Background:Higher exportation of harvest residues from forests due to increased demand for woody biomass,has reportedly diminished soil mineral resources and may lead to degraded tree nutrition as well as growth.Howev...Background:Higher exportation of harvest residues from forests due to increased demand for woody biomass,has reportedly diminished soil mineral resources and may lead to degraded tree nutrition as well as growth.However,as nutrients become less available in the soil,the remobilization of nutrients in biomass tissues(plant internal cycling)helps sustain tree nutrition.Our study aims to quantify the impact of Removing Harvest Residues and Litter(RHRL)during five years on tree growth,wood density,and stem wood nutrient concentrations in young beech and oak forest stands.Result:Our study found that,RHRL significantly decreased tree growth ring width by 14%,and wood density by 3%,in beech trees,in near bark rings.RHRL also significantly reduced nutrient concentration in near bark and near pith areas of both studied species.Mg,Na and S were found lower by 44%,76%,and 56%,respectively,in near bark area of beech trees.In near bark area of oak trees,K,Ca,Mg,Na,S,and Fe were lower by 20%,25%,41%,48%,41%,and 16%,respectively.K and Mg concentrations decreased more strongly in near pith area compared to near bark area suggesting internal translocation of these two elements.Conclusion:In beech trees,wood density proved to be an important factor while quantifying the effect of removing harvest residuals on tree growth and biomass.Soil nutrient loss intensified the remobilization of nutrients con-tained in older tree rings(close to the pith)towards newly formed rings(close to bark).In our study,in beech trees,K was found to be the most recycled major nutrient.These results demonstrate the potential of such analysis for providing valuable insight into the effect of RHRL in premature stands on the physiological adaptive strategies of trees and an indication of soil fertility status.展开更多
The consequences of climate change continue to threaten European forests,particularly for species located at the edges of their latitudinal and altitudinal ranges.While extensively studied in Central Europe,European b...The consequences of climate change continue to threaten European forests,particularly for species located at the edges of their latitudinal and altitudinal ranges.While extensively studied in Central Europe,European beech forests require further investigation to understand how climate change will affect these ecosystems in Mediterranean areas.Proposed silvicultural options increasingly aim at sustainable management to reduce biotic and abiotic stresses and enhance these forest ecosystems'resistance and resilience mechanisms.Process-based models(PBMs)can help us to simulate such phenomena and capture early stress signals while considering the effect of different management approaches.In this study,we focus on estimating sensitivity of two state-of-the-art PBMs forest models by simulating carbon and water fluxes at the stand level to assess productivity changes and feedback resulting from different climatic forcings as well as different management regimes.We applied the 3D-CMCC-FEM and MEDFATE forest models for carbon(C)and water(H_(2)O)fluxes in two sites of the Italian peninsula,Cansiglio in the north and Mongiana in the south,under managed vs.unmanaged scenarios and under current climate and different climatic scenarios(RCP4.5 and RCP8.5).To ensure confidence in the models’results,we preliminary evaluated their performance in simulating C and H_(2)O flux in three additional beech forests of the FLUXNET network along a latitudinal gradient spanning from Denmark to central Italy.The 3D-CMCC-FEM model achieved R^(2)values of 0.83 and 0.86 with RMSEs of 2.53 and 2.05 for C and H_(2)O fluxes,respectively.MEDFATE showed R^(2)values of 0.76 and 0.69 with RMSEs of 2.54 and 3.01.At the Cansiglio site in northern Italy,both models simulated a general increase in C and H_(2)O fluxes under the RCP8.5 climate scenario compared to the current climate.Still,no benefit in managed plots compared to unmanaged ones,as the site does not have water availability limitations,and thus,competition for water is low.At the Mongiana site in southern Italy,both models predict a decrease in C and H_(2)O fluxes and sensitivity to the different climatic forcing compared to the current climate;and an increase in C and H_(2)O fluxes when considering specific management regimes compared to unmanaged scenarios.Conversely,under unmanaged scenarios plots are simulated to experience first signals of mortality prematurely due to water stress(MEDFATE)and carbon starvation(3D-CMCC-FEM)scenarios.In conclusion,while management interventions may be considered a viable solution for the conservation of beech forests under future climate conditions at moister sites like Cansiglio,in drier sites like Mongiana conservation may not lie in management interventions alone.展开更多
