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Research on mixed forests has mostly focused on tree growth and productivity, or resistance and resilience in changing climate conditions, but only rarely on the effects of tree species mixing on timber quality. In particular, it is still unclear whether the numerous positive effects of mixed forests on productivity and stability come at the expense of timber quality. In this study, we used photographs of sawn boards from 90 European beech (Fagus sylvatica L.) trees of mixed and pure forest stands to analyze internal timber quality through the quality indicator knot surface that was quantitatively assessed using the software Datinf® Measure. We observed a decrease in knot surface with increasing distance from the pith as well as smaller values in the lower log sections. Regarding the influence of neighborhood species identity, we found only minor effects meaning that timber qualities in mixed stands of beech and Norway spruce (Picea abies (L.) H. Karst.) tended to be slightly worse compared to pure beech stands.

In Europe, the non-native Northern red oak (Quercus rubra L.) is widely recommended for future cultivation. However, outside its natural range, Northern red oak has to date been insufficiently studied both in terms of silviculture and genetics. To clarify this, we studied the architecture of 92 (pre-) dominant Northern red oak trees in five German federal states using the non-destructive terrestrial laser scanning method (TLS). In addition, individual-based heterozygosity was calculated based on microsatellite data obtained by analyzing twelve potentially adaptive genic (EST derived markers) and eight putatively selectively neutral nuclear microsatellite markers. With these data the individual heterozygosity of the sample trees was calculated. Mean or median branch angles as well as branch angle ranges of first order branches decreased with individual heterozygosity calculated group-wise for all markers (HoAll) and for EST-derived markers (HoEST). Most other tree characteristics, including the number of bark anomalies and mean stem non-circularity and crown characteristics such as crown volume, crown surface area, or mean branch length of first order branches responded exclusively to competition. We conclude that competition, not genetics, is the main driver of Northern red oak stem and crown characteristics. Thus, stem quality and crown dimension can primarily be controlled by silvicultural interventions. The significant relationship between Northern red oak branch angle traits and individual tree heterozygosity was unexpected, and at this time we do not have any validated explanation for this. This issue needs to be further investigated.

The introduction of non-native species with various ecological and functional traits to European forests may be a potential tool for mitigating climate risks. We analyzed the growth sensitivity to climate of seven alien (Acer rubrum, Betula maximowicziana, Castanea sativa, Cryptomeria japonica, Metasequoia glyptostroboides, Thuja plicata and Tsuga heterophylla) and two native (Fagus sylvatica and Picea abies) tree species on a productive forest site in western Germany in order to assess their potential suitability in light of climate change. Retrospective basal area increment at breast height (BAI) and total stem volume increment (VI) were statistically related to a total of 11 multiscale climatic variables showing minor discrepancies between BAI and VI in climatic sensitivity. Across the tree species, the strongest climate signals were found for the standardized precipitation evapotranspiration index (spei), vapor pressure deficit (vpd) and the number of frost days (nfr) representing water availability, heat and coldness, respectively. Growth of most species was positively affected by mild winters and growing season spei. Importance of the investigated variables differed among tree species with, e.g., C. sativa and T. plicata being mainly driven by winter vpd and A. rubrum, C. japonica and P. abies by water availability in the growing seasons. We conclude that particularly more anisohydric species (e.g., C. sativa) may profit from their low sensitivity to drier conditions. Highly sensitive and isohydric species (e.g., A. rubrum) will undergo significant growth reductions when climate becomes more variable.

