Bark stripping by sika deer on veitch fir related to stand age, bark nutrition, and season in northern Mount Fuji district, central Japan

We carried out this study to clarify the relationships between the seasonal changes of bark stripping and food quality, and between bark-stripping intensity and bark nutrition with age of veitch fir (Abies veitchii) by sika deer (Cervus nippon) in the northern Mount Fuji district, from June 2000 to July 2003. We found that sika deer gnawed and ate all of the bark stripped, and a seasonal change in bark stripping occurred from December to May or June with a peak in March–April. The stripping period largely overlapped with the periods of low food availability and poor food nutrition (indicated by fecal chemical component index) of sika deer, from January to April. Both bark nutritional quality and bark-stripping intensity related to stand age and tree size of veitch fir negatively. Consequently, bark-stripping intensity related to bark nutritional quality positively. February is the worst forage period in terms of both quantity (due to deep snow) and quality (indicated by fecal chemical components). There was a time lag of 1 to 2 months in the peak of bark stripping in March–April when compared with the poor forage period in February. This time lag may suggest that sika deer need more nutritious and easily digested food from March due to increased nutrient demands that result from depleted body condition in both sexes, gestation of pregnant females, and the recovery of active metabolism.     

Effects of heavy,repeated bark stripping by Cervus nippon on survival of Abies veitchii in a subalpine coniferous forest in central Japan

The management of deer impacts on forested lands requires quantification of the negative factors(e.g.,bark stripping) on tree survival in relation to other ecological variables(e.g.,competition from neighboring trees).This study measured the effects of bark stripping by sika deer,Cervus nippon,and competition among trees on the survival of Abies veitchii in a subalpine coniferous forest in central Japan over 12 years.Most of the trees subjected to bark stripping by deer were small(10 cm in diameter at breast height);however,some trees were stripped repeatedly.Although light bark stripping did not strongly influence tree survival after 12 years,heavily stripped stems(i.e., 65% of the stem circumference stripped) were severely affected.The effect on longevity for each tree after bark stripping was explained by maximum bark stripping intensity during the study period,rather than initial bark stripping intensity.When 85% of the stem circumference had been stripped,survival rates decreased.Bark stripping influenced survival rates much more than competition from neighboring trees.Because bark stripping occurred repeatedly,frequent measurements are important to grasp the full effects caused by this action.Heavy bark stripping of a stem enhances tree mortality.Thus,management of bark stripping is an essential element of stand maintenance and species composition in subalpine coniferous forests in Japan.     

Effects of bark stripping by sika deer, Cervus nippon, on wind damage to coniferous trees in subalpine forest of central Japan

We evaluated the effect of bark stripping by sika deer (Cervus nippon), and subsequent wood decay, on tree fall in a coniferous forest on Mt Ohdaigahara in central Japan from July to September 2006. This valuable primeval coniferous forest is declining because of bark stripping. Broken trunks of Abies homolepis and Picea jezoensis var. hondoensis had more serious decay and larger bark-stripping wounds on the trunk than standing trees, suggesting that bark stripping causes trunk decay and results in broken trunks and uprooting by typhoons.     

Impact of bark stripping by sika deer, Cervus nippon, on subalpine coniferous forests in central Japan

We investigated the effect of bark stripping by sika deer, Cervus nippon, on forest regeneration in subalpine coniferous forests on Mt. Ohdaigahara and in the Ohmine Mountains of central Japan. Bark stripping by sika deer occurred in five major tree species: Abies homolepis; Abies Veitchii; Tsuga diversifolia; Picea jezoensis var. hondoensis; and Chamaecyparis obtusa. The percentage of damaged trees on Mt. Ohdaigahara was higher than in the Ohmine Mountains, probably because of the higher deer density. On Mt. Ohdaigahara, the DBH distributions of stems for P. jezoensis var. hondoensis, A. homolepis, T. diversifolia andC. obtusa were bell-shaped with fewer smaller and larger trees. On the other hand, in the Ohmine Mountains the distributions for P. jezoensis var. hondoensis and A. Veitchii showed a reverse-J shaped with more smaller trees. Larger overstory conifers on Mt. Ohdaigahara were killed by bark stripping when 100% barked, although in the Ohmine Mountains ca. 50% of the trees survived even when 100% barked. After the disappearance of the overstory conifers on Mt. Ohdaigahara, the dwarf bamboo, Sasa nipponica, expanded into the forest floor due to changes in light reaching the forest floor. Since S. nipponica is the main forage of deer in this area, this increase caused a corresponding increase in the deer population, which in turn, could cause a further decline in the coniferous forests.     

