Bark Stripping Damage Research Articles

The Effectiveness of Tannin on the Amount of Damage to Forest Trees and Stands Caused by Red Deer in the Western Carpathians

Damage caused by cloven-hoofed game and wild animals is a serious problem in Slovakia and neighboring countries. In 2022, the damage to forests in Slovakia was estimated at a level of almost EUR 2.9 million. Despite several implemented measures, the situation is so severe that successfully restoring some trees in some heavily attacked stands is impossible. This paper deals with the preventive elimination of damage caused by red deer in forest stands by the biological method of applying tannin-based mineral licks. Specifically, licks containing tannin obtained from the edible chestnut were used for testing. Several positive effects are attributed to tannins in developing livestock and animal fitness status. To date, however, the question of using tannins as biological agents for the possible protection of forest stands has not been addressed. Therefore, red deer damage was assessed at two localities with similar natural conditions in the central part of the Western Carpathians to explore such a possibility. After the initial sample measurement of the bark-stripping damage caused by the red deer in the autumn, mineral licks with tannin were placed in one selected study area over the winter. The levels of and differences in forest damage by deer between areas with the application of licks with tannin and without tannin were detected in spring of the following year. In the location treated with tannin, the number of damaged sample plots decreased, and the mean plot damage did not increase (no statistically significant differences were registered in mean plot damage between autumn and spring). Meanwhile, in the control location, the total amount of bark-stripped area doubled, mainly due to a statistically significant increase in mean plot damage between autumn and spring. Based on this, we conclude that tannin had a significant preventive effect and considerably reduced the extent of bark stripping. Such promising results indicate that tannin licks can effectively mitigate the problem of bark-stripping damage in areas heavily attacked by red deer.

Stand-level sampling designs for bark stripping caused by red deer (Cervus elaphus L.): simulation studies based on nine fully censused stands

AbstractPrecise assessment of bark stripping damage is of high economic importance, since bark stripping makes wood unusable for saw timber and it is important for compensation payments for game damage. Bark stripping is clustered and decreases with increasing tree diameter, so that common forest inventories, optimized for assessing timber production variables such as standing timber volume, do not provide adequately precise estimates of bark stripping damage. In this study we analysed different sampling designs (random sampling, systematic sampling), tree selection methods (fixed radius plot, angle count sampling) and number of plots and plot sizes (plot radius: 2–20 m; basal area factor: 1–6m2/ha) for bark stripping assessment. The analysis is based on simulation studies in 9 fully censused stands (9026 trees). Simulations were done for actually assessed damage and randomly distributed damage and each scenario was repeated 100 times with different random points or different random grid locations. Systematic sampling was considerably more precise than random sampling in both scenarios. Sampling intensities to attain a standard error of 10% ranged between 12 and 18% dependent on the plot size. For a given sampling intensity, precision increased with decreasing plot size or increasing basal area factor. This implies, however, a large number of plots to be measured, which is expensive, when travel costs are high. Differences between tree selection by fixed radius plots or angle count sampling were minor. For bark stripping damage, we recommend sampling with fixed radius plots with a radius of 4–6 m and the measurement of approximately 230 or 150 plots, respectively.

Predicting forest damage using relative abundance of multiple deer species and national forest inventory data

Deer, both native and non-native, can damage forest ecosystems when occurring at high densities, impacting biodiversity and ecological functioning at multiple levels. The ecological drivers of forest damage and the roles of single and multiple co-occurring deer species are not well understood due to a scarcity of simultaneous high resolution multi-species deer distribution and forest damage data. Here, we aimed to disentangle the relationship between forest damage, forest characteristics and the roles deer play in damaging forest ecosystems. To achieve this, we integrated novel high resolution deer distribution data for multiple deer species (native and non-native) with forest inventory data collected in 1,681 sampling stations across Ireland to (i) understand environmental drivers of damage, and (ii) demonstrate the utility of this approach in providing predicted damage scenarios based on the relative abundance of different co-occurring deer species. We found that forest characteristics played a key role in the severity and type of damage risk that deer posed. All damage types were more prevalent in forests with greater tree densities where deer are more likely to find refuge from human disturbance. Bark stripping damage was more prevalent in mature forests with high tree diversity and ground level flora (e.g., bryophytes, herbs, and shrubs). Similarly, browsing damage was more prevalent in forests with greater tree richness but with understorey vegetation dominated by grass and ferns. Fraying damage was more common in mixed woodlands with understories dominated by bryophytes and grass. Crucially, we found that type and severity of forest damage were shaped by the interaction of multiple deer species occurring simultaneously, particularly at high densities, suggesting subtle inter-species competition and exclusion/partition dynamics that require further investigation to understand the ecological mechanism. Finally, we developed predicted damage scenarios to precisely predict where damage is likely to occur based on relative densities of two co-occurring deer species. We predicted high levels of damage in sika and/or red deer hotspots, matching areas of highly concentrated deer distributions. Our study highlights the ecological drivers of deer-caused forest damage, the role that co-occurring native and non-native deer species may play on forest damage within a large spatial scale and describes an approach that can be replicated in other countries with similar datasets. By combining reliable species distribution models with the national forest inventory data, we can now provide a useful tool for practitioners to help alleviate and mitigate forest damage and human wildlife conflicts.

