Effects of roe deer browsing and site preparation on performance of planted broadleaved and conifer seedlings when using temporary fences

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.     

Effects of forest floor planting and stock type on growth and root emergence of Pinus contorta seedlings in a cold northern cutblock

A two-year field trial was conducted to determine the growth response, and root emergence pattern of interior lodgepole pine (Pinus contorta Dougl. var. latifolia Engelm.) seedlings in response to container type and forest floor removal. Seedlings were grown in Styroblocks^TM, Copperblocks^TM, or AirBlocks^TM, and were planted directly into the undisturbed forest floor or into manually prepared planting spots where the forest floor had been scraped away to expose the mineral soil. Seedlings planted into scalped planting spots exhibited marginally but significantly (7%) greater above-ground growth rates (seedling stem volume); whereas seedlings planted into the forest floor produced significantly more (11%) new roots. There were no differences in above- or below-ground biomass. Seedlings grown in Copperblock^TM containers produced a higher proportion of roots near the top of the plug when tested at lifting, however this pattern was not observed in the field. Given that scalping is more costly than forest floor planting, and that the increased shoot growth was relatively small, we recommend that forest floor planting be considered as an alternative to manual spot scalping for sites, such as the site tested here: those with cold, but well-drained soils and where competition from other plants is not a serious problem.     

ORDINATION AND GRADIENT ANALYSIS OF CONIFEROUS FOREST IN DAXINGANLING

In this paper,the quantitative approach is applied on the study of coniferous forestbased on the data which were collected by the field investigation in Daxinganling region.The mainpurpose is objectively to show the position of communities in the space and the relationship be-tween the community and environment.By means of ordination,it is found that dahurian larch for-est,mongolian scots pine forest and korean fir forest lie in different positions. Gradient analysis ofthree dominant types of conigerous forest has revealed the difference of ecological amplitude,thedifference is one of the important reasons that determine the different communities in the differentenvironment.     

Relationships between long-term trends of air temperature,precipitation, nitrogen nutrition and growth of coniferous stands in Central Europe and Finland

Height growth of 19 Scots pine (Pinus sylvestris) and Norway spruce (Picea abies) stands in Germany, Austria and Finland, for which long-term records of foliar nutrient levels were available, was assessed retrospectively by stem analyses and compared with data from regionally applied yield tables as references. Gridded historical time series of monthly temperature and precipitation were used to characterise the meteorologic conditions at the sampling sites. Climate parameters were tested against height growth in period 1950–2000, and needle N content was tested against height growth for the periods where N measurements were available by means of graphical comparison, as well as simple and multiple regression analyses with the aim to get evidence for causes of possible growth acceleration. Trends of referenced height increment of six out of nine Scots pine stands in Germany were positive during the observation period, and improved N nutrition appeared to be the most important driving factor for this growth acceleration. The variation of precipitation—exhibiting no consistent and uniform long-term temporal trend during the observation period—in contrast seems to be mainly responsible for the interannual fluctuation of height growth. We were not able to detect any general statistical influence of temperature parameters on height growth, although they generally increased. The referenced height growth of three Finnish pine stands slightly decreased during the observation period and there was no indication of a significant improvement of their N supply. Among four Norway spruce stands investigated in Germany and Austria, referenced height increment also increased in three cases; there was again some evidence that improved N nutrition was the stimulating factor. At three study sites in Finland, however, referenced height growth of this species decreased at least from 1985 onwards, whereas mostly no significant trends in N nutrition or precipitation were identified. These differences observed between species and regions are discussed in detail.     

Nutrients in litterfall,forest floor and mineral soils in two adjacent forest ecosystems in Greece

The fluxes of masses and the nutrients Ca,Mg,K,N,P and S were determined in the litterfall of two adjacent forest ecosystems of Hungarian oak(Quercus frainetto L.)and European beech(Fagus sylvatica L.)in a mountainous area of northeastern Greece in 2010–2015.The foliar litterfall for both species reached about 70%of the total litterfall,and was significantly higher from the other two fractions(woody and rest litterfall).The fluxes of masses and nutrients were compared between ecosystems for each fraction separately.Only one significant statistical difference was found,that of K in the woody litterfall.In addition,the stocks of masses and nutrients were calculated in the forest floors and mineral soils of the two ecosystems.Likewise,the stocks of nutrients in the forest floors and mineral soils were compared between ecosystems.In the L horizon of the forest floors,statistical differences,as a result of species effect,were found for the stocks of Ca and N.In the FH horizons,the masses and all the nutrient stocks differed significantly,as the beech plot had much higher quantities of organic matter and nutrients.These higher quantities were probably due to low soil temperatures(microclimate)and high acidity in the beech plot(species effect)that slowed down decomposition.In the mineral soils,the propagation of random error derived from random errors of the individual soil layers was an important factor in the statistical comparisons.Because of the soil acidity in the beech plot,the stocks of exchangeable base cations were significantly higher in the oak plot,whereas the other nutrient stocks did not differ.     