Assessing decline in physical structure of deciduous hardwood forest stands under sika deer grazing using shrub-layer vegetation cover

For 345 stands of deciduous hardwood forest in Hyogo Prefecture, Western Japan, we assessed the decline of shrub-layer vegetation due to sika deer in each stand by using the shrub-layer decline rank (SDR), determined by combining the shrub-layer vegetation cover and the presence of signs of grazing by sika deer in a stand. Since there was a geographical correlation between SDR and sighting per unit effort (SPUE), which is an index of the relative density of sika deer, it appeared that decline of shrub-layer vegetation in a stand can be accurately evaluated by SDR. There were correlations between SDR and several variables that indicate the status of components in forests (presence of saplings of tall trees, occurrence of bark stripping of tall trees, proportion of bark-stripped stems of Clethra barvinervis, decline of subtree-layer vegetation by bark stripping, cover of litter on the ground, and area of soil surface erosion). These results indicate that the status of these components changes with decline of shrub-layer vegetation by sika deer grazing. It is thought that such synchronizations are caused by sika deer grazing or a direct or indirect effect by decline of shrub-layer vegetation due to sika deer. Therefore, it is reasonable to assess decline in physical structure due to sika deer for stands of deciduous hardwood forests according to SDR.     

Expansion of dwarf bamboo, Sasa nipponica, grassland under feeding pressure of sika deer, Cervus nippon, on subalpine coniferous forest in central Japan

The long-term changes of the area of Sasa nipponica grassland, bark stripping damage to trees by sika deer, Cervus nippon, and sika deer densities on Mt. Ohdaigahara were assessed with aerial photographs, information from previous studies, and field experiments. The grasslands expanded year after year. The expansion rate was highest from 1982 to 1992, and lowest from 1992 to 1997. Bark-stripping damage on coniferous trees was heavier than that on broadleaf trees in both the early 1980s and 1998. The deer density in the eastern part of the area had been high (14.4–64.3 km⁻²) from 1984 until 1998. We presume that rich growth of S. nipponica and heavy feeding pressure by sika deer over the long term caused expansion of S. nipponica grasslands by killing canopy trees by bark stripping and preventing forest regeneration.     

Deer density effects on vegetation in aspen forest understories over site productivity and stand age gradients

Studies examining the interacting effects of ungulate herbivore pressure and site productivity on vegetation are mostly on grassland-grazing systems and have shown conflicting patterns. Here we examine the effects of deer density (>30 years differences in density between two landowners), site productivity (site index, SI) and stand age on subcanopy vegetation characteristics in 60 closed canopy, clear-cut origin Populus tremuloides dominated stands, Michigan, USA. Stand age effects were included because age varied among stands and can affect subcanopy vegetation patterns. Compared with fewer deer, stands with more deer had greater total forest floor vegetation mass, and its major components bracken fern (Pteridium aquilinum), sedge (mostly Carex pensylvanica) and trees/shrubs <0.25 m tall, but lower forb mass and lower forest floor vegetation species richness and diversity. Deer density and SI had strong interacting effects on total forest floor mass, forb mass, and species richness. Forb mass increased with SI, but only in stands with fewer deer, whilst total vegetation mass was greater in stands with more deer at lower SI and declined with SI more sharply than for stands with fewer deer. Species richness increased with SI but more so at lower than higher deer density. Deer density and age had interacting effects on mass of trees/shrubs <0.25 m tall and sedge. Compared with fewer deer, stands with more deer had greater sedge and tree/shrub mass, and sedge mass decreased and tree/shrub mass increased more sharply with age. In lower deer stands there was a dense subcanopy tree and shrub strata within and beyond the reach of deer 0.9-10 m tall whereas in higher deer stands this vegetation layer was nearly absent. We conclude that higher deer browse pressure in early successional Populus stands (1) strongly limits the recruitment of woody stems to larger (>0.9 m tall) size classes, which could affect long-term successional trajectories, and (2) diminishes forb density and species richness, especially at higher site productivity, but increases total forest floor vegetation mass (mostly bracken fern and sedge), especially at lower site productivity. Given associations of bracken fern and sedge with poorer and/or more open sites and assuming high palatability of forbs, this pattern may result from the combination of selective herbivory and higher light availability caused by limited recruitment of trees and shrubs to taller strata.     