In this era of biodiversity loss and climate change,quantifying the impacts of natural disturbance on forest communities is imperative to improve biodiversity conservation efforts.Epiphytic and epixylic lichens are ef...In this era of biodiversity loss and climate change,quantifying the impacts of natural disturbance on forest communities is imperative to improve biodiversity conservation efforts.Epiphytic and epixylic lichens are effective forest quality bioindicators,as they are generally long-lived organisms supported by continuity of specific forest structures and their associated microclimatic features.However,how lichen communities respond to the effects of fluctuating historical disturbances remains unclear.Using a dendrochronological approach,this study investigates how natural disturbance dynamics indirectly influence various lichen community metrics in some of Europe's best-preserved primary mixed-beech forests.Mixed modelling revealed that natural historical disturbance processes have decades-long effects on forest structural attributes,which had both congruent and divergent impacts on lichen community richness and composition.Total species richness indirectly benefited from both historical and recent higher-severity disturbances via increased standing dead tree basal area and canopy openness respectively-likely through the presence of both pioneer and late-successional species associated with these conditions.Red-listed species richness showed a dependence on habitat continuity(old trees),and increased with disturbance-related structures(standing dead trees)whilst simultaneously benefiting from periods without severe disturbance events(old trees and reduced deadwood volume).However,if the disturbance occurred over a century in the past,no substantial effect on forest structure was detected.Therefore,while disturbance-mediated forest structures can promote overall richness,threatened species appear vulnerable to more severe disturbance events-a concern,as disturbances are predicted to intensify with climate change.Additionally,the high number of threatened species found reinforce the critical role of primary forest structural attributes for biodiversity maintenance.Hence,we recommend a landscape-scale conservation approach encompassing forest patches in different successional stages to support diverse lichen communities,and the consideration of long-term disturbance dynamics in forest conservation efforts,as they provide critical insights for safeguarding biodiversity in our changing world.展开更多
Deadwood plays a key role for biodiversity in forests.A significant number of beetles from this group are currently listed as endangered in the Red List.In addition to other management recommendations,there have been ...Deadwood plays a key role for biodiversity in forests.A significant number of beetles from this group are currently listed as endangered in the Red List.In addition to other management recommendations,there have been recent efforts to enrich stands with dead wood to promote biodiversity.An important parameter for forestry enterprises is the optimization of these interventions.The study investigated the abundance,species richness,gamma diversity,conservation value and biomass of saproxylic beetles in natural forests using window traps.A total of 89traps were used for saproxylic beetle monitoring,of which 29 were placed on lying logs,30 on snags and 30 as controls in forest stand space.A total of 35,011 beetles were recorded in 564 species(61 families).Notably,20,515 of these belong to saproxylic beetles(59%)in 311 species(55%),with 62 classified as Red-List species(20%).In the group of'all saproxylic beetles',the results indicate that a diversity and y diversity(q=0)remain consistent across various deadwood types,whileβdiversity showed significant differences.Significant differences were found in the Red-List species group,where a diversity and y diversity differed,with higher values observed in snags.Rarefaction based total species richness of site was estimated to be 391 species,including 74 Red-Listed species.Comparing the sample coverage of the studied stand categories showed that all saproxylic species exhibit a pronounced preference for inhabiting areas featuring lying logs.Conversely,Red-List species mainly inhabit snags,withβdiversity being more similar to snags and forest stand space.Notably,both the conservation value(weighted average by conservation status)and beetle biomass are significantly highest in snags,whereas stand space shows the lowest values across all measured saproxylic beetle indices.Furthermore,the use of traps set on the poles in forest stand space resulted in an underestimation of the actual stand richness by 20%-25%.Our results support the conclusion that snags are indispensable features in beech forests,playing a key role in promoting high species diversity,especially among Red-List species,and supporting the biomass of saproxylic beetles.Consequently,it becomes crucial to incorporate a higher percentage of standing deadwood in managed forests or actively create equivalent environments by introducing high stumps.展开更多
