Arp, P.A., Leger, W., Moayeri, M.H., and Hurley, J.E. 2001. Methods for mapping forest sensitivity to acid deposition for northeastern North America. Ecosystem Health 7: 35-47.
For comparison purposes, two methods are proposed for mapping sustainable acid deposition within the context of natural and managed (harvested) forest biomass growth in northeastern North America. One method uses existing geospatial data for forest cover type, soil type, local climate, topography, and atmospheric deposition. The other method uses data specific to well-studied sites. Maps will be developed that show the spatial distributions of sustainable acid deposition rates by tree type, eco-unit, and local forest disturbance regimes (by harvest method). Additional maps will be produced to show where these rates are likely exceeded, and by how much. The information so generated will be presented to policy and decision makers who deal with forest health and abatement control measures regarding regional sulfur (S) and nitrogen (N) emissions.
Cameron, S.I. 2001. Use of a prototype gel hardness tester to demonstrate the effect of variable calcium concentration on gel rigidity. In Vitro Cell. Dev. Biol.--Plant 37: 419-424.
Construction and operation of a device to measure gel rigidity is described. A commercially available force gauge capable of recording peak force measurements of up to 200±0.1 g is mounted on an easily constructed device consisting of a frame with a motor which moves a platform supporting a Petri plate up or down at a controlled speed. The force gauge probe pierces the gel in the Petri plate, at which time the peak force is recorded to give an estimate of gel hardness. Using both agar and gelrite, an example of the use of the device is given. Tests on a series of different calcium concentrations in gels of varied strengths demonstrate that the patterns of gel hardness differ. Finally, the rigidities of three typical media (half-strenth Litvay, DCR, and Murashige and Skoog) on both gel types are compared.
Cox, R.M., Malcolm, J.W., Hughes, R.N., and Williams, T.P.W. 2001. Sampling ozone exposure of Canadian forests at different scales: some case studies. The Scientific World 1: xxx-xxx.
The use of passive samplers in extensive monitoring, such as that used in national forest health monitoring plots, indicates that these devices are able to determine both spatial and temporal differences in ozone exposure of the plots. This allows for categorisation of the plots and the potential for cause-effect analysis of certain forest health responses. Forest exposure along a gradient of air pollution deposition demonstrates large variation in accumulated exposures. The efficacy of using passive samplers for in situ monitoring of forest canopy exposure was also demonstrated. The sampler data produced weak relationships with ozone values from the nearest "continuous" monitor, even though data from colocated samplers showed strong relationships. This spatial variation and the apparent effect of elevation on ozone exposure demonstrates the importance of topography and tree canopy characteristics in plant exposure on a regional scale. In addition, passive sampling may identify the effects of local pollutant gases, such as Nox, which may scavenge ozone locally only to increase the production of this secondary pollutant downwind, as atmospheric reactions redress the equilibrium between concentrations of this precursor and those of the generated ozone. The use of passive samplers at the stand level is able to resolve vertical profiles within the stand and edge effects that are important in exposure of understorey and ground flora. Recent case studies using passive samplers to determine forest exposure to ozone indicate a great potential for the development of spatial models on a regional, landscape and stand level scale.
Isebrands, R., McDonald, E.P., Kruger, E., Hendrey, G., Percy, K.E., Pregitzer, K., Sober, J., and Karnosky, D.F. 2001. Growth responses of Populus tremuloides clones to interacting elevated carbon dioxide and tropospheric ozone. Environ. Pollut. 115: 359-371.
The Intergovernmental Panel of Climate Change (IPCC) has concluded that the greenhouse gases carbon dioxide (CO2) and tropospheric ozone (O3) are increasing concomitantly globally. Little is known about the effect of these interacting gases on growth, survival, and productivity of forest ecosystems. In this study, we assess the effects of three successive years of exposure to combinations of elevated CO2 and O3 on growth responses in a five trembling aspen (Populus tremuloides) clonal mixture in a regenerating stand. The experiment is located in Rhinelander, Wisconsin, USA (45N 89W) and employs free air carbon dioxide and ozone enrichment (FACE) technology. The aspen stand was exposed to a factorial combination of four treatments consisting of elevated CO2 (560 ppm), elevated O3 (episodic exposure-90 l 1-1 hour-1), a combination of elevated CO2 and O3, and ambient control in 30 m treatment rings with three replications.
Our overall results showed that our three growth parameters including height, diameter and volume were increased by elevated CO2, decreased by elevated O3, and were not significantly different from the ambient control under elevated CO2+O3. However, there were significant clonal differences in the responses; all five clones showed an increase over the control with elevated CO2, one clone showed an increase with elevated O3, and two clones showed an increase over the control with elevated CO2+O3, two clones showed a decrease, and one was not significantly different from the control. Notably, there was a significant increase in current terminal shoot dieback with elevated CO2 during the 1999-2000 dormant season. Dieback was especially prominent in two of the five clones, and was attributed to those clones growing longer into the autumnal season where they were subject to frost. Our results show that elevated O3 negates expected positive growth effects of elevated CO2 in Populus tremuloides in the field, and suggest that future climate model predictions should take into account the offsetting effects of elevated O3 on CO2 enrichment when estimating future growth of trembling aspen stands.
Li, S.Y., and Otvos, I.S. 2001. Differences in activity enhancement of a baculovirus by an optical brightener between Choristoneura fumiferana and Choristoneura occidentalis (Lepidoptera: Tortricidae). Can. Ent. 133: 329-332. (Note.)
Longauer, R., Gömöry, D., Paule, L., Karnosky, D.F., Mankovska, B., Müller-Starck, G., Percy, K.E., and Szaro, R. 2001. Selection effects of air pollution on gene pools of Norway spruce, European silver fir and European beech. Environ. Pollut. 115: 405-411.
