decision making literature, including applications in forestry. A comparative study was made to explore some specific issues that have received limited attention in previous multiple criteria decision making studies, including scale transformations, criterion weighting, ranking algorithms, choice of criteria, and specification of alternatives. Methods were compared based on the ranking and degree of discrimination among alternatives for a case study previously published. Recommendations are made regarding the application of multiple criteria decision making techniques to forestry problems.
Comparison of wet chemistry and near infrared reflectance measurements of carbon-fraction chemistry and nitrogen concentration of forest foliage
Authors: McLellan Toni M. , Martin Mary E. , Aber John D. , Melillo Jerry M. , Nadelhoffer Knute J. , Dewey Bradley
Published: July 2007

An interlaboratory comparison was designed to test the precision and relative accuracy of a method using near infrared spectroscopy for the determination of nitrogen, lignin, and cellulose concentrations in green and senescent foliage. A total of five laboratories were involved. Two methods of nitrogen analysis (Kjeldahl and CHN analysis) and two methods of carbon-fraction (lignin and cellulose) analysis were used. Equations for converting near infrared reflectance spectra into estimates of nitrogen and carbon-fraction concentrations are presented, along with estimates of relative bias between laboratories and methods. Analytical errors (variation among repeated measurements of the same sample) associated with each of the different methods are also presented. Results show that the near infrared reflectance method gives values that lie within the range of values generated by wet chemistry methods and so introduces no additional bias. Analytical errors are one-third to one-fifth those of wet chemistry methods for nitrogen concentration and one-fifth to one-eighth those of wet chemistry methods for lignin and cellulose concentration.
Carbohydrate dynamics in mature Pinuselliottii var. elliottii trees
Authors: Gholz Henry L. , Cropper Jr. Wendell P.
Published: July 2007

Starch is the main carbohydrate storage form in conifers and is derived from the translocation of photosynthate (soluble sugars) in the phloem. We examined seasonal patterns in concentrations of both carbohydrate forms in the needles, twigs and branches, stems, and coarse and fine roots of mature Pinuselliottii Engelm. var. elliottii trees in a north Florida plantation. Starch showed marked and similar seasonality in all the tissues, with maxima in the late winter near the time of the inception of new growth in the spring. Sugars showed little seasonality, except in the fine roots. Repeated fertilization had little effect on either sugar or starch concentrations in all tissues. Using published biomass data from these same stands, we estimated that coarse roots store more than half of the starch in these stands over the year, with foliage and fine roots storing less than 5%.
Hurricane damage to old-growth forest in Congaree Swamp National Monument, South Carolina, U.S.A.
Authors: Putz Francis E. , Sharitz Rebecca R.
Published: July 2007

Hurricane Hugo caused much damage to the old-growth forests of the Congaree Swamp National Monument, but most of the damage to trees >20 cm dbh consisted of crown breakage and defoliation. Serious damage (>25% of crown lost, snapped trunk, or uprooted) was more common in mixed bottomland forest (49% of trees seriously damaged) than in adjacent sloughs dominated by Taxodiumdistichum (L.) L.C. Rich, and Nyssaaquatica L. (19% of trees seriously damaged). Of the trees >20 cm dbh, about 12% were uprooted in the bottomland forest, whereas only 2% were uprooted in sloughs. The storm reduced diversity in sloughs because most trees of species characteristic of better drained sites, and especially those rooted on nurse logs and other unstable elevated microsites, were uprooted. Dynamics of the entire forest were greatly influenced by the capacity of most tree species to recover vegetatively after suffering even severe crown and stem damage. Trees with resprouted crowns, however, were particularly likely to be broken, presumably owing to the presence of stem rots and architecturally unsound branching patterns.
Genetic variation of wood density components in young coastal Douglas-fir: implications for tree breeding
Authors: Vargas-Hernandez Jesus , Adams W. T.
Published: July 2007