Increased coniferous needle inputs accelerate decomposition of soil carbon in an old-growth forest

Changes in temperature, precipitation, and atmospheric carbon dioxide (CO₂) concentration that are expected in the coming decades will have profound impacts on terrestrial ecosystem net primary production (NPP). Nearly all models linking forest NPP with soil carbon (C) predict that increased NPP will result in either unchanged or increased soil C storage, and that decreased NPP will result in decreased soil C storage. However, linkages between forest productivity and soil C storage may not be so simple and direct. In an old-growth coniferous forest located in the H.J. Andrews Experimental Forest, OR, USA, we experimentally doubled needle litter inputs, and found that actual soil respiration rates exceeded those expected due to the C added by the extra needles. Here, we estimated that this ‘priming effect’ accounted for 11.5–21.6% of annual CO₂ efflux from litter-amended plots, or an additional 137–256 g C m⁻² yr⁻¹ loss of stored C to the atmosphere. Soil priming was seasonal, with greatest amounts occurring in June–August coincident with peaks in temperature and dry summer conditions. As a result of priming, mineral soil was more resistant to further mineralization during laboratory incubations. Soil lignin-derived phenols in the Double Litter plots were more oxidized than in the control, suggesting that the soil residue was more degraded. Our hypothesis that excess dissolved organic C produced from the added litter provided the link between the forest floor and mineral soil and a substrate for soil priming was not supported. Instead, the rhizosphere, and associated mycorrhizal fungi, likely responded directly to the added aboveground litter inputs. Our results revealed that enhanced NPP may lead to accelerated processing of some stored soil C, but that the effects of increased NPP on ecosystem C storage will be based on a net balance among all ecosystem C pools and are likely to be ecosystem-dependant. Forest C models need to include these complex linkages between forest productivity and soil C storage.     

Effects of deer browsing on the survival and growth of <Emphasis Type="Italic">Abies homolepis</Emphasis> and <Emphasis Type="Italic">Picea jezoensis</Emphasis> var. <Emphasis Type="Italic">hondoensis</Emphasis> seedlings after fencing on Mt. Ohdaigahara

We evaluated the survival and growth of Abies homolepis and Picea jezoensis var. hondoensis seedlings on Mt. Ohdaigahara, where the population of sika deer (Cervus nippon) is high and an experimental fence has been in place for 13 years. No significant differences were detected in the survival of small seedlings between fenced and unfenced plots. The growth of A. homolepis was significantly higher in the fenced plot, but growth of P. jezoensis var. hondoensis did not show significant differences between fenced and unfenced plots. Seedlings of height ≤5 cm in the forest floor vegetation of the unfenced plot were probably too small for deer to find and browse, so they survived.     

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 clearfelling on forest floor accumulation and litter decomposition in a radiata pine plantation

The short-term effects of clearfelling a Pinus radiata D. Don. stand in Catalonia (NE Spain) under Mediterranean conditions were assessed. Harvesting had little effect on the surface soil distribution and accumulation. However, after clearfelling the range of soil temperatures increased, the moisture content of the L layer decreased, and the decomposition of brown needles was retarded (mass loss rate for the first year of the incubation 0.47 year⁻¹ vs. 0.29 year⁻¹). Green needles incorporated as a result of harvesting operations showed the same rates of mass loss as brown needles. Brown needles released substantial amounts of all major nutrients, especially at the beginning of the incubation. In both clearfelled and undisturbed stands, this sudden nutrient flush may have important implications in the nutrient economy of the vegetation. In contrast, green needles behaved as a sink of nitrogen and calcium, therefore representing a temporary reservoir after clearfelling.     

