Tree Bole Research Articles

Type 3 functional response of mice to gypsy moth pupae: is it stabilizing?

We conducted field experiments in 2002 and 2003 to determine whether the functional response of white‐footed mice (Peromyscus leucopus) to gypsy moth (Lymantria dispar) pupae is decelerating (e.g. type 2) or accelerating (e.g. type 3) at low pupal density. In both experiments, live gypsy moth pupae were deployed in June (prior to the appearance of natural pupae) at densities of approximately 1, 8, and 35 pupae per mouse home range in oak‐forest grids in upstate New York and monitored over 10 days for signs of predation. Pupae were deployed 1.5‐m high on tree boles in 2002, whereas in 2003 the three density treatments were crossed with a height treatment: ground level vs 1.5‐m high. The relationship between daily predation rate (proportion of pupae eaten/day) and pupal density was significantly positive in both years, indicating an accelerating functional response. Daily predation rates on ground‐level pupae were substantial in the lowest density treatment, suggesting that dense mouse populations could drive gypsy moths to extinction despite an accelerating functional response. Daily predation rates on elevated pupae increased over several days in the medium and high density treatments, suggesting a lagged shift from ground‐ to tree‐level foraging by mice. Within the high‐density treatments, predation rates on pupae showed no apparent relationship with the number of pupae on a tree. Our results disagree qualitatively with simple models of type 3 functional response, in which predation rate of prey approaches zero as prey approach extinction, and support the contention that an accelerating functional response alone may be insufficient to prevent prey extinction.

Seasonal variation and partitioning of ecosystem respiration in a southern boreal aspen forest

Continuous automatic chamber and eddy covariance (EC) measurements were made at an old aspen forest (SOA) located at southern boreal treeline in Saskatchewan, Canada to examine the temporal variability in soil ( R s), tree bole ( R b), and ecosystem respiration ( R E) during 2001. Climatic conditions were significantly warmer and drier than the 30-year climate normal, resulting in lower R E and an unprecedented increase in net ecosystem productivity (NEP). In the 7-year record (1994, and 1996–2001) of CO 2 exchange at SOA, the year 2001 showed the greatest carbon gain (300 g C m −2 year). Scaled chamber measurements (1315 g C m −2 per year) were 37% larger than the EC estimate of R E (961 g C m −2 per year). The difference between the scaled chambers and the EC estimate was reduced to 20% after correcting for lack of energy balance closure. Annual R E was approximately 170 g C m −2 per year lower than the average of the previous 6 years. Annual estimates of microbial-heterotrophic ( R h) (510 g C m −2 per year) and autotrophic respiration ( R a) (805 g C m −2 per year), based on chamber measurements, were used to help validate the EC estimate of R E. R a represented 61% of the total chamber respiration. This fraction was used to partition R E into R a and R h to calculate net primary production (NPP). The values of NEP (300 g C m −2 per year) and NPP (675 g C m −2 per year) were more characteristic of temperate forests. The NPP/ P g ratio of 0.54 was within the range of recently published values using biometric techniques and supports that the annual ecosystem respiration budget and its partitioning was well constrained. We recognize, however, that this ratio will vary interannually depending on climatic conditions. In 7 years of annual EC CO 2 flux measurements at SOA, this study provides the first evidence that drought can lead to a transient increase in CO 2 sequestration resulting from a reduction of R E.

Slash Compression Treatment Reduced Tree Mortality from Prescribed Fire in Southwestern Ponderosa Pine

Abstract Intensive thinning prescriptions intended to restore historic forest structure have produced heavy broadcast slash fuel loads in northwestern Arizona, sometimes leading to high tree mortality following prescribed burning. Mechanical slash compression with a D-6 bulldozer to reduce the severity of fire effects on residual trees was evaluated. Ten of 42 measured trees (24%) died within 2 years after burning of broadcast slash, and crown scorch of trees without slash compression treatment averaged 26%. In contrast, no trees died after burning of compressed slash and crown scorch averaged <3%, even though the total fuel loading was indistinguishable from the broadcast slash treatment. The practice of raking fuels away from the boles of old-growth trees also contributed to reduced scorch as compared to younger, unraked trees. Slash compression is a viable method of reducing mortality, offering ecological and economical tradeoffs. Benefits include the ability to reduce large quantities of slash, safeguarding old-growth tree survival while rapidly achieving open forest structure. Costs include paying for equipment operation as well as the possibility of damage to soils or plants. West. J. Appl. For. 19(3):149–153.

