Fraser Fir Research Articles

Solid phase microextraction for the determination of volatile organics in the foliage of Fraser fir ( Abies fraseri)

Solid phase micro extraction (SPME) was investigated for the determination of volatile chemicals in the foliage of Fraser fir ( Abies fraseri). Advantages of SPME include its speed, sensitivity, and ability to determine volatiles without chemical solvents. In this study, qualitative comparisons were performed of the volatiles emitted from living foliage (in situ), damaged living foliage (in situ damaged), and severed foliage (ex situ). These studies suggest that β-phellandrene and γ-terpinene may be emitted as a response to foliar injury. Comparisons were made of the volatiles collected by SPME with ex situ sampling to previous studies in our laboratory using methylene chloride extraction. Similar results were obtained by the two extraction methods.

Nitrogen Increases Fresh Weight and Retail Value of Fraser Fir Christmas Trees

Abies fraseri (Pursh) Poir. Christmas trees were fertilized for 5 years with four levels of N (0, 56, 113, or 170 kg·ha–1 per year) in spring, fall, or equally split between spring and fall. Nitrogen did not affect leader length, number of leaders, or bud frequency on the upper (distal) portion of the leader. Nitrogen increased bud frequency on the lower (proximal) 20 cm of the leader in only 1 of 3 years of measurement. All application schedules increased the number of apical buds on branches, whereas the number of lateral buds was increased only by spring applications. Nitrogen increased tree fresh weight and retail value as well as weight, length, and surface area of needles. Foliar N concentrations in the fall varied with fertilization schedule, and were higher in November than in October.

Genetic discontinuity revealed by chloroplast microsatellites in eastern North American Abies (Pinaceae)

Development of conservation strategies for Fraser fir (Abies fraseri) in the southern Appalachian Mountains depends in part on recognition of the extent to which Fraser fir is genetically distinct from the closely related balsam (A. balsamea) and intermediate (A. balsamea var. phanerolepis) fir. These sibling species have exhibited intergrading, clinal variation in morphological, chemical, and genetic characteristics in prior research. Chloroplast microsatellite markers were polymerase chain reaction amplified from genomic DNA samples of 78 individuals representing the geographic ranges of Fraser, balsam, and intermediate fir. Gene diversity levels at two loci ranged among taxa from 0.65 to 0.84. Allele frequencies demonstrated significant differentiation among taxa, with R(ST) values of 0.36 and 0.10. Haplotype diversity and D(SH) were highest for balsam fir and lowest for intermediate fir. A haplotype network analysis based on allele size distribution for the two loci revealed two distinct clusters of haplotypes and population-specific haplotypes. Ninety-two percent of the haplotypes in one cluster were from balsam fir and intermediate fir, and 84% of the haplotypes in the other cluster were from Fraser fir and intermediate fir. The genetic differentiation of chloroplast DNA markers provides justification for the recognition of Fraser fir as a distinct Management Unit (MU) for conservation purposes, regardless of its taxonomic classification.

Size- and age-class distributions of Fraser fir following balsam woolly adelgid infestation

Fraser fir (Abies fraseri (Pursh) Poir.) has suffered catastrophic mortality throughout most of its native range from an exotic insect, the balsam woolly adelgid (Adelges piceae Ratz.). To assess the regeneration potential and viability of fir populations, overstory and understory Fraser fir size and age structure were analyzed. The data were collected from thirty-six 400-m2 permanent plots, stratified into four stand canopy composition types, established near the summits of five mountains in the Great Smoky Mountains. We found that, where canopy mortality was severe, fir advance regeneration was re-entering the overstory. In seriously impacted stands, mortality of large fir and increased recruitment have produced distributions characterized by few large fir and relatively high densities of small fir. Densities of 0- to 10-year-old fir seedlings and fir seedlings [Formula: see text]0.25 m tall were much lower in stands dominated by dead fir than in mostly intact fir stands. While the lack of reproducing adults appears to be the main cause, competition with invasive species and higher seedling mortality from environmental factors probably contribute. These results lead to a hypothesis that Fraser fir will undergo a regeneration-mortality cycle with a decrease in the numbers of each successive generation.

Incidence of Phytophthora Root Rot of Fraser Fir in North Carolina and Sensitivity of Isolates of Phytophthora cinnamomi to Metalaxyl.