In Central Europe,anthropogenic coniferous monocultures have been subject to conversion to more diverse mixed forests since the 1990s,however,they are still abundant across many forest landscapes.Artificial and natura...In Central Europe,anthropogenic coniferous monocultures have been subject to conversion to more diverse mixed forests since the 1990s,however,they are still abundant across many forest landscapes.Artificial and natural tree regeneration both play a key role during conversion by determining the species composition and structure of the future forests.Many abiotic and biotic factors can potentially influence the regeneration process and its specific combinations or interactions may be different among tree species and its developmental stages.Here,we aimed to identify and quantify the effect of the most important drivers on the density of the most abundant regenerating tree species(i.e.,Norway spruce and European beech),as well as on species and structural diversity of the tree regeneration.We studied tree regeneration in four former monospecific coniferous stand types(i.e.,Norway spruce,Scots pine,European larch,and Douglas fir)in Southwest Germany that have been under conversion to mixed forests since the 1990s.We sampled tree regeneration in four growth height classes together with a variety of potentially influencing factors on 108 sampling plots and applied multivariate analyses.We identified light availability in the understorey,stand structural attributes,browsing pressure,and diaspore source abundance as the most important factors for the density and diversity of tree regeneration.Particularly,we revealed speciesspecific differences in drivers of regeneration density.While spruce profited from increasing light availability and decreasing stand basal area,beech benefited either from a minor reduction or more strikingly from an increase in overstorey density.Increasing diaspore source abundance positively and a high browsing pressure negatively affected both species equally.Our results suggest that humus and topsoil properties were modified during conversion,probably due to changes in tree species composition and silvicultural activities.The species and structural diversity of the tree regeneration benefitted from increasing light availability,decreasing stand basal area,and a low to moderate browsing pressure.We conclude that forest managers may carefully equilibrate among the regulation of overstorey cover,stand basal area,and browsing pressure to fulfil the objectives of forest conversion,i.e.,establishing and safeguarding a diverse tree regeneration to promote the development of mature mixed forests in the future.展开更多
Background： Wood density is considered to be the most important predictor of wood quality but despite its importance, diffuse-porous tree species have been the subject of only a limited number of studies. The importa...Background： Wood density is considered to be the most important predictor of wood quality but despite its importance, diffuse-porous tree species have been the subject of only a limited number of studies. The importance of European beech forests for Central Europe calls for profound research to examine the potential impact of a warmer climate on the quality of beech timber. Methods： In this study we analysed the influence of tree-ring width and tree-ring age on the wood density of beech, and whether the wood density response to these two parameters is modified by aspect. A linear mixed-effects model for wood density was constructed for mean density data measured with high frequency densitometry on stem discs from 72 beech trees sampled from two different aspects （northeast -NE and southwest -SW） of a valley in southwestern Germany. Results： Part of the variability of mean annual wood density was explained by cambial age： an increase in cambial age resulted in an increase in mean wood density. Tree-ring width and aspect had only a small influence on wood density, Wood density on the SW aspect was lower than on the NE with a difference of approximately 0.006 g/cm3. The between-tree variability was very high. Conclusions： The significant interaction between cambial age and aspect reflects the importance of site conditions at older tree ages： with increasing cambial age the difference between aspects becomes stronger. Our results give a better understanding of the importance of site conditions on the wood quality of beech.展开更多
Background:Organic carbon stored in forest soils(SOC)represents an important element of the global C cycle.It is thought that the C storage capacity of the stable pool can be enhanced by increasing forest productivity...Background:Organic carbon stored in forest soils(SOC)represents an important element of the global C cycle.It is thought that the C storage capacity of the stable pool can be enhanced by increasing forest productivity,but empirical evidence in support of this assumption from forests differing in tree species and productivity,while stocking on similar substrate,is scarce.Methods:We determined the stocks of SOC and macro-nutrients(nitrogen,phosphorus,calcium,potassium and magnesium)in nine paired European beech/Scots pine stands on similar Pleistocene sandy substrates across a precipitation gradient(560–820mm∙yr−1)in northern Germany and explored the influence of tree species,forest history,climate,and soil pH on SOC and nutrient pools.Results:While the organic layer stored on average about 80%more C under pine than beech,the pools of SOC and total N in the total profile(organic layer plus mineral soil measured to 60 cm and extrapolated to 100 cm)were greater under pine by about 40%and 20%,respectively.This contrasts with a higher annual production of foliar litter and a much higher fine root biomass in beech stands,indicating that soil C sequestration is unrelated to the production of leaf litter and fine roots in these stands on Pleistocene sandy soils.The pools of available P and basic cations tended to be higher under beech.Neither precipitation nor temperature influenced the SOC pool,whereas tree species was a key driver.An extended data set(which included additional pine stands established more recently on former agricultural soil)revealed that,besides tree species identity,forest continuity is an important factor determining the SOC and nutrient pools of these stands.Conclusion:We conclude that tree species identity can exert a considerable influence on the stocks of SOC and macronutrients,which may be unrelated to productivity but closely linked to species-specific forest management histories,thus masking weaker climate and soil chemistry effects on pool sizes.展开更多