The genetic control of wood density components (earlywood density, latewood density, and latewood proportion) and their relationships with overall density in coastal Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco var. menziesii) were examined to assess the usefulness of this information in breeding for wood density. The genetic relationships of wood density with intraring density variation and bole volume growth were also investigated. Increment cores were taken at breast height from 15-year-old trees of 60 open-pollinated families. Averages across each core for overall wood density, its components, and intraring density variation were determined by using X-ray densitometry. Bole volume at age 15 for the same trees was derived from tree height and diameter at breast height measurements. Although wood density components varied significantly among families and were under moderate genetic control (individual-tree heritability (hi2) > 0.24), none had a higher heritability than overall density (hi2 = 0.59). Density components had strong genetic correlations with overall density (r ≥ 0.74) but were also strongly related among themselves (0.57 ≤ r ≤ 0.92). Thus, density components have limited value in improving the efficiency of selection for overall density. Overall density was positively correlated with intraring density variation (r = 0.72) and negatively correlated with bole volume (r = −0.52). Comparison of several selection indices incorporating wood density and one or more growth traits, however, showed that it is possible to obtain substantial gains in bole volume without loss in (or even with a modest increase in) wood density. By restricting the response in wood density, the change in intraring density variation can also be limited.
Influence of relative humidity and temperature on storage of Alnuscordata pollen
Authors: Falleri Elisabetta
Published: July 2007

The influence of relative humidity and temperature on germination of Italian alder (Alnuscordata Loisel.) pollen was studied for storage periods of up to 180 and 360 days, respectively. Three different levels of relative humidity were tested (75, 35, and 0%) while constantly maintaining the temperature at 2 °C. The storage temperatures studied were −80, −20 and 2 °C at a constant relative humidity of 0% to avoid ice formation. The results showed that the storage conditions that best preserve pollen viability were temperatures below 0 °C and relative humidity at 0%.
Fire history in the southern boreal forest of northwestern Quebec
Authors: Dansereau Pierre-René , Bergeron Yves
Published: July 2007

Age determination of post-fire forests and the analysis of fire scars on surviving trees have allowed for the historical reconstruction and mapping of fires in a forest area of 11 715 ha in northwestern Quebec, south of Lake Abitibi. Most of the study area was burnt by two large fires (>1000 ha) in 1760 and 1923. All the other fires recorded (1797, 1823, 1870, 1907, 1919) were smaller in extent and occurred in a restricted part (1984 ha) of the study area, characterized by the fragmentation of the forest landscape by water bodies. The compilation of data concerning area burnt per type of surficial material confirms that the physical environment exerts a stronger control on the delimitation of these smaller fires. The data do not allow for the estimation of the fire cycle owing to the small size of the study area and possible temporal changes during the observation period. However, methodological observations are formulated for future studies covering a larger area in the bioclimatic region.
Pretreating dogwood seedlings with simulated acidic precipitation increases dogwood anthracnose symptoms in greenhouse–laboratory trials
Authors: Anderson Robert L. , Berrang Paul , Knighten John , Lawton K. Ann , Britton Kerry O.
Published: July 2007

One-year-old Cornusflorida L. seedlings were randomly assigned to four treatments of simulated rain (pH 2.5, 3.5, 4.5, and 5.5) in two greenhouse–laboratory studies in 1989 and 1990. After 10 applications over a 42-day period, the seedlings were moved to a temperature-controlled laboratory, placed in plastic bags, humidified, and sprayed with a spore suspension of five Disculadestructiva isolates. About 30 days later, the seedlings were examined for percentage of leaves exhibiting anthracnose symptoms and disease severity on affected leaves. Both trials showed that as the acidity of the simulated rain increased, the incidence and severity of anthracnose leaf symptoms increased. The 1989 study included a soil lime treatment that showed the same trend but the overall occurrence and severity of symptoms was higher.
Growth responses of ponderosa pine to long-term exposure to ozone, wet and dry acidic deposition, and drought
Authors: Temple Patrick J. , Riechers George H. , Miller Paul R. , Lennox Robert W.
Published: July 2007

A 3-year field study of the cumulative effects of ozone (O3), wet and dry acidic deposition, and soil water availability was conducted on ponderosa pine (Pinusponderosa Laws.) in the Sierra Nevada of California from 1988 to 1990. Thirty-six 2-year-old potted seedlings were placed in each of 30 chambers and exposed from May through October to three levels of O3 (charcoal-filtered (CF), nonfiltered (NF), and NF plus 1.5 times ambient O3 (NF150)); three levels of acidity in simulated rain (pH 3.5, 4.4, 5.3); two levels of dry deposition (60 or 90% filtration), and two levels of soil water availability (well watered (WW) or drought stressed (DS)). An additional six plots served as ambient air (AA) controls. One-third (432) of the trees were harvested at the end of each exposure season. Low soil water availability was the only stress factor to significantly affect growth following the first exposure season. After the second season, O3 significantly reduced foliar biomass in WW–NF150 trees, but DS seedlings did not respond to O3. After 3 years of exposure, WW–NF150 trees averaged 70% loss of 1988 needles and 48% loss of 1989 foliage. Ozone-injured seedlings compensated for these losses by increased growth of current-year needles and stems and also increased growth of fine feeder roots. Radial stem growth and coarse-root growth were significantly reduced in O3-injured trees. DS trees in NF150 chambers averaged half the needle loss of WW trees and showed no reduction in radial growth in response to O3. Rain pH and dry deposition had no direct effects on growth of ponderosa pine. These cumulative responses to interacting stresses indicate the importance of multifactorial, long-term studies to evaluate forest tree responses to atmospheric deposition.
Equilibrium analysis of carbon pools and fluxes of forest biomes in the former Soviet Union
Authors: Kolchugina Tatyana P. , Vinson Ted S.
Published: July 2007