Development of a method for forest cafeteria tests for evaluating chemical deterrents against bark stripping by sika deer (Cervus nippon yesoensis)

Damage caused by sika deer (Cervus nippon yesoensis) is a serious problem in commercial and environmental (non-harvested) forests in Hokkaido, northern Japan. Cafeteria tests in forests may be useful for evaluating the efficacy of chemical deterrents against bark stripping by deer. To develop a method for forest cafeteria tests in the continuous snow cover period, two experiments were carried out. In the experiments, logs were produced from tree trunks, and used as carriers of chemical deterrents. Carriers were installed in forests and fed to deer. The first experiment was to find suitable sites and installation methods for carriers. Criteria for the local suitability and the installation methods were as follows: a) Sites where deer are active should be selected; b) Carriers should be installed along actively used deer trails; c) Installation sites of carriers should be changed in response to deer movement; d) Carriers should be produced from tree species that deer naturally prefer; and e) Each carrier should be partially buried in the snow. The second experiment evaluated the feasibility of a cafeteria test method based on the results of the first experiment. The method was used for 13 sets of the cafeteria test, in which the deterrent effectiveness of 5 chemicals (wood tar, rosin, wood vinegar, and 2 pyroligneous liquors) was examined. We obtained results from all the sets. The chemicals tested did not deter bark stripping by deer. Nevertheless, the method used in the present study was practical for the cafeteria tests.     

Effects of sika deer (Cervus nippon yakushimae) population growth on saplings in an evergreen broad-leaved forest

An increase in size of sika deer populations has caused severe damage to forest vegetation in many regions of Japan. In a Natural World Heritage area on the western part of Yakushima Island, existing high densities of deer are thought to be increasing, but the impact of deer on forest vegetation has not been estimated. Roadside censuses of deer between 1988 and 2006 showed that encounter rates are continuing to increase. Long-term monitoring of individual tree saplings in a 0.13 ha area of the forest between 1992 and 2005 showed that many saplings still remain despite increases in sika deer density. However, differences in growth and mortality rates of preferred, neutral (neither preferred nor avoided) and avoided sika deer food species varied over time. As a group, preferred species continuously had a low growth rate, while their mortality rate increased through time. The growth rates of the neutral and avoided groups decreased especially in the second half of our study period at the same time that their mortality rates increased. These data suggest that in spite of food species preference, direct feeding pressures as well as indirect physical effects by increasing sika deer density are affecting growth and mortality of tree saplings. Clearly, it is difficult to predict how plant communities will respond to possible continued sika deer population growth, and it is therefore important to continue monitoring these forest communities in the interest of preserving the unique ecosystems on Yakushima Island.     

Resistance of larches to bark stripping by sika deer in Hokkaido,northern Japan

Resistance of the Japanese larch (Larix kaempferi) (Lk), the Kurile larch (L. gmelinii var. japonica) (Lg), and their F₁ hybrid (Lg × Lk) to bark stripping by sika deer (Cervus nippon yesoensis) were studied in a forest in Hokkaido by cafeteria tests. Several sets of logs prepared from Lk, Lg, and Lg × Lk were fed to the deer. The stripped areas of logs significantly differed between the Lk/Lg set and the Lk/Lg × Lk set (P 0.05). The resistances of Lg and Lg × Lk to bark stripping was stronger than Lk. This result was similar to those of previous studies on gray-sided voles and mountain hares in Hokkaido.     