A survey of Fraser fir Christmas trees in North Carolina for incidence of Phytophthora root rot was conducted during 1997 and 1998. Field sites (7- to 13-year-old trees) and nursery transplant beds (4- to 5-year-old trees) selected at random were surveyed based on foliar symptoms of Phytophthora root rot. Field sites were surveyed with a random transect method (>3,000 trees/field) or by counting all trees (<3,000 trees/field). Overall, incidence of Phytophthora root rot averaged 9% over the 58 field sites sampled, with a range of 0 to 75%. No relationship was found between number of years Fraser fir had been planted in the field site and disease incidence. Disease incidence did not increase as field sites were rotated through second or third crops of Fraser fir. Phytophthora spp. were recovered from 1.8% of asymptomatic trees sampled from 58 field sites across the state. P. cinnamomi accounted for 91% of the Phytophthora isolates recovered. In nursery transplant beds where a systematic sampling procedure was used, incidence of diseased trees averaged 2%, with a range of 0 to 12% across 16 locations. Recovery of Phytophthora spp. averaged 1.2% from root samples collected from 50 asymptomatic seedlings at each location. Isolates collected from the field and nursery transplant beds were grown on cornmeal agar incorporated with 0, 1, 1.25, 10, or 100 μg a.i. metalaxyl/ml. All 166 isolates of P. cinnamomi tested were sensitive to metalaxyl at 1 or 1.25 μg a.i. metalaxyl/ml. Although incidence of Phytophthora root rot has not increased in the state compared to a survey done in 1976 to 1977, the disease continues to limit production of Fraser fir in North Carolina.

Evaluation of Seedlings of Fraser, Momi, and Siberian Fir for Resistance to Phytophthora cinnamomi

Containerized seedlings of Fraser fir [Abies fraseri (Pursh) Poir.], momi fir (A. Firma Sieb. &amp; Zucc.), and Siberian fir (A. siberica Ledeb. var. argentea) were tested for resistance to Phytophthora cinnamomi Rands (two experiments). Fraser fir was very susceptible, with many plants dead after 4 to 5 weeks. Symptoms developed more slowly in Siberian fir, but most plants were dead or dying after 10 weeks. Momi fir appeared somewhat resistant to the pathogen. Though undesirable as a Christmas tree, momi fir might be useful as a rootstock for grafting better quality species in areas affected by root rot.

Size- and age-class distributions of Fraser fir following balsam woolly adelgid infestation

Fraser fir (Abies fraseri (Pursh) Poir.) has suffered catastrophic mortality throughout most of its native range from an exotic insect, the balsam woolly adelgid (Adelges piceae Ratz.). To assess the regeneration potential and viability of fir populations, overstory and understory Fraser fir size and age structure were analyzed. The data were collected from thirty-six 400-m2 permanent plots, stratified into four stand canopy composition types, established near the summits of five mountains in the Great Smoky Mountains. We found that, where canopy mortality was severe, fir advance regeneration was re-entering the overstory. In seriously impacted stands, mortality of large fir and increased recruitment have produced distributions characterized by few large fir and relatively high densities of small fir. Densities of 0- to 10-year-old fir seedlings and fir seedlings 0.25 m tall were much lower in stands dominated by dead fir than in mostly intact fir stands. While the lack of reproducing adults appears to be...

Nitrogen saturation and soil N availability in a high-elevation spruce and fir forest

A field study was conducted during the summer of 1995 to gain abetter understanding of the causes of nitrate (NO3-N)leaching and ongoing changes in soil nitrogen (N) availabilityin high-elevation (1524–2000 m) spruce (Picea rubens) andfir (Abies fraseri) forests of the Great Smoky MountainsNational Park, Tennessee and North Carolina, U.S.A. Indicatorsof soil N availability (total soil N concentrations,extractable NH4-N, extractable NO3-N, and C/N ratios)were measured in Oa and A horizons at 33 study plots. Dynamicmeasures included potential net soil N mineralization determinedin 12-week aerobic laboratory incubations at 22 °C.Potential net nitrification in the A horizon was correlated (r =+0.83, P < 0.001) with total soil N concentrations. Mostmeasures of soil N availability did not exhibit significanttrends with elevation, but there were topographic differences.Potential net soil N mineralization and net nitrification in theA horizon were higher in coves than on ridges. Relative amountsof particulate and organomineral soil organic matter influencedpotential net N mineralization and nitrification in the Ahorizon. Calculations indicate that soil N availability andNO3-N leaching in high-elevation spruce and fir forests ofthe Great Smoky Mountains National Park will increase inresponse to regional warming.

The Christmas Tree: Traditions, Production, and Diseases

This article takes a historical look at the Christmas tree industry and discuss three diseases limiting growers' ability to meet the demand for noble and Fraser fir in North America: Phytophthora root rot and stem canker, current season needle necrosis (CSNN), and interior needle blight. Accepted for publication 14 September 2000. Published 13 October 2000.