Natural processes in ocean and terrestrial ecosystems together with human activities have caused a measurable increase in the atmospheric concentration of CO2. It is predicted that an increase in the concentration of CO2 will cause the Earth's temperatures to rise and will accelerate rates of plant respiration and the decay of organic matter, disrupting the equilibrium of the terrestrial carbon cycle. Forests are an important component of the biosphere, and sequestration of carbon in boreal forests may represent one of the few realistic alternatives to ameliorate changes in atmospheric chemistry. The former Soviet Union has the greatest expanse of boreal forests in the world; however, the role of Soviet forests in the terrestrial carbon cycle is not fully understood because the carbon budget of the Soviet forest sector has not been established. In recognition of the need to determine the role of Soviet forests in the global carbon cycle, the carbon budget of forest biomes in the former Soviet Union was assessed based on an equilibrium analysis of carbon cycle pools and fluxes. Net primary productivity was used to identify the rate of carbon turnover in the forest biomes. Net primary productivity was estimated at 4360 Mt of carbon, the vegetation carbon pool was estimated at 110 255 Mt, the litter carbon pool was estimated at 17 525 Mt, and the soil carbon pool was estimated at 319 100 Mt. Net primary productivity of Soviet forest biomes exceeded industrial CO2 emissions in the former Soviet Union by a factor of four and represented approximately 7% of the global terrestrial carbon turnover. Carbon stores in the phytomass and soils of forest biomes of the former Soviet Union represented 16% of the carbon concentrated in the biomass and soils of the world's terrestrial ecosystems. All carbon pools of Soviet forest biomes represented approximately one-seventh of the world's terrestrial carbon pool.
Spatial patterns of giant sequoia (Sequoiadendrongiganteum) in two sequoia groves in Sequoia National Park, California
Authors: Stohlgren Thomas J.
Published: July 2007

Although Muir Grove and Castle Creek Grove are similar in area, elevation, and number of giant sequoias, various spatial pattern analysis techniques showed that they had dissimilar spatial patterns for similar-sized trees. Two-dimensional and transect two-term local quadrat variance techniques detected general trends in the spatial patterns of different-sized trees, detected multiple-scale patterns within individual size classes, and provided information on the scale and intensity of patches of individual size classes of trees in Muir and Castle Creek groves. In Muir Grove, midsized sequoias (1.5 to 2.4 m DBH classes) had major pattern scales 350–450 m in diameter, whereas the same-sized trees in Castle Creek Grove had pattern scales >1000 m in diameter. Many size classes of trees had minor patches superimposed on larger scale patterns in both groves. There may be different recruitment patterns in core (i.e., central) areas compared with peripheral areas of sequoia groves; core areas of both groves had more small live sequoias and dead sequoias than peripheral areas of the groves. Higher densities of sequoias and, perhaps, more rapid turnover of individuals in core areas may indicate (i) differences in disturbance histories and favorability of microsites in the core and peripheral areas of groves; (ii) different responses to disturbance due to shifts in the species composition of the stand and thus, the relative influences of intra- to inter-specific competition; or (iii) slower growth or lower survivorship rates in marginal habitat (i.e., peripheral areas).
Climate stress as a precursor to forest decline: paper birch in northern Michigan, 1985–1990
Authors: Jones Elizabeth A. , Reed David D. , Mroz Glenn D. , Liechty Hal O. , Cattelino Peter J.
Published: July 2007