Altitudinal variability of stand structure and regeneration in the subalpine spruce forests of the Pol’ana biosphere reserve,Central Slovakia

The structure of natural subalpine spruce forest in the Zadná Pol’ana massif of the Western Carpathians was analysed. We focused on the variability of different aspects of stand structure, tree decay and regeneration processes in altitudinal gradient. We used systematic sampling, covering an area of 2 km², to detect even subtle changes in stand structure within one forest type over a range of less than 200 m in elevation. Mean stand density was 290 trees (>7 cm DBH) per hectare, average basal area was 41 m² ha⁻¹, and the volume accumulation in living trees amounted to 500 m³/ha⁻¹. Stand volume decreased by more than 50% between 1,260 and 1,434 m a.s.l. This means for an increase of altitude of 100 m that stand volume decreased by nearly 200 m³. Neither stand density nor basal area was related to elevation. Maximum tree height was strongly correlated to elevation, and it decreased on average by 6 m for each 100 m increment of altitude. No significant changes in the maximum spruce diameter were recorded in relation to the elevation gradient. Spatial distribution of trees was biased toward regularity at lower altitudes. Tree clustering increased with increasing altitude. The stock of coarse woody debris (CWD) decreased slightly along the altitudinal gradient, but changes were not significant. Density of spruce saplings and their number growing on CWD significantly increased across the elevation gradient. Despite the fact that the analysed forest tract was relatively large, highly variable in respect to environmental factors, and that stand volume, spatial structure, and tree height displayed strong variability along the elevation gradient, the diameter structure of stands and regeneration measures were uniform. Our results suggest that the recruitment of new trees in the Zadná Pol’ana subalpine spruce forest is not temporally continuous even at a scale of several square kilometres.     

Profound impoverishment of the large-tree stand in a hyper-fragmented landscape of the Atlantic forest

Large tree species have a disproportional influence on the structure and functioning of tropical forests, but the forces affecting their long-term persistence in human-dominated landscapes remain poorly understood. Here we test the hypothesis that aging forest edges and small fragments (3.4–295.7 ha) are greatly impoverished in terms of species richness and abundance of large trees in comparison to core areas of forest interior. The study was conducted in a hyper-fragmented landscape of the Atlantic forest, northeast Brazil. Large tree species were quantified by recording all trees (DBH ≥ 10 cm) within fifty-eight 0.1-ha plots distributed in three forest habitats: small forest fragments (n = 28), forest edges (n = 10), and primary forest interior areas within an exceptional large forest remnant (n = 20). Large tree species and their stems ≥10 cm DBH were reduced by half in forest edges and fragments. Moreover, these edge-affected habitats almost lacked large-stemmed trees altogether (0.24 ± 0.27% of all stems sampled), and very tall trees were completely absent from forest edges. In contrast, large trees contributed to over 1.5% of the whole stand in forest interior plots (2.9 ± 2.8%). Habitats also differed in terms of tree architecture: relative to their DBH trees were on average 30% shorter in small fragments and forest edges. Finally, an indicator species analysis yielded an ecological group of 12 large tree species that were significantly associated with forest interior plots, but were completely missing from edge-affected habitats. Our results suggest a persistent and substantial impoverishment of the large-tree stand, including the structural collapse of forest emergent layer, in aging, hyper-fragmented landscapes.     