A novel but simple approach for describing stand structure in natural and managed forests driven by small-scaled disturbances is introduced. A primeval beech forest reserve in Slovakia and two beech stands in Germany ...A novel but simple approach for describing stand structure in natural and managed forests driven by small-scaled disturbances is introduced. A primeval beech forest reserve in Slovakia and two beech stands in Germany with different management histories were studied, and their forest stand texture was analysed in terms of tree coordinates, stem diameter, and crown radius. Neigh-bouring trees of similar size with estimated contact of their crowns were assigned to tree groups. The study goal was to estimate the number and size of such homogeneous patches. In all cases, the number of tree groups in a particular diameter class decreased exponentially as group size increased. Single trees were predominant. Compared to simulated random tree distributions, the natural stand exhibited a more clumped distribution of small trees and more regular distribution of larger ones. The natural forest generally had smaller groups than the managed even aged stand, but the smallest group sizes were found in the uneven-aged selection forest. The simple analytical approach provided new spatial insights into neighbourhood relations of trees. The continuous scale from single trees to larger tree groups is an important achievement compared to other analytical methods applied in this field. The findings may even indicate a certain degree of self-organization in natural forests. Due to the limitations associated with each method or statistical models, a joint consideration of 1) gap dynamics, 2) forest developmental stages, and 3) size classes of homogeneous tree groups is recommended. Relevant to forest practitioners, the size class distributions enhance an understanding of the complex stand structures in natural forests and therewith support an emulation of natural forest dynamics in managed beech forests.展开更多
Equilibrium moisture contents (EMC) of wood species are very necessary in the utilization of these in service. This study investigated the EMC of five lesser utilized species of Ghana and compared it with that of thre...Equilibrium moisture contents (EMC) of wood species are very necessary in the utilization of these in service. This study investigated the EMC of five lesser utilized species of Ghana and compared it with that of three European species. Sixteen randomly sampled specimens of each of the eight species (heartwood and sapwood) with dimensions 3 cm × 3 cm × 3 cm were exposed at various relative humidity conditions of 30%, 45%, 60%, 75% and 90% in a temperature and humidity-controlled climate chamber at a temperature of 25°C in accordance to German standard DIN 52182. The species are Albies alba, Fagus sylvatica and Picea abies which are European species and Amphimas pterocarpoides, Antiaris toxicaria, Canarium schweinfurthii, Celtis zenkeri and Cola gigantea are wood species from Ghana. Internal wood temperature and humidity were measured with datalogger. Samples were considered to have reached equilibrium at any given humidity when the daily weight changes were less than 0.1 mg according to German standard DIN 52183. After the last measurements of the weight changes, the samples were dried at 103°C until there was a constant weight. The five tropical hardwoods had low sorption values recorded and high sorption values for the European species and this could be attributed to differences in the microstructure of these woods.展开更多
Background： An examination of the distribution of ancient charcoal kiln sites in the forest landscape seems to be worthwhile, since general trends in the selection of suitable kiln site locations in the past might be...Background： An examination of the distribution of ancient charcoal kiln sites in the forest landscape seems to be worthwhile, since general trends in the selection of suitable kiln site locations in the past might become obvious. In this way forest landscape elements with a more intense usage by charcoal burning can be identified. By doing this, we can expect to gain information on the former condition and tree species composition of woodland. Investigations on the spatial distribution of charcoal kiln sites in relation to landscape attributes are sparse, however, probably due to the high on-site mapping effort. The outstanding suitability of LiDAR-derived digital terrain models （DTMs） for the detection of charcoal kiln sites has been recently proved. Hence, DTM-based surveys of charcoal kiln