From the simulation of forest plantation dynamics to the quantification of bark-stripping damage by ungulates

From the simulation of forest plantation dynamics to the quantification of bark-stripping damage by ungulates

Bark stripping damage by red deer (Cervus elaphus L.): assessing the spatial distribution on the stand level using generalised additive models

Bark stripping damage by red deer (Cervus elaphus L.): assessing the spatial distribution on the stand level using generalised additive models

Cervid Bark-Stripping Is an Explicit Amplifier of Storm Legacy Effects in Norway Spruce (Picea abies (L.) Karst.) Stands

The interactions between wind damage and biotic agents, such as root-rot and cervids (bark-stripping), amplify the effects of storms on forests in Europe and Norway spruce (Picea abies (L.) Karst.) stands, in the Eastern Baltic region in particular. Due to uneven manageability of the biotic agents, the information about their effects on susceptibility to wind damage can aid the prioritization of management for sustaining spruce stands. This study compared the effect of root-rot and bark-stripping on the mechanical stability of Norway spruce via mixed covariance analysis of basal bending moments, based on static tree-pulling test data of 87 trees from five stands in Latvia. Bark-stripping caused a significantly stronger reduction in resistance against the intrinsic wood damages (primary failure) compared to root-rot, while showing a similar effect on resistance to fatal (secondary) failure. This suggests that bark-stripping damage increases the susceptibility of spruce to storm legacy effects, and, hence, is a higher priority risk factor in Norway spruce stands under the climate-smart management approach.

Scots pine (Pinus sylvestris L.) demonstrates a high resistance against bark stripping damage

Bark stripping damage reduces timber quality due to fungal infection and structural defects. Weakened stems may break and induce the death of trees, which strongly affects forest stability. Some tree species, such as Norway spruce (Picea abies [L.] Karst.), are highly susceptible to bark stripping, but Scots pine (Pinus sylvestris L.) has been studied to a lesser extent. The objective of this study was to predict the effect of the degree of bark stripping damage and rot on the production parameters of Scots pine and to determine the influence of climatic factors on various damaged trees. The research was conducted on 15 pine forest stands aged 40–42 years with a numerous sika deer (Cervusnippon nippon) population in the western part of the Czech Republic (425–492 m a.s.l.). The results showed significant differences in tree diameter and volume (but not height) between healthy and extensively damaged trees according to 417 pines measured. However, no differences were found between lightly damaged trees. Similarly, circumference damage did not significantly affect mean tree stem volume, in contrast to previously reported results for Norway spruce. The trees were first damaged by deer at the age of 18.5 years on average. According to the prediction model based on 40 felled and sampled trees, rot did not reach a distance > 50 cm from the site of the bark stripping on the stem, with a mean speed of vertical spreading of 0.9 cm yr−1. Concerning the effect of climatic factors on radial growth (60 core samples taken), the difference between healthy and minor to extensively damaged trees was negligible. However, healthy trees responded more to the effects of temperature, and damaged trees were more sensitive to the precipitation amounts. Scots pine appears to be a suitable tree species for afforestation in areas with high game pressure during continuing climate change.