The effects of industrial pollution on allelic and genotypic structures of Norway spruce, European silver fir and European beech were investigated by means of isozyme analysis. In a mixed Norway spruce-silver fir forest stand in an area heavily polluted by sulphur dioxide and heavy metals in the region of Spis (eastern Slovakia), pairs of neighbouring damaged and apparently healthy trees were selected in two replicates (44 and 69 pairs in a heavily and moderately damaged stand, respectively). Pairwise sampling of trees with contrasting vitality was applied to reduce potential effects of site heterogeneity on the vitality of sampled trees. No significant differences in allelic and genotypic frequencies were found between sets of healthy and declining trees. There were differences in the single-locus heterozygosities, but these were not consistent between the replicates. However, the set of damaged trees exhibited higher levels of genetic multiplicity and diversity, possibly due to the deleterious effect of rare alleles under the conditions of air pollution. Consequently, following the decline of pollutant-sensitive trees, the remaining stand will be depleted of a part of alleles with unknown adaptive value to future selection pressures.
Piene, H., Ostaff, D.P., and Eveleigh, E.S. 2001. Growth loss and recovery following defoliation by the balsam fir sawfly in young, spaced balsam fir stands. Can. Ent. 133: 675-686.
Two stands of intensively managed balsam fir [Abies balsamea (L.) Mill. (Pinaceae)] in western Newfoundland, located within an area infested by the balsam fir sawfly, Neodiprion abietis (Harr.) (Hymenoptera: Diprionidae) complex, were selected to study growth loss and recovery following severe defoliation by the balsam fir sawfly in the early 1990s. Four years after the start of the outbreak, volume increments were reduced by 78-81%. The decreased volume increment and recovery coincided well with the balsam fir sawfly outbreak and decline. The growth recovery rates following severe balsam fir sawfly defoliation were slow due to the absence of bud destruction, which triggers the release of suppressed buds, and thus increases foliage production. It is imperative that the severe losses in volume growth caused by balsam fir sawfly defoliation are incorporated into wood supply analyses so that future annual allowable cuts may be adjusted. In addition, to ensure maximum recovery rates at the end of an outbreak, future populations must be kept at a minimum to avoid additional foliage loss.
Royama, T. 2001. Measurement, analysis, and interpretation of mortality factors in insect survivorship studies, with reference to the spruce budworm, Choristoneura fumiferana (Clem.) (Lepidoptera: Tortricidae). Population Ecology 43: 157-178.
A theory and practical method are developed to evaluate insect survivorship as a continuous process in time and the effects of major factors that determine it, with a view to providing solutions to certain problems in survivorship studies. There are two ways of assessing mortality rates: nominal and marginal. A nominal rate is based on the number tallied in terms of the immediate cause of death; it depends on the method of observation employed and can be inconsistent between studies. A marginal rate is free of such inconsistency. The marginal rate attributable to the union of parasitism and disease is evaluated by frequent sampling in the field and rearing of each batch of samples in the laboratory for a short period of time. Comparing this rate with the field mortality rate, directly evaluated by sampling, determines marginal predation rate. The marginal parasitism and disease rates cannot be determined by observation. A computational method is developed to evaluate their approximate values. A step-by-step procedure of numerical calculations with data is provided in an appendix. The accuracy of estimating mortality depends on the frequency of sampling in the field and that of inspecting dead individuals in rearing. How frequently sampling and inspection should be conducted is discussed. The method of assessing parasitism developed here has a great advantage over the conventional method based on dissecting the samples, or rearing them through, that often results in a serious underestimation. Also discussed is the relative importance of mortality factors from the pest control point of view, and the concept of "joint contribution" is introduced. Other practical considerations include transportation of samples; rearing conditions; and how to deal with the "dead-in-the-field" in the samples, the "rearing-death syndrome," and the "virtually dead" individuals.
Beckley, T.M., and Reimer, W. 1999. Helping communities help themselves: Industry-community relations for sustainable timber-dependent communities. For. Chron. 75: 805-810.
Social, political and economic conditions are changing in rural Canada. The forest industry has operated in rural communities throughout the nation for several centuries and the relationships between forest companies and communities have evolved over that time. This paper outlines a model for company-community relations that will foster sustainable communities given the new realities that exist in rural Canada. The model will benefit forest industry firms as well as the communities that host them. Six problems that inhibit sustainability in timber-dependent communities are outlined and several ideas for corporate action to address these challenges are offered. Among these are supporting human capital development, leadership development, and entrepreneurship; nurturing healthy communities; and ensuring that costs and benefits associated with timber-dependence are distributed evenly across regions where specific companies have a sphere of influence and within specific communities where companies operate.
Trees were regenerated from six white spruce embryogenic clones after cryopreservation for 3 and 4 years, respectively. Genetic stability was evaluated using randomly amplified polymorphic DNA (RAPD) fingerprints. Somaclonal variation was detected in some in vitro embryogenic cultures 2 and 12 months after they were re-established following cryopreservation but not in the corresponding regenerated trees. These results suggest that trees regenerated from cryopreserved cultures in subsequent years are primarily genetically stable in the genomic regions tested and that variation observed due to the in vitro culture process infrequently affects trees regenerated from normally maturing and germinating somatic embryos. However, trees regenerated from somatic embryos that matured or germinated abnormally in in vitro culture exhibited altered RAPD fragment patterns.
The terminal (1-year-old) shoot of dormant, 2-year-old balsam fir (Abies balsamea (L.) Mill.) seedlings was either left vertically oriented or tilted to an angle of 60 from the vertical (tilting experiment), or was ringed with N-1-naphthylphthalamic acid (NPA), an inhibitor of indole-3-acetic acid transport, at a concentration of 0, 1 or 10 mg g-1 lanolin (NPA experiment). After 6 weeks of growth, ethylene evolution from the cambial region was measured by gas chromatography — flame ionization detection, and tracheid production and compression wood formation were determined by microscopy. In vertical seedlings of the tilting experiment and in 0 mg g-1-treated seedlings of the NPA experiment, compression wood was not formed and neither ethylene evolution nor tracheid production varied longitudinally or circumferentially within the stem. Tilting induced compression wood formation and increased ethylene evolution and tracheid production on the lower side of the stem, while decreasing tracheid production on the upper side. Compression wood formation was induced and tracheid production and ethylene evolution were stimulated at and above the point where 1 or 10 mg NPA g-1 was applied, whereas below this point compression wood was not formed and tracheid production was inhibited. In both tilting and NPA experiments, there was a positive correlation between ethylene evolution and tracheid production when data from all seedlings were analyzed, but not when data from seedlings forming compression wood were excluded. The results indicate that cambial region ethylene evolution is enhanced when compression wood is being formed, and that the enhancement is related to compression wood formation per se rather than the associated increase in tracheid production.