Black walnut (Juglans nigra L.) is a light-demanding, competition-intolerant, and tall forest tree species, introduced in Europe from North America at the beginning of the seventeenth century. It has an important economic role in Europe for producing wood and fruits, in agroforestry systems, as an ornamental tree for parks and avenues, for rehabilitation/restoration of degraded lands. The best sites for black walnut growth have warm and mild climates, with frequent and well-spread precipitation, and rich, deep, near neutral, well-drained and moist soils. Black walnut is a fast grower in youth and its height and diameter growth reach their peaks before age 30–35 years. It is globally the best known allelopathic species due to the juglone substance present in all parts of black walnut trees. The species is storm-resistant and not affected by any major pest or disease in Europe. It is regenerated by planting or direct seeding on bare land, in monocultures and mixed stands. The management of stands with black walnut, with a rotation period generally up to 80 years, include weeding (mandatory), cleaning-respacing (in dense stands), thinning (mostly from above), high and formative pruning (mandatory), with the aim of producing valuable wood for sliced veneer, solid furniture, flooring/parquet, cabinetry, panelling, sculpture, musical instruments, gunstocks.

Timber quality is the main driver of timber prices and is strongly influenced by the competition a tree experiences until its day of harvest. Regulating competition is an integral part of silviculture, and therefore, deeper understanding of the competitor’s influence on timber quality is important. Since mixed forest stands and the share of broadleaved tree species have increased in the recent past because of a changed forest policy in several countries, effects of mixture types on timber quality are of increasing importance. In this study, we investigated the effects of intra- and interspecific competition on the internal timber quality of European beech (Fagus sylvatica L.). To analyze the effects of competition intensity and competitor species identity on the timber quality of 82 target beech trees, three different approaches were used: terrestrial laser scanning (TLS), a quality assessment on the standing tree by local district foresters, and a quality assessment of the sawn wood (boards) after harvesting. We investigated the relationship between external and internal quality features and additionally compared the different approaches to assess quality. We found that the present competitive situation was partly related to internal timber quality, with increasing competition leading to increased internal timber quality. We further observed more discoloration in timber of beech trees growing in mixture with other broadleaved tree species. We also showed that predicting discoloration is possible through the number of bark anomalies on the stem surface. Also, the external quality assessment of local foresters on standing trees predicted the internal timber features well. Finally, TLS appeared to be a valuable addition for assessing timber quality in situ.

Many non-native tree species have been introduced to Europe to improve forest productivity. It is assumed that some of these species are better able than native species to mitigate negative effects of climate change. A high growth-related tolerance to climatic extremes is essential to qualify a tree species’ suitability for cultivation and must be quantified before initiating adaptation measures. This study investigated basal area and volume increment (BAI and VI) data at various stem height positions to evaluate inter-annual growth variation (mean sensitivity) and drought tolerance of seven alien tree species (Acer rubrum L., Betula maximowicziana Regel, Castanea sativa Mill, Cryptomeria japonica D. Don, Metasequoia glyptostroboides Hu et Cheng, Thuja plicata Donn and Tsuga heterophylla Sarg.) which are considered stress tolerant, and two native species (Fagus sylvatica L., Picea abies H. Karst.) in the Arboretum Burgholz in West Germany. We found that mean sensitivity and response to drought (resistance, recovery, resilience) were related; i.e., sensitive species exhibited greater drought response than less sensitive species. In the drought years 2003, 2006 and 2010/2011, VI of the highly sensitive species C. japonica and P. abies and rather moderate sensitive A. rubrum decreased most strongly (36%), while less sensitive C. sativa and T. heterophylla were the most resistant tree species (25% decrease). B. maximowicziana, F. sylvatica, M. glyptostroboides and T. plicata were moderately sensitive to drought events (growth depression by 29%). Recovery after drought showed mainly a reverse response pattern; species with lower resistance recovered faster, but this trade-off was not uniform among species. Across drought events, we observed high variation in the response of individual trees and between different tree species. This finding indicates that species’ drought sensitivity depends strongly on the drought’s onset, duration and frequency. Along tree stems, mean sensitivity and response to drought in 2003 decreased species-specifically from lower to upper stem section height. Thus, quantifying drought sensitivity based solely on breast height measures may result in biased estimates of production declines.

