Konara Oak Research Articles

Six-year monitoring study of radiocesium transfer in forest environments following the Fukushima nuclear power plant accident

The study investigated temporal changes in the 137Cs concentrations in vegetal and hydrological samples collected from various forests in Yamakiya District, Kawamata Town of Fukushima prefecture over six years following the Fukushima Dai-ichi nuclear power plant accident. Cesium-137 was detected in all forest environmental samples. However, the concentration in most samples decreased exponentially with time. The 137Cs concentrations in throughfall samples exhibited a double-exponential decreasing trend with time. Temporal changes in the 137Cs concentration in vegetal samples and stemflow were approximated by using a single-exponential equation. A comparison of the decline coefficient for the latter observation period (>2 y since the accident) revealed that the declining trend of 137Cs concentrations varied between foliage and the outer barks of the Japanese cedar and Japanese konara oak trees. The 137Cs concentration in cedar needles decreased exponentially while that in konara oak leaves was constant over the last six years. Conversely, the declining trend of 137Cs concentration in the outer bark of konara oak exceeded that of cedar. The results suggested that self-decontamination processes and internal recycling of 137Cs varied among tree species and different tree parts. The results indicated that the leaching of 137Cs in the throughfall in Japanese cedar was dependent on the 137Cs concentration in needles. However, a comparison of 137Cs concentrations in vegetal and hydrological samples from each sampling year showed that the leaching rate decreased with time. Conversely, the 137Cs concentrations in the stemflow were independent of the concentrations in the outer bark. The declining trend of 137Cs concentrations in litterfall (λ: 0.31–0.33 y−1) was similar to that of the mean of new/old needles (λ: 0.26–0.33 y−1) for cedar stands. With respect to the hydrological components, the 137Cs concentration in the stemflow (λ: 0.32–0.33 y−1) decreased at a slightly slower rate than that in the throughfall (λ: 0.36–0.54 y−1) for the cedar forest. The decline coefficients of 137Cs concentration in the aforementioned types of hydrological components slightly exceeded that for the vegetal samples. The results suggest that monitoring of 137Cs concentrations in hydrological components and vegetal samples can aid in further understanding the leaching mechanisms of 137Cs from trees to rainwater.

Species diversity of woody recruits within Japanese cedar (Cryptomeria japonica) plantations established on grasslands: the effects of site conditions and landscape

ABSTRACTPlantations established on grasslands have low recruitment of broadleaved trees and therefore may require particular attention when developing biodiversity-oriented management practices. In this study, we tested four hypotheses concerning woody recruits in Japanese cedar (Cryptomeria japonica) plantations established on grasslands with respect to their distance from the nearest Konara oak (Quercus serrata) forest. Our four hypotheses were as follows: (1) both species richness and occurrence frequency (the number of subplots in which recruits were present) decline with increasing distance; (2) the strength of the effect of distance differs depending on the growth form, seed dispersal type, or life history trait; (3) the species richness of recruits does not increase in response to a disturbance or other site conditions; (4) and species composition of recruits also changes with distance. Our results showed that species richness and occurrence frequency generally declined with increasing distance. This result supports the first hypothesis. The effect of distance was stronger in wind-dispersed species than in bird-dispersed species, as predicted by the second hypothesis. Disturbances such as thinning or wind throw did not increase but rather did decrease species richness, as predicted by the third hypothesis. Furthermore, distance had the strongest impact on species composition, as predicted by the fourth hypothesis. These findings show that, in biodiversity-oriented management, it may be more challenging to increase biodiversity using stand-level management in plantations established on grasslands than in plantations established after clear-cutting of broadleaved forests. Thus, landscape-level management may be required for these cases.

Absorption and translocation of cesium through Konara oak (Quercus serrata) bark

ABSTRACT Bark–wood translocation has been suggested as an important route for the contamination of trees via radiocesium in the initial stage of deposition. In this study, we investigated the cesium absorption through bark of mature Konara oak (Quercus serrata). Stable Cs (133Cs) was applied onto the bark at 1.2 m, and then after 8 weeks, the 133Cs concentration was determined in the outer bark, inner bark, sapwood, and heartwood of stem disks at several heights, as well as in the current-year leaves and branches from the tree tops. At the height of 1.2 m, the 133Cs concentration was significant higher in the sapwood of the treated trees than in those of the control trees. However, no difference was found in the 133Cs concentration in the heartwood of the treated and control trees not only in the wood above and below 1.2 m but also at 1.2 m. There was no significant difference in the 133Cs concentration of the current-year leaves and branches of the treated and control trees. Our results suggest that Cs absorption through bark may occur even in the dormant period of tree and the absorption is probably independent of cambial activities.

