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1.
Browsing by sika deer (Cervus nippon) has significant negative effects on regeneration in many forests in Japan; however, the effects of browsing on regeneration processes have not been determined quantitatively. Our study was conducted in Abies sachalinensis plantations in seven tracts with differences in deer abundance on Hokkaido, northern Japan, to identify indicators for the effects of deer on the regeneration of broad-leaf species from observing seedlings. Five 5 × 20-m plots were located within each tract, and the densities of seedlings 30–200 cm tall and percentages of browsed seedlings were determined. We used sightings per unit effort (SPUE) by hunters and spotlight survey counts (SLCs) as indices of deer abundance for each tract. Seedling density was negatively correlated with deer abundance and coverage of dwarf bamboo, and basal areas of overstory trees also affected number of seedlings. Percentage of browsed seedlings was positively correlated with deer abundance, and it was affected by deer preferences among seedling species. However, the percentage of browsed seedlings was more clearly related to deer abundance than seedling density. There were few seedlings of tree species ≥100 cm tall in tracts with the highest deer abundance. Based on these results, deer abundances of SPUE >6 sightings per hunter-day or SLC >15 animals per 10 km are likely to prevent regeneration of broad-leaf species. The percentage of browsed seedlings and density and browsing damage on tree seedlings ≥100 cm tall are useful indicators of the effects of deer.  相似文献   

2.
The effect of browsing frequency by Sika deer (Cervus nippon yezoensis) on the height growth of Japanese larch (Larix kaempferi) in Hokkaido, Japan, was analyzed. Tree heights at the time of the census and at the start of the current growing season were determined for 100 trees selected randomly at each site. The tallest shoot on each tree was identified and the number of browsing occurrences on the current-year shoot was determined. Young larches browsed by deer repeatedly develop new shoots during a growing season. Larch is a browsing-tolerant species, and the average height growth of the most heavily browsed trees was >15 cm. Although resprouting partly compensated for decreased height growth caused by browsing, the annual increase in height decreased with increased browsing frequency. Thus, browsing frequency during a growing season best reflects the intensity of browsing damage to larch trees.  相似文献   

3.
We investigated how partial overstory retention, understory vegetationmanagement, and protective Vexar® tubing affected the frequency andseverityof biotic injuries in a two-storied stand underplanted with western redcedar(Thuja plicata Donn ex D. Don), Douglas-fir(Pseudotsuga menziesii (Mirb.) Franco, grand fir(Abies grandis (Dougl.) Lindl), and western hemlock(Tsuga heterophylla (Raf.) Sarg.). The most prevalentsource of damage was browsing by black-tailed deer (Odocoileushemionis columbiana); deer browsed over 74% of Douglas-fir and over36% of western redcedar seedlings one or more times over the four years of thisstudy. Neither the spatial pattern of thinning (even or uneven) nor the densityof residual overstory affected browsing frequency. Spraying subplots may haveslightly increased browsing frequency, but the resulting reduction of theadjacent understory vegetation increased the volume of all seedlings by 13%,whether or not they were browsed. Vexar® tubing did not substantiallyaffectseedling survival, browsing damage frequency, or fourth-year volume. Greaterlevels of overstory retention reduced frequency of second flushing. Chafing bydeer and girdling by rodents and other small mammals began once seedlingssurpassed 1 m in height. Essentially all grand fir seedlingsexhibited a foliar fungus infection.  相似文献   

4.
We examined the effects of fencing on deer browsing on seedlings 13 years after the building the experimental fence on Mt. Ohdaigahara, central Japan, where the sika deer (Cervus nippon) population is high. There was no difference in the species number of seedlings between 1991 and 2004. The density of seedlings in the fenced plot in 2004 was three times higher than in 1991. Although the unfenced plots had no seedlings higher than 20 cm, there were seedlings up to 120 cm in the fenced plot. These results suggest that 13-year fencing promoted regeneration of seedlings in this area.  相似文献   