Animal-vehicle collisions (AVCs) pose a serious threat to human and animal welfare, and result in increasing costs for society. Mitigation efforts have been in the focus of research for decades but have revealed only few generalities on where and why AVCs occur. Uncertainty therefore remains on how to make decisions regarding nature conservation, wildlife and transportation management. In our study, we used GPS data on almost 1000 AVCs between October 2014 and October 2016 involving roe deer (Capreolus capreolus L.) in the administrative district of Gottingen, Germany, to identify accident hotspots based on Kernel Density analysis. We then used information from a mapping campaign of trees outside forests (TOF), including hedges, bushes, groves, isolated trees and other non-forest vegetation to investigate whether TOF abundance is larger near accident hotspots when compared to areas showing no hotspots (assumed as reference area). We found that near hotspots, TOF are significantly more abundant than in the remaining reference area. We conclude that future transportation management should consider TOF management as a possible indicator for AVCs.

Black locust (Robinia pseudoacacia L.), a species native to the eastern North America, was introduced to Europe probably in 1601 and currently extends over 2.3 × 106 ha. It has become naturalized in all sub-Mediterranean and temperate regions rivaling Populus spp. as the second most planted broadleaved tree species worldwide after Eucalyptus spp. This wide-spreading planting is because black locust is an important multipurpose species, producing wood, fodder, and a source of honey as well as bio-oil and biomass. It is also important for carbon sequestration, soil stabilization and re-vegetation of landfills, mining areas and wastelands, in biotherapy and landscaping. In Europe, black locust is drought tolerant so grows in areas with annual precipitation as low as 500–550 mm. It tolerates dry, nutrient poor soils but grows best on deep, nutrient-rich, well-drained soils. It is a fast-growing tree and the height, diameter and volume growth peak before the age of 20. It mostly regenerates vegetatively by root suckers under a simple coppice system, which is considered the most cost-effective management system. It also regenerates, but less frequently, by stool sprouts. Its early silviculture in production forests includes release cutting to promote root suckers rather than stool shoots, and cleaning-respacing to remove low-quality stems, reduce the number of shoots per stool, and adjust spacing between root suckers. In addition, early, moderate and frequent thinning as well as limited pruning are carried out focusing on crop trees. The species is regarded as invasive in several European countries and its range here is expected to expand under predicted climate changes.

The long-term (>20 yr) effects of canopy opening and liming on leaf litter production over 2 periods (1990–1997; 2000–2010), and fine root and litter decomposition over 3 periods (1992–1993; 1996–1997; 2012–2013) were examined in a mature European beech ( Fagus sylvatica L . ) stand on a nutrient-poor site. The results did partially support the hypothesis that the combined or single effects of liming and/or canopy removal on the litter production and decomposition lasted for more than 20 years. The main results were: (1) Along with beech regeneration, the annual leaf litter input in all study plots was higher for the period 2000–2010 (2.9 Mg ha −1 yr −1 ) than for 1990–1997 (2.5 Mg ha −1 yr −1 ), and the differences among the treatments were getting smaller; (2) The mass of beech leaf litter fall was higher in the stands than in the gaps; (3) Liming accelerated the fine root and OF layer litter decomposition in the period April 1992 to July 1993, and fine root and leaf litter from June 1996 to September 1997, but this effect was not observed in the period March 2012 to July 2013; (4) The gap effect alone did not accelerate the litter decomposition rate in the first period, but in the second and third periods; (5) 23 years after liming and canopy opening, the quality of the leaf litter was different, and the canopy opening continued to accelerate both leaf litter and fine-root decomposition.