Temporal trends in 137Cs concentrations in the bark, sapwood, heartwood, and whole wood of four tree species in Japanese forests from 2011 to 2016

To understand the changes in radiocesium (137Cs) concentrations in stem woods after the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident, we investigated 137Cs concentrations in the bark, sapwood, heartwood, and whole wood of four major tree species at multiple sites with different levels of radiocesium deposition from the FDNPP accident since 2011 (since 2012 at some sites): Japanese cedar at four sites, hinoki cypress and Japanese konara oak at two sites, and Japanese red pine at one site. Our previous report on 137Cs concentrations in bark and whole wood samples collected from 2011 to 2015 suggested that temporal variations were different among sites even within the same species. In the present study, we provided data on bark and whole wood samples in 2016 and separately measured 137Cs concentrations in sapwood and heartwood samples from 2011 to 2016; we further discussed temporal trends in 137Cs concentrations in each part of tree stems, particularly those in 137Cs distributions between sapwood and heartwood, in relation to their species and site dependencies. Temporal trends in bark and whole wood samples collected from 2011 to 2016 were consistent with those reported in samples collected from 2011 to 2015. Temporal variations in 137Cs concentrations in barks showed either a decreasing trend or no clear trend, implying that 137Cs deposition in barks is inhomogeneous and that decontamination is relatively slow in some cases. Temporal trends in 137Cs concentrations in sapwood, heartwood, and whole wood were different among species and also among sites within the same species. Relatively common trends within the same species, which were increasing, were observed in cedar heartwood, and in oak sapwood and whole wood. On the other hand, the ratio of 137Cs concentration in heartwood to that in sapwood (fresh weight basis) was commonly increased to more than 2 in cedar, although distinct temporal trends were not found in the other species, for which the ratio was around 1 in cypress and pine and below 0.5 in oak, suggesting that 137Cs transfer from sapwood to heartwood shows species dependency. Consequently, the species dependency of 137Cs transfer within the tree appears easily, while that from the environment to the trees can be masked by various factors. Thus, prediction of 137Cs concentrations in stem wood should be carried out carefully as it still requires investigations at multiple sites with a larger sample size and an understanding of the species-specific 137Cs transfer mechanism.

Viscoelastic modeling of wood in the process of formation to clarify the hygrothermal recovery behavior of tension wood

To explain the hygrothermal recovery (HTR) behavior of tension wood (TW) from the physical and chemical point of view in relation to the time, species and microfibril angle, a theoretical discussion using an analytical one-dimensional viscoelastic modeling was made. The chosen model includes an elastic element, a deformation mechanism and two viscoelastic elements called also as Kelvin–Voigt model. In this analysis, a top-down approach between the model and the experimental data was introduced to find the realistic parameters for the model. It enables us to fit the model to the HTR experimental data for three wood species: konara oak (Quercus serrata Murray), urihada maple (Acer rufinerve Siebold et Zucc.) and keyaki wood (Zelkova serrata Makino). The fitted experimental data show that the two compliances of the two viscoelastic elements are the most important parameters that explain the evolution of TW longitudinal strain during the thermal treatment.

Using a novel method of potential available energy to determine masting condition influence on sex-specific habitat selection by Asiatic black bears

Abstract Habitat selection is assumed to accrue fitness benefits. Where resource availability is variable, individuals should respond by changing habitat selection to increase resource availability. However, direct links between observed changes in habitat selection and energetic benefits of this behavior are rarely detected. We used a novel method whereby we converted interannual production levels of three hard-mast-producing Fagaceae species into a comparative energetic productivity score to investigate potential energetic benefits of Asiatic black bear habitat selection. We captured and fitted GPS collars on 19 bears between 2006 and 2010 in the Ashio-Nikko Mountains, Japan. We also collected data on hard-mast production and integrated these data with fine-scale vegetation maps. Then we mapped the potential available mast energetic production for each vegetation type to evaluate their potential energetic benefit for bears. Habitat use differed between poor and good mast years. Bears mostly used Japanese oak in good mast years, and there were sexual differences in September of poor mast years; females used mostly Japanese oak, whereas males used Konara oak. In those years, bears may have benefitted energetically by changing habitat use; however, the mean potential available energy to bears never exceeded that in good mast years, even if they used different habitats.

