Tree Bole Research Articles

RED-COCKADED WOODPECKER FORAGING BEHAVIOR

Abstract We studied Red-cockaded Woodpeckers (Picoides borealis) to examine the effect of status and gender on foraging behavior. Foraging behavior of breeding pairs extended beyond separation by foraging height to include zones (bole, trunk in crown, primary limb, secondary limb) of the tree used and foraging methods (scaling, probing, excavating). Helper males and juvenile females maintained partial spatial separation from breeding adults. Helper males maintained spatial separation from breeding adults by exploiting limbs within tree crowns in both longleaf (Pinus palustris) and loblolly-shortleaf (P. taeda, P. echinata) pine forests, but also increased use of boles in loblolly-shortleaf pine in concert with reduced use of boles by adult females. Breeding males tended to forage less by scaling, probably due to the reduced proportion of foraging on boles of trees where scaling tends to predominate.

The reduction of organic-layer depth by wildfire in the North American boreal forest and its effect on tree recruitment by seed

We compared prefire and postfire organic-layer depths in boreal forest types (14 fires) across Canada, and examined tree recruitment as a function of depth. There was extensive within-stand variation in depth, much of it due to clustering of thinner organic layers around boles. There were no significant differences in postfire organic-layer depth among sites with different prefire forest species composition, but sites in the eastern boreal region had thicker postfire organic layers than those in the western boreal region. Mean organic-layer depth was much greater in intact stands than after fires; overall, fire reduced organic-layer depth by 60%, largely because of increases in the area of thin (<3 cm) organic layers (1% in intact stands vs. 40% in postfire stands). There was more variation in organic-layer depth within postfire than within prefire stands; notably, some areas in postfire stands were deeply combusted, while adjacent parts were only lightly combusted. We speculate that the diminished role of energy loss to latent heat around tree boles increased organic-layer consumption around tree boles. Seedlings were clustered around burned tree bases, where organic layers were thinner, and the dependence of a species on thin organic layers was an inverse function of seed size.

Optimization of Sampling Methods for Within-Tree Populations of Red Oak Borer, <I>Enaphalodes rufulus</I> (Haldeman) (Coleoptera: Cerambycidae)

In the Ozark Mountains of northern Arkansas and southern Missouri, an oak decline event, coupled with epidemic populations of red oak borer (Enaphalodes rufulus Haldeman), has resulted in extensive red oak (Quercus spp., section Lobatae) mortality. Twenty-four northern red oak trees, Quercus rubra L., infested with red oak borer, were felled in the Ozark National Forest between March 2002 and June 2003. Infested tree boles were cut into 0.5-m sample bolts, and the following red oak borer population variables were measured: current generation galleries, live red oak borer, emergence holes, and previous generation galleries. Population density estimates from sampling plans using varying numbers of samples taken randomly and systematically were compared with total census measurements for the entire infested tree bole. Systematic sampling consistently yielded lower percent root mean square error (%RMSE) than random sampling. Systematic sampling of one half of the tree (every other 0.5-m sample along the tree bole) yielded the lowest values. Estimates from plans systematically sampling one half the tree and systematic proportional sampling using seven or nine samples did not differ significantly from each other and were within 25% RMSE of the "true" mean. Thus, we recommend systematically removing and dissecting seven 0.5-m samples from infested trees as an optimal sampling plan for monitoring red oak borer within-tree population densities. This optimal sampling plan should allow for collection of acceptably accurate within-tree population density data for this native wood-boring insect and reducing labor and costs of dissecting whole trees.