Four gaps of 30 m diameter were cut in a mature European beech (Fagus sylvatica L.) forest in 1989. In two of the gaps and their surrounding areas, dolomite lime (3 t ha−1) was applied. The study was designed to examine the long-term effects of lime application and canopy removal on element input via throughfall and output in seepage water at 80 cm depth in this European beech forest. Throughfall and seepage water were collected in the unlimed gap center, the limed gap center and the undisturbed beech stand in 1991, 1992, 1993, 1996 and 2012. The canopy opening increased the seepage water acidity from 1991 to 1996. The pH values of the seepage water were higher in the limed gaps than in the unlimed gaps during the five study periods. The amount of annual throughfall and of seepage water were higher in the gaps during the study period; in 2012, the annual amounts of seepage water were significantly higher in the gaps than in the closed stand, whereas the input of most elements decreased from 1991 t...

Climate change includes not only shifts in mean conditions but also changes in the frequency and timing of extreme weather events. Tree seedlings, as the potential future overstory, are responding to the selective pressures of both mean and extreme conditions. We investigated how increases in mean temperature and the occurrence of late spring frosts affect emergence, development, growth, and survival of 13 native and non-native broadleaf and conifer tree species common in central Europe. Three temperature levels (ambient, +3, and +6 °C) and three spring frost treatments (control, late, and very late) were applied. Development responses of first-year seedlings to warmer temperatures were similar in direction and magnitude for broadleaf and conifer species. Stem size also increased with rising mean temperature for most species, though broadleaf species had maximal height advantage over conifer species in the warmest treatment. Sensitivity to frost differed sharply between the broadleaf and conifer groups. Broadleaf survival and stem length exhibited strong reductions due to frost events while conifer species only showed minor decreases in survival. Importantly, more rapid development and earlier leaf-out in response to warmer temperatures were associated with increased mortality from frost for broadleaf species but decreased mortality for conifer species. This research suggests that compositional shifts in the direction of species favored by increasing mean temperatures may be slowed by extreme events, and thus, the occurrence and impacts of such weather events must be acknowledged and incorporated into research and forest planning.

Feedbacks between plants and soil microbes can play an important role in competition between potential invaders and the resident community. However, the role of saprophytic soil microbes is poorly understood because research largely focuses on the role of specific soil-borne pathogens. Our aim was to examine the role of plant-saprophyte feedbacks in soil processes (decomposition and enzyme activities) and plant competition. We preconditioned a common soil in microcosms by decomposing litter of four species; two exotic invasive species (Microstegium vimineum and Berberis thunbergii) and two native species (Viburnum acerifolium and Vaccinium corymbosum). We then replaced the litter with either the same species’ litter or a different species’ litter on the preconditioned soil. We measured the effect of preconditioning on subsequent litter decomposition, microbial community structure (phospholipid fatty acids) and function (soil enzyme activities and decomposition). We then grew Berberis and Viburnum seedlings in preconditioned soils under intraspecific and interspecific competition to determine whether litter preconditioning had a feedback effect on competition. Changes in microbial community structure during preconditioning persisted through time and altered subsequent soil enzyme activities and litter decomposition. These changes also affected the growth rate of two shrub species, but because both shrubs grew best in soil that previously contained Berberis litter, competition between these species was not directly affected. Plant litter creates a legacy that influences the future structure of the microbial community even after that litter is gone. This legacy effect has functional consequences on decomposition and plant growth, and could be an important but under-appreciated factor in soil and plant community ecology. Further study is needed to determine how these consequences affect plant community composition and invasibility.