5.
Browsing by mammals can have a substantial impact on the survival, growth and form of regenerating forest trees. This study investigated the severity and distribution of mammalian browsing damage, and the degree to which eucalypt seedlings (Eucalyptus spp.) were selected for browsing on three regenerating native forest coupes in southeastern Australia. Damage was greatest 6 months after eucalypt germination and at this time, both messmate (Eucalyptus obliqua) and blue gum (E. globulus) seedlings were browsed at similar intensity. Nine and 12 months after germination, messmate was browsed more heavily than blue gum. Consistent relationships between browsing damage and both distance from the forest edge and wallaby density were not observed. Analysis of use and availability data for messmate, blue gum and manna gum (E. viminalis) seedlings showed that messmate was selected for browsing more than expected by chance while manna gum was browsed less than expected. Mammalian browsing affects a substantial portion of Victorias native forest estate, and could alter the species composition of future forests. Research into the ecology of browsing species and the development of non-lethal browsing reduction strategies is seen as a priority for the management of mammalian browsing in Victoria.  相似文献   

6.
We studied the effect of roe deer (Capreolus capreolus) browsing on the growth and mortality of sessile oak (Quercus petraea) seedlings. First, we measured the height and basal diameter, and counted the number of shoots of the 849 seedlings of an experimental plantation, 60 of which were individually protected by fencing. We then introduced two tame roe deer females every day for three weeks from late May to mid-June. Measurements and counts were repeated after roe deer removal, then once again the following winter. We found no significant effect of browsing on mortality, total height, or basal diameter of the seedlings. However, the browsed seedlings exhibited a lower number of shoots despite regrowth observed after roe deer removal. We propose to use the tolerance of oak to deer browsing to promote natural and inexpensive methods, to protect oak during regeneration, such as the spatial arrangement of plants or the use of slash or surrounding vegetation in favourable environments.  相似文献   

7.
We examined the defensive function of spines of Damnacanthus indicus against deer herbivory by experimentally removing spines in the field where deer density is high. Individuals of D. indicus whose spines had been removed had a higher probability of being browsed by deer than control individuals. In addition, plant height was significantly lower for individuals that were browsed than those that were not. These results support the notion that spines of D. indicus have a function to deter deer browsing. This study is the first to demonstrate experimentally the defensive function of spines against large mammals in temperate areas.  相似文献   

8.
Forest grazing has been recognised as being a useful tool in fire-risk reduction, in addition to having the potential to preserve or enhance forest biodiversity if managed correctly. Concern for natural regeneration of forest trees in Europe has also prompted interest in the effects of large herbivores on seedling and sapling growth and mortality. An investigation was carried out into sapling damage and density of natural regeneration of oak (Quercus robur) in a mature, pony-grazed, Pinus radiata forest in Galicia, NW Spain under two different grazing regimes (continuous and rotational). In all treatments significantly more oak seedlings and saplings were recorded in areas of grass sward than areas dominated by taller ground flora species. Damage to oak saplings was assessed from the form (height and canopy) relative to stem diameter. The height and average canopy diameter of similar-aged saplings were found to be significantly greater in ungrazed (control) than both continuous and rotationally grazed treatments. Height and canopy diameters of similar-aged oak were not significantly different between the two grazing treatments. Significant differences were observed in tree form, with unbrowsed saplings having the greatest height to canopy width ratio and those in the continuously browsed plots having the smallest. An obvious decrease in the goodness of fit (R2) of regression analyses were found in continuously grazed areas compared to rotational and control plots for both height and canopy data. The differences in damage observed were not significantly different enough to suggest one method of grazing over the other as being better for minimising sapling damage. Management requirements are more likely to dictate grazing regime. Overall, stock density is likely to have a more significant effect on damage than stocking system.  相似文献   