Wildland fire effects on forest structure over an altitudinal gradient, Grand Canyon National Park, USA

Summary Restoration of wildland fire to forests is a challenge when historical fire regimes have been altered. We studied four fires that burned over approximately 7865 ha on an altitudinal gradient in Grand Canyon National Park, USA, in 2003. The fires met criteria for the current USA policy allowing the restoration of fire's ecological role in forest landscapes: Wildland Fire Use for Resource Benefits. After the fires burned out, we remeasured 82 permanent pre‐established monitoring plots burned by the fires plus 43 additional plots on unburned companion sites. The maximum height of charring of tree boles and basal area mortality increased in mean value and variability with altitude. At a low‐altitude Pinus–Quercus site, tree density declined significantly but basal area was unchanged. At a mid‐altitude mixed‐conifer site and a high‐altitude Picea/Abies/Populus site, both density and basal area declined. The thinning effect of fire was concentrated on smaller, shorter, fire‐susceptible trees. Small‐diameter trees (< 20 cm diameter) made up 79–95% of all tree mortality. Shade‐tolerant conifers, particularly true firs and spruce, experienced disproportionate mortality (31–82% basal area decline), while fire‐resistant ponderosa pine and Douglas fir tended to survive (2–8% basal area decline). Delayed mortality between the first and second years following the fires accounted for only 4·2% of trees dying at the low‐altitude site but 15·6% and 11·2% at the mid‐ and high‐altitude sites, respectively. Regeneration density was highly variable but forest floor and woody debris declined in burned areas. Synthesis and applications. This study shows that, even after an unusually long fire‐free period (1880–2003), at the mid‐ and high‐altitude burned sites fire effects were consistent with restoration of historical patterns, moving the ecosystems closer to historical reference conditions. Fires simultaneously reduced the living, dead and ladder fuels that made the forest vulnerable to uncharacteristically severe fire. These effects make the forests more resistant to the expected increases in fire size and severity under future climate conditions. Even at longer‐than‐historical fire intervals, the wildland fire use policy can benefit Grand Canyon forests.

Growing‐season stemflow production within a deciduous forest of southern Ontario

AbstractStemflow production within a red oak (Quercus rubra L.)–sugar maple (Acer saccharum Marsh.)–American beech (Fagus grandifolia Ehrh.) dominated stand in southern Ontario was evaluated during the growing season of 1995. For events that produced stemflow from all sampled tree boles (rainfall ≥ 4·3 mm), the geometric mean Herwitz (Earth Surf. Process. Landforms 11 (1986) 401) funnelling ratios were 7·3, 20·6, and 26·3 for oak, maple, and beech, respectively. Geometric mean funnelling ratios for these three species increased in a linear fashion with increasing rainfall depth for events ranging from 4·3 to 17·4 mm. However, funnelling ratios for the two larger rainfall events measured during the study (27·4 and 40·1 mm) were relatively small, suggesting that after a certain rainfall depth threshold has been reached, trees become less efficient at diverting intercepted rainfall to their boles. Significant (α = 0·10) positive linear relationships were found between stemflow production (l/tree) and beech basal area for all rainfall events ≥ 2·2 mm, while for oak and maple such relationships corresponded with only some relatively large rainfall events. Possible causes for the discrepancies in the funnelling efficiencies of the three tree species and between relatively small and large events are provided. Copyright © 2006 John Wiley & Sons, Ltd.

Crown shyness in lodgepole pine stands of varying stand height, density, and site index in the upper foothills of Alberta

Crown shyness is the empty space between crowns in fully stocked stands that is not related to tree-fall gaps. The objectives of this study were to determine the stand and site factors that control crown shyness in lodgepole pine (Pinus contorta Dougl. ex Loud.) stands and to evaluate whether stands experiencing crown shyness compensate for leaf area losses by maintaining longer crowns. We measured canopy closure (i.e., the inverse of crown shyness), crown radius and length, and green litterfall in stands of various height, relative density, and site index. Canopy closure decreased with stand height and increased with site index and relative density. Green litterfall increased with height and relative density. Crown radius and crown length reached a plateau by 8-10 m height, despite increased spacing between tree boles with increasing stand height. Crown radius increased with height and site index but declined with relative density and slenderness coefficient. Crown length also increased with height and site index but declined with slenderness coefficient. Despite the fact that, in tall stands, where >50% of the sky was not covered by crowns, there was not an accompanying increase in crown length to take advantage of the apparent increase in light transmission to the lower crown.