Temporal changes in the radiocesium distribution in forests over the five years after the Fukushima Daiichi Nuclear Power Plant accident

To elucidate the temporal changes in the radiocesium distribution in forests contaminated by the Fukushima Daiichi Nuclear Power Plant accident, we monitored the 137Cs concentration and inventory within forests from 2011 to 2015 across nine plots containing variable tree species and different contamination levels. The 137Cs concentrations in needles and branches decreased exponentially at all coniferous plots, with effective ecological half-lives of 0.45–1.55 yr for needles and 0.83–1.69 yr for branches. By contrast, the 137Cs concentration in deciduous konara oak leaves did not change over the five years. The concentration of 137Cs in oak wood increased by 37–75%, whereas that in Japanese red pine decreased by 63% over the five years. In Japanese cedar and hinoki cypress, the 137Cs concentration in wood showed an increasing trend in half of the plots. The changes in 137Cs in the organic and mineral soil layers were not strongly related to the tree species or contamination level. Our multi-site, multi-species monitoring results revealed that the pattern of temporal changes in radiocesium in the 9 forest plots was similar overall; however, changes in 137Cs in needles/leaves and wood differed among tree species.

Stemflow-induced spatial heterogeneity of radiocesium concentrations and stocks in the soil of a broadleaved deciduous forest

The transport of radiocesium from the canopy and quantification of the spatial distribution of radiocesium in the soil of konara oak forests are important to better understand the variability of 137Cs stocks in the soil between proximal and distal stem areas as well as fine-scale variations around the tree trunk. Moreover, a better understanding of fine-scale spatial variabilities of 137Cs concentrations and stocks will provide insights for optimizing soil sampling strategies to provide a more robust estimation of contamination at the stand scale. This study aims to elucidate the transport of 137Cs by stemflow in a radioactively contaminated konara oak forest in Tsukuba, Japan by describing and quantifying the fine-scale spatial distribution of 137Cs in the soil and preferential flowpaths of stemflow on the tree stem by a dye tracing experiment. 137Cs concentrations and stocks were higher in the soils of the proximal stem area than distal stem area when they corresponded with the preferential flowpaths of stemflow. There was a significant relationship between canopy projection area of individual trees and average soil 137Cs concentrations and stocks, even though canopies of the trees overlapped. Our results demonstrate that the spatiality of 137Cs concentrations and stocks in the soil of the proximal stem area are governed (at least partially) by the preferential flowpaths of stemflow along the tree trunk. In addition, higher 137Cs concentrations and stocks in the near-trunk soils of trees with larger crown areas might be caused by an enhanced ability to capture dry deposition.

Effects of Ozone and Sulfuric Acid on Konara Oak Leaves and Method to Mitigate the Effects

Effects of Ozone and Sulfuric Acid on Konara Oak Leaves and Method to Mitigate the Effects

Increased phytotoxic O3 dose accelerates autumn senescence in an O3-sensitive beech forest even under the present-level O3

Ground-level ozone (O3) concentrations are expected to increase over the 21st century, especially in East Asia. However, the impact of O3 has not been directly assessed at the forest level in this region. We performed O3 flux-based risk assessments of carbon sequestration capacity in an old cool temperate deciduous forest, consisting of O3-sensitive Japanese beech (Fagus crenata), and in a warm temperate deciduous and evergreen forest dominated by O3-tolerant Konara oak (Quercus serrata) based on long-term CO2 flux observations. On the basis of a practical approach for a continuous estimation of canopy-level stomatal conductance (Gs), higher phytotoxic ozone dose above a threshold of 0 uptake (POD0) with higher Gs was observed in the beech forest than that in the oak forest. Light-saturated gross primary production, as a measure of carbon sequestration capacity of forest ecosystem, declined earlier in the late growth season with increasing POD0, suggesting an earlier autumn senescence, especially in the O3-sensitive beech forest, but not in the O3-tolerant oak forest.