9.
Mountain forests are traditionally used for cattle grazing during the dry season in southern Bolivia. To evaluate browsing intensity and damage to young trees and shrubs, a forest grazing area was monitored for about 3 months in both 2006 and 2007. Three similar paddocks of about 3 ha each, consisting of grassland and forest in a ratio of about 1:3 were stocked with 0.9, 1.6 and 2.6 tropical livestock units per ha (equivalents of 250 kg of body weight), reflecting low, medium and high stocking densities. Six 5 m × 5 m plots were mapped out within each paddock in 2006. Three additional plots per paddock were added in 2007. Within plots, the individuals of 18 woody species were coded and evaluated weekly for intensity of browsing. Intensity was quantified using five-scale categories reflecting the proportions of plant tissue removed (0 = no browsing, 1 = 1–25%, 2 = 26–50%, 3 = 51–75% and 4 = 76–100%). Across all plant species, the average category of browsing intensity, as determined in the post-grazing evaluation, was affected (P < 0.001) by stocking density. Browsing intensity increased in an approximately linear manner from 1.58 to 2.18 and 2.77 with low, medium and high stocking density, respectively. There was no significant difference between years. Most woody species followed the same general response pattern to stocking density, although some species were only noticeably browsed at high stocking density while a few others were intensively browsed at all stocking densities. The onset of browsing on woody species was observed only after some weeks had passed, indicating that herbaceous plants were preferred as a forage resource. The proportion of fatally damaged individuals, as assessed about 8 months after grazing in 2006, were 10.6%, 8.6% and 11.4% for low, medium and high stocking density, respectively. The percentage of completely browsed individuals increased with stocking density, but 80% of those plant individuals recovered following a resting period of 8 months. However, although most woody species recovered from browsing and fatal damage was infrequent, long-term changes in woody plant species composition and structure caused by grazing cannot be excluded. High stocking density in particular may reduce the vigour of heavily browsed species.  相似文献   

10.
Absence of, or poor, oak (Quercus spp.) regeneration is a problem in uneven-aged, mixed closed-canopy broadleaved forests. Browsing by ungulates on small trees may contribute to poor oak regeneration in such forests. This possibility was investigated in 25 Swedish stands, and browsing damage was analysed in relation to landscape and stand factors. The proportion of browsed small (<20 cm tall) oak seedlings and other seedlings was low, and apparently a minor mortality factor. For saplings (20–130 cm tall), accumulated browsing damage was generally higher on oak than on five major competing tree species: Fraxinus excelsior, Corylus avellana, Tilia cordata, Acer platanoides and Sorbus aucuparia. Leaf removal was rare in late summer, except for rowan. The amount of cover (shelter) for ungulates near plots was positively correlated with oak browsing intensity; within plots, a high density of ash saplings may reduce browsing on oak saplings. In these forests, browsing probably retards growth of oak saplings relative to competing trees. Oak may persist as a minor stand component, but monitoring is needed to study future changes.  相似文献   

11.
Excessive browsing by herbivorous mammals can adversely effect both forestry operations and ecosystem structure and function, and effective management of the problem across large forest estates requires the spatial extent of browsing impact to be determined. We conducted a browsing impact survey within 1.3 million ha of commercially managed Eucalyptus forest, and hypothesised that browsing impact would be related to variables reflecting habitat suitability for a major browsing species, the swamp wallaby (Wallabia bicolor Desmarest), at both large and small spatial scales. A simple spatial analysis showed that browsing severity varied across the landscape, but was high in a number of districts (30,000–100,000 ha land management units) grouped in a similar part of the surveyed area, identifying this region as a focus for management and research. Ordinal logistic regression showed that browsing impact was related to (a) the location of districts and (b) the number of times post-harvest regeneration had been attempted, with browsing impact generally worse in areas where regeneration had occurred twice. The latter result was consistent with our original hypothesis, as multiple regeneration attempts promote high quality habitat patches for wallabies. In most heavily browsed districts browsing severity varied substantially between harvested sites, suggesting that processes operating at the site scale were important. Our results describe the spatial extent of browsing within the surveyed area, and identify high risk localities and states, but additional data are required to understand the processes regulating browsing impact.  相似文献   