Estimating relative error in growth ring analyses of second-growth coast redwood (Sequoia sempervirens)

Coast redwood (Sequoia sempervirens (D. Don) Endl.) grows in the coastal zone of north-central California and southern Oregon in pure and mixed-species forests. Redwood has long been recognized to exhibit unusual patterns within the annual growth rings typical of temperate forest trees, including partial and missing rings and ring-width anomalies. However, these patterns have not been quantified beyond a few suppressed trees. This study quantified the variation in ring counts occurring in 22 second-growth redwood trees from different canopy classes. Ring counts from cross sections taken at sample points along each tree bole revealed missing or incomplete rings in all sample trees and 70% of the cross sections. Ring counts along multiple radii were used to calculate probability of obtaining a maximum ring count along one radius. This probability was lowest at the tree base (0.25) and breast height (0.30) and highest near the top of the tree (0.90). Because of the high amount of variation present in ring counts at breast height, care should be taken when drawing conclusions regarding stand ages from increment cores. Increment cores should be taken from the longest axis of the tree and coring at tree base can be abandoned as cores are not likely to have higher ring counts than breast height cores.

Tree bole mineralization rates of four species of the Canadian eastern boreal forest: implications for nutrient dynamics following stand-replacing disturbances

To assess nutrient dynamics in decomposing logs of trembling aspen (Populus tremuloides Michx.), white birch (Betula papyrifera Marsh.), white spruce (Picea glauca (Moench) Voss), and jack pine (Pinus banksiana Lamb.), we monitored mass losses and changes in N and P contents in dead boles from a chronosequence of sites following stand-replacing disturbances. To assess the importance of wood decomposition to nutrient cycling, we compared net estimates of nutrient release from logs with net nutrient immobilization in live-tree biomass of stands as a function of time since disturbance. Mineralization rates were 0.060, 0.053, 0.038, and 0.020·year–1 for trembling aspen, white birch, white spruce, and jack pine logs, respectively. Trembling aspen boles released large quantities of N and P during the first year of decomposition (51 kg·ha–1 of N and 7 kg·ha–1 of P, assuming a bole volume of 150 m3·ha–1). White birch boles acted initially as a nutrient sink and delayed the release of immobilized nutrients until a period when the stand's net nutrient immobilization rates were highest. Jack pine boles appeared to be intermediate in terms of their contribution as a sink or a source of nutrients but, in mature stands, provided up to 40% of N and 26% of P immobilized annually in tree biomass. As pure stands of white spruce are rare in boreal Quebec, information on nutrient accumulation in white spruce stands was not available.

Bark Consumption by the Painted Ringtail (Pseudochirulus forbesi larvatus) in Papua New Guinea1

ABSTRACTWe documented bark consumption by painted ringtails (Pseudochirulus forbesi) and other arboreal marsupials at Mt. Stolle, Papua New Guinea. Evidence consisted of scratch marks on the boles of trees in conjunction with the removal of all moss and direct sightings of animals eating bark. Only 43 trees ≥10 cm diameter at breast height (DBH) of 19 species showed signs of consumption at the study site; five of these species were confirmed by direct sighting to be consumed by painted ringtails. We sought to determine if bark of these trees contained important dietary minerals. Analyses showed that calcium and potassium, individually and combined, were significantly more abundant in eaten versus uneaten trees of the same species. On average, eaten trees showed 4.7 and 2.2 times the amount of these minerals, respectively, as found in uneaten trees. Adult males were more likely than adult females or juvenile males to be captured at eaten trees than away from them. Two species of Syzygium and one species of Sloanea were highly selected for bark consumption, but not all trees of a species were eaten; rather, particular individuals of these species were preferred. We conclude that bark appears to be an important source of calcium and potassium, and speculate on the relationship between the limited availability of these special trees and the social behavior of painted ringtails.