Widespread paper birch (Betulapapyrifera Marsh.) mortality associated with the activity of the bronze birch borer (Agrilusanxius Gory) was observed across northern Michigan in 1991. This mortality occurred at two study sites on which paper birch growth has been intensively monitored since 1985. Recent warmer than normal growing seasons and lower than normal moisture availability are statistically associated with a reduction in annual diameter growth. On one study site 62% of the paper birch study trees were dead and 13% were visibly declining; on the other study site, although no trees were dead, 25% of the paper birch study trees were visibly declining. Growth reductions since 1985 suggest that the species was under climatic stress, making it more vulnerable to pest–pathogen activity. The evidence of the role of climatic conditions acting as a precursor to decline and mortality on these sites is of serious concern given recent projections of warmer temperatures and lower precipitation for this region by several global-climate models.
Effects of different nitrogen sources on the growth of Scots pine seedlings and the ultrastructure and development of their mycorrhizae
Authors: Holopainen Toini , Heinonen-Tanski Helvi
Published: July 2007

Scots pine (Pinussylvestris L.) seedlings were grown in a natural forest humus and exposed to three different N sources, NaNO3, ammonium acetate, and urea formaldehyde, each at four levels corresponding to 0, 50, 150, and 300 kg N/ha. Application of all levels of the three N sources caused increased shoot growth, but response was especially prominent in the nitrate treatments. At the higher concentrations of ammonium N and urea formaldehyde, a decline in root growth was observed together with a decreased root/shoot ratio with increasing levels of all the N sources. The numbers of mycorrhizal rootlets decreased with increasing concentration of nitrate, but the ammonium N and urea formaldehyde treatments did not significantly affect the total number of mycorrhizae counted against root length. Ultrastructural observations revealed a developing cellular injury pattern in the fungal tissues of Cenococcumgeophilum and unidentified brown dichotomous mycorrhizae of seedlings exposed to all N sources and levels. Changes were first detected in the sheath tissue and were characterized by the formation of dark accumulations in fungal vacuoles, decrease in numbers of cytoplasmic storage bodies, swelling of mitochondria, and dark staining and disintegration of the cytoplasm. Increased severity of the changes was correlated with increasing N application level, being most severe in the ammonium acetate treatment. These observations suggest that high N levels originating from industrial fallout and N fertilization could be harmful to Scots pine mycorrhizae.
Harvest scheduling with spatial constraints: a simulated annealing approach
Authors: Lockwood Carey , Moore Tom
Published: July 2007

Simulated annealing is a stochastic approach to solving large combinatorial problems. This approach was used to model a harvest scheduling problem having block size constraints (no limit, 100–200, and 200–400 ha), a 20-year adjacency delay, and objectives to meet harvest volume targets on the minimum area possible. Spatially explicit harvest schedules complying with the constraints were successfully generated on test data sets of 6148 and 27 548 forest stands.
Stand response to western spruce budworm and Douglas-fir bark beetle outbreaks, Colorado Front Range
Authors: Hadley Keith S. , Veblen Thomas T.
Published: July 2007

The montane forests (i.e., below ca. 2900 m) of the Colorado Front Range have experienced repeated outbreaks of western spruce budworm (Choristoneuraoccidentalis Free.) and Douglas-fir bark beetle (Dendroctonuspseudotsugae Hopk.), both of which locally attack Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco). In this study we examine the effects of historically documented outbreaks of these insects on succession, stand structure, and radial growth of host and nonhost species in Rocky Mountain National Park. The most recent budworm (1974–1985) and bark beetle (1984–present) outbreaks resulted in the most severe and widespread disturbance of these forests since the late 1800s. Stand response to these outbreaks is primarily a function of stand structure and age characteristics of Douglas-fir prior to an outbreak. Young, vigorous postfire stands show minimal budworm defoliation, and in these stands only remnant trees from the prefire generation appear susceptible to beetle-caused mortality. Dense stands exhibit higher budworm-induced mortality, which hastens the natural thinning process and shifts dominance towards the nonhost species. The stands most severely disturbed by the combined insect agents are multistoried stands with high host densities and a wide range of stem sizes. The stand response to these disturbances include the growth release of shade-intolerant, seral species, and in some cases, a higher survivorship among midsized individuals of the host Douglas-fir. The net result of the combined insect outbreaks is the temporary slowing of the successional trend towards a steady-state Douglas-fir forest. Fire suppression, by increasing the density of suppressed Douglas-fir, has previously been shown to favor increased outbreak severity of western spruce budworm in the northern Rockies. However, in the Front Range, recent increases in outbreak severity and their synchroneity may also be the result of large areas of forest, burned during the late 19th century during European settlement, simultaneously entering structural stages susceptible to insect outbreak.
Relationships between litter quality and nitrogen availability in Rocky Mountain forests
Authors: Stump Laura M. , Binkley Dan
Published: July 2007