601 An Evaluation of Sulphosate and Four Glyphosate Formulations on Conifers

Though glyphosate is considered to be a nonselective herbicide, conifer growers have long known that under certain conditions, they could contact the lower branches of their trees with the herbicide Roundup without injuring them. Species, time of application, rate of application, surfactant, method of application, and pruning wounds are all factors affecting conifer tolerance to glyphosate. Because Roundup was widely used by conifer growers, they were very concerned when the formulation of Roundup was changed to contain a more active surfactant. The new product was marketed under the name Roundup Pro. This change increased its herbicidal activity and raised the possibility that it could damage trees if applied in the same way as Roundup. To determine the tolerance of conifers grown in the northeast to a variety of glyphosate formulations, and sulfosate, a set of studies was established. Roundup, Roundup Pro, Glyfos, Accord, and Sulfosate were all applied to field grown hemlock, white fir, Canaan fir, fraser fir, douglas fir, Colorado spruce, and eastern white pine. Rates of 1 to 3 lb active ingredient/A were applied in the fall after new growth was hardened off. In general, it was found that the risk of injuring trees with Roundup Pro is greater than with the old formulation of Roundup. However, in all cases in which Roundup Pro caused more injury than Roundup, the Roundup Pro was applied at 3 lb active ingredient/A. This rate is double the rate recommended for this use. In calibrated, directed spray applications at 1.5 lb active ingredient/A or less, Roundup Pro should be safe for use around the species tested after their growth has fully hardened in the fall.

Highly Oriented Pyrolytic Graphite as a Platform for Atomic Absorption Spectrometry

Compared to pyrolytic graphite (PG) and pyrolytically coated polycrystalline graphite (PCPG), which are commonly employed substrates for graphite furnace atomic absorption spectrometry (GFAAS), highly oriented pyrolytic graphite (HOPG) is characterized by a high degree ofc-axis alignment with relatively few active sites and imperfections present on the surface. The usefulness of HOPG and commercial PG platforms for the determination of lead, copper, and aluminum by GFAAS was compared. Qualitative comparison of the absorption profiles and temperature optimizations suggest that lead, copper with a chemical modifier (palladium), and aluminum interact similarly with the two graphite substrates, while copper without a modifier interacts less strongly with HOPG than with PG. These results are in agreement with previous studies that have demonstrated that copper interacts strongly with PG and PCPG. HOPG and PG were employed for the determination of a pine needles standard reference material (SRM) and Fraser fir (Abies fraseri) samples. The analyses of the SRM gave good agreement with the certified value using both substrates, and comparable values were obtained for the samples. These results suggest that HOPG may be useful as a model for PG or PCPG when techniques such as scanning tunneling microscopy that require a high degree ofc-axis alignment are employed.

Long-term growth trends of red spruce and fraser fir at Mt. Rogers, Virginia and Mt. Mitchell, North Carolina

Cross-sectional area growth and height growth of Fraser fir and red spruce trees growing in Virginia and North Carolina were analyzed to identify possible long-term growth trends. Cross-sectional area growth provided no evidence of growth decline. The individual discs were classified according to parameter estimates of the growth trend equation. The predominant pattern of growth was a steady increase followed by fluctuation about a horizontal line. Other cross-sections exhibited a steady increase throughout the series. The only discs that represent declining growth patterns were from trees in subordinate crown position or which had previous top damage. No unexplained growth decline was present in any disc. The results regarding height growth were uncertain. A slight decline in height growth was present although we suggest that this observation was due to problems with the data or the model used to fit height growth. These findings contradict other studies suggesting that a recent growth decline has occurred in red spruce in the southern Appalachians.

Damage Assessment in Christmas Tree Plantations following Vegetation Control with Sheep and Geese