Throughfall and throughfall spatial variability in Madrean oak forest communities of northeastern Mexico

Point throughfall data were generated in two representative red oak stands of a small Madrean watershed in northeastern Mexico during the 2000 and the 2001 wet seasons. Cumulative gross precipitation for 18 selected events was 392.9 mm, while the mean cumulative point throughfall flux from 38-fixed gauges was 331.0±9.0 mm (84.2±2.3%). The influence of canopy and understory cover fraction, vegetation area index (VAI), distance to nearest tree bole, as well as the basal area and height of that tree may have on point throughfall depth were evaluated. No significant ( α=0.05) relationship between point throughfall and these stand characteristics could be established for gross precipitation inputs >5 mm. However, excluding events in which occult precipitation was thought to contribute to throughfall generation, the spatial distribution of throughfall was found to be a function of at least one of these factors during each of the gross precipitation inputs <5 mm. For gross precipitation events >5 mm point throughfall for all but one event did not significantly deviate from the normal distribution, suggesting that stand-scale throughfall fluxes associated with these relatively larger events may be estimated from a random array of gauges. An average of 9 (range=3–14) and 34 (range=11–54) gauges would have been required to estimate mean event throughfall input to the red oak forest floor to within ±10 and ±5% at the 95% confidence level, respectively, for gross precipitation events >5 mm.

A Survey of Hymenopteran Parasitoids of Forest Macrolepidoptera in the Central Appalachians

In 1995 and 1996, we conducted a study of the hymenopteran parasitoids of macrolepidopteran larvae in the George Washington National Forest (GWNF), Augusta County, Virginia, and the Monongahela National Forest (MNF), Pocahontas County, West Virginia. Macrolepidopteran larvae were collected from canopy foliage and from under canvas bands placed around tree boles. A total of 115 macrolepidopteran species and 5,235 individual larvae were reared. Forty-two percent (2,221) of the larvae were gypsy moth, Lymantria dispar (L.) (Lymantriidae). A total of 43 primary and seven secondary (hyperparasitoid) hymenopteran parasitoid species were reared from 46 macrolepidopteran species. Hymenopteran families represented included Ichneumonidae (23 species), Braconidae (19), Eulophidae (6), Perilampidae (1), and Trigonalidae (1). We reared 41 and 28 parasitoid species from the GWNF and the MNF, respectively, with 19 species reared from both forests. Many parasitoid species were collected infrequently, suggesting that they are relatively rare on the sampled hosts. The introduced species Cotesia melanoscela (Ratzeburg) (Braconidae), and Euplectrus bicolor (Swederus) (Eulophidae) were among the most commonly reared parasitoids, the latter reared from native hosts. The four most commonly reared native parasitoids were Meteorus hyphantriae Riley (Braconidae), Microplitis near hyphantriae (Ashmead) (Braconidae), Aleiodes preclarus Marsh & Shaw, and Euplectrus maculiventris (Westwood) (Eulophidae). A total of 53 new hymenopteran parasitoid-macrolepidopteran host records were documented. Results from this study will be used to evaluate long-term treatment effects of regional applications of Bacillus thuringiensis kurstaki, and the gypsy moth fungus Entomophaga maimaiga Humber, Shimazu & Soper on hymenopteran parasitoids of macrolepidopteran larvae.

A survey of hymenopteran parasitoids of forest macrolepidoptera in the central Appalachians.