The potential to measure indices of forest vigor from foliar spectral reflectance was assessed in a range of balsam fir conditions achieved through stand manipulations. In order of increasing vigor, treatments consisted of root pruning, control, thinning, and thinning in combination with fertilization. Concentrations of chlorophyll and nitrogen increased significantly from the low to high vigor plots, and shoot lengths increased by more than three times. Balsam fir shoots from each treatment were measured for reflectance under laboratory conditions by a portable spectroradiometer with a spectral range from 350 nm to 2500 nm. Reflectance decreased consistently with vigor throught the spectral region analyzed. Most wavebands showed significant effects of the treatments, with the most significant wavebands in the region of chlorophyll absorption between 500 nm and 740 nm. Foliage age class and sample date also affected reflectance in these wavebands. Reflectance indices, defined as the ratio and normalized difference of the most signficant waveband at 711 nm and the least significant waveband at 913 nm, were affected by the treatments (P<0.0001). The normalized difference index correlated strongly with concentrations of chlorophyll a (r2 > 0.69), nitrogent (r2 >0.52), and shoot lengths (r2 > 0.69), thereby comprising a spectral index of balsam fir vigor that integrates several aspects of forest physiological condition.
Patterns of shoot numbers, shoot length, needle length, and foliage weight were examined throughout a spruce budworm (Choristoneura fumiferana (Clem.)) outbreak cycle, for young balsam fir (Abies balsamea (L.) Mill.), representing four spacing and defoliation conditions. Treatments were defoliated spaced and unspaced, and protected (control, by annual insecticide spraying to prevent defoliation) spaced and unspaced. Foliage parameters were measured on one branch from every second whorl of 20-38 trees per treatment, each year from 1976 to 1984. We found that the number of shoots for protected spaced trees was about three times higher (1140 vs. 400 shoots/tree) than for unspaced trees. There was, in general, no significant difference between protected spaced and defoliated spaced trees, and between protected unspaced and defoliated unspaced trees. For protected trees, the number of shoots increased from the top toward mid-crown and then decreased or stabilized toward the base, whereas defoliated trees had the greatest number of shoots in the lower crown. Shoots were longer on protected than on defoliated trees (means of 3.9-4.0 vs. 2.2 cm/shoot), but there was no effect of spacing. Shoot length was greatest in the uppermost whorls of protected trees and decreased toward the base, while defoliated trees had similar shoot lengths throughout the crown, but were converging to the non-defoliated pattern by 1984. Defoliation resulted in longer needles in one year and shorter needles in three years; there were no consistent relationships with crown position while spacing affected needle lengths in three and two years for protected and defoliated trees, respectively. Foliage weight per tree was 2.7-3.3 times higher for the protected spaced than unspaced trees, while by 1981, foliage weight of defoliated trees was only 7-12% that of the protected trees. However, by 1984, the rate of foliage weight increase was similar between protected and defoliated trees. Regardless of treatment, the maximum foliage weight was in the lower crown. For protected, unspaced suppressed trees, there was a shift in the foliage weight distribution over time, with increased weight in the upper crown.
In a previous investigation, the lignin content of the xylem in the tobacco stem was shown to be greater in transgenic IAA-overproducing line C plants than in wild-type plants (Sitbon et al., Plant Physiol. 99 (1992) 1062-1069). Here, we confirm this observation and also show that the lignin composition in the transformants is altered, the ratio of syringyl to guaiacyl units being decreased due to an increase in guaiacyl units. Line C plants displayed an increased ethylene production in leaves and internodes, as well as a greater capacity to evolve ethylene in response to wounding and exogenous IAA. Line C plants also had greater peroxidase (POD) activity, whereas cinnamyl alcohol dehydrogenase and B-glucosidase activities were similar in the two genotypes. The mRNA level of a tobacco anionic POD, previously associated with increased levels of lignin and related polyphenols when overexpressed in transgenic tobacco plants (Lagrimini, Plant Physiol. 96 (1991) 577-583), was increased in line C plants. It is suggested that the high IAA level in the transformants, through an induction of ethylene synthesis, increases POD activity and hence also lignin deposition.
A survey of larval and pupal populations of the spruce bud moth, Zeiraphera canadensis Mutuura and Freeman (Lepidoptera: Tortricidae), conducted from 1994 to 1996 in eastern Newfoundland, disclosed that the incidence of endemic parasitism by Hymenoptera was up to 50% for Tycherus osculator (Thünberg) (Ichneumonidae), up to 15% for Earinus zeirapherae (Walley), under 3% for Ascogaster (Wesmael 1835) sp. and Clinocentrus (Haliday 1833) sp. (Braconidae), and under 1% for Lamachus (Foerster 1868) sp. and Triclistus (Foerster 1868) sp. (Ichneumonidae). Tycherus osculator, E. zeirapherae, Ascogaster sp., and Clinocentrus sp. represent new distributional range extensions to Newfoundland, and to the nearctic region in the case of T. osculator. The biology of European populations of males overwintered and ovarian maturation did not occur until after several months of exposure to near-freezing temperatures. Tycherus osculator successfully parasitized prepupae and pupae of Z. diniana of all ages but, in the laboratory, appeared to prefer pupae. Host feeding by T. osculator was common but not necessary for ovarian maturation. Tycherus osculator imported from Europe attacked and successfully developed within the spruce bud moth host in laboratory screenings. Morphological comparisons indicated that T. osculator reared from Z. canadensis were smaller than those reared from Z. diniana. Tycherus osculator obtained from either Newfoundland or Europe may have potential as a biological control of Z. canadensis in mainland Canada, where it is presently absent.