Abstract Christmas tree farming in the Southern Appalachian Mountains is a potentially profitable but labor and chemical intensive enterprise. Control of competition from unwanted vegetation usually requires multiple applications of herbicides. Because geese and sheep have traditionally been used as “weeders” in orchards and cropland, the objective of this experiment was to evaluate the potential of these animals for herbaceous vegetation control in Christmas tree plantations. Three types of field trials were conducted at the Upper Mountain Research Station located near Laurel Springs, NC, during two growing seasons (1992 and 1993) to evaluate the natural browsing tendency displayed by sheep and different breeds of geese for different tree species. Food aversion training in a Fraser fir plantation was a special focus of the trials. Sheep and geese were managed to consume herbaceous vegetation through controlled, rotational grazing. Herbage mass of the residue was maintained between 693 and 2,000 kg/ha. Damage observed on four tree species (white pine, Fraser fir, Canadian hemlock, Colorado blue spruce) by “weeder” sheep and geese was dependent on animal species or breed. Untrained sheep and Pilgrim geese were most damaging to 1 yr old transplants (damage scores of 5.3 to 2.3). Trees with damage scores of less than 7 were judged to have reduced commercial potential. "Training" sheep to avoid browsing trees (using a gelatin capsule containing lithium chloride to affect feed selection) is a promising technique worthy of further research. South. J. Appl. For. 23(1):11-15.

Chemical Analysis of an Endangered Conifer: Environmental Laboratory Experiments

Environmental chemistry has been investigated as a mechanism to increase student interest in chemistry. Here are described three examples of environmental chemistry experiments derived from research involving a conifer, the Fraser fir (Abies fraseri), that has suffered decline in its native sites in the Southern Appalachian Mountains. Elemental analysis of foliage was used to assess the effects of acidic deposition and pollution levels. Volatile compounds were identified and determined in foliage and other plant tissues by gas chromatography-mass spectrometry (GC-MS) and GC. Chlorophylls a and b were determined by ultraviolet-visible spectroscopy by simultaneous analysis of a two-component mixture. Each of these experiments may be performed as a two-week experiment with procedures provided to students, or used as a semester-long project. These experiments may be readily adapted for use with different plant species or tissues.

PALEOECOLOGICAL INSIGHTS ON CONSERVATION OF BIODIVERSITY:A FOCUS ON SPECIES, ECOSYSTEMS, AND LANDSCAPES

Environmental changes of the Quaternary have driven changes in biodiversity at every level of organization from genetic variation within populations of individual species to gradients in composition of biotic communities and heterogeneity of vegetation mosaics across landscapes. In the southern Appalachian Mountains, increased seasonality of climate during the changeover from glacial to interglacial conditions in the late Pleistocene and Holocene resulted in landscape instability that fostered a fine-grained, heterogeneous mosaic of habitats supporting a diverse biota. Ecotones between alpine, boreal, and temperate ecosystems in the Appalachians shifted dramatically through the Holocene in response to the passage of critical thresholds of temperature and changing disturbance regimes. Regional projections of future greenhouse-gas-induced climatic warming indicate that alpine tundra may be lost between 44° and 57° N and Picea rubens–Abies fraseri forests may become extinct in the southern Appalachians. Montane Picea rubens–Abies balsamea forests probably will be perpetuated between 44° and 49° N. Disjunct populations of alpine tundra species may persist below climatic treeline in small patches of open habitat. Biotic responses to late-Quaternary environmental changes indicate that a primary conservation emphasis should be to predict the effects of changes in landscape-level environmental processes on biodiversity.

Patterns of Overstory Composition in the Fir and Fir-Spruce Forests of the Great Smoky Mountains After Balsam Woolly Adelgid Infestation

In 1957, the exotic balsam woolly adelgid (Adelges piceae Ratz.) was discovered in the southern Appalachians. It quickly spread throughout the spruce-fir forests, decimating adult Fraser fir (Abies fraseri (Pursh) Poir.) populations. In 1990 and 1991, a system of temporary and permanent plots was established on five mountains in the Great Smoky Mountains. Almost seventy percent of total standing fir basal area in the study area was dead. Mt. Collins, which experienced the major wave of fir mortality about 4 yr before sampling, had the greatest percentage (91%) of dead fir basal area of the five mountains. Despite catastrophic mortality, fir dominated (11–16 m2/ha) live stand basal area on the tops of the three higher elevation mountains, whereas red spruce (Picea rubens Sarg.) and deciduous taxa dominated the two lower mountains. Live fir density over the short term was positively associated with time since the major wave of mortality. Patterns of fir mortality, treefall rates and recruitment determined the proportion of dead fir stems in the overstory. These three factors in turn were dependent on time since major mortality. A logistic regression model predicted that the proportion of standing dead fir would increase until 5—8 yr after an episode of major mortality and decrease thereafter as dead trees fall and young fir reach the overstory.