The effect of fertilization on early growth of konara oak and Japanese zelkova seedlings planted in a harvested pitch pine plantation

We determined a suitable amount of fertilizer for konara oak (Quercus serrata) and Japanese zelkova (Zelkova serrata) planted in a harvested pitch pine (Pinus rigida) plantation. Two-year-old bare-root seedlings of konara oak and one-year-old containerized seedlings of Japanese zelkova were planted in April 2011. Three plots were established for each tree species to evaluate each of three fertilization applications. Solid compound fertilizer (N:P:K = 3:4:1) was applied yearly in three amounts (control: no fertilization, F1: 180 kg ha−1, and F2: 360 kg ha−1), every May from 2011 to 2013. We measured the root collar diameter and height, and analyzed the compartmental N and P concentrations. Compartmental N concentrations of konara oak and Japanese zelkova were not consistent based on amount of fertilization. However, the compartmental P concentrations of konara oak and Japanese zelkova were significantly different in the order of F2, F1, and control. Although the differences in growth of konara oak appeared after 3 years of fertilization, Japanese zelkova showed differences after only 2 years of fertilization owing to differences in seedling type. Growth of konara oak was affected by fertilization at F1 and F2 in 2013. However, growth of Japanese zelkova was affected only at F2. Nutrient demand of Japanese zelkova appeard to be higher than that of konara oak, at least during the early growing period. Results from this study could be practically used in harvested pitch pine plantations to determine appropriate fertilization regimes.

실내 사용 목재의 연소 특성 분석 (II)

The aim of this study is to analyze the combustion and thermal properties in order to establish baseline data for the fire safety evaluation of domestic timbers. The combustion properties such as heat release rate, total heat release, gas yield, and mass loss were analyzed by the method of cone calorimeter test and thermogravimetry (TGA). Thermal de- composition temperatures of the specimens by TGA were recorded as 359.83℃ for White pine, 359.80℃ for Red-Leaved Hornbeam, 363.14℃ for Carolina poplar, 358.59℃ for Konara oak, and 362.11℃ Sargent cherry. Red-Leaved Hornbeam showed the highest value of heat release rate, but, Carolina poplar wood showed the lowest value. In case of the total heat release, Red-Leaved Hornbeam wood showed the highest value and Carolina poplar wood showed the lowest one. The gas analysis results showed that Sargent cherry wood had the lowest value of 0.021, and Konara oak had the highest at 0.031 in the CO/CO2. The minimum value of mass reduction was recorded as 87.57% for Sargent cherry, but, on the other hand, it was 95.03% for Konara oak. There was a correlation between the gas generation of CO and CO2, and combustion behavior of woods. These results are expected to be usful for providing a fundamental guideline with the fire safety of wood use in interior applications.

Effect of the warming experiment using open chambers on the production of the konara oak(Quercus serrata)

Effect of the warming experiment using open chambers on the production of the konara oak(Quercus serrata)

실내사용 목재의 연소 특성 분석(I)

The aim of this study is to analyze the combustion and thermal properties in order to establish baseline data for the fire safety evaluation of domestic timbers. The combustion properties such as heat release rate, total heat release, gas yield, and mass loss were analyzed by the method of cone calorimeter test and thermogravimetry (TGA). Thermal de- composition temperatures of the specimens by TGA were recorded as 359.83℃ for White pine, 359.80℃ for Red-Leaved Hornbeam, 363.14℃ for Carolina poplar, 358.59℃ for Konara oak, and 362.11℃ Sargent cherry. Red-Leaved Hornbeam showed the highest value of heat release rate, but, Carolina poplar wood showed the lowest value. In case of the total heat release, Red-Leaved Hornbeam wood showed the highest value and Carolina poplar wood showed the lowest one. The gas analysis results showed that Sargent cherry wood had the lowest value of 0.021, and Konara oak had the highest at 0.031 in the CO/CO2. The minimum value of mass reduction was recorded as 87.57% for Sargent cherry, but, on the other hand, it was 95.03% for Konara oak. There was a correlation between the gas generation of CO and CO2, and combustion behavior of woods. These results are expected to be usful for providing a fundamental guideline with the fire safety of wood use in interior applications.