White-tailed deer activity reconstructed from tree-rings in eastern boreal Canada

We evaluated the potential of tree-ring techniques for the reconstruction of recent and past seasonal activity of introduced white-tailed deer in a boreal environment of eastern Canada. Hoof scrape scars on balsam fir stems and trampling scars on roots were used to reconstruct deer activity during the winter and snow-free seasons, respectively. Tree damage showed that there was continuous deer activity in the north-central part of Anticosti Island since the mid-1960s. High scrape scars along tree stems (3–3.5 m from the ground) indicate that 1975, 1976, 1981, 1983 and 1985 were years of intensive food search by deer on high balsam fir foliage. The annual number of hoof scrape scars was low between 1982 and 1985, when severe defoliation by the spruce budworm, combined with deer browsing, led to high fir sapling mortality, food depletion, degradation of the winter shelter forests and a decrease in deer activity. The lowest scrape scars 50 cm above ground correspond to the mean height of the residual snowpack in the shelter forest at springtime, when deer start searching for food in nearby open sites and use logging roads, where dead and bonsai-like fir predominate due to overbrowsing. The trampling scar age frequency distribution from two sites indicated that deer activity during the snow-free season started synchronously in the late 1960s. In response to degradation of winter shelter forests, deer may have moved from the southern part to the north-central part of the island and other sectors to survive. Deer-induced tree damage and tree-ring techniques can thus be used to reconstruct past seasonal activity of white-tailed deer.     

An increase in the upper tree-limit of silver fir (Abiesalba Mill.) in the Alps since the mid-20th century: A land-use change phenomenon

Global environmental changes observed during recent decades are likely to have had an impact on the distribution of species. Currently, silver fir (Abies alba) is becoming established in the subalpine forests of the west central Alps at elevations higher than 2000 m a.s.l.; prior to the 1970s its upper altitudinal limit was 2000 m. Several hypotheses could explain this recent expansion of the upper tree-limit. Silver fir regeneration could be linked (1) to land-use changes or (2) to current climatic warming. Using dendrochronology, the age structure of 31 forest plots containing at least one silver fir was examined in order to elucidate the population dynamics of subalpine communities. This allowed us to decipher the timing of fir regeneration in relation to the mean age of the stands examined and of the other tree-canopy species present. The majority of the firs germinated sporadically since 1950, before the regional temperature increase. The pattern of fir recruitment did not appear to relate to altitude, but followed a pattern characteristic of secondary succession. The age structures identified showed an exponential increase in tree-density during the 20th century; the stands were first dominated by Larix decidua during the 18th and 19th centuries, and then by Pinus cembra during the 20th century. In most stands, fir regeneration occurred after Larix and before P. cembra dominated, following a similar pattern to Picea abies regeneration. The number of local inhabitants and temperature both exhibited a negative relationship with fir tree recruitment, thus supporting the land-use change hypothesis. There has been a significant upward shift of the altitudinal range of fir, amounting to an increase of about 300 m since 1950. This followed the abandonment of low-productivity land. This trend is likely to continue during the 21st century, because of new agricultural and forestry practices which involve limited intervention in low-productivity areas and may be because of the effects of global warming.     

Early-stage impacts of sika deer on structure and function of the soil microbial food webs in a temperate forest: A large-scale experiment

Modification of forest vegetation caused by an overabundance of mammalian herbivores has been reported in temperate and subarctic regions all over the world. However, the indirect effects of these herbivores on the structure and functions of soil decomposer systems are not fully understood, especially in temperate forests. We investigated the early effects of sika deer invasion on soil decomposer systems in a Japanese temperate forest using two large-scale experimental enclosures with low and high densities of deer (LD: 25 ha, 4 deer km⁻²; HD: 6.25 ha, 16 deer km⁻²) including control plots without deer (WD). Three years after deer introduction the understory cover of dwarf bamboo (Sasa nipponica) declined due to deer browsing in both enclosures. At the same time, measurements were made of the soil microbial community, soil nematode community, soil nitrogen (N) mineralization rate, and carbon (C) and N content in dwarf bamboo leaves. In LD, soil microbial biomass was lower from WD, probably due to the decrease of fresh aboveground litter from dwarf bamboo. Surprisingly, there were no cascading effects on total abundance of soil nematodes and soil total N mineralization potential which were unaffected by deer in the LD treatment, while soil NH₄⁺-N content was lower and soil nematode community structure was different (abundance of 4 families was higher and that of 3 families was lower, but the functional structure was not different) from WD. Specifically, the responses to deer introduction varied between microbes and nematodes, and the change of balance in the microbial food webs may have altered N mineralization processes. In contrast, in the HD treatment, all the variables measured were not significantly different from those of WD treatment. Intensive browsing by deer may have cancelled out the effects of the decrease in aboveground litter input on the soil decomposer systems through other pathways, such as a transitory increase in belowground litter input caused by induced changes in allocation patterns of bamboo. No changes in total N mineralization potential, leaf N, and composition of understory vegetation in both enclosures indicated that deer introduction did not facilitate nor retard N cycling regardless of deer density. This study showed that sika deer browsing can affect soil decomposer systems at an early stage of invasion even at low density, which contrasts with previous studies on the subject. Linking our findings of early-stage effects of deer on soil decomposer systems to longer-term dynamics of understory vegetation and tree regeneration will be needed to evaluate the adequacy of deer management practices with respect to the sustainability of soil nutrient supplies.     