sites represent a promising attempt to fill this research gap. Methods： Based on DTM-based surveys, we analyzed the spatial distribution of charcoal kiln sites in two forest landscapes in the German federal state of Hesse： Reinhardswald and Kellerwald-Edersee National Park. In doing so, we considered the landscape attibutes ＂tree species composition＂, ＂water supply status＂, ＂nutrient supply status＂, ＂soil complex classes＂, ＂altitude＂, ＂exposition＂, and ＂inclination＂. Results： We found that charcoal kiln sites were established preferably on hillside locations that provided optimal growing and regeneration conditions for European beech （Fagus sylvatico） due to their acidic brown soils and sufficient water supply. These results are in line with instructions for the selection of appropriate kiln site locations, found in literature from the 18th to the 19th century. Conclusions： We conclude that there were well-stocked, beech-dominated deciduous forest stands in northern Hesse before 1800, particularly at poorly accessible hillside locations. These large stocks of beech wood were utilized by the governments of the different Hessian territories through the establishment of ironworks and hammer mills. Our argumentation is well in line with findings which underline that not all Hessian forests were overexploited in the 18th century. Frequently repeated complaints about ＂wood shortage＂ seemed to be more a political instrument than reality, not only in Hesse, but all over Europe. Consequently, a differentiated assessment of woodland conditions in proto-industrial times is strictly advised, even if contemporary sources draw a dark picture of the historic situation.展开更多
Aims Forest fragmentation and the associated augmentation of forest edge zones are increasing worldwide.Forest edges are characterized by altered plant species richness and community composition.As the tree layer and ...Aims Forest fragmentation and the associated augmentation of forest edge zones are increasing worldwide.Forest edges are characterized by altered plant species richness and community composition.As the tree layer and its species composition has been shown to influence herb layer composition,changes in tree species composition or richness may weaken or strengthen edge effects in forest ecosystems.We studied effects of the edge-center transition,tree species composition and their potential interaction on the understory vegetation in the Hainich National Park,Germany’s largest connected deciduous forest,allowing to cover large edge-center transects.Methods We established 12 transects in an area of 75 km^(2) of continuous forest,6 beech-dominated and 6 in multispecies forest stands.Each transect reached from the forest edge up to 500 m into the forest interior.Vegetation relevés were conducted in regular,logarithmic distances along each transect.Important Findings Herb species richness was influenced by an interaction of edge effects and tree diversity level.With increasing distance from the forest edge,herb species richness remained constant in multispecies forest stands but rapidly decreased in beech-dominated forest stands.Further,herb richness was higher in the interior of multispecies forest stands.Percent forest specialists increased and percent generalists decreased with distance from the edge and this contrasting pattern was much more pronounced in beech-dominated transects.By using structural equation modeling,we identified litter depth mediated by tree species composition as the most important driver of herb layer plant species richness.展开更多
Mast seeding causes strongfluctuations in populations of forest animals.Thus,this phenomenon can be used as a natural experiment to examine how variation in host abundance affects parasite loads.We investigatedfleas inf...Mast seeding causes strongfluctuations in populations of forest animals.Thus,this phenomenon can be used as a natural experiment to examine how variation in host abundance affects parasite loads.We investigatedfleas infesting yellow-necked mice in beech forest after 2 mast and 2 non-mast years.We tested 2 mutually exclusive scenarios:(1)as predicted by classical models of density-dependent transmission,an increase in host density will cause an increase in ectoparasite abundance(defined as the number of parasites per host),versus(2)an increase in host density will cause a decline inflea abundance(“dilution,”which is thought to occur when parasite population growth is slower than that of the host).In addition,we assessed whether masting alters the relationship between host traits(sex and body mass)andflea abundance.We found a hump-shaped relationship between host andflea abundance.Thus,the most basic predictions are too simple to describe ectoparasite dynamics in this system.In addition,masting modified seasonal dynamics offlea abundance,but did not affect the relationship between host traits andflea abundance(individuals with the highest body mass hosted the mostfleas;after controlling for body mass,parasite abundance did not vary between sexes).Our results demonstrate that pulses of tree reproduction can indirectly,through changes in host densities,drive patterns of ectoparasite infestation.展开更多
基金This work was supported within the XyloDensMap project,INRAE funded by the French Ministry of Agriculture under the convention n°A6.01/2017.