Foliar rinse study of atmospheric black carbon deposition to leaves of konara oak (Quercus serrata) stands

Dry deposition of Black Carbon (BC) to the actual leaves of konara oak (Quercus serrata) was evaluated in a foliar rinse method in an experimental forest in the suburbs of Tokyo, Japan in order to explore deposition levels and vertical profile within the forest. At three heights of the forest of 20 m height, 20 m, 15 m, and 6 m or 4 m, leaves were sampled on a weekly basis for a couple of months in 2011 and 2012 and subjected to rinsing with water and chloroform. The BC in the rinse solution was collected on a quartz fiber filter and determined by spectrophotometry. The BC mass deposited to leaves increased with height and this profile pattern was generally maintained in the study period. The specific BC mass deposited to leaves showed considerable fluctuations with time, but the deposited BC increased rapidly with time in the bud flushing stage, then attained to a plateau, and began to decrease as the defoliation advanced. The plateau is a result of a simple accumulation with time and occasional removal due to rainfall and strong winds. The maximum BC mass deposited to leaves per leaf surface unit area occurred in June where the level was 10–15 mg-BC m−2. The rate of BC mass deposited to leaves at the time of leaves growing was determined to be 0.237 and 0.277 mg-BC m−2 day−1 for measurements in 2011 and 2012, respectively. On the basis of the observed BC mass deposited to the leaves, BC mass deposited to leaves per forest floor unit area estimated with LAI showed a strong seasonality. The BC mass deposited to leaves per forest floor unit area was compared to the deposition flux from the atmosphere to the forest canopy, which would be interpreted as indicating that 30% of atmospheric BC deposition to the canopy was retained on the leaves in time of leaves growing.

Radial and vertical distributions of radiocesium in tree stems of Pinus densiflora and Quercus serrata 1.5 y after the Fukushima nuclear disaster

The radial and vertical distributions of radiocesium in tree stems were investigated to understand radiocesium transfer to trees at an early stage of massive contamination from the Fukushima nuclear disaster. A conifer species (Japanese red pine) and a broad-leaved species (Japanese konara oak) were selected to determine whether the radiocesium contamination pattern differs between species. Stem disks were collected at several heights and separated into outer bark, inner bark, and wood. The radiocesium concentration was the highest in the outer bark, followed by that in the inner bark and wood. The vertical distribution of the radiocesium concentration at each stem part differed between the species. The difference between species in radiocesium concentration of the outer bark could be explained by presence or absence of leaves at the time of the disaster. However, the reasons for the differences between species in the radiocesium concentration of the inner bark and wood are unclear. The radial distribution in the wood of the studied species showed a common pattern across stem disk heights and species. However, the radiocesium concentration ratio between sapwood and inner bark was significantly different between species. Although the radial contamination pattern in the wood was similar in the studied species during the early stage of contamination, the radiocesium transport pathway and allocation would be different between the species, and the contamination pattern will likely be different between the species at later stages. Continued investigations are important for understanding the radiocesium cycle and the accumulation of radiocesium in the tree stems of each species.

Changes in the Quality of Chromophoric Dissolved Organic Matter Leached from Senescent Leaf Litter during the Early Decomposition

Chromophoric dissolved organic matter (CDOM) leached from leaf litter is a major source of humus in mineral soil of forest ecosystems. While their functions and refractoriness depend on the physicochemical structure, there is little information on the quality of CDOM, especially for that leached in the very early stages of litter decomposition when a large amount of dissolved organic matter (DOM) is leached. This study aimed to better understand the variations/changes in the composition of CDOM leached from senescent leaf litter from two tree species during the early stage of decomposition. Leaf litter from a conifer tree (Japanese cedar, D. Don) and a deciduous broad-leaved tree (Konara oak, Thunb.) were incubated in columns using simulated rainfall events periodically for a total of 300 d at 20°C. The quality of CDOM was investigated based on the fluorescence properties by using a combination of excitation-emission matrix fluorescence (EEM) and parallel factor analysis (PARAFAC). In addition, the phenolic composition of DOM was investigated at a molecular level by thermally assisted hydrolysis and methylation-gas chromatography-mass spectrometry (THM-GC-MS) in the presence of tetramethylammonium hydroxide (TMAH). The EEM was statistically decomposed into eight fluorescence components (two tannin/peptide-like peaks, one protein-like peak, and five humic-like peaks). A significant contribution of tannin/peptide-like peaks was observed at the beginning of incubation, but these peaks decreased quickly and humic-like peaks increased within 1 mo of incubation. The composition of humic-like peaks was different between tree species and changed over the incubation period. Since tannin-derived phenolic compounds were detected in the DOM collected after 254 d of incubation on THM-GC-MS, it was suggested that tannins partially changed its structure, forming various humic-like peaks during the early decomposition.