Riparian tree fall directionality and modeling large wood recruitment to streams

Directionality of tree fall in riparian forests can strongly influence predictions of large wood recruitment to streams, yet accuracy of this model parameter has rarely been assessed with field data. We measured fall directions of 1202 riparian trees distributed among 21 stream sites across the Pacific Northwest, USA. Fall directions were oriented towards the stream at 16 sites, upstream at four sites, and not distinguishable from random at one site. Average tree fall direction across sites was correlated with valley constraint (Spearman r = –0.53; p = 0.02), but variability of fall directions was not correlated with this variable. When grouped by species (six conifers and one deciduous), individual trees exhibited stronger tendency to have fallen towards the channel on steep hillslopes (>40%) than on moderately sloped landforms (<40%). Integration of field data into an established recruitment model indicated that 1.5 to 2.4 times more large wood (by number of tree boles) would be recruited to stream reaches with steep hillslopes than to reaches with moderate side slopes or flat banks, if riparian forest conditions are assumed to be constant. We conclude that stream valley topography should be considered in models that use tree fall directions in predictions of large wood recruitment to streams.

Effects of forest roads on the growth of adjacent lodgepole pine trees

The effects of roads on growth of adjacent lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia Engelm.) trees were studied in an area near Williams Lake, British Columbia. Plots were established in a range of stand ages, site qualities, stand densities (stems/ha), stand basal areas (m2/ha), edge aspects, and adjacent road widths. Plots were divided into five zones beginning at the road edge: 0–5 m (zone 1), 5–10 m, 10–20 m, 20–30 m, and 30–40 m (zone 5) from the edge. When the 5 years prior to road establishment were used to scale growth rates, relative tree basal growth rates for zone 1 differed significantly from those for the other zones, with zone 1 rates being 32.1% higher, on average, for 3 to 15 years after the road opening was established. Fewer dead standing trees were found nearest the road edge. Tree bole shapes at breast height were not significantly different among zones, and no significant increases in average basal area per tree or in average height were found. On average, zone 1 had a 31.3% greater stand basal area than zone 5. For a 23.4 m wide road, the increased stand basal area translates to 3.13 m (2 × 31.3% × 5 m for zone 1), or 13.4% recovery of timber losses, if both sides of the road were similarly impacted. This estimate can be improved by using stand basal area to reduce variability.

Vertical Variation of Bark Water Storage Capacity of Pinus strobus L. (Eastern White Pine) in Southern Illinois

Abstract Knowledge of the vertical variation of bark water storage capacity (BWSC) is essential in understanding the processes of throughfall and stemflow yield in forest ecosystems. Determination of vertical variation of BWSC is also necessary to understand microscale variations in moisture availability that affect the diversity and distribution of corticolous lichen and bryophyte communities on tree boles. This field note reports that BWSC of a tree bole of Pinus strobus L. (eastern white pine; 28.4 cm dbh, 22.5 m tall) differs substantially as a function of height above ground. BWSC of the bottom section of the tree bole (5.6 L m−2) was approximately twice as much as the top section (2.5 L m−2). Total BWSC for this tree's bole was 52.5 L. Further research of the interactions among bark water storage capacity, stemflow yield, and the diversity and distribution of corticolous lichens and bryophytes will improve our understanding of the canopy water balance and the functional ecology of forest ecosystems.

Polyurethane foam strips to estimate parasitism of hemlock looper (Lepidoptera: Geometridae) eggs by Telenomus spp. (Hymenoptera: Scelionidae)

AbstractAn oviposition trap recently developed to survey hemlock looper (Lambdina fiscellaria (Guenée)) eggs and consisting of a small strip of white polyurethane foam stapled to the tree bole provides reliable estimates of Telenomus spp. parasitism on hemlock looper eggs. Oviposition traps are a standard tool that never varies. They allow us to avoid the tedious and expensive extraction process used when collecting eggs from branches. This new method can be implemented rapidly in a high number of plots and provides the egg parasitism estimates needed in spring to improve hemlock looper population management.