Bark stripping, the crucial factor affecting stem rot development and timber production of Norway spruce forests in Central Europe

Bark stripping damage and the resultant stem rot to Norway spruce (Picea abies [L]. Karst), one of the most important tree species, poses a serious problem for forest management in Europe. Our research objective was to determine the effect of bark stripping, the subsequent rot decay and the impact of climatic factors in young (42–49 years) spruce stands. Moreover, we compared the differences between damage caused by red deer (Cervus elaphus L.) and sika deer (Cervus nippon Temminck). In all the cases studied, game damage was lower in forest stands when caused by sika deer (SD − 77.3%) compared to red deer (RD − 88.8%); 27.8% (SD) – 32.0% (RD) of stem circumference was damaged in average. Damaged trees showed higher growth variability and were more sensitive to a lack of precipitation and droughts, while air temperature had a higher effect on the growth of healthy trees. The initial game damage was observed in the 11 (SD) – 14 (RD) year of the mean tree age. The stem volume was lower by 25% (SD) – 28% (RD) in lightly damaged trees, and 50% (SD) – 71% (RD) in heavily damaged trees compared to healthy trees. The vertical stem decay reached a maximum of up to 4.5 m (SD) – 6.0 m (RD) (mean 1.9–3.1 m) with the mean speed of vertical spreading of 5.7 cm yr−1 (SD) – 9.6 (RD) cm yr−1. The mean decayed wood accounted for 30% (SD) – 39% (RD) of the stem volume. The peripheral stem damage by bark stripping and the age of the first occurrence were significant factors in predicting damaged crosscut area and vertical rot spreading in the stem. During this time of climate change, the stability of damaged spruce stands has been significantly disturbed by deer game.

Debarking damage by alien Pallas’s squirrel, Callosciurus erythraeus, in Argentina and its effects on tree growth

Introduced squirrels threaten forest ecosystems by debarking, resulting in economic losses to the timber industry and additional damage mitigation and pest control costs. The Pallas’s squirrel, also called the red-bellied squirrel. (Callosciurus erythraeus), originally from Asia, is the first squirrel species introduced to South America. In Argentina, C. erythraeus causes bark stripping damage in several tree species but their impact on tree growth and wood quality has not been evaluated yet. Field work was undertaken during 2016 in a forest establishment in Lujan district, Buenos Aires Province, Argentina. Samples were taken in plantations of Pinus elliottii, Eucalyptus dunnii and Populus deltoides. For each tree species, we sampled two plantations (1–3 ha) that belonged to two age classes comprised of young and mature trees. Two or three transects, 50 m apart, were set up within each plantation and data collected from individual trees. We evaluated affected tissues, percentage of girdling (percentage of circumference of stem with damage), wood volume and stem defects on damaged and undamaged trees. Wounds damaged live tissues and reached the xylem, causing deformations in the growth rings of all the evaluated trees. Partial girdling was prevalent in younger P. elliottii and P. deltoides (more than 40% on average) and in both ages of E. dunnii (more than 50% on average). Minimum damage caused by squirrels was statistically significant among age classes for both P. elliottii and P. deltoides at 3 m and 6 m tree height. This is the section of the tree most relevant to the wood market. The damage resulted in wood-volume losses between 20% and 58% with diameter at breast height and/or height reduction in some plantations. In E. dunnii and P. deltoides the stem breaks were significant. The results of this study suggest that the Pallas’s squirrel may have an adverse impact on commercial forestry as a result of their continuous damage to trees, which leads to yield reduction and consequent economic losses.

Effect of Bark-Stripping on Mechanical Stability of Norway Spruce

The increasing effects of storms are considered the main abiotic disturbance affecting forest ecosystems. Bark-stripping damage from the growing ungulate populations, in turn, are among the main biotic risks, which might burden the stability of trees and stands. Therefore, the aim of our study is to estimate the effect of cervid bark-stripping on the mechanical stability of Norway spruce using a static tree-pulling test. For the test, eight damaged and 11 undamaged canopy trees were selected from a 40-year old stand (plantation with 1 × 3 m spacing) growing on mineral mesotrophic soil. The selected trees were bark-stripped 7–9 years prior to the experiment. Uprooting was the most frequent type of failure; only two trees broke at the stem. For the damaged trees, the resistance to pulling was significantly reduced (p-value < 0.001). Stem volume and presence of bark-stripping were the best linear predictors of the basal bending moment at the primary failure (irreversible deformation of wood structure) and secondary failure (collapse of the tree). A significant (p-value < 0.001) interaction between stem–wood volume and presence of bark-stripping was observed for primary failure, indicating a size-dependent reduction of stability of the damaged trees. Such interaction lacked significance (p-value = 0.43) for the secondary failure (mostly uprooting), indicating a decrease in stability irrespectively of tree size. Somewhat surprisingly, the decrease in the overall mechanical stability of the bark-stripped trees appeared not to be related to a direct reduction of the strength of the stems, but rather to physiological effects such as altered allocation of carbon, increased drought stress because of interfered hydraulic conductance of wood, or secondary infestation. The reduced stability also suggests that bark-stripped trees can act as the weak spots decreasing the collective stability of stands in the long term, thus increasing the susceptibility to storms.