12.
Abstract

Food selection by large herbivores occurs at a hierarchy of scales, for example landscape, patch or plant. Several hypotheses regarding food plant selection on patch or plant level have been developed. In this cafeteria-type design field experiment, conducted during one winter immediately after planting, we tested the effect of species mixture on browsing by large herbivores (mainly roe deer) on Scots pine seedlings in mixture with seedlings of ash (highly preferred) or silver birch (less preferred). Browsing on Scots pine was not affected by species mixture, neither in terms of the number of browsed pines nor browsing intensity. Instead, browsed biomass was positively and significantly correlated to the total biomass available for browsing. Also, there were differences due to species, with ash being most browsed (44.6%), followed by Scots pine (18.9%) and silver birch (11.6%). Browsed biomass per browsed seedling, however, was largest for Scots pine. In addition, browsed seedlings were initially taller compared to unbrowsed seedlings for all species. The main management implication in this study is that the species mixture did not influence large herbivore browsing on Scots pine seedlings. Hence, removing or discouraging more (or less) attractive browse species in early stages of pine regeneration activities seems unnecessary from the point of large herbivore browsing.  相似文献   

13.
Silvicultural treatments creating large canopy openings failed to restore regeneration of balsam fir (Abies balsamea (L.) Mill.) due to browsing pressure from white-tailed deer (Odocoileus virginianus Zimmermann). Consequently, we tested two alternative silvicultural treatments aimed at improving balsam fir establishment on Anticosti Island (Québec, Canada). In 1998 and 1999, we set up shelterwood seed cutting using three harvest intensities (0, 25 and 40% of basal area) and strip clearcutting with scarification using three different strip widths (15, 30 and 45 m), both with fenced and unfenced regeneration plots, in balsam fir stands. After 8 years, shelterwood seed cutting did not allow the establishment of new balsam fir seedlings, nor the development of unbrowsed balsam fir seedlings. In the strip clearcutting, deer browsing suppressed growth of palatable species in all strip widths. This favoured the development of unpalatable species, especially white spruce (Picea glauca (Moench) Voss). Our study demonstrates that the use of silvicultural treatments alone is unlikely to restore balsam fir regeneration on Anticosti Island, as long as the deer population remains higher than 20 deer/km2.  相似文献   

14.
Techniques for encouraging natural tree regeneration are of increasing interest to managers of Scots pine Pinus sylvestris forests. We tested prescribed fire at a management scale, with deer present or excluded, as a means of increasing rates of Scots pine forest expansion on heathland. At a semi-natural pinewood in Scotland, ten experimental blocks were established, within range of pine seed-fall. Each block comprised four, 100 m2 plots. Two plots at each site were burnt and two fenced, allowing the effects of burning on pine regeneration to be measured at two levels of deer abundance. We monitored pine seedlings, seed-fall, deer dung and vegetation for 5 years following treatment. Differences in seedling detection rates between treatments were quantified using dummy seedlings, and analyses corrected accordingly. Mean new pine seedling establishment was 9.8 times higher on burnt ground than unburnt ground (confidence intervals 3.2–30). Differences were even more pronounced in a year of high seed-fall, and following fires with low rates of spread. Establishment rates varied strongly between experimental blocks. Exclusion of deer increased establishment rates, but only in the first 2 years after fire. There was evidence that both seedling survival, and cumulative recruitment of older (over 12 months) seedlings, were improved by prescribed burning. Our results support the use of prescribed fire as a tool to promote increased Scots pine seedling establishment. This technique is likely to give strong fine-scale variation in seedling densities, and so would most suit areas where a variable spatial pattern of regeneration is sought, for landscape or naturalness reasons. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   