In 1995 and 1996, we conducted a study of the hymenopteran parasitoids of macrolepidopteran larvae in the George Washington National Forest (GWNF), Augusta County, Virginia, and the Monongahela National Forest (MNF), Pocahontas County, West Virginia. Macrolepidopteran larvae were collected from canopy foliage and from under canvas bands placed around tree boles. A total of 115 macrolepidopteran species and 5,235 individual larvae were reared. Forty-two percent (2,221) of the larvae were gypsy moth, Lymantria dispar (L.) (Lymantriidae). A total of 43 primary and secondary (hyperparasitoid) hymenopteran parasitoid species were reared from 46 macrolepidopteran species. Hymenopteran families represented included Ichneumonidae (23 species), Braconidae (19), Eulophidae (6), Perilampidae (1), and Trigonalidae (1). We reared 41 and 28 parasitoid species from the GWNF and the MNF, respectively, with 19 species reared from both forests. Many parasitoid species were collected infrequently, suggesting that they are relatively rare on the sampled hosts. The introduced species Cotesia melanoscela (Ratzeburg) (Braconidae), and Euplectrus bicolor (Swederus) (Eulophidae) were among the most commonly reared parasitoids, the latter reared from native hosts. The four most commonly reared native parasitoids were Meteorus hyphantriae, Riley (Braconidae), Microplitis near hyphantriae (Ashmead) (Braconidae), Aleiodes preclarus Marsh & Shaw, and Euplectrus maculiventris (Westwood) (Eulophidae). A total of 53 new hymenopteran parasitoid-macrolepidopteran host records were documented. Results from this study will be used to evaluate long-term treatment effects of regional applications of Bacillus thuringiensis kurstaki, and the gypsy moth fungus Entomophaga maimaiga Humber, Shimazu & Soper on hymenopteran parasitoids of macrolepidopteran larvae.

Liana loads and post-logging liana densities after liana cutting in a lowland forest in Bolivia

Liana infestations can be a problem in forests managed for timber because lianas decrease rates of tree growth, damage tree boles, and inhibit tree regeneration. To determine the area from which lianas colonize tree crowns in a liana-rich moist lowland forest in a timber concession in the Department of Santa Cruz, Bolivia, we described “liana sheds” of individual canopy trees (the area under the crown and beyond its margins from which lianas colonize trees). In the same area we tested the hypothesis that pre-logging cutting of lianas in a harvested tree’s liana shed reduces post-logging liana infestations. Prior to logging, 73% of 570 trees >10 cm in DBH representing 12 commercial species, carried at least one liana >2 cm DBH. Liana-infested trees hosted an average of 9.3 lianas (±0.45 S.E., range: 1–68). The mean area of the crown covered by lianas was 35% (±29.7 S.E.) but some trees (10%) were completely covered by lianas. “Liana shed areas” were a function of crown area and varied among tree species. Most lianas on trees were rooted below the crown of their host (90%); the number of lianas decreased with increasing distance from the crown edge, but lianas colonized trees from as far as 8 m beyond the crown. Overall, there was a significant reduction in the number of lianas in 22 felling gaps 8 months after logging where lianas were cut before logging compared with 22 control gaps. In control gaps, the majority of climbing lianas sprouted from the prostrate stems of fallen canopy lianas (81%), including 3.1 km/ha of stems that were rooted along the ground before logging. Liana regeneration in gaps after pre-logging liana cutting occurred mainly by stump sprouting (41%) and sprouting from prostrate stems (48%). Pre-felling liana cutting reduced liana cover in felling gaps by 9% only but reduced liana basal area by 69%. The results of this study suggest that tree crown area, shape, and height are among the most important factors determining the likelihood of liana colonization of canopy trees and that pre-logging liana cutting reduces post-logging liana proliferation in logging gaps.

Splitting in Fire-Killed Trees in the Boreal Forest of Alberta

Abstract Tree boles in the boreal forests of Alberta, Canada will split once killed by a stand-replacing crown fire. A total of 1,485 fire-killed trees were sampled, 1 yr after burning, in 23 plots in 14 widely separated stands within a 370,000 ha fire. Sampling occurred in the Upper and Lower Foothills natural subregions. The frequency of splitting varied by species but averaged 41% for all species. The order in the frequency of splitting was balsam fir, black spruce, white spruce and lodgepole pine. The type of splitting (straight, spiral, or multiple) varied by species, as did the position of the split on the tree bole. Aspect or solar angle was not statistically related to the type or occurrence of splitting.