Tick-borne encephalitis virus (TBEV) causes one of the most important flavivirus infections of the central nervous system, affecting humans in Europe and Asia. It is mainly transmitted by the bite of an infected tick and circulates among them and their vertebrate hosts. Until now, TBE risk analysis in Germany has been based on the incidence of human cases. Because of an increasing vaccination rate, this approach might be misleading, especially in regions of low virus circulation.To test the suitability of rodents as a surrogate marker for virus spread, laboratory-bred Microtus arvalis voles were experimentally infected with TBEV and analyzed over a period of 100 days by real-time (RT)-quantitative polymerase chain reaction. Further, the prevalence of TBEV in rodents trapped in Brandenburg, a rural federal state in northeastern Germany with autochthonous TBE cases, was determined and compared with that in rodents from German TBE risk areas as well as TBE nonrisk areas.In experimentally infected M. arvalis voles, TBEV was detectable in different organs for at least 3 months and in blood for 1 month. Ten percent of all rodents investigated were positive for TBEV. However, in TBE risk areas, the infection rate was higher compared with that of areas with only single human cases or of nonrisk areas. TBEV was detected in six rodent species: Apodemus agrarius, Apodemus flavicollis, Apodemus sylvaticus, Microtus agrestis, Microtus arvalis, and Myodes glareolus. M. glareolus showed a high infection rate in all areas investigated.The infection experiments proved that TBEV can be reliably detected in infected M. arvalis voles. These voles developed a persistent TBE infection without clinical symptoms. Further, the study showed that rodents, especially M. glareolus, are promising sentinels particularly in areas of low TBEV circulation.

Plant invasions can have substantial consequences for the soil ecosystem, altering microbial community structure and nutrient cycling. However, relatively little is known about what drives these changes, making it difficult to predict the effects of future invasions. In addition, because most studies compare soils from uninvaded areas to long-established dense invasions, little is known about the temporal dependence of invasion impacts. We experimentally manipulated forest understory vegetation in replicated sites dominated either by exotic Japanese barberry (Berberis thunbergii), native Viburnums, or native Vacciniums, so that each vegetation type was present in each site-type. We compared the short-term effect of vegetation changes to the lingering legacy effects of the previous vegetation type by measuring soil microbial community structure (phospholipid fatty acids) and function (extracellular enzymes and nitrogen mineralization). We also replaced the aboveground litter in half of each plot with an inert substitute to determine if changes in the soil microbial community were driven by aboveground or belowground plant inputs. We found that after 2 years, the microbial community structure and function was largely determined by the legacy effect of the previous vegetation type, and was not affected by the current vegetation. Aboveground litter removal had only weak effects, suggesting that changes in the soil microbial community and nutrient cycling were driven largely by belowground processes. These results suggest that changes in the soil following either invasion or restoration do not occur quickly, but rather exhibit long-lasting legacy effects from previous belowground plant inputs.

In order to identify variables associated with the presence of the tick-borne encephalitis (TBE) virus, we conducted a serological survey of roe deer [Capreolus capreolus (Artiodactyla: Cervidae, Linnaeus 1758)] in three forest districts of southern Hesse, Germany. Overall, 24 out of 105 (22.9%) of the sera were positive (≥1 : 10 plaque reduction neutralization test). Using a logistic regression approach, we found that unexplained spatial variation, indexed roe deer density (positive correlation), hind foot length of the tested roe deer (positive correlation) and infestation with female Ixodes spp. ticks (negative correlation) predicted the probability of TBE virus antibody presence in individual roe deer sera. Spring temperature increase and host sex were rejected as explanatory variables. We found considerable differences in TBE virus antibody seroprevalence (50.0% vs. 17.6%) between two forest districts located in the same county; this finding questions the current county-resolution of public health recordings. Given the high seroprevalence of roe deer and the considerable explanatory power of our model, our approach appears suitable to delineate science-based risk maps at a smaller spatial scale and to abandon the current human incidence per county criterion. Importantly, using roe deer as sentinels would eliminate the inherent bias of risk maps based on human incidence (varying levels of immunization and exposure of humans).