Agrilus planipennis

<i>Agrilus planipennis</i>

Use of modern tree‐fall patterns as a guideline for interpreting prostrate trees at a pre–Last Glacial Maximum paleoforest site, upper North Island, New Zealand

Wind throw, as evidenced by a tree bole with an attached root plate, is an indicator of forest disturbance, and can often be used as direct evidence of surface winds during a single storm event. We assess tree‐fall patterns resulting from the 1982 Cyclone Bernie event in the North Island, New Zealand, and apply these findings to interpretation of a pre–Last Glacial Maximum (LGM) tree‐fall site to determine if the subfossil tree‐fall pattern could have been caused by a single extropical cyclone. There is insufficient evidence to recommend that a single extropical storm event could have caused the forest destruction observed at our pre‐LGM tree‐fall site, and therefore multiple possibilities for enhanced wind flow that could have caused tree throw are possible.

A lightning fire occurrence model for Ontario

Lightning strike, fire weather, and fire occurrence data were used to model (i) the probability that a lightning strike causes a sustainable ignition on the forest floor and (ii) the probability of an ignition being detected and reported to the fire management agency for each ecoregion in the province of Ontario. An index that tracks duff moisture content in very sheltered areas of a forest stand (near the tree boles) was the most significant predictor in each ignition model. The presence of positive cloud-to-ground lightning strikes was also found to have a significant and positive influence on the probability of ignition in most areas of the province with the exception of the far northwest. Weather conditions following a lightning storm influence the probability that a lightning strike causes a sustainable ignition. Models of the probability of detecting a fire ignited by lightning were also created for each of the ecoregions across Ontario. The form of these models varied somewhat among ecoregions, but contained an indicator of receptive surface fire spread conditions and an indicator of the dryness of the heavier fuels (the organic layer) in the forest floor.

Influence of Colophospermum mopane on surface soil properties and understorey vegetation in a southern African savanna

The influence of Colophospermum mopane (Kirk ex Benth.) Kirk ex J. Leonard on surface soil properties and understorey vegetation was investigated in a semi-arid southern African savanna in Bulawayo, Zimbabwe. Soil samples were collected (depth 0–10 cm) under and outside small, medium and large canopied mopane trees in open woodland on shallow sandy loam soils. The concentration of soil nutrients beneath trees increased with tree size. Soils beneath trees had higher fertility than between tree interspaces. Trees seem to be the major suppliers of nutrients to the understorey vegetation in the crown zone in the form of litter. Soil nutrient concentrations outside canopies of small, medium and large trees were significantly similar, implying that tree size had no significant influence on soil nutrient concentrations in the tree interspaces. Soils were sandier and slightly acidic under canopies of medium and large trees compared to small trees, which had slightly alkaline soils. Soils in the tree interspaces had significantly higher silt and clay content than beneath trees suggesting loss of soil nutrients from surface soils through erosion in the former. Standing herbaceous biomass was significantly lower in the tree interspaces than in the below-crown microhabitats. Species richness and diversity increased significantly with canopy distance from the tree bole. The results suggest that C. mopane has a positive influence on soil fertility in its environment and the fertility improvement beneath trees is not at the expense of soil fertility in the tree interspaces.