Endophytes and mycoparasites associated with an indigenous forest tree, Theobroma gileri, in Ecuador and a preliminary assessment of their potential as biocontrol agents of cocoa diseases

The main constraint and continuing threat to cocoa production in Latin America is disease caused by two basidiomycete fungi belonging to the genus Crinipellis (Agaricales), both of which are currently on an invasive front. Classical biological control, in which coevolved natural enemies are considered to offer the most potential for sustainable control of invasive alien organisms, is investigated as a management strategy. Our initial approach has been to search for the suspected coevolved host (Theobroma gileri) of one of these pathogens, Crinipellis roreri, the causal agent of frosty pod rot, in the mesic forests of north-west Ecuador; to isolate the endophytes and mycoparasites associated with both host and pathogen; to screen selected fungi in the greenhouse and laboratory, in order to determine their biocontrol potential. Endophytes were isolated directly in the field from healthy tree boles and pods, and over 40 genera were recorded, mainly representing anamorphs of Hypocreales in the genera Acremonium, Clonostachys, Trichoderma and Verticillium, as well as basidiomycetes belonging to the Agaricales and Polyporales. Of the endophytic fungi tested, most can be inoculated into and recovered from asymptomatic cocoa seedlings. Twenty-eight mycoparasitic species were isolated from diseased pods and selected mycoparasites as well as endophytes were screened against C. roreri using the pre-colonised plate method. Consistently high mycoparasitism of the C. roreri pseudostroma was demonstrated, particularly by a complex of Clonostachys and Trichoderma species.

Positional influence on rooting of shoots forced from the main bole of swamp white oak and northern red oak

The transition of ontogenetic maturity was assessed in two oak species by forcing softwood shoots from main bole stem sections in the greenhouse and from intact crowns, stumps, and hedged trees in situ and subsequently subjecting the new shoots to rooting trials. Mean shoot production was greater from forced stem sections of northern red oak (Quercus rubra L.) than from those of swamp white oak (Quercus bicolor Willd.) (14.6 and 4.6 shoots/m, respectively). Northern red oak stem sections exhibited a vertical gradient in the number of forced shoots; greater numbers originated from basal and juvenile sections of trees than from distal and mature sections. Rooting of swamp white oak shoots was low, 1.4% for forced shoots and none from hedged trees. Rooting of northern red oak was greater but variable, averaging 40.3% from greenhouse forced shoots and 0-35% from field-grown trees. Moreover, percent rooting was greatest for forced shoots originating from basal stem sections and declined with increasing distance from the tree base. The results suggest that ontogenetic maturation gradually increases, and rooting response decreases, along the bole of northern red oak trees.

Development of epicormic sprouts in Sitka spruce following thinning and pruning in south-east Alaska

Summary The frequency and size of epicormic sprouts in Sitka spruce (Picea sitchensis (Bong.) Carr.) were assessed in five 23-29 year-old mixed Sitka spruce-western hemlock (Tsuga heterophylla (Raf.) Sarg.) stands that were uniformly thinned and pruned to 2.4, 3.7 and 5.2 m lift heights. Six to nine years after treatment sprouts were very common with 232 of 236 trees producing sprouts and an average of 9-11 sprouts m -1 of tree bole. The total numbers of sprouts were similar for the different pruning treatments but significantly more large sprouts (P = 0.025) were produced in the 5.2 m pruning lift. Trees that developed large sprouts were significantly smaller, shorter and had less crown length at the time of pruning than trees without large sprouts. Our results suggest that spruce responds to thinning and pruning treatments with the production of numerous epicormic sprouts. If one of the main goals of pruning is to produce clear, higher valued wood, Sitka spruce may be a poor candidate species for pruning.

Holaspis, a lizard that glided by accident: mosaics of cooption and adaptation in a tropical forest lacertid (Reptilia, Lacertidae)

Holaspis is the most morphologically apomorphic lacertid taxon with 42 or more derived morphological features arising on its exclusive lineage. Nearly all of these confer advantages in three specialised activities, or ameliorate problems resulting from them. The activities are: climbing on the often vertical open surfaces on tree boles and branches, utilising very narrow crevices in wood and beneath bark, and the ability, unique among lacertids, to glide from tree to tree. Although many of the features related to these activities are likely to result from direct adaptation to the situations concerned, exaptation has been critical in the development of gliding. Two behaviours present in the earliest lacertids have been coopted to this activity: rib spreading associated with basking contributes to an effective aerofoil, and balance control associated with running helps maintain appropriate posture in the air. Features originally developed in the context of crevice use also contribute to the aerofoil and a high surface: weight ratio. So, while natural selection has moulded Holaspis for its present activities, multiple accidents of history have also been important, as they also have in the evolution of bird flight.