Identifying factors affecting individual vector burdens is essential for understanding infectious disease systems. Drawing upon data of a rodent monitoring programme conducted in nine different forest patches in southern Hesse, Germany, we developed models which predict tick (Ixodes spp. and Dermacentor spp.) burdens on two rodent species Apodemus flavicollis and Myodes glareolus. Models for the two rodent species were broadly similar but differed in some aspects. Patterns of Ixodes spp. burdens were influenced by extrinsic factors such as season, unexplained spatial variation (both species), relative humidity and vegetation cover (A. flavicollis). We found support for the ‘body mass’ (tick burdens increase with body mass/age) and for the ‘dilution’ hypothesis (tick burdens decline with increasing rodent densities) and little support for the ‘sex-bias’ hypothesis (both species). Surprisingly, roe deer densities were not correlated with larvae counts on rodents. Factors influencing the mean burden did not significantly explain the observed dispersion of tick counts. Co-feeding aggregations, which are essential for tick-borne disease transmission, were mainly found in A. flavicollis of high body mass trapped in areas with fast increase in spring temperatures. Locally, Dermacentor spp. appears to be an important parasite on A. flavicollis and M. glareolus. Dermacentor spp. was rather confined to areas with higher average temperatures during the vegetation period. Nymphs of Dermacentor spp. mainly fed on M. glareolus and were seldom found on A. flavicollis. Whereas Ixodes spp. is the dominant tick genus in woodlands of our study area, the distribution and epidemiological role of Dermacentor spp. should be monitored closely. peerReviewed

In our study we assessed the tick burden on roe deer (Capreolus capreolus L.) in relation to age, physical condition, sex, deer density and season. The main objective was to find predictive parameters for tick burden. In September 2007, May, July, and September 2008, and in May and July 2009 we collected ticks on 142 culled roe deer from nine forest departments in Southern Hesse, Germany. To correlate tick burden and deer density we estimated deer density using line transect sampling that accounts for different detectability in March 2008 and 2009, respectively. We collected more than 8,600 ticks from roe deer heads and necks, 92.6% of which were Ixodes spp., 7.4% Dermacentor spp. Among Ixodes, 3.3% were larvae, 50.5% nymphs, 34.8% females and 11.4% males, with significant seasonal deviation. Total tick infestation was high, with considerable individual variation (from 0 to 270 ticks/deer). Adult tick burden was positively correlated with roe deer body indices (body mass, age, hind foot length). Significantly more nymphs were found on deer from forest departments with high roe deer density indices, indicating a positive correlation with deer abundance. Overall, tick burden was highly variable. Seasonality and large scale spatial characteristics appeared to be the most important factors affecting tick burden on roe deer. peerReviewed

Despite the importance of gaps in the dynamics and management of many forest types, very little is known about the medium- to long-term soil C and N dynamics associated with this disturbance. This study was designed to test the hypothesis that gap creation and lime application, a routine measure in many European forests to ameliorate soil acidity, lead to accelerated litter decomposition and thus a reduction in the forest floor and soil C and N pools. Four gaps were created in 1989 in a mature European beech (Fagus sylvatica L.) forest on acid soil with a moder humus, and lime (3 t dolomite·ha–1) was applied to two of these and surrounding areas. Litter and fine-root decomposition was measured in 1992–1993 and 1996–1998 using litterbags. Forest floor (L, F, and H layers) and mineral soil (0–40 cm) C and N pools were determined in 1989 and 1997. Eight years following silvicultural treatments, there was no change in C and N over the entire forest soil profile including forest floor. Reductions in the F and H layers in limed gaps were compensated for by increases in soil C and N in the surface (0–10 cm) mineral soil. Decomposition of F litter was significantly accelerated in limed gaps, leading to the development of a mull–moder, whereas gap creation alone had no effect on mass loss of F material in litterbags. Gap size disturbances in this acid beech forest appear to have minimal influences on soil C and N stocks. However, when combined with liming, changes in the humus form and vertical distribution of soil C and N may occur.

Closed tubes are commonly used for soil incubations in the field to determine net nitrogen mineralization (NNM). This study showed that gaseous losses of N in the form of N2O during this type of field incubations can lead to substantial underestimations of NNM. NNM was not underestimated in a 146-year-old beech stand, but underestimated by 15% in a gap of the same stand, by 6% in a limed stand and by 80% in a limed gap. Compared to closed chamber measurements, N2O output of the incubated tubes was on average 6, 90, 300 and 570% higher in the stand, the gap, the limed stand and the limed gap, respectively. CO2 respiration was enhanced in all tubes between 80% (stand) and 260% (gap), indicating a higher microbial activity after insertion of the tubes into the soil.