文摘Background:Higher exportation of harvest residues from forests due to increased demand for woody biomass,has reportedly diminished soil mineral resources and may lead to degraded tree nutrition as well as growth.However,as nutrients become less available in the soil,the remobilization of nutrients in biomass tissues(plant internal cycling)helps sustain tree nutrition.Our study aims to quantify the impact of Removing Harvest Residues and Litter(RHRL)during five years on tree growth,wood density,and stem wood nutrient concentrations in young beech and oak forest stands.Result:Our study found that,RHRL significantly decreased tree growth ring width by 14%,and wood density by 3%,in beech trees,in near bark rings.RHRL also significantly reduced nutrient concentration in near bark and near pith areas of both studied species.Mg,Na and S were found lower by 44%,76%,and 56%,respectively,in near bark area of beech trees.In near bark area of oak trees,K,Ca,Mg,Na,S,and Fe were lower by 20%,25%,41%,48%,41%,and 16%,respectively.K and Mg concentrations decreased more strongly in near pith area compared to near bark area suggesting internal translocation of these two elements.Conclusion:In beech trees,wood density proved to be an important factor while quantifying the effect of removing harvest residuals on tree growth and biomass.Soil nutrient loss intensified the remobilization of nutrients con-tained in older tree rings(close to the pith)towards newly formed rings(close to bark).In our study,in beech trees,K was found to be the most recycled major nutrient.These results demonstrate the potential of such analysis for providing valuable insight into the effect of RHRL in premature stands on the physiological adaptive strategies of trees and an indication of soil fertility status.
基金the Institute Research Centre for Ecological and Forestry Applications (CREAF) of Barcelona that supported the research by the Spanish “Ministerio de Ciencia e Innovacio'n”(MCIN/AEI/ 10.13039/501100011033) (grant agreement No. PID 2021-126679OBI00)partially supported by MIUR Project (PRIN 2020) between WATER and carbon cycles during droug“Unraveling interactionsht and their impact on water resources and forest and grassland ecosySTEMs in the Mediterranean climate (WATERSTEM)”(Project number: 20202WF53Z),“WAFER”at CNR (Consiglio Nazionale delle Ricerche)+3 种基金Priwitzer et al. (2014) (cod. 2020E52THS)-Research Projects of National Relevance funded by the Italian Ministry of University and Research entitled: “Multi-scale observations to predict Forest response to pollution and climate change”(MULTIFOR, project number: 2020E52THS)funding by the project OptForEU Horizon Europe research and innovation programme under grant agreement No. 101060554the project funded under the National Recovery and Resilience Plan (NRRP), Mission 4 Component 2 Investment 1.4-Call for tender No. 3138 of December 16, 2021, rectified by Decree n.3175 of December 18, 2021 of Italian Ministry of UniversityResearch funded by the European UnionationEU under award Number: Project code CN_00000033–Next Gener, Concession Decree No. 1034 of June 17, 2022 adopted by the Italian Ministry of University and Research, CUP B83C22002930006, Project title“National Biodiversity Future Centre-NBFC”
文摘The consequences of climate change continue to threaten European forests,particularly for species located at the edges of their latitudinal and altitudinal ranges.While extensively studied in Central Europe,European beech forests require further investigation to understand how climate change will affect these ecosystems in Mediterranean areas.Proposed silvicultural options increasingly aim at sustainable management to reduce biotic and abiotic stresses and enhance these forest ecosystems'resistance and resilience mechanisms.Process-based models(PBMs)can help us to simulate such phenomena and capture early stress signals while considering the effect of different management approaches.In this study,we focus on estimating sensitivity of two state-of-the-art PBMs forest models by simulating carbon and water fluxes at the stand level to assess productivity changes and feedback resulting from different climatic forcings as well as different management regimes.We applied the 3D-CMCC-FEM and MEDFATE forest models for carbon(C)and water(H_(2)O)fluxes in two sites of the Italian peninsula,Cansiglio in the north and Mongiana in the south,under managed vs.unmanaged scenarios and under current climate and different climatic scenarios(RCP4.5 and RCP8.5).To ensure confidence in the models’results,we preliminary evaluated their performance in simulating C and H_(2)O flux in three additional beech forests of the FLUXNET network along a latitudinal gradient spanning from Denmark to central Italy.The 3D-CMCC-FEM model achieved R^(2)values of 0.83 and 0.86 with RMSEs of 2.53 and 2.05 for C and H_(2)O fluxes,respectively.MEDFATE showed R^(2)values of 0.76 and 0.69 with RMSEs of 2.54 and 3.01.At the Cansiglio site in northern Italy,both models simulated a general increase in C and H_(2)O fluxes under the RCP8.5 climate scenario compared to the current climate.Still,no benefit in managed plots compared to unmanaged ones,as the site does not have water availability limitations,and thus,competition for water is low.At the Mongiana site in southern Italy,both models predict a decrease in C and H_(2)O fluxes and sensitivity to the different climatic forcing compared to the current climate;and an increase in C and H_(2)O fluxes when considering specific management regimes compared to unmanaged scenarios.Conversely,under unmanaged scenarios plots are simulated to experience first signals of mortality prematurely due to water stress(MEDFATE)and carbon starvation(3D-CMCC-FEM)scenarios.In conclusion,while management interventions may be considered a viable solution for the conservation of beech forests under future climate conditions at moister sites like Cansiglio,in drier sites like Mongiana conservation may not lie in management interventions alone.