Life History and Habitat Associations of the Broad Wood Cockroach, &lt;I&gt;Parcoblatta lata&lt;/I&gt; (Blattaria: Blattellidae) and Other Native Cockroaches in the Coastal Plain of South Carolina

Abstract Wood cockroaches (Blattaria: Blattellidae) are important prey of the red-cockaded woodpecker, Picoides borealis Wilson (Piciformes: Picidae), an endangered species inhabiting pine (Pinus spp.) forests in the southern United States. These woodpeckers forage on the boles of live pine trees, but their prey consists of a high proportion of wood cockroaches, Parcoblatta spp., that are more commonly associated with dead plant material. Consequently, we sampled large woody debris, logs and standing dead trees (snags), in a South Carolina pine forest to determine densities of wood cockroaches in these habitats. Nearly 80% of the 662 wood cockroaches we collected from woody debris were found in snags. However, when we estimated the number of wood cockroaches per hectare, we found that the two habitats contained approximately equal numbers because logs are more abundant than snags. The broad wood cockroach, Parcoblatta lata Brunner, was the most common cockroach on live pine boles constituting 46% of the w...

Dendroglaciological investigations at Hilda Creek rock glacier, Banff National Park, Canadian Rocky Mountains

Dendroglaciological techniques are used to provide evidence of historical rock glacier activity at Hilda Creek rock glacier in the Canadian Rockies. The research focuses on the sedimentary apron of the outermost morainal deposit, where excavations in 1997 uncovered six buried tree boles that had been pushed over and entombed by distally spilled debris. Cross-sectional samples cross- dated with a local Engelmann spruce tree-ring chronology were shown to have been killed sometime after 1856. Based on the extent of the excavation, the data indicate that Hilda Creek rock glacier has continued to advance along the present ground surface at a rate exceeding 1 cm/year.

ARBORISTS SHOULD HAVE A CENTRAL ROLE IN EDUCATING THE PUBLIC ABOUT VETERAN TREES

Summary Ancient trees need to be marketed. There is a major need for them to be interpreted to the public in a way which reflects their true value to society. Some of the key factors which are all too often not considered in their management are firstly reviewed: These include: lack of consideration of the tree-fungus ecosystem, allowing urban structures (roads, paths, car-parks) to impinge too closely onto tree root systems, the common occurrence of harsh and unnecessary pruning regimes, and (in an agricultural context) ploughing up to the tree boles. These examples are quite deliberately alternated with good practice, culminating in an example of a resolution, successfully adopted by the National Trust, seeking to protect and interpret ancient trees to the public. Finally, it is argued that arboriculturalists need to become much more pro-active ‘tree-ecologists’ taking a firm ethical stance in favour of ancient tree preservation on all occasions. Some of the linguistic challenges surrounding discussion of tree preservation are briefly discussed, and the point is made that ancient trees are a vital part of our cultural heritage, their main (potential) protectors being arboriculturalists.

Predation of Gypsy Moth (Lepidoptera: Lymantriidae) Pupae in Three Ecosystems Along the Southern Edge of Infestation

The predation potential of small mammals, in particular mice, Peromyscus spp., and invertebrates, was evaluated from 1992 to 1995 near the leading edge of gypsy moth, Lymantria dispar (L.), spread into the southeastern United States. Two study sites were established in each of three geographic areas: the coastal plain, Piedmont, and mountains. All sites were mixed hardwood stands with varying amounts of oak, Quercus spp., and all were classified for gypsy moth susceptibility. Small mammal density was estimated using Sherman live-traps and pitfall traps within these 4.68-ha sites in early and late summer. Each site contained 75 trapping stations located on a 25-m grid. Predation was measured by offering freeze-dried gypsy moth pupae near trapping stations at four heights (0, 0.25, 1.0, and 2.0 m) on different tree boles. Pupal predation was monitored for three consecutive nights. Vertebrate predation was positively correlated with good mast production in the previous autumn. Predation data showed that when mice were at high densities they were the major source of pupal predation. However, within these southern sites, when densities of Peromyscus spp. were low, predation by invertebrates was occasionally greater than predation by vertebrates. These data suggest that in some years invertebrates may retard gypsy moth buildup when small mammals are scarce due to mast crop failures.