15.
Abstract

The effects of fencing and site preparation on performance of birch (Betula pendula Roth), oak (Quercus robur L.), pine (Pinus sylvestris L.) and spruce [Picea abies (L.) Karst.] seedlings were studied over four growing seasons in southern Sweden. The experiment was composed of four browsing treatments, from which roe deer (Capreolus capreolus L.) were excluded for 0, 12, 24 or 42 months, and four soil treatments. Natural browsing was combined with artificial browsing (clipping). It was demonstrated that browsing by roe deer could be isolated from browsing by moose (Alces alces L.) by selective fencing. Except for birch, browsing had little effect on seedling survival. Browsing reduced height growth by more than 100% for oak and pine, and more than 60% of pine seedling developed multiple stems. Except for oak, site preparation increased seedling survival. Inverting site preparation, in combination with or without fertilization, produced positive growth responses in seedlings, whereas patch scarification did not. There was no interaction between browsing and soil treatments on seedling performance. It was concluded that long-term protection against browsing by roe deer is needed for oak and pine, whereas short-term fences might be used for birch, and that spruce is relatively unaffected by browsing.  相似文献   

16.
Herbivory by white-tailed deer (Odocoileus virginianus) can affect forest regeneration. Typical measures to ensure forest regeneration have included physical barriers or direct manipulation of deer densities. However, altering silvicultural practices to provide abundant deer forage has not been tested thoroughly. We examined browse species preferences and changes in herbivory rates in 1–6 year old regeneration areas from 2001 to 2004 in the central Appalachians on the MeadWestvaco Wildlife and Ecosystem Research Forest in West Virginia. Woody vegetation reached the maximum plot coverage by the 4th growing season. However, the establishment of less abundant woody species, such as northern red oak (Quercus rubra), may be inhibited when browsed greater than or proportionally to occurrence. Herbivory rates declined precipitously as the amount of early successional habitat increased on our study site. We conclude that providing approximately 14% of an area in well-distributed, even-aged managed forests can have substantial impacts on reducing herbivory rates. However, management practices also should consider harvesting effects on hard mast production, habitat requirements of other species, and hardwood lumber marketability.  相似文献   

17.
A 3-year field experiment with paired exclosure (fenced areas, excluding deer) and control plots (unfenced areas, free access to deer), with two treatments with and without woody debris, was carried out at two sites in a temperate forest in eastern France. The aim of the experiment was to assess the effect of browsing by roe deer (Capreolus capreolus) and red deer (Cervus elaphus) on the diversity and richness of plant species and to test the effectiveness of using woody debris to protect seedlings and saplings from deer browsing. In presence of deer, both plant species richness and diversity were reduced the first year of the study, but this negative impact of deer then disappeared after 3 years. Deer browsing mostly affected species composition of plant communities. We observed a decrease in the abundance of preferred species such as Carpinus betulus, Rubus fructicosus, Rubus idaeus, Anemone nemorosa and Epilobium angustifolium, and palatable species such as Acer spp., Carex spp., Festuca spp. and Mycelis muralis, whereas unpalatable species such as Lamium spp., or species particularly resilient to browsing such as grasses (Brachypodium spp. and Luzula spp.) increased in abundance. The use of woody debris as protection against browsing by deer did not limit damage to seedlings and saplings of the main commercially valuable species, Abies alba and Quercus spp. Instead of limiting deer impact, use of woody debris seemed to increase the negative effect of deer browsing on regeneration in control plots relatively to those without protection.  相似文献   