Miscellaneous
The temporal pattern of pheromone emission by Anaphes listronoti females was established in a four-arm olfactometer by observing, at 2-hr intervals, the response of 2-hr-old males to odor produced by individual virgin females of 1, 1, and 2 days of age. This is the first evidence of a sexual pheromone in a Mymaridae. Under a 16L : 8D photoperiod and 24EC constant temperature, the responsiveness of males to females of different ages varied signficantly during the photophase. When 1-day-old females were used, males made signficanlty more final choices in the pheromone field than odorless fields at 4 and 6 hr after the onset of the photophase, and their walking speed was significantly higher from 4 to 12 hr, suggesting that females began to release a long-range pheromone during this period. Final choices and high walking speed were observed earlier with 1-, and 2-day-old females than with 1-day-old females, and there was a significant decrease in male responses at 6 hr after the onset of the photophase, suggesting a bimodal temporal pattern of sexual pheromone emission.
Collections of greenheads from tidal salt marshes in Nova Scotia, New Brunswick, and Maine yielded a primary sample of 384 females and 650 males. A running net technique permitted collection of more males than females on most sites. A method of separating male Tabanus nigrovittatus from T. conterminus by the number of rows of ommatidia between the center of curvature and lower divergence on the compound eyes is introduced. Total body length of females from north of Cape Cod is compared with those in a Cape Cod sample. The northern population appears to be a T. nigrovittatus which lacks the presence of T. conterminus and in which females have a larger mean body length than those in N.J.
Pressure-volume curves were determined for black spruce (Picea mariana (Mill.) B.S.P.) trees from four full-sib families. During the first two years, trees were measured from a plantation on a dry site. In the third year, trees were sampled from the dry site and a wet site. Diurnal measurements of shoot water potential allowed in situ shoot turgor to be estimated in addition to standard water relations traits. Over all years, Female 59 progeny displayed lower osmotic potentials at saturation (Qsat) than Female 63 progeny. Genetic differences in Qsat were similar on both the dry and wet sites. Modulus of elasticity (E) was greater for Female 59 progeny than for Female 63 progeny, producing a compensatory effect resulting in no genetic or site differences in osmotic potential at turgor loss point (Qtlp) or relative water content at turgor loss point (RWCtlp). Mean and predawn shoot turgor pressures (Px and Ppd) were higher for Female 59 progeny than for Female 63 progeny and higher at the wet site than the dry site. Genotype x environment trends were observed; compared to Female 63 progeny, Female 59 progeny displayed 9.8 and 5.1% higher Ppd on the dry and wet sites, respectively, and 3.4 and 9.8% greater Ppd values in wet and dry years, respectively. Tree volume growth showed no relationship to Qtlp or RWCtlp, but was correlated with Qsat and Px; however, the strongest correlation was with Ppd (r = 0.90).
In 1989, the first recorded outbreak of hemlock looper (Lambdina fiscellaria fiscellaria (Guen.)) occurred in New Brunswick, Canada. Data were collected from ten plots established in an area infested from 1992-1994, to assess impacts of hemlock looper. Ocular and branch sample assessments of current defoliation and ocular assessments of total defoliation (all age classes of foliage) were conducted for balsam fir (Abies balsamea (L.) Mill.), white spruce (Picea glauca (Moench) Voss), and black spruce (Picea mariana (Mill.) B.S.P.). Stand response was assessed and related to cumulative defoliation. Ocular assessments were found to accurately estimate defoliation, which was significantly related to tree mortality. Ninety-two percent of balsam fir trees that had cumulative defoliation >90% died. Mortality of balsam fir was significantly (p < 0.05) related to tree size, in both lightly and severely defoliated plots; trees with DBH < 11 cm sustained 22-48% higher mortality than larger tees. Mortality of balsam fir, in terms of both percent stems/ha and in m3/ha merchantable volume, increased exponentially in relation to three estimates of cumulative (summed) plot mean defoliation. The strongest relationships (r2 = 0.75=0/79) were between mortality and the ocular defoliation assessment for 1990-1993 foliage. Tree mortality caused by the looper outbreak ranged from 4-14% stems/ha in lightly defoliated and from 32-100% in severely defoliated plots; merchantable volume killed was 3-14 m3/ha and 51-119 m3/ha, respectively. Relationships between mortality and defoliation were similar when defoliation was assessed for 1987-1993 foliage age classes.
Scenario planning was used to develop a consensus-based, multi-stakeholder management planning process for a 114000-ha land base in New Brunswick, Canada. This is part of the Fundy Model Forest, which involves four major landowner groups, along with 26 other Partnership organizations. Public consultation and Partnership input were used to define 25 scenarios, determining effects of alternative means of riparian strip management, road construction, vegetation and insect control, harvesting, maintenance of biodiversity, and plantation establishment. The Woodstock forest modelling software was used to determine effects of each scenario on timber supply, forest structure, measures of biodiversity and ecological integrity, areas of mature forest, and wildlife habitat. In a series of workshops, the Partners were successful in reaching consensus on a Fundy Model Forest “preferred” management scenario, which was conveyed to the land managers for implementation. Development of the management planning process and the use of scenario planning procedures in the Fundy Model Forest are described.
Pressure-volume curves and shoot water potentials were determined for black spruce (Picea mariana (Mill.) B.S.P.) trees from four full-sib families at the Petawawa Research Forest, Ontario, Canada. Trees were sampled from a dry site in 1992 and from the dry site and a wet site in 1993. Modulus of elasticity (E), osmotic potential at turgor loss poin (Qtlp) and relative water at turgor loss point (RWCtlp) all decreased during the growing season. Osmotic potential at saturation (Qsat) and turgor displayed no general temporal trend. Across a range of environmental conditions, Female 59 progeny had equal or lower Qsat, and higher or similar E, mean turgor pressure (Px) and predawn turgor pressure (Ppd) compared with Female 63 progeny. Osmotic potential at saturation decreased as water stress increased from mild to moderate and increased as water stress increased from moderate to severe. Stable genetic differences in Qsat were maintained by the same rate of osmotic adjustment from low to moderate water stress. Modulus of elasticity and RWCtlp decreased with decreasing water availability, whereas Qtlp showed no response. The combined effects of Qsat and E resulted in no change in Ppd as water stress increased from low to moderate values, but turgor declined sharply as water stress increased from moderate to high values. We conclude that drought tolerance traits strongly influence the growth of these black spruce families across sites of varying water availability.