Development and Comparison of Intensive and Extensive Sampling Methods and Preliminary Within-Tree Population Estimates of Red Oak Borer (Coleoptera: Cerambycidae) in the Ozark Mountains of Arkansas

Populations of red oak borer, Enaphalodes rufulus (Haldeman), a native wood-boring beetle, seem to be at unprecedented levels that are coinciding with extensive oak mortality occurring in the Ozark Mountains of Arkansas, Oklahoma, and Missouri. To quantify population levels, we developed intensive and extensive sampling methods with respect to the seasonal phenology of active and quiescent stages of the borer’s synchronous 2-yr life cycle. Intensive whole-tree sampling yields data for the entire infested tree bole and provides baseline data for development of less time-consuming sampling methods. Extensive partial-tree sampling uses a nine-sample proportional sampling scheme to estimate densities, which are extrapolated to the whole tree. Data comparison reveals extensive estimates and intensive data are not significantly different, thus verifying extensive sampling as a relatively accurate and acceptable sampling method. Preliminary data from 58 trees confirm epidemic population levels in three areas of the Ozark National Forest in northern Arkansas. Mean number of phloem galleries initiated by current generation larvae on 38 trees was 599 ± 50 (SE) per tree, average number of live red oak borer found in 57 trees was 77 ± 15 per tree, and mean number of previous generation heartwood galleries present in 38 trees was 185 ± 30. Data generated through this research will permit detailed studies of red oak borer biology and mortality, facilitate development of less time-consuming field sampling techniques, and set the stage for further study of factors contributing to the current outbreak and associated tree mortality.

An index for tracking sheltered forest floor moisture within the Canadian Forest Fire Weather Index System

The Duff Moisture Code (DMC) component of the Canadian Forest Fire Weather Index (FWI) System is used by fire management agencies across Canada as an indicator of the susceptibility of the forest floor to lightning fire ignition. However, this model was developed for the moisture content of the forest floor away from the sheltering influences of overstory trees, an area where lightning strikes usually ignite the forest floor. Through destructive sampling of the forest floor in a mature jack pine stand in northern Ontario over several summers, the moisture content of the forest floor in sheltered areas close to the boles of dominant overstory trees was found to be significantly lower than in other less heavily sheltered areas of the stand. Observations from a network of in-stand rain gauges revealed that rainfall penetration through the canopy (throughfall) was correlated with both open rainfall amount and the duration of a storm. Observed throughfall amounts were used to develop a throughfall relationship for extremely sheltered locations (within ~0.5 m of the boles) in a mature jack pine stand. This throughfall model was used, along with differences in forest floor drying rate, to develop a new duff moisture index for strongly sheltered areas of the forest floor. Calculated values of this new moisture model, which has the same daily weather observation requirements as the FWI System’s DMC model, were found to match observed moisture contents quite well.

Estimates of Douglas-fir fine root production and mortality from minirhizotrons

Minirhizotrons were used to assess the influence of soil resources on fine root (diameter ≤ 2 mm) production, mortality, and standing crop over a 2-year period. Two study sites were located, along an elevational transect, in the Oregon Cascade Mountains in mature (>100 years old), closed-canopy Douglas-fir ( Pseudotsuga menziesii (Mirb.) Franco) stands growing on soils with differing resource levels. The low resource site (LRS) had lower soil N (0.15% total N) and lower available water capacity (83 mm) than the high resource site (HRS), where soil N was 0.25% total N and available water capacity was 145 mm. Minirhizotron tubes were installed at each site during August 1994. To allow time for recovery from tube installation, the first root images were collected in late fall 1995 and then at ∼4 week intervals thereafter, except when snow prevented sample collection at the LRS. Root data from soil cores collected near the minirhizotron tubes were used to convert the minirhizotron data to the units of g m −2 (to a depth of 60 cm). Tree bole growth, at the HRS, was about twice that at the LRS, while fine root biomass, at the HRS, was only a third of that at the LRS. Seasonally, fine root production started before the onset of bole growth. Fine root standing crop, production, and mortality were consistently higher at the LRS than at the HRS. These findings support the concept that plants allocate more C to fine roots when soil resources are low. Our estimates of fine root production and mortality tend to be larger than previous reports for Douglas-fir stands. These differences can be attributed, in part, to the failure of the previous studies to account for fine root production and mortality between sampling events.