The benefit of wrapping trees in biodegradable material netting to protect against bark stripping by bears extends to surrounding stands

Bark stripping by Asian black bears (Ursus thibetanus) has a serious impact on conifer plantations in Japan. Prevention strategies tend to be implemented on a tree-by-tree basis by wrapping standing trees in biodegradable tape or netting. It remains unclear, however, whether installing these materials has a beneficial effect on untreated trees in surrounding stands. The aim of this study was to clarify the effects of installing these materials on bark stripping by bears in neighboring areas. The study was conducted in eastern Gunma Prefecture, central Japan. We selected 113 stands of Cryptomeria japonica and Chamaecyparis obtusa treated with these materials and 162 untreated stands (7963 trees). In untreated stands, we established square plots and calculated the rates of damage by bears. Generalized linear mixed models were used to analyze the effects of various factors on bark stripping, and segmented regression analysis was used to determine whether the rate of bark stripping in untreated stands had increased after material installation in treated stands. The rates of damage to Japanese cedar and Japanese cypress by bears in treated stands 1 or 2 years after material installation were 0% and 0%, respectively. In contrast, rates of damage to Japanese cedar and Japanese cypress in untreated stands surrounding the treated stands were 2.6% ± 1.8% and 2.7% ± 1.2%, respectively, at 1 year and 2.7 ± 1.5% and 2.8 ± 1.2%, respectively, at 2 years after material installation. We found that bark stripping by bears tended to occur in untreated stands far from treated stands at 1 or 2 years after installation. The segmented regression models showed that the rate of occurrence of bark-stripping damage at 1 and 2 years after treatment was markedly lower in untreated stands close to treated stands than in those beyond the breakpoints, and it increased only weakly in farther stands. Our findings indicate that installing tape or netting in selected stands can curb the occurrence of bark-stripping damage in surrounding stands within a certain distance. That is, material installation in individual stands did not lead to displaced bark-stripping activity in surrounding areas.

Bark-stripping damage by Callosciurus finlaysonii introduced into Italy

AbstractThe Finlayson’s squirrel

Bark stripping of Pinus contorta caused by moose and deer: wounding patterns, discoloration of wood, and associated fungi

The aim of this study was to assess the extent of bark stripping wounds, subsequent wood discoloration, and associated fungi in 30-year-old Pinus contorta Douglas ex Loudon stems damaged by large game. In total, 90 trees were evaluated, and 170 bark stripping wounds of different ages (1–20 years) were measured. From each wound, wood samples were collected for subsequent fungal isolation. Thirty trees were cut to evaluate the length of the discoloration column. Of 170 injuries, 16 of them represented closed scars and 154 of them represented open wounds that exposed 4–4355 cm2 of sapwood. The wound length had a strong impact on the length of decay (r = 0.716); however, the spread of discoloration beyond the wound margin was limited (0–20 cm). The most commonly isolated fungus was Sarea difformis (Fr.) Fr. and, among the Basidiomycetes, Peniophora pini (Schleich.) Boidin. The results suggest that when planning to grow P. contorta in areas of Europe, the population size of large game animals needs to be considered, in view of potential risk of bark stripping damage.

Bark stripping damage by red deer (Cervus elaphus L.) in the fenced rearing centre “Lomnicka Reka“

Bark stripping damage is a serious problem in some forest hunting grounds in Serbia. This study aimed at assessing the incidence and intensity of bark stripping by red deer in the fenced rearing centre ?Lomnicka Reka? (Mt. Veliki Jastrebac, central Serbia). The data were collected by detailed surveying of the entire rearing centre over spring and autumn 2008, 2009 and 2010. Our results show that, in spring and summer, it is exclusively broadleaf tree species that are bark stripped by red deer, mainly beech (86.3% or 536 trees) and hornbeam (10.1% or 63 trees). The incidence and intensity of bark stripping were the highest in the diameter class of 20-39.9 cm. Damaged trees were identified in all parts of the rearing centre, at all aspects and at different slopes. Beech bark was stripped over the period May-August, with the focus in June or July.