Betula papyrifera (White birch) is a common tree throughout the boreal forest of Canada; it makes up 12% of the total tree volume in insular Newfoundland. It forms pure stands after harvesting and wildfire disturbance and it is a common component in most softwood stands. Little is known regarding the environmental impact of whole-tree or conventional harvesting of this species and variation in impact related to variation in soil and site conditions.
This study investigates litter and organic matter production and related site ecology in nine medium to high quality Betula papyrifera stands in three locations in central Newfoundland on a variety of land form and drainage conditions. Three sites, Badger West (BW), Moose Pond (MP) and Middleton Lake (ML) were selected. The ML site has the highest quality (with the best height/age ratio, 18 m/60 yr, and height/DBH ratio, 18 m/30 cm, followed by MP and BW. Litter depth on well developed moders or mulls was usually 203 cm and varied from 1-15 cm. Forest floor depth (measured in 324 profiles) rarely reached 20 cm and was commonly 5-10 cm; it varied with position and site. Total and available nutrients indicate that B. papyrifera produces one of the highest-quality organic matter types of the local forest types and is important in improving site quality. The mean N-concentration in green foliage (2.21%) and trapped litter (1.03% was highest at the best quality site ML, followed by MP and BW. The concentration of calcium, 0.85%, was highest at the poorest quality site. Four years after harvesting, litter depth significantly decreased in all sites and treatments with the exception of the BW whole-tree harvest treatment. Total forest floor depth significantly decreased at all sites in the stem-only harvest treatment as well as the MP whole-tree harvest treatment. There was a significant decrease in available nitrogen following harvesting in both treatments at both the MP and BW sites. Change in available phosphorus was insignificant, with the exception of an increase in the MP stem-only harvest treatment.
There was a significant decrease in available potassium at both the ML and BW whole-tree harvest treatments at ML and MP. There was a significant decrease in available calcium in both treatments at both the MP and BW sites.
Alechara bilineata Gyll. (Coleoptera: Staphylinidae) adults feed on eggs and larvae of cabbage maggot, Delia radicum (L.) (Diptera: Anthomyiidae), and might be used to control this pest. We undertook tests in a Y-tube olfactometer to determine if infochemicals are involved in the food foraging behaviour of A. bilineata adults and to precisely determine the potential sources of stimuli. A. bilineata adults oriented toward the stimuli from both the food-plant of the prey (rutabaga: Brassica napus var. napobrassica (L.) Reichb.) and the prey-plant complex (rutabaga infested by cabbage maggot larvae), but adults significantly preferred the effluvia of infested to uninfested rutabaga in a choice test. The sources of infochemicals in the infested rutabaga were the cabbage maggot larvae themselves and their frass. However, in a choice test adults preferred the effluvia of the larvae to that of the damaged rutabaga from which those larvae were obtained. It is not expected that a generalist predator uses precise herbivore-derived signals in food foraging activity, but the preference of A. bilineata adults for the larval volatiles over frass volatiles may reflect the dependence of this species on dipteran pupae for reproduction.
Intraspecific host discrimination host discrimination is widespread in solitary parasitoids whose adult females forage for and evaluate host suitability, whereas interspecific discrimination is less common. In some parasitoid species, mostly Diptera and Coleoptera, the larva performs the last step of host searching. It has been suggested that host discrimination will rarely occur in such host-seeking larvae because their low mobility results in a low host encounter rate. We determined the extent to which the larvae of Aleochara bilineota Gyllenhal (Coleoptera: Staphylinidae), a solitary parasitoid of aggregated Diptera pupae: (1) discriminated between unparasitized hosts and hosts parasitized by conspecifics; (2) used semiochemical cues to discriminate; (3) were influenced by life expectancy, presence of conspecifics and host availability in their host acceptance decision; and the extent to which (4) A. bilineata and A. bipustulata L., a species exploiting the same hosts and occurring sympatrically, showed interspecific host discrimination. A. bilineata larvae were able to discriminate between unparasitized hosts and hosts parasitized by conspecifics in a choice experiment. Such behavior has never previously been described for a coleopteran parasitoid or for a parasitoid species whose larvae perform host searching. Host discrimination in this species was not based on the presence of visual or tactile cues (e.g., entrance holes) but rather on chemical cues. The life expectancy of A. bilineata larvae was significantly shorter in the presence than in the absence of hosts, and older larvae had lower parasitism success than young larvae in a 24-h experiment. However, the host acceptance decision of A. bilineata larvae was not influenced by larval age or the presence of conspecifics when the ratio of hosts per larva was greater than or equal to 1. When hosts were scarce, the degree of superparasitism increased significantly with the number of foraging conspecifics and the age of the larvae. Both species of Aleochara showed intra- and interspecific host discrimination in a choice experiment. In contrast to A. bipustulata, A. bilineata larvae more frequently parasitized hosts parasitized by conspecifics. We suggest that host discrimination will be frequent in solitary parasitoids with host-seeking larvae when hosts are aggregated.
Butternut (Juglans cinerea L.) survival is threatened in North America by the fungus Sirococcus clavigigenti-juglandacearum. To date, there is no control for this fungal disease and long-term seed storage, to ensure survival of the species, is not a viable option. Initially, low (0, -5, -10, -15, and -40EC) and ultralow (-196EC, cryopreservation) temperature tolerance of butternut embryonic axes isolated from the nuts collected from one tree was examined. Embryonic axes with approximately 3 mm of cotyledonary tissue attached to the hypocotyl area germinated after exposure to 0, -5, -10, -15, and -40EC for 4 h and to -196EC for 24 h. Percent germination after exposure to 0 and -5EC was 87 and 82%, respectively, and after -10 and -15EC was 29 and 27%, respectively. Thirty-two percent of axes germinated after -40EC, and 36% germinated after exposure to -196EC. Tolerance to -196EC was examined in the embryonic axes isolated from the nuts of 13 other trees. Significant tree-to-tree variation was found in the tolerance of the embryonic axes to low temperature. This variation corresponded to the water content of the embryonic axes; water contents of 4.8% and lower resulted in an increased tolerance to -196EC. These results suggest that low and ultralow temperature storage of embryonic axes may be a viable method for butternut ex situ conservation.