The spatio-temporal attachment site patterns of ticks feeding on their hosts can be of significance if co-feeding transmission (i.e. from tick to tick without a systemic infection of the host) of pathogens affects the persistence of a given disease. Using tick infestation data on roe deer, we analysed preferred attachment sites and niche width of Ixodes ticks (larvae, nymphs, males, females) and investigated the degree of inter- and intrastadial aggregation. The different development stages showed rather consistent attachment site patterns and relative narrow feeding site niches. Larvae were mostly found on the head and on the front legs of roe deer, nymphs reached highest densities on the head and highest adult densities were found on the neck of roe deer. The tick stages feeding (larvae, nymphs, females) on roe deer showed high degrees of intrastadial spatial aggregation, whereas males did not. Male ticks showed large feeding site overlap with female ticks. Feeding site overlap between larval-female and larval-nymphal ticks did occur especially during the months May–August on the head and front legs of roe deer and might allow pathogen transmission via co-feeding. Tick density, niche width and niche overlap on roe deer are mainly affected by seasonality, reflecting seasonal activity and abundance patterns of ticks. Since different tick development stages occur spatially and temporally clustered on roe deer, transmission experiments of tick-borne pathogens are urgently needed. peerReviewed

Macroparasites feeding on wildlife hosts follow skewed distributions for which basic statistical approaches are of limited use. To predict Ixodes spp. tick burden on roe deer, we applied Generalized Additive Models for Location, Scale and Shape (GAMLSS) which allow incorporating a variable dispersion. We analysed tick burden of 78 roe deer, sampled in a forest region of Germany over a period of 20 months. Assuming a negative binomial error distribution and controlling for ambient temperature, we analysed whether host sex and body mass affected individual tick burdens. Models for larval and nymphal tick burden included host sex, with male hosts being more heavily infested than female ones. However, the influence of host sex on immature tick burden was associated with wide standard errors (nymphs) or the factor was marginally significant (larvae). Adult tick burden was positively correlated with host body mass. Thus, controlled for host body mass and ambient temperature, there is weak support for sex-biased parasitism in this system. Compared with models which assume linear relationships, GAMLSS provided a better fit. Adding a variable dispersion term improved only one of the four models. Yet, the potential of modelling dispersion as a function of variables appears promising for larger datasets.

Die ökologischen und ökonomischen Risiken, die sich aus der in Deutschland üblichen Schalenwildbewirtschaftung für Waldökosysteme ergeben, werden allgemein unterschätzt. Die vor allem durch Wildverbiss verursachten Schäden verringern die Schutzwirkung von Wäldern und beeinträchtigen den vor dem Hintergrund des Klimawandels notwendigen Waldumbau. Die gesetzlichen Grundlagen für eine Verbesserung der Situation sind größtenteils bereits vorhanden, in einigen entscheidenden Punkten jedoch verbesserungsbedürftig. Es fehlt aber an deren Umsetzung. Es werden Möglichkeiten aufgezeigt, die Probleme zwischen der forstlichen Haupt- und der jagdlichen Nebennutzung zu lösen oder zumindest zu entschärfen. Das in dem Band diskutierte Instrumentarium reicht von der Stärkung des Verantwortungsbewusstseins aller Akteure bis hin zu denkbaren Sanktionen bei gleichbleibenden Verbissschäden. peerReviewed

Nutrient cycling in forest gaps has received little attention until now, although gap regeneration is important for natural dynamics and forest management practices in temperate forests. Gaps of 30 m diameter were cut in a mature European beech forest (Fagus sylvatica L.) in the Soiling Hills in Northwest Germany. The forest has been destablished through prolonged atmospheric pollutants. Deposition, plant uptake, nitrogen mineralization, seepage water chemistry and element losses were compared between limed and untreated gaps and the mature beech stand. The most obvious changes in the element cycle in gaps occurred in the output fluxes of nitrate, cations, heavy metals and laughing gas. The seepage water concentrations of nitrate and cadmium in the unlimed gaps exceeded drinking water thresholds. The major difference in seepage water concentrations of nutrients between gaps was caused by the development of the herbaceous vegetation in the limed gaps. Gap creation did not increase N mineralization as repeatedly reported for large-scale clear cuts.