Ammonium nitrate-impregnated woodchips: a slow-release nitrogen fertilizer for plants

Different types of fertilizers are widely used throughout the world for successful crop production. Chemical fertilizers have some adverse effects on the environment if used indiscriminately and are a major source of soil and water pollution. To minimize environmental pollution, use of slow-release fertilizer (SRF) in agricultural practices is an important and effective method. Different materials have been used so far to formulate SRF, but SRF from wood is a unique technique which reflects a new dimension of wood use. In this aspect, present study was designed to develop a slow-release nitrogen fertilizer using three kinds of woodchips: Japanese red pine (Pinus densiflora S. et Z.), eunsasi poplar (Populus tomentiglandulosa T. Lee), and konara oak (Quercus serrata Thunb.). Fertilizers were prepared from woodchips after full-cell treated with a saturated solution (2140 g/l at 25°C) of ammonium nitrate (NH4NO3). The morphology of woodchip fertilizer was investigated by using a field-emission electron microscope (FE-SEM) equipped with an energy-dispersive X-ray (EDX) spectrometer to locate NH4NO3 in woodchips. Deposition of nitrogen in the cell lumen was verified by FE-SEM. Deposition inside the cell wall was confirmed by EDX mapping. This study also evaluated the release pattern of nitrogen from impregnated woodchips in distilled water for 768 h and found that nitrogen was released from poplar, pine, and oak in a slow-release pattern. The encapsulated nutrient in the void volume of wood facilitated the slow release. The above findings confirm that woodchip fertilizers can be used as a slow-release nitrogen source for plants.

Liquid penetration in different cells of two hardwood species

Two experimental techniques were used to test the water permeability of two Korean hardwood species: diffuse porous Populus tomentiglandulosa T. Lee (eunsasi poplar) and ring porous white oak, Quercus serrata Thunb (konara oak). The first technique measured the void volume filled at different moisture content (MC) levels. Samples were treated with water via a schedule of full-cell impregnation. A significant relation between MC and permeability (the fractional void volume) was found. A reduction in liquid permeability was observed at MC above the fiber saturation point (FSP), whereas the opposite result was observed at MC below FSP due to the effect of the voids available in the wood. However, the differences of increased permeability from MC level 20% to 0% were found satistically the same in either wood species. The second technique measured the speed of liquid penetration in vessels, fibers, and rays with no application of external pressure. In this method, liquid flow was captured via video and the penetration speed was measured. Vessels, fibers, and rays in poplar were found to be more permeable than those in oak. Different anatomical factors such as cell diameter, cell length, pit number, pit aperture area, and thickness of the pit membrane seemed to be responsible for the variation of liquid flow rate in different cells of the two hardwood species.

Effect of mast production on home range use of Japanese black bears

AbstractAlthough bears may expand their home ranges in times of low food availability, it is unclear what mechanisms directly affect home range extension in times of low mast production in Japanese forests. To clarify the relationship between home range utilization by Japanese black bears (Ursus thibetanus) and abundance and distribution of mast production, we collected data on habitat use from 13 bears (6 M and 7 F) fitted with Global Positioning System (GPS) collars equipped with activity sensors in the Ashio‐Nikko Mountains on the eastern part of Honshu Island, Japan, during 2006–2008. We also collected data on mast production by 5 Fagaceae species. We categorized each fall as either poor (2006) or relatively‐good (2007 and 2008) based on mast production. Bears used small patches in their large home ranges and the distances between core areas increased in the fall of 2006, when the mast of Japanese oak (Quercus crispula) were poorly distributed. Our findings suggest that localized patches of Japanese oak are the staple food for bears in our study area, even in poor mast years. However, in the fall of 2006, we also found that bears moved to lower elevations, relative to 2007 and 2008, in search of alternative foods (e.g., Konara oak [Q. serrata] and Japanese chestnut [Castanea crenata]), which were mostly at lower elevations and produced mast consistently over the study period. Our results suggest that dispersion and elevational distribution of mast‐producing trees affect bear habitat use in fall, as well as amount of mast. © 2011 The Wildlife Society.