We assessed the relationships between net nitrogen mineralization, litter quality, and litter decomposition rates in 30 Colorado forests to test three hypotheses of the LINKAGES forest ecosystem model: (i) nitrogen release from litter decay in the forest floor correlates with total (forest floor plus mineral soil) net nitrogen mineralization; (ii) net nitrogen mineralization can be predicted from litter chemistry; and (iii) lignin:nitrogen ratio is the litter quality parameter most closely correlated with decomposition rates. Net nitrogen mineralization was measured for 1 year in 10 stands each of lodgepole pine (Pinuscontorta var. latifolia Engelm.), aspen (Populustremuloides Michx.), and Engelmann spruce–subalpine fir (Piceaengelmannii Parry and Abieslasiocarpa (Hook.) Nutt.), using a sequence of on-site incubations in closed-top tubes. We analyzed foliage litter and fine-root samples for initial concentrations of nitrogen, lignin, carbon, and cellulose, and determined litter mass remaining after 2-, 4-, and 6 months of laboratory decomposition. Net nitrogen mineralization in the forest floor correlated highly with total net nitrogen mineralization both within and across species. Net nitrogen mineralization also correlated significantly with litter quality across species, as did litter mass remaining after each decay period. Initial lignin:nitrogen ratio showed as strong a relationship with net nitrogen mineralization and litter decay rates as any of the litter quality variables assessed. The three tested hypotheses were thus broadly supported in these forest ecosystems.
An index of site productivity for uneven-aged or mixed-species stands
Authors: Huang Shongming , Titus Stephen J.
Published: July 2007

A site productivity measure based on the relationship between total tree height and diameter at breast height of dominant and codominant trees was presented for four major tree species (white spruce (Piceaglauca (Moench) Voss), lodgepole pine (Pinuscontorta Dougl.), trembling aspen (Populustremuloides Michx.), and black spruce (Piceamariana (Mill.) B.S.P.)) growing in boreal mixed-species stands in Alberta. The measure is based on a three-parameter modified Weibull function fitted to growth data from permanent sample plots using the difference-equation method; R2-values ranged from 0.90 to 0.97. The measure has many logical properties similar to those of the site-index approach and produces curves that are polymorphic and reference-diameter invariant. It can be used as a simple and quick method of quantifying site productivity for uneven-aged and (or) mixed-species stands.
Temperature increase accelerates nitrate release from high-elevation red spruce soils
Authors: Joslin J.D. , Wolfe M.H.
Published: July 2007

One possible consequence of predicted increases in global temperature is an increase in soil organic matter decomposition rates and (or) nitrification rates. In nitrogen-saturated ecosystems, such a change could lead to an increase in nitrate production, since much of the ammonium released from decomposition of organic matter would be converted to nitrate rather than taken up by plants or microorganisms. In a high-elevation red spruce (Picearubens Sarg.) stand, soil at 15 cm below the surface of the sunny and shaded sides of a recent clearing were found to exhibit a significant temperature differential (Δ = 1.2 °C, p < 0.01). Soil solutions collected at 15 cm from the warmer, sunny side over an 18-month period had higher (p < 0.01) mean concentrations of nitrate (71% greater), Mg (58% greater), and Al (24% greater) than those from the shaded side. Fluxes of nitrate and Mg were 30–33% higher on the sunny side of the clearing (p = 0.10, p < 0.01, respectively). If global climate changes result in accelerated releases of nitrate that are widespread in high-elevation spruce–fir forests, elevated Al levels and (or) base cation leaching losses may result, with possible negative consequences for forest health.
Biomass and production of southern Appalachian cove forests reexamined
Authors: Busing R.T. , Clebsch E.E.C. , White P.S.
Published: July 2007