Effect of Uniconazole on Shoot Growth and Budset of Containerized Fraser Fir

In two experiments, uniconazole (0.25 to 16 mg·L-1 a.i.) was applied as a root drench to containerized Fraser fir [Abies fraseri (Pursh) Poir.] at various times of the year. Leader length, stem diameter, length of laterals, and number of subterminal buds were reduced the following growing season. Treatment during the 1994 growing season reduced lateral bud formation on the leader in 1995, whereas treatment with 8 or 16 mg·L-1 in Mar. 1995 (prior to budbreak) increased it. Uniconazole caused needle discoloration and abscission at concentrations ≥4 mg·L-1. Leader growth was reduced more than branch elongation, which tended to make plants more decurrent. The utility of uniconazole in production of tabletop Fraser fir Christmas trees was unclear; reduced shoot elongation was often accompanied by fewer lateral buds and needle discoloration and/or abscission. Chemical name used: E-1-(p-Chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazole-1-penten-3-ol) (uniconazole).

Effect of Uniconazole on Shoot Growth and Budset of Containerized Fraser Fir

In two experiments, uniconazole (0.25 to 16 mg·L-1 a.i.) was applied as a root drench to containerized Fraser fir [Abies fraseri (Pursh) Poir.] at various times of the year. Leader length, stem diameter, length of laterals, and number of subterminal buds were reduced the following growing season. Treatment during the 1994 growing season reduced lateral bud formation on the leader in 1995, whereas treatment with 8 or 16 mg·L-1 in Mar. 1995 (prior to budbreak) increased it. Uniconazole caused needle discoloration and abscission at concentrations ≥4 mg·L-1. Leader growth was reduced more than branch elongation, which tended to make plants more decurrent. The utility of uniconazole in production of tabletop Fraser fir Christmas trees was unclear; reduced shoot elongation was often accompanied by fewer lateral buds and needle discoloration and/or abscission. Chemical name used: E-1-(p-Chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazole-1-penten-3-ol) (uniconazole).

Midseason Insecticide Treatment of Balsam Twig Aphids (Homoptera: Aphididae) and their Aphidophagous Predators in a Wisconsin Christmas Tree Plantation

The balsam twig aphid, Mindarus abietinus Koch, is a pest of balsam fir, Abies balsamea (L.) Mill., and Fraser fir, Abies fraseri (Pursh) Poir., Christmas trees. This study evaluated the impact of a growers' application of an insecticide (Phosphamidon-8) upon populations of aphids and their arthropod predators (Coccinellidae larvae and adults, Syrphidae larvae, Chrysopidae and Hemerobiidae larvae) in a plantation in western Wisconsin. Spraying occurred on 27 May 1994 as a result of aphids (fundatrigenia and sexuparae) visibly damaging Christmas trees targeted for December 1994 sales. Aphids and predators were sampled by visual counts of infested shoots before and after insecticide treatment. Percentages of treated aphid-infested shoots significantly decreased from 86% prespray to 3% postspray, whereas percentages of untreated infested shoots increased from 75-88%. Two weeks postspray, percentages of both sprayed and unsprayed infested shoots were 5%. Numbers of aphidophagous predators significantly decreased on sprayed trees and significantly increased on unsprayed trees. Spiders increased on all trees. Assessment of needle damage 9 mo after treatment revealed no significant differences in the mean number of damaged shoots between sprayed and unsprayed trees. However, during the following growing season, treated trees contained significantly less numbers of aphids and predators than did unsprayed trees. This indicates that insecticide treatment of the shoot-feeding stages (fundatrigenia and sexuparae) can reduce numbers of aphids and their predators in the current and subsequent year, but will not necessarily reduce needle damage.

Embryogenic Callus Induction in Fraser Fir

Mass propagation of Fraser fir [Abies fraseri (Pursh) Poir], a valuable Christmas tree species in the United States, is problematic because methods currently used are inadequate. According to our results with somatic embryogenesis, the culturing methods used with other Abies species are applicable to Fraser fir. Stage 1 somatic embryogenic callus, characterized by suspensor cells and embryo heads, was obtained at low frequency using Schenk and Hildebrandt medium supplemented with 5 mm glutamine, 0.05% casein hydrolysate, 0.01% myoinositol, 2% sucrose, 5 μM benzyladenine, and 0.6% agar. The developmental stage of the embryo was important; embryogenic callus was obtained only with immature, precotyledonary embryos, not with fully formed embryos. Cold storage of cones containing immature embryos inhibited callus proliferation. Genotype was significant in that 35 of 44 families tested proliferated callus; however, only one embryo within one family continued proliferation to produce stage 1 embryogenic callus. Fully formed somatic embryos were not produced because the callus did not continue to proliferate. Although these experiments met with only limited success, they demonstrate the potential for somatic embryogenesis in Fraser fir and the general applicability of methods used with other Abies species.