The calyx epithelium of the campoplegine was, Tranosema rostrale, contains typical ichneumonid polydnaviruses (PVs) that display an apparently uncommon association with the egg chorion. The latter structure features fine hair-like projections, longest around the egg’s apices. In the lumen of the ovary, T. rostrale virus becomes lodged between these projections and forms a particulate coat around the egg. In the host, Choristoneura fumiferana, projections and associated virions are observed in close contact with basement membranes of fat body and muscle tissues, to which the eggs rapidly become attached following introduction into the host hemocoel. We discuss the implications of this unusual virus-chorion association in terms of immune protection, delivery of virus to specific host tissues, and the evolution of PVs.
The seasonal flight activity of both sexes of the eastern hemlock looper, Lambdina fiscellaria fiscellaria Guenée (Lepidoptera: Geometridae) was studied during two years in Quebec and Newfoundland, using light (L), pheromone (P) and combined light and pheromone (LP) traps. Moth density significantly affected the performance of the different traps, with P traps being more effective at low than high density. However, P trap catches decreased just prior to the onset of female captures, prbably as a result of competition between traps and virgin calling females. Nearly all females caught in L and LP traps were already mated and even the first females caught had laid at least half of their egg complement. In Quebec under warm nights, the pattern of male activity occurred at different times, with peak P catches being later in the scotophase than those of L traps, but overall similar numbers of males were caught in both traps. In contrast, under cool nights, males were caught early in the night in both P and L traps, suggesting a strong competition effect between traps, although more males were caught in P than L traps overall. In Newfoundland, the pattern of male captures in L and P traps was similar at both high and low temperatures, so competition between trap types would always be high. Under these conditions P traps were more effective than L traps. Irrespective of the region, year or temperature, significantly more males were captured in LP, with the effect of L and P being additive. In both regions, females responded similarly to L and LP traps with peak activity occurring early in the night. Captures of females were lower than those of males under cool temperatures, suggesting that the temperature threshold for flight is higher for females. The use of L and p traps simultaneously and/or in combination is discussed in relation to integrated pest management programs and ecological considerations.
Quantitative assessment of forest pest impacts is an important element in design of forest and pest management programs. Such assessment requires forecasts of pest populations, definition of the nature and extent of damage inflicted on trees by those populations, and translation of the damage effects across scales, from the tree to the stand to the forest. Central to this process are stand development forecasts which embody tree-level impacts of damage and which provide input to forest-level models. We discuss the role of stand growth forecasting in this context and propose a method for calibrating stand growth models that can be used to incorporate the effects of pest damage on tree and stand development. This calibration methodology is demonstrated for spruce budworm (Choristoneura fumiferana Clem.) effects on spruce (Picea sp.) and balsam fir (Abies balsamea (L.) Mill.) stands using permanent sample plot data acquired in New Brunswick over the past 20 years. The results showed linear relationships between tree diameter growth loss and cumulative defoliation, and non-linear relationships between reduced survival and cumulative defoliation. Growth loss relationships were similar for the species considered, while reduced survival relationships varied between species and age classes. Using these relationships as input to the STAMAN stand growth model, forecasts were made and compared against empirical studies of stand development under defoliation during spruce budworm outbreaks. The results suggest that reasonable approximations of stand response to pest incidence can be generated with relatively simple models and data sets. Judicious use of stand growth forecasts generated by such methods can help serve the needs of forest and pest management strategy design.
Economic base analysis is a limited but useful tool for measuring forest dependence. It cannot measure the full range of forest values (e.g., subsistence, amenity, bequest, and existence values). However, economic base analysis utilizes widely available census data to provide accurate measures of communities dependent on industrial forest activity. This analysis includes Indian reserves and rural census subdivisions previously excluded in studies of economic base dependence. Economic base dependence measures are further improved by including a transfer payment sector. This paper presents findings of forest industry dependence measures using 1991 census data. Results show that including Indian reserves and other rural census subdivisions in the analysis increases the number of forest industry dependent places and population throughout the Prairie Provinces. The addition of the transfer payment sector to the economic base provides a more comprehensive account of the sources that contribute to the economic diversity of rural locations. These geographical and sectoral refinements to economic base calculations result in a more accurate accounting of forest industry dependence.
Biological databases are needed for the development of ecologically sensitive land management strategies. Quantitative information that would serve this purpose is typically unavailable or limited to a few species. An alternative is qualitative herbarium data. While often collected unsystematically, herbarium records are usually available for many taxa. We explored the use of herbarium records for defining conservation priorities for plant taxa found in southeastern New Brunswick, Canada. Our objectives were: (1) to identify rare plant taxa collected in the study area; and (2) to group these taxa by habitat affinity, and refine their conservation status based on the vulnerability of the habitats to current and anticipated land use. The temporal and geographical variations in the collection of the herbarium records are described. A total of 351 herbarium records were found, representing 161 different taxa from 46 families. Nine habitat types were identified. Two of these habitats, rich tolerant hardwood forest and wet Thuja occidentalis forest, were classified as endangered. Collections were concentrated near settlements, in areas with road access, or in known species-rich hotspots that were repeatedly revisited. Despite limitations, herbarium data served as a valuable first step in identifying species of conservation concern and highlighting information gaps requiring further investigation.
Betula papyrifera (White birch) is a common tree throughout the boreal forest of Canada; makes up 12% of the total tree volume in insular Newfoundland. It forms pure stands after harvesting and wildfire disturbance and it is a common component in most softwood stands. Little is known regarding the environmental impact of whole-tree or conventional harvesting of this speceis and variation in impact related to variation in soil and site conditions.