Aboveground biomass and aboveground net primary production (ANPP) were determined for leaf, branch, and bole compartments of cove forests in the Great Smoky Mountains, Tennessee. The sample plots included young stands (42-63 years following agricultural abandonment) and old stands with no history of logging or catastrophic fire. Tree species, diameter at breast height (DBH), and 10-year radial growth increment data were collected on plots of 0.4–1.0 ha. Biomass was estimated with species-specific allometric equations for the Great Smoky Mountains and eastern Tennessee. ANPP was estimated using diameter growth measurements to determine biomass accumulation over the preceding 10-year interval. Biomass estimates for the predominantly deciduous old-growth stands ranged from 326 to 394 Mg•ha−1 on plots ≥ 0.4 ha. These were consistently greater than the corresponding estimates of 216–277 Mg•ha−1 for young stands. The old Tsuga-dominated stands had the highest biomass estimates of 415–471 Mg•ha−1 for 1.0-ha plots. Annual ANPP estimates were high (11.7–13.1 Mg•ha−1) among the young stands. These stands had particularly high bolewood production. ANPP of the old-growth plots ≥ 0.4 ha ranged from 6.3 to 8.6 Mg•ha−1•year−1 for the deciduous stands and 8.0–10.1 Mg•ha−1•year−1 for the coniferous–deciduous stands. Previous biomass estimates for primeval cove forests were well above temperate forest means of 300–350 Mg•ha−1. Our estimates based on larger plots were lower than previous estimates of 500–610 Mg•ha−1, but they still exceeded temperate forest means. Our deciduous values were 26–94 Mg•ha−1 above the temperate deciduous forest mean of 300 Mg•ha−1, and our Tsuga–deciduous values were 65–121 Mg•ha−1 above the temperate coniferous forest mean of 350 Mg•ha−1.
A physiological approach to dendroclimatic modeling of oak radial growth in the midwestern United States
Authors: Foster Jeffrey R. , LeBlanc David C.
Published: July 2007

This paper describes the development of OAKWBAL, a physiologically based model that integrates daily weather data with site and species-specific ecophysiological data to estimate climate effects on physiology and radial growth of oak (Quercus) species. This model generates relative physiological response indices for cumulative canopy net photosynthesis and woody tissue respiration during the season of radial growth and the season of carbohydrate storage. These indices are entered as predictor variables in regression models, with detrended annual basal area increment as the response variable. Separate analyses were performed for seven similar sites located from northwest Arkansas to eastern Ohio. The analyses showed that (i) individual physiological response indices produced by the OAKWBAL model were better correlated with radial growth of black oak (Quercusvelutina Lam.) and white oak (Quercusalba L.) than were monthly climate variables; (ii) coefficients of determination for dendroclimatic regression models based on monthly weather variables were slightly higher than those for models based on physiological indices, but the monthly weather models included an average of three more predictor variables; and (iii) dendroclimatic regression models using physiological indices exhibited greater consistency across sites and were more amenable to biological interpretation than models using monthly climate variables.
Genetic structure of geographical marginal populations of Cryptomeriajaponica
Authors: Tsumura Yoshihiko , Ohba Kihachiro
Published: July 2007

Although reaching its southern limit of distribution on Yaku Island, sugi (Cryptomeriajaponica D. Don) grows well in large forests protected from logging. Using isozyme analysis, we investigated 14 stands from Yaku Island to clarify the genetic structure of the most southern forests. Thirteen loci encoding nine enzyme systems were analyzed. The polymorphic indexes yielded a proportion of polymorphic loci of 0.330, an average number of alleles per locus of 2.19, an effective number of alleles per locus of 1.16, and a mean expected heterozygosity of 0.138. Most of the allozyme variation was within stands (97.17%), 2.83% being between stands. Comparing marginal populations of Yaku Island with those of mainland Japan, Yaku Island C. japonica forests have maintained a relatively large genetic variation mainly because Yaku Island (i) was a refugia during the last glacial period, (ii) has a suitable climate and adequate precipitation, and (iii) contains a relatively large area (about 8000 ha) of natural forests as protected areas.
Determination of Pinussylvestris seed maturity using leachate conductivity measurements
Authors: Sahlén Kenneth , Gjelsvik Svein
Published: July 2007

To determine whether leakage from seeds during imbibition could be used to determine maturity of Pinussylvestris L. seeds, leachate conductivity and amounts of carbohydrates and inorganic phosphorus were measured for seeds repeatedly collected from three localities in northern Fennoscandia during the ripening season. The seeds were also radiographed and tested for germination. Leachate conductivity as well as the leakage of inorganic phosphorus and carbohydrates decreased during ripening with increasing anatomical and physiological maturity until the approximate time for cessation of anatomical development. No further anatomical development occurred when leachate conductivity was lower than 6 μS•cm−1•seed−1 and the seeds were not physiologically mature as long as leachate conductivity exceeded 3–5 μS. Leachate conductivity and the amount of leached carbohydrates were 4–8 and 10–15 times higher, respectively, in nongerminable than in germinable seeds. Using regression analysis the germination percentage during ripening could be estimated with r2 between 0.96 and 0.99 with anatomical potential and leachate conductivity as explanatory variables. It is concluded that leachate conductivity measurements can be very useful for determination of Scots pine seed maturity.