Effects of the feeding of wild Yeso sika deer (Cervus nippon yesoensis) on the prevention of damage due to bark stripping and the use of feeding sites

Feeding sites for wild Yeso sika deer around Lake Akan, Japan, were established. Effects on the number of deer using the feeding sites, the prevention of bark stripping damage, the amount of feeding, and eating time in a 5-year period (1999-2003) were evaluated. The number of deer using feeding sites increased with years during the feeding period. The damaged tree ratio after the initiation of feeding markedly decreased compared with 16.5% before the initiation of feeding. After the start of feeding, there were no trees with damage the entire circumference. According to tree species, the number of damaged trees of Ulmus laciniata Mayr as a percentage of all investigated trees was high (5.2%). The total amount of beet pulp feeding increased with the feeding year, showing 4.5-fold increase. At feeding sites in deer culling, eating behavior was observed during the night. The preventive effects on bark stripping damage continued during the 5-year feeding period. However, with the course of feeding years, the number of deer using feeding sites and the level of feeding increased.

Influence of tree size and dominance on incidence of bark stripping by grey squirrels to oak and impact on tree growth

Summary Grey squirrel damage was monitored annually in a stand of naturally regenerating oak in the Forest of Dean, UK, between 1998 and 2003. Incidences of damage and wound size were signifi cantly related to tree size, with dominant oak trees and those above 7.5 cm diameter at breast height, most at risk of damage on the main stem. Fresh damage occurred on 9 – 38 per cent of trees each year, with 2 – 17 per cent of trees ring barked in any year. Damage was concentrated above 4 m up the main stem and for some trees led to dieback and loss of apical dominance accompanied by a reduction in top height increment. Continuing damage is likely to lead to a general reduction in yield of the stand. As with other species, tree diameter and dominance appear to be useful predictors of bark-stripping damage risk on oak.

Bark stripping damage by sika deer in thinning and pruning stands

Bark stripping damage by sika deer in thinning and pruning stands

Probability of recent bark stripping damage by red deer (Cervus elaphus) on Norway spruce (Picea abies) in a low mountain range in Germany – a preliminary analysis

Red deer (Cervus elaphus) can cause considerable damage to forest stands by bark stripping. Here, we examined the probability of bark stripping of susceptible Norway spruce (Picea abies) during winter in relation to local environmental characteristics in the western Harz Mountains, Lower Saxony, Germany. We present the results of a multiple logistic regression model for recent bark stripping damage by red deer which we developed from two systematic cluster sampling inventories after two winter periods along with associated meteorological data and records of bagged deer. Our model suggests that the risk of bark stripping increased significantly (P  0.05) with rising slope angle, cumulating snow depth and increasing index values of red deer population density. Spruces growing in closed forest stands were debarked at a higher probability than spruces located close to forest edges. Further on, spruce stands on eastern slopes had a lower probability of bark damage than spruce stands on northern slopes. Other tested variables (altitude, length of daily solar irradiation, duration of snow cover, age of spruce stand within the age range of 16–50 years) had no significant effect on the probability of new bark stripping. We conclude that red deer in the western Harz Mountains seem to use bark as food resource at preferred locations and in times of low food availability. To improve fit and predictive power of bark stripping models we recommend including stand characteristics. We propose to reduce the population size of red deer in order to diminish bark stripping damages to an economically acceptable level.

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 (14.4–64.3km−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.

Probability of bark stripping damage by red deer (Cervus elaphus) in Austria

Bark stripping by red deer (Cervus elaphus) causes considerable damage to Austrian forests, however, the incidence of bark stripping was never examined from large scale survey data. In this manuscript we present a logistic regression model for bark stripping damage (static model) and a model for recent (5-year period) bark stripping damage to previously undamaged trees (dynamic model) developed from Austrian National Forest Inventory data. Both models showed bark stripping damage to be most frequent in core red deer habitat areas and less frequent in less suitable habitat. Damage was concentrated at elevations of 400–1200 m and in alluvial forests (only static model). Norway spruce (Picea abies), European ash (Fraxinus excelsior), Sweet chestnut (Castanea sativa) and Sorbus spp. had 11–12 times more injuries than all the other species. Red deer preferred the smallest trees with a breast height diameter of 5 cm for bark stripping and damage probability decreased rapidly for trees with a breast height diameter greater than 25 cm. Our static model showed a maximum of bark stripping damage in stands with a mean height of 20 m. In the dynamic model the probability for bark stripping damage decreased with decreasing mean height. Also, in the static model the probability for bark stripping damage increased with increasing spruce proportion and with increasing stand density whereas in the dynamic model the proportion of previous bark stripping damage was a good predictor. Goodness of fit and discrimination of both models were good. In combination with forest growth models, the bark stripping models can be used to predict the risk of damage associated with different forest and habitat management options.