Short-term browsing by roe deer has little effect on survival and growth of sessile oak seedlings

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.     

长白山阔叶红松林林地附近湍流特征分析

2001年8月使用三维超声风温仪(IA-SA 485)测定并分析了中国科学院长白山森林生态系统开放站阔叶红松林样地(12828扙,4224?N,吉林省,中国)林地附近湍流特征。发现林地附近气流具有高度间歇性和不对称性,并为活跃的向上运动主导。垂直方向的湍流受到抑制,其时间尺度和长度尺度都小于水平两个分量的相应值,林地附近的气团呈偏平结构。热力作用对当地湍流产生和维持过程起到了主导作用。图4表3参15。     

Estimation of biomass and carbon stocks in plants,soil and forest floor in different tropical forests

An accurate characterization of tree carbon (TC), forest floor carbon (FFC) and soil organic carbon (SOC) in tropical forest plantations is important to estimate their contribution to global carbon stocks. This information, however, is poor and fragmented. Carbon contents were assessed in patula pine (Pinus patula) and teak (Tectona grandis) stands in tropical forest plantations of different development stages in combination with inventory assessments and soil survey information. Growth models were used to associate TOC to tree normal diameter (D) with average basal area and total tree height (H_T), with D and H_T parameters that can be used in 6–26 years old patula pine and teak in commercial tropical forests as indicators of carbon stocks. The information was obtained from individual trees in different development stages in 54 patula pine plots and 42 teak plots. The obtained TC was 99.6 Mg ha⁻¹ in patula pine and 85.7 Mg ha⁻¹ in teak forests. FFC was 2.3 and 1.2 Mg ha⁻¹, SOC in the surface layer (0–25 cm) was 92.6 and 35.8 Mg ha⁻¹, 76.1 and 19 Mg ha⁻¹ in deep layers (25–50 cm) in patula pine and teak, respectively. Carbon storage in trees was similar between patula pine and teak plantations, but patula pine had higher levels of forest floor carbon and soil organic carbon. Carbon storage in trees represents 37 and 60% of the total carbon content in patula pine and teak plantations, respectively. Even so, the remaining percentage corresponds to SOC, whereas FFC content is less than 1%. In summary, differences in carbon stocks between patula pine and teak trees were not significant, but the distribution of carbon differed between the plantation types. The low FFC does not explain the SOC stocks; however, current variability of SOC stocks could be related to variation in land use history.     

Altitudinal differences in bark stripping by sika deer in the subalpine coniferous forest of Mt. Fuji

Deer expansion is a growing concern for forest ecosystem management. In Japan, upward expansion to subalpine and alpine areas has reached alarming proportions in recent years. We examined bark stripping by sika deer along an altitudinal gradient in the subalpine coniferous forest at three altitude ranges (1800-2000 m, 2000-2200 m, and 2200-2400 m) on the southern slope of Mt. Fuji. We tested differences in densities and diameter at breast height (DBH) of trees and those with bark-stripped stems of all tree species among the three altitude ranges. Then, we compared the relative densities of deer, based on pellet counts, to determine the impact of deer in relation to deer use and forest stand patterns across the altitudinal range studied. The results of the study show that differences in bark stripping by sika deer depended largely on the elevation and the species. Larger stems were sparsely distributed in the lowest elevation zone between 1800 and 2000 m. The relative density of deer was highest in the areas exhibiting high bark-stripping intensity on small regenerating trees of the dominant coniferous species, Abies veitchii, and on broadleaf species. In the highest elevation zone between 2200 and 2400 m, smaller stems were densely distributed, and the relative deer density was lowest where the bark-stripping intensity on small stems was lower for all three species studied. The damage to subalpine tree stems corresponded to the availability of palatable tree species with a small diameter, as reflected by the successional stage along the elevational gradient of subalpine forest on Mt. Fuji. These results suggest that the continuous impact of bark stripping on the dominant tree species might cause severe changes in forest succession.     