Effects of sika deer (Cervus nippon) and dwarf bamboo (Sasamorpha borealis) on seedling emergence and survival in cool-temperate mixed forests in the Kyushu Mountains

Effects of sika deer (Cervus nippon) and dwarf bamboo (“sasa;” Sasamorpha borealis) on seedling emergence and survival were investigated in cool-temperate mixed forests in the Kyushu mountain range, Japan. We compared the effects of sika deer between two sites with different sika deer densities. One site (no-sasa forest) has sparse cover of S. borealis and a high density of sika deer, and the other site (sasa forest) has dense cover of S. borealis with a low density of sika deer. In the no-sasa forest, more seedlings emerged and the survival rate of the seedlings was higher compared with the sasa forest. Compared with the sasa forest, the canopy in the no-sasa forest was more open, the organic layer was shallower and drier, the mean daily soil temperature was higher, and soil temperature fluctuated more widely. Those environmental parameters did not differ between unfenced and fenced plots. The comparison between the sasa and no-sasa forests suggested that removal of S. borealis by sika deer had an indirect positive effect on seedling emergence and survival. However, the fenced-plot experiments indicated that sika deer inhibited seedling emergence and survival. These contradictory conclusions could result from the much larger negative effects of S. borealis on seedling emergence and survival compared with the effects of sika deer browsing.     

Medicinal plants in old-growth, degraded and re-growth forests of NW Pakistan

Many old-growth forest stands in northwest Pakistan have been structurally transformed as a consequence of logging and livestock grazing, some of which are thereafter left to secondary succession. These forests represent an important resource for local inhabitants who gather and sell medicinal plants as part of their livelihood. With this in mind, the main objectives of our study were: (1) to assess differences in the structure of the tree layer and the abundance of medicinal plants among differently transformed forests, (2) to evaluate the recovery potential of medicinal plants under re-growth forests, and (3) to assess relationships between tree stand structural characteristics and the occurrence of medicinal plants.The first step of the study involved creating an approximate map covering an area of 90 km² for five forest-use types (old-growth forest, forest degraded by logging, derived woodland, agroforest and re-growth forest). Fifteen plots per forest-use type were randomly allocated at altitudes ranging from 2200 m to 2400 m asl, within which the abundance of 10 locally important medicinal herb species was assessed.The study stands differed greatly in tree basal area, which was highest in old-growth forest (48 m² ha⁻¹), lowest in agroforest areas (6 m² ha⁻¹) and intermediate in re-growth forest (20 m² ha⁻¹). All ten medicinal plant species were encountered in old-growth and in re-growth forests, but only five of these species also occurred on agroforest plots. The mean coverage of study medicinal plants was highest in old-growth forest (7%), low in forest degraded by logging, derived woodland and agroforest (0.3-2%), and intermediate in re-growth forest (4%). The Jaccard abundance based similarity index indicates a considerable similarity (0.6) between re-growth and old growth forest for both trees and medicinal plants. The overall abundance of medicinal plants increased with increasing tree basal area and canopy cover. The abundance of some particular species decreased; however, the most sought-after medicinal species Bergenia ciliata, Valeriana jatamansi and Viola cancescens increased with tree basal area within specific forest-use type and also across forest-use types. In conclusion, our data suggest that anthropogenic forest degradation leads to a reduction in the abundance of economically viable medicinal plants for the study region. It is further indicated that this can be reversed if degraded forests are allowed to regenerate.     