This study investigates litter and organic matter production and related site ecology in nine medium to high quality Betula papyrifera stands in three locations in central Newfoundland on a variety of land form and drainage conditions. Three sites, Badger West (BW), Moose Pond (MP) and Middleton Lake (ML) were selected. The ML site has the highest quality (with the best height/age ratio, 18 m/60 yr, and height/DBH ratio, 18 m/30 cm), followed by MP and BW. Litter depth on well developed moders or mulls was usually 2-3 cm and varied from 1 - 15 cm. Forest floor depths (measured in 324 profiles) rarely reached 20 cm and was commonly 5-10 cm; it varied with position and site. Total and available nutrients indicate that B. papyrifera produces one of the highest-quality organic matter types of the local forest types and is important in improving site quality. The mean N-concentration in green foliage (2.21%) and trapped litter (1.03%) was highest at the best quality site ML, followed by MP and BW. The concentration of calcium, 0.85%, was highest at the poorest quality site. Four years after harvesting, litter depth significantly decreased in all sites and treatments with the exception of the BW whole-tree harvest treatment. Total forest floor depth significantly decreased at all sites in the stem-only harvest treatment as well as the MP whole-tree harvest treatment.
There was a significant decrease in available nitrogen following harvesting in both treatments at both the MP and BW sites. Change in available phosphorus was insignificant, with the exception of an increase in the MP stem-only harvest treatment. There was a significant decrease in available potassium at both the ML and BW whole-tree harvest treatments, but a significant increase in the stem-only harvest treatments at ML and MP. There was a significant decrease in available calcium in both treatments at both the MP and BW sites.
The effect of mulches on the persistence of entomopathogenic nematodes, Steinernema spp., for infecting larvae of the spruce cone maggot, Strobilomyia neanthracina Michelsen, was tested in a series of field trials conducted in New Brunswick, Canada. Peat mulch increased the percentage of maggots infected with Steinernema feltiae strain 27 (= bibionis) (Filipjev) strain 27, S. feltiae Umea, and Steinernema carpocapsae (Weiser) All strain, when maggots were placed on nemtaode-treated soil beneath the peat layer. However, when maggots were placed on the surface of the peat (to simulate larvae dropping) in a subsequent experiment, the percentage of maggots infected by S. feltiae strain 27 was less than half of that for maggots placed beneath the peat. Significantly fewer maggots were infected in peat than in either sand or potting soil in a laboratory experiment. Mean percentage of maggots infected by S. feltiae strain 27 over a 21-d period after application was not increased by retaining a natural vegetative cover, or by mulching with hay, wood-bark chips, or bark. Bark mulch, however, did reduce the rate of decline in percentage of infection over time. The numbers of S. feltiae infective juveniles present in the soil from 0 to 3 wk after application were estimated in 2 field trials by repeated baiting with greater wax moth larvae. Numbers of infective juveniles per gram of soil were positively related to percentage of cone maggots infected in 1 of 2 yr, but were not significantly affected by mulching. Mulching with hay, bark or wood-bark resulted in significantly lower soil moisture potentials compared with nonmulched treatments. The results suggest that the mulches tested in this study would not maintain adequate efficacy or persistence of S. feltiae strain 27 for suppression of cone maggot over the 2- to 4-wk period of larval drop.
Sweeney, J., and Quiring, D.T. 1998. Oviposition site selection and intraspecific competition influence larval survival and pupal weight of Strobilomyia neanthracina (Diptera: Anthomyiidae) in white spruce. Ecoscience 5: 454-462.
Densities of coniferous seed cones fluctuate greatly from year to year, and thus cones may be a limiting resource for obligate endoparasites of seed cones during years of low cone abundance. We examined this for the spruce cone maggot, Strobilomyia neanthracina Michelsen, whose larvae feed entirely within the cones of white spruce, Picea glauca (Moench) Voss. During a year of very low cone densities, we tested the predictions that egg density, larval survival, and pupal weight would be positively related to cone size, and that larval survival and pupal weight were negatively related to the number of fly larvae developing in a cone. Although previous studies demonstrated that S. neanthracina avoids ovipositing on cones containing a conspecific, we observed that more than 90% of the cones examined contained three or more eggs. This suggests that cones were a limiting resource for females. The number of eggs laid per cone increased with cone size but the slope of this relationship varied significantly among clones of trees in this seed orchard. Survival of fly larvae and weight of pupae were positively related to cone size and negatively related to the number of hatched eggs per cone in at least one of two samples of cones. Reductions in pupal weight with decreased cone size and increased egg densities suggests that exploitation competition occurred among third (last) instar larvae. However, because most larvae died during the second instar, before consuming much food, most larval mortality was probably due to interference competition among larvae. Tree clone signficantly influenced larval survival in one cone sample and the relationship between survival and number of hatched eggs per cone in another. Our results support a link between the preference by spruce cone flies for larger cones and the performance of their progeny. Reduced larval survival when more than one individual developed in a cone indicates that selection of unoccpied cones, when available, is adaptive.
Since 1995, the government of Nova Scotia has had to develop woodlot owner management programs that encourage timber production without depending on cost-shared Federal-Provincial agreements. These new programs must be as cost-effective as possible. A possible policy tool to overcome these new challenges would be the development of a method of identifying those woodlot owners who would be most willing to participate in management programs. Using data from a province-wide woodlot owner survey, two logit models, based on the woodlot owner’s characteristics, determine the likelihood that management and marketing activity will be undertaken. The management logit model identified those owners who had received advice, who sold wood products from their woodlots in the past five years, or owned larger than average-sized woodlots as most likely to engage in management activity. The marketing logit model identified those woodlot owners who were aware of existing programs, who managed, sold Christmas trees, logging contractors, members of group ventures, or owned larger than average-sized woodlots as more likely to sell forest products.