18.
To detect the magnitude of indirect positive effects of deer and mice on seedling survival of some woody species in a Japanese temperate forest, we analyzed the data from an earlier field experiment using a hierarchical Bayesian approach. The forest studied was inhabited by sika deer (Cervus nippon) and mice (Apodemus spp.), and the floor was covered with dwarf bamboo, Sasa nipponica, which negatively affected tree seedlings and was in turn negatively affected by deer and mice. The field experiment was designed as the combination of exclusion or removal of these factors: deer, mice and dwarf bamboo. A hierarchical Bayesian model was constructed and the parameters were estimated by the Markov chain Monte Carlo method. The model successfully showed the indirect positive effects of deer and mice, which improved the survival rate of five cohorts of the seedlings of three tree species by ameliorating the direct negative effect of dwarf bamboo. The cohorts studied were formed by the seedlings of Abies homolepis that emerged in 1997 and 2002, those of Fraxinus lanuginosa f. serrata that emerged in 1998 and 2002, and those of Fagus crenata that emerged in 1999. The positive indirect effect was especially large in F. crenata, which is known to be severely affected by dwarf bamboo. The total effect of deer was shown to be positive for all cohorts except the A. homolepis cohort that emerged in 1997, at which time the dwarf bamboo had not yet fully recovered from the browsing pressure of deer. The total effect of mice was shown to be positive for all of the cohorts. We conclude that these positive effects were due to the large negative effect of dwarf bamboo on the seedlings.  相似文献   

19.
Burton  P.  Bedford  L.  Goldstein  M.  Osberg  M. 《New Forests》2000,20(1):23-44
A disk-trenching experiment in thesub-boreal spruce zone of central British Columbia,Canada, established three plots (0.12 to 0.26 ha each)with trenches running east–west, and another threeplots with north–south trenches. Approximately 200Pinus contorta Dougl. seedlings were planted ineach of 13 microsites: berm, hinge, and trenchpositions in each of north, south, east, and westaspects, and in untreated locations between furrows.Soil temperature and soil moisture of representativemicrosites were monitored for 3 years; seedlingdiameter, height, and vigour were monitored annuallyfor ten growing seasons. Based on tenth-year stemvolumes, performance on south-, east-, and west-facingmicrosites was significantly greater than onnorth-facing or untreated microsites. Superior growthwas noted on all berm and hinge positions other thanthose facing north. Microsites identified as best inyear 5 were also best in year 10. On east-, south- orwest-facing berm positions, stem volume averaged 47%to 54% greater than that of control seedlings in year5, but had suffered greater mortality. Seedlings oneast-, south- or west-facing hinges were 46% to 61%(year 5), or 36% to 47% (year 10) larger thancontrol seedlings. Both east–west and north–southdisk-trenching treatments are useful for increasingseedling growth, with planting spot selection beingmore important overall than trench orientation. Thestand-level effectiveness of north–south disktrenching was greatest, because the creation of coolnorth-facing microsites was avoided.  相似文献   

20.
At moderate to high densities ungulates can impact negatively on forest crops and these may be managed by lethal control. In production forestry an understanding of the relationship between ungulate density, habitat-related factors and the incidence of tree damage may promote more efficient ungulate damage management than by lethal control alone. In plantation forests in the north east of England, the incidence of conifer leader browsing by roe deer (Capreolus capreolus) was positively associated with an index of deer density (at the site scale) and planted crop tree density (at the feeding patch scale) and was negatively associated with the relative abundance of palatable understorey vegetation (at the site scale). An interaction between the deer density index and palatable understorey browse abundance was positively associated with leader browsing. Coefficients from the optimal model were used to construct a browse probability surface across a matrix of values of deer dung density and palatable understorey vegetation abundance. This illustrated a very different relationship between dung density and conifer leader browsing probability across the various levels of palatable understorey vegetation abundance. From this we hypothesise that in areas of limited palatable understorey vegetation abundance, higher levels of culling may be required to achieve reductions in the incidence of conifer leader browsing than would be necessary in areas with moderate to high palatable understorey vegetation abundance. Improvements to understorey vegetation in concert with roe deer population control may enhance the efficiency of deer damage management in upland areas with nutrient-poor soils.  相似文献   

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