The long-term effects of gap creation and liming on tree regeneration and understory competition were examined in a mature European beech (Fagus sylvatica) stand on a nutrient-poor site. In 1989, trees were felled to create four 30 m wide circular gaps, and 3 t ha-1 fine dolomite was applied to two of these gaps and the surrounding area, whereas the remaining two gaps and most parts of the stand remained untreated. In 2010, the stand density was 153 trees x ha-1 and the basal area was 29.51 m2 x ha-1. Testing a factorial combination of two levels of canopy cover (gap and stand) and two levels of lime application (limed and unlimed), the results of the case study partly support our initial hypothesis that the combined or single effects of liming and canopy removal on understory plant communities last for more than 20 years. Some effects disappeared slowly over time, while others did not. Understory vegetation of the unlimed gaps and thelimed and unlimed stands was rapidly dominated by beech regeneration, whereas limed gaps were dominated by fireweed (Epilobium angustifolium), bramble (Rubus fruticosus agg.) and raspberry (Rubus ideaus) for around 14 years. There, the density of the beech regeneration was reduced by competitive ground vegetation species. Plant species richness (n/100 m²) was still significantly different after 23 years, with an average 10 species per 100 m² in the limed stand area, 5 species in the unlimed stand area, 25 species in the limed gaps, and only 5 species in the unlimed gaps. Only the combination of liming and canopy removal enhanced the species richness in the long run. On our study site, this combination of liming and canopy opening had a long lasting influence on the ground vegetation in terms of retarding the beech regeneration and enhancing species’ richness.

Despite the importance of roe deer as a host for Ixodes ticks in central Europe, estimates of total tick burden on roe deer are not available to date. We aimed at providing (1) estimates of life stage and sex specific (larvae, nymphs, males and females, hereafter referred to as tick life stages) total Ixodes burden and (2) equations which can be used to predict the total life stage burden by counting the life stage on a selected body area. Within a period of 1(1/2) years, we conducted whole body counts of ticks from 80 hunter-killed roe deer originating from a beech dominated forest area in central Germany. Averaged over the entire study period (winter 2007-summer 2009), the mean tick burden per roe deer was 64.5 (SE +/- 10.6). Nymphs were the most numerous tick life stage per roe deer (23.9 +/- 3.2), followed by females (21.4 +/- 3.5), larvae (10.8 +/- 4.2) and males (8.4 +/- 1.5). The individual tick burden was highly aggregated (k = 0.46); levels of aggregation were highest in larvae (k = 0.08), followed by males (k = 0.40), females (k = 0.49) and nymphs (k = 0.71). To predict total life stage specific burdens based on counts on selected body parts, we provide linear equations. For estimating larvae abundance on the entire roe deer, counts can be restricted to the front legs. Tick counts restricted to the head are sufficient to estimate total nymph burden and counts on the neck are appropriate for estimating adult ticks (females and males). In order to estimate the combined tick burden, tick counts on the head can be used for extrapolation. The presented linear models are highly significant and explain 84.1, 77.3, 90.5, 91.3, and 65.3% (adjusted R (2)) of the observed variance, respectively. Thus, these models offer a robust basis for rapid tick abundance assessment. This can be useful for studies aiming at estimating effects of abiotic and biotic factors on tick abundance, modelling tick population dynamics, modelling tick-borne pathogen transmission dynamics or assessing the efficacy of acaricides.