Spectral reflectance of elm tree foliage was measured with a spectroradiometer under laboratory conditions to examine reflectance characteristics associated with various stages of Dutch elm disease. Early disease conditions resulted in a rapid increase in green and red reflectance and a decrease in near-infrared reflectance. Late symptoms included a decrease in green and near-infrared reflectance. Recommendations for early detection and monitoring programs for native and urban situations are discussed.
We present a checklist of the 634 moth species, in 14 selected families that contain the larger species of moths - the macromoths, identified from Fundy National Park and the immediately adjacent forests of the Greater Fundy Ecosystem. Species are arranged in the sequence of the most recent checklist (Hodges et al. 1983), with nomenclature following Handfield (1997). Apart from the records of a few day-flying species, all the data are from light traps operating over a 5-year period (1993-1997). Included in our checklist are, for each species, the number of successful trapping nights over the 5-year period and the total number of individuals captured. These data give an indication of the relative abundance of each species. We also include the extreme flight dates (over the 5-year period) for each species and summarize these as the total number of days.
A gene located immediately upstream of the granulin gene of Choristoneura fumiferana (ChfuGV) granulovirus was identified, sequenced and named ORF891. The determined, putative open reading frame (ORF) of 891 bp encodes an estimated 34.6 kDa protein. The 5' end transcript of the gene was mapped and analysed. A putative promoter region organization of ChfuGV ORF891 contains a consensus late baculovirus promoter element, TAAG, and two putative early TATA boxes similar to the promoters of ORF909 of Cryptophlebia leucotreta granulovirus (CIGV). Sequence comparisons of ChfuGV ORF891 with CIGV ORF909 and Cydia pomonella granulovirus (CpGV) ORF 124R showed respective homologies of 60.9 and 63.9% for nucleotides and 46.3 and 49.3% for amino acids. Homology of ChfuGV ORF891 with ME53 ORF of Autographa californica multicapsid nucleopolyhedrovirus (AcMNPV) was 68.2% for nucleotides but a total lack of homology for amino acid sequences. Two zinc finger motifs are also associated with ChfuGV ORF891.
Blue spruce (Picea pungens Engelmann.) seedlings were reared from seed for 8 weeks under one of seven UV-B doses ranging from 0.0 to 9.2 kJ m-2 d-1. Emerging primary needles were chopped and incubated 48 h (22 C; 750 mmol m-2 s-1 PAR) with [1-14C] CH3COONa. Radioactivity incorporated into epicuticular waxes was measured using radio thin-layer chromatography. Biosynthesis of nonacosan-10-ol, the dominant constituent, was affected by the UV-B dose. The results suggest that, if no other factors are limiting, the optimum UV-B dose fro wax in some northern temperate forests and well within the range of predicted values under stratospheric ozone depletion scenarios. UV-B dose levels above this threshold may cause changes to the wax composition that may predispose the tree to damage from other environmental stresses.
The perceived health of forest ecosystems over large temporal and spatial scales can be strongly influenced by the frames of reference chosen to evaluate both forest condition and the functional integrity of sustaining forest processes. North American forests are diverse in range, species composition, past disturbance history, and current management practices. Therefore, the implications of changes in environmental stress from atmospheric pollution and/or global climate change on health of these forests will vary widely across the landscape. Forest health surveys that focus on the average forest condition may do a credible job of representing the near-term trends in economic value while failing to detect fundamental changes in the processes by which these values are sustained over the longer term. Indications of increased levels of environmental stress on forest growth and nutrient cycles are currently apparent in case studies with four forest types (southern pine, western pine, high elevation red spruce, and northeastern hardwoods) indicate that ambient levels of ozone and/or acidic deposition can alter basic processes of water, carbon, and nutrient allocation by forest trees. These changes then provide a mechanistic basis for pollutant stress to enhance a wider range of natural stresses that also affect and are affected by these resources. Future climatic changes may ameliorate (+CO2) or exacerbate (+ temperature + UV-B) these effects. Current projections of forest responses to global climate change do not consider important physiological changes induced by air pollutants that may amplify climatic stresses. These include reduced rooting mass, depth, and function, increased respiration, and reduced water use efficiency. Monitoring and understanding the relative roles of natural and anthropogenic stress in influencing future forest health will require programs that are structured to evaluate responses at appropriate frequencies across gradients in both forest resources and the stresses that influence them. Such programs must also be accompanied by supplemental process-oriented and pattern-oriented investigations that more thoroughly test cause and effect relationships among stresses and responses of both forests and the biogeochemical cycles that sustain them.
Current IUFRO Working Party (WP sessions were convened and structured to address the state of science within each subject area. Oral summary presentations were made by rapporteurs during the closing plenary. The written output from the five sessions convened is included here in order of IUFRO WP designation.
The theme of the Conference was “Protected Areas and the Bottom Line”, a phrase which seems to preoccupy much of our thinking these days, whether we are making personal decisions, formulating public policy or creating marketable products. Although the “bottom line” in these situations usually refers to financial considerations, we believe that our individual and collective well-being requires a more elaborate accounting of the ecological processes and life forms that support us. The conference logo is the Greek symbol for oikos, which is the origin of word “ecology” (oecology), meaning the study of the household. This figure surrounds or embodies a stylized image of the Earth, representing the dynamic interplay of air, land and water. In another sense, then, the conference theme inspires us to contemplate the idea of a multi-faceted “bottom line” that integrates ecological, societal, and economic values.
Defoliation coverages for five major forest insect pests in Canada have been prepared for the first time on a national, ecologically stratified, base map. Reporting in an ecological framework, while satisfying updated reporting needs for international and national requirements, gives greater detail about these insect disturbance events in the form of maps, tables, and histograms, and offers analytical opportunities for several ecosystem health issues, such as climate change. This Forest Health Network report focuses on spruce budworm (Choristoneura fumiferana Clem.), forest tent caterpillar (Malacosoma disstria Hbn.), jack pine budworm (Choristoneura pinus pinus Free.), hemlock looper (Lambdina fiscellaria fiscellaria Gn.), and mountain pine beetle (Dendroctonus ponderosae Hopkins) for the period 1980-1996.