The influence of forest cover on mule deer habitat selection, diet, and nutrition during winter in a deep-snow ecosystem

Recent research in western North America suggests that open forage areas are a greater limiting factor to mule deer abundance than closed conifer forests. However, much of this work was conducted in ecosystems prone to fire and low snow depths compared to the limits of mule deer range such as the Columbia Mountains, British Columbia, where snow is deep and fires are rare. We used snow track surveys as a measure of habitat use and fecal nitrogen as an index of dietary quality to compare the relative value to mule deer of open deciduous canopies to closed coniferous canopies in a wet ecosystem with deep snow and few fires. Deciduous canopies contain higher levels of understory forage compared to dense coniferous canopies, which are better at intercepting snow. We also evaluated food habits across landscapes with contrasting forest canopies. Results corroborated previous work in that foraging areas such as deciduous stands were strongly selected by deer, despite deeper snow relative to closed coniferous stands. Deer consumed fewer understory shrubs in coniferous-dominated stands, suggesting lower nutritional intake in these stands. Finally, deer appeared to derive a nutritional benefit in landscapes that had a higher proportion of open deciduous canopies, as indexed by fecal nitrogen. However, not all open canopy stands were of equal value to deer – deciduous-dominated stands were selected, whereas clearcuts were avoided. Similarly, not all closed coniferous stands were equally selected: cedar–hemlock stands were avoided whereas Douglas-fir stands were selected and indeed contained the highest proportion of deer tracks. We suggest that winter foraging areas have been underrepresented in management policy in British Columbia, but that snow-interception cover provided by coniferous stands still plays a role in winter deer ecology in deep-snow ecosystems.     

Long-term deer exclusion in yew-wood and oakwood habitats in southwest Ireland: Changes in ground flora and species diversity

Changes in ground flora were monitored over a 32-year period in deer exclosures in a yew-wood and a neighbouring oakwood in Killarney National Park, southwest Ireland; both woods are Annex I habitats under the European Habitats Directive. Comparison was made with unfenced plots adjacent to each of the exclosures. During the period of the study, both woods were heavily grazed by introduced sika deer (Cervus nippon). In the yew-wood exclosures, total ground flora cover increased markedly during the period of deer exclusion, the main species to increase in abundance being Rubus fruticosus agg. and Hedera helix. Herbaceous species increased initially in frequency but subsequently declined; herbaceous species had higher total cover in unfenced plots than in fenced plots at the end of the study. In the oakwood, Luzula sylvatica and Vaccinium myrtillus expanded their cover in one exclosure with cover in ferns declining, but in other exclosures where dense holly thickets developed, it was instead R. fruticosus and H. helix that became more abundant within the fences than outside. Overall, long-term fencing has caused a shift from vegetation characterised by woodland specialist to woodland generalist species and there are indications of a long-term decline in diversity. We conclude that chronic heavy grazing in these woodlands has strongly influenced the overall abundance and composition of the ground flora, but that complete exclusion of grazing is also undesirable due to potential declines in diversity of woodland specialists.     

Effect of tree species on carbon stocks in forest floor and mineral soil and implications for soil carbon inventories

Forest soil organic carbon (SOC) and forest floor carbon (FFC) stocks are highly variable. The sampling effort required to assess SOC and FFC stocks is therefore large, resulting in limited sampling and poor estimates of the size, spatial distribution, and changes in SOC and FFC stocks in many countries. Forest SOC and FFC stocks are influenced by tree species. Therefore, quantification of the effect of tree species on carbon stocks combined with spatial information on tree species distribution could improve insight into the spatial distribution of forest carbon stocks.We present a study on the effect of tree species on FFC and SOC stock for a forest in the Netherlands and evaluate how this information could be used for inventory improvement. We assessed FFC and SOC stocks in stands of beech (Fagus sylvatica), Douglas fir (Pseudotsuga menziesii), Scots pine (Pinus sylvestris), oak (Quercus robur) and larch (Larix kaempferi).FFC and SOC stocks differed between a number of species. FFC stocks varied between 11.1 Mg C ha⁻¹ (beech) and 29.6 Mg C ha⁻¹ (larch). SOC stocks varied between 53.3 Mg C ha⁻¹ (beech) and 97.1 Mg C ha⁻¹ (larch). At managed locations, carbon stocks were lower than at unmanaged locations. The Dutch carbon inventory currently overestimates FFC stocks. Differences in carbon stocks between conifer and broadleaf forests were significant enough to consider them relevant for the Dutch system for carbon inventory.     