Response of white-footed mice ( Peromyscus leucopus) to coarse woody debris and microsite use in southern Appalachian treefall gaps

The influence of treefall gaps and coarse woody debris (CWD) on white-footed mouse ( Peromyscus leucopus) abundance was tested experimentally during 1996–1999 in a southern Appalachian hardwood forest. I compared the relative abundance and body size of P. leucopus among unsalvaged gaps that were created by wind disturbance and retained high CWD levels, salvage logged gaps where fallen and damaged tree boles had been removed, and closed-canopy controls. I also tested the relative use by mice of four microsite types: CWD, pits, woody brush, and open ground. One-hundred and forty-one P. leucopus were captured 310 times during the study. There were no differences in capture success, body size, or sex ratio among treatments before or after salvage logging, but abundance varied among years. Capture success was higher at traps set adjacent to CWD ( P<0.05) and in pits ( P<0.10) than at traps set under brush or on open ground. In the southern Appalachians, windthrow-created canopy gaps and associated microsites do not affect habitat use by P. leucopus at a landscape level (as measured by relative abundance among treatments), but CWD influences the microdistribution of P. leucopus where it is present.

Fine roots of trees - a new perspective.

Fine roots of trees - a new perspective.

Hollows in jarrah ( Eucalyptus marginata) and marri ( Corymbiacalophylla) trees : I. Hollow sizes, tree attributes and ages

One hundred and fifty-four jarrah ( Eucalyptus marginata) and 85 marri ( Corymbia calophylla) trees were measured and assessed, and the numbers and sizes of hollows in these trees were determined by destructive sampling; 665 hollows were located and measured. The relationship between tree diameter and tree age was determined from counts of annual growth rings on 162 of these trees. Large trees and trees with moderately senescent crowns individually bear the most hollows. Although the number of hollows found in individual trees increased with tree diameter, the distribution of tree diameters in the forest is skewed and the large number of small trees with diameters between 40 and 80 cm contribute approximately 50% of all hollows in the jarrah forest. The distributions of entry size, and of hollow depth, are highly skewed, with small hollows occurring more frequently than large hollows. Although jarrah trees bear more hollows than marri trees and the distribution of entry sizes is similar for both tree species, the hollows in jarrah are significantly smaller than the hollows in marri. Most hollows are cylindrical in shape, vertically oriented and occur in dead wood in the tree crown. Relatively few hollows (14%) occur in the tree bole or at crown break. Counts of hollows made from ground level are inaccurate as estimates of the actual number of hollows in trees.

An explanation of patterns of breeding bird species richness and density following clearcutting in northeastern USA forests

We surveyed breeding birds for an average of 4 years on 23 primarily even-aged successional stands ranging from 2 to 120 years old to observe changes in species richness and density following clearcutting in central New York. An initial sharp increase in richness and density from post-cut years 2–6 preceded a steep decline by year 25. Cubic functions best fit this ( P<0.0007) and a second, smaller increase and decline in richness and density between years 25 and 120 ( P<0.03). The rapid initial increases in richness and density were highly correlated with leaf area which, on plots that were heavily stocked prior to cutting, returned to precut levels by year 6 or 7. Species richness on 6-year-old clearcuts was more than twice that of any mature stand sampled. Similarly, 6-year-old clearcuts exhibited a mean avian density (501 pr/40 ha), more than 2.5 times that of any mature stand (184 pr/40 ha). The decline in avian populations from years 7 to 25 accompanied canopy closure and was likely associated with the loss of foraging and nesting sites near ground level. The second, less pronounced increase in avian richness and density from years 25 to 100 was associated with (1) the redistribution of foliage to all vertical layers of the forest resulting from the increasing size and duration of canopy gaps caused by tree deaths; and (2) the increasing size and bark complexity of tree boles, which provided new foraging and nesting substrates. Overall, avian successional trends appear to be determined by the development and decline of vegetation patch types appropriate to specific guilds of birds. We suggest that, while lacking the vertical heterogeneity and bole-related substrates traditionally cited as correlates of avian richness and density in older forests, early successional stages of northeastern forests support significantly higher avifaunal richness and density due to a combination of high productivity of leaves and insects along with increased horizontal structural complexity. Even-aged stand management, carefully implemented through clearcutting, has the potential to increase the species richness of forested landscapes and provide important habitat for early successional Neotropical migrants, while effectively meeting demands for marketable timber.