Initial performance and reforestation potential of 24 tropical tree species planted across a precipitation gradient in the Republic of Panama

Decades of deforestation and unsustainable land use have created large expanses of degraded lands across Central America. Reforestation may offer one means of mitigating these processes of degradation while sustaining resident human communities. However, a lack of information regarding tree species performance has been identified as an important limitation on the success and adoption of diversified reforestation strategies. We analyzed the initial growth of 22 native and 2 exotic tree species planted at three sites across a precipitation gradient in the Republic of Panama (1100–2200 mm year⁻¹), and identify promising species for use in forest restoration, timber production and on-farm systems.     

Response of Ocotea bullata,Curtisia dentata and Rapanea melanophloeos to medicinal bark stripping in the southern Cape,South Africa: implications for sustainable use

Tree bark is commonly used for traditional medicine in southern Africa and further afield. Increasing demand and commercialisation have resulted in the overexploitation of many species, posing a major challenge to forest managers to develop mechanisms for sustainable resource use. An experimental bark harvesting research project was initiated in the southern Cape, South Africa, to inform best practices for bark harvesting based on tree response to bark stripping. The species selected for the study, Ocotea bullata, Curtisia dentata and Rapanea melanophloeos, are much sought after and well represented in southern Cape forests. The treatment entailed removing vertical strips of bark, 1 m in length and of different strip widths, covering the full range of tree size classes ≥10 cm DBH. The treatments were applied during two seasons, winter and summer. Evaluations were done every six months to assess tree response to bark stripping in terms of bark regrowth through phellogen edge and sheet development, and susceptibility to insect and fungal damage. The results show a differential response of tree species in terms of phellogen edge and sheet growth, as well as susceptibility to fungal and insect attack. Rapanea melanophloeos was the most vulnerable to fungal and insect damage and displayed little bark regrowth following wounding. Curtisia dentata showed best bark regrowth through sheet development. Only O. bullata, though, showed adequate bark regrowth (through edge development) to allow for sustainable strip harvesting. Bark regrowth is influenced by season of stripping, although this is difficult to define considering the wide range of environmental and other factors affecting tree response to bark removal. Smaller trees are more vulnerable to bark stripping, especially with a wide strip, with poorer bark regrowth than bigger trees.     

A geostatistical approach to spatial density distributions of sika deer (Cervus nippon)

Sika deer (Cervus nippon) cause serious damage to trees in Japanese forests. Browsing, bark stripping, and tree abrasion with antlers account for 50% of total wildlife damage over the past decade. The extent of forest damage depends on deer population density. We determined the spatial distribution of sika deer population density on Mt. Hiko (Fukuoka Prefecture, southwestern Japan). We also investigated changes in population density distribution over time. Determinants of population density were examined, with particular emphasis on the hunting cull. Deer densities in 1999 and 2004 were estimated by fecal pellet counts at 86 sites. We used kriging, a geostatistical technique that is a component of geographic information systems, to interpolate site-specific point data over large areas of landscape. Mapping procedures showed that high-density (≥30.0 deer km^?2) and low-density sections of landscape (≤10.0 deer km^?2) decreased in areal extent between 1999 and 2004. Contractions of high-density sections were attributable to intensive hunting. In low-density landscape sections, reduced hunting pressure allowed increased persistence of adult animals whose high fecundity led to population growth and higher deer densities. Landscape tracts with medium deer densities (10.0–30.0 deer km^?2) expanded, adding further difficulties to the task of wildlife management. Given the scale of the problems caused by deer, it is clear that reliable estimates of population size across space and time are essential components of the wildlife manager’s toolbox.