Ground floor vegetation assessment within the intensive (Level II) monitoring of forest ecosystems in Germany: chances and challenges

As a part of the ‘Intensive Forest Monitoring Programme’ of ICP Forests, ground floor vegetation has been surveyed along with parameters of other relevant components of the forest ecosystems and their environment at 80 permanent plots all over Germany. Its floristic composition and their changes can therefore be linked to a wide variety of potentially influencing factors, scrutinising recent hypotheses on floristic changes, mainly soil eutrophication and acidification due to air pollutants. Results of a broad-scaled feasibility study are presented and critically discussed with regard to future in-depth evaluations. After an overview on the most abundant species, the syntaxonomic allocation of the plots is given. An ordination reveals a gradient from nutrient and base rich soils to poor acidic soils. Floristic dynamics are mainly aligned with the main axis, but conclusions about the medium-term development cannot be stated yet. Ordination and subsequent statistics are recommended to open up a wide field for explorative investigations. Indicator values for soil acidity and nutrient supply corroborate the main floristic gradient. Based on an empirical species–area relationship (SAR), species numbers for a common plot size of 400 m² were calculated. Basic relationships among different diversity measures and between diversity measures and basic stand and site-related parameters were elaborated. Recommendations focus on enhancements of the assessment of ground floor vegetation within the context of the Level II monitoring like annual sampling or harmonisation of the plot sizes.     

内蒙古阿尔山市国有林区濒危野生动物——梅花鹿的保护与繁育

文章阐述梅花鹿的形态特征及生活习性以及阿尔山市国有林区梅花鹿资源现状。重点阐述了梅花鹿资源的保护和繁育措施,以利于该地区梅花鹿种群数量的递增。     

Effects of forest canopy gap on biomass of Abies faxoniana seedlings and its allocation in subalpine coniferous forests of western Sichuan

Using a strip transect sampling method, the density, height (≤ 100 cm), basal diameter and components of biomass of Abies faxoniana seedlings, living in a forest gap (FG) and under the forest canopy (FC) of subalpine natural coniferous forests in western Sichuan, were investigated and the relationships among different components of biomass analyzed. The results indicated that the density and average height (H) of A. faxoniana seedlings were significantly different in the FG and under the FC, with the values being 12903 and 2017 per hm², and 26.6 and 24.3 cm. No significant differences were found in the average basal diameter (D) and biomass. The biomass allocation in seedling components was significantly affected by forest gap. In the FG, the biomass ratio of branch to stem reached a maximum of 1.54 at age 12 and then declined and fluctuated around 0.69. Under the FC, the biomass ratio of branch to stem increased with seedling growth and exceeded 1.0 at about age 15. The total biomass and the biomass of leaves, stems, shoots and roots grown in the FG and under the FC were significantly correlated with D ² H. There were significant and positive correlations among the biomass of different components. __________ Translated from Chinese Journal of Applied Ecology, 2007, 18(4): 721–727 [译自: 应用生态学报]     

Carbon and nitrogen in forest floor and mineral soil under six common European tree species

The knowledge of tree species effects on soil C and N pools is scarce, particularly for European deciduous tree species. We studied forest floor and mineral soil carbon and nitrogen under six common European tree species in a common garden design replicated at six sites in Denmark. Three decades after planting the six tree species had different profiles in terms of litterfall, forest floor and mineral soil C and N attributes. Three groups were identified: (1) ash, maple and lime, (2) beech and oak, and (3) spruce. There were significant differences in forest floor and soil C and N contents and C/N ratios, also among the five deciduous tree species. The influence of tree species was most pronounced in the forest floor, where C and N contents increased in the order ash = lime = maple < oak = beech ? spruce. Tree species influenced mineral soil only in some of the sampled soil layers within 30 cm depth. Species with low forest floor C and N content had more C and N in the mineral soil. This opposite trend probably offset the differences in forest floor C and N with no significant difference between tree species in C and N contents of the whole soil profile. The effect of tree species on forest floor C and N content was primarily attributed to large differences in turnover rates as indicated by fractional annual loss of forest floor C and N. The C/N ratio of foliar litterfall was a good indicator of forest floor C and N contents, fractional annual loss of forest floor C and N, and mineral soil N status. Forest floor and litterfall C/N ratios were not related, whereas the C/N ratio of mineral soil (0–30 cm) better indicated N status under deciduous species on rich soil. The results suggest that European deciduous tree species differ in C and N sequestration rates within forest floor and mineral soil, respectively, but there is little evidence of major differences in the combined forest floor and mineral soil after three decades.