基金supported by the Czech Science Foundation(grant no.GACR 22-31322S)the Czech University of Life Sciences Prague(grant no.IGA A_19_22)+3 种基金supported by the Operational Programme Integrated Infrastructure(OPII)funded by the ERDF(ITMS313011T721)Specific research PrF UHK 2114/2022 for the financial supportthe financial support of the Rita-Levi Montalcini(2019)programmefunded by the Italian Ministry of University。
文摘In this era of biodiversity loss and climate change,quantifying the impacts of natural disturbance on forest communities is imperative to improve biodiversity conservation efforts.Epiphytic and epixylic lichens are effective forest quality bioindicators,as they are generally long-lived organisms supported by continuity of specific forest structures and their associated microclimatic features.However,how lichen communities respond to the effects of fluctuating historical disturbances remains unclear.Using a dendrochronological approach,this study investigates how natural disturbance dynamics indirectly influence various lichen community metrics in some of Europe's best-preserved primary mixed-beech forests.Mixed modelling revealed that natural historical disturbance processes have decades-long effects on forest structural attributes,which had both congruent and divergent impacts on lichen community richness and composition.Total species richness indirectly benefited from both historical and recent higher-severity disturbances via increased standing dead tree basal area and canopy openness respectively-likely through the presence of both pioneer and late-successional species associated with these conditions.Red-listed species richness showed a dependence on habitat continuity(old trees),and increased with disturbance-related structures(standing dead trees)whilst simultaneously benefiting from periods without severe disturbance events(old trees and reduced deadwood volume).However,if the disturbance occurred over a century in the past,no substantial effect on forest structure was detected.Therefore,while disturbance-mediated forest structures can promote overall richness,threatened species appear vulnerable to more severe disturbance events-a concern,as disturbances are predicted to intensify with climate change.Additionally,the high number of threatened species found reinforce the critical role of primary forest structural attributes for biodiversity maintenance.Hence,we recommend a landscape-scale conservation approach encompassing forest patches in different successional stages to support diverse lichen communities,and the consideration of long-term disturbance dynamics in forest conservation efforts,as they provide critical insights for safeguarding biodiversity in our changing world.
基金supported by the Ministry of Agriculture of the Czech Republic(Grant No.QK23020008)。
文摘Deadwood plays a key role for biodiversity in forests.A significant number of beetles from this group are currently listed as endangered in the Red List.In addition to other management recommendations,there have been recent efforts to enrich stands with dead wood to promote biodiversity.An important parameter for forestry enterprises is the optimization of these interventions.The study investigated the abundance,species richness,gamma diversity,conservation value and biomass of saproxylic beetles in natural forests using window traps.A total of 89traps were used for saproxylic beetle monitoring,of which 29 were placed on lying logs,30 on snags and 30 as controls in forest stand space.A total of 35,011 beetles were recorded in 564 species(61 families).Notably,20,515 of these belong to saproxylic beetles(59%)in 311 species(55%),with 62 classified as Red-List species(20%).In the group of'all saproxylic beetles',the results indicate that a diversity and y diversity(q=0)remain consistent across various deadwood types,whileβdiversity showed significant differences.Significant differences were found in the Red-List species group,where a diversity and y diversity differed,with higher values observed in snags.Rarefaction based total species richness of site was estimated to be 391 species,including 74 Red-Listed species.Comparing the sample coverage of the studied stand categories showed that all saproxylic species exhibit a pronounced preference for inhabiting areas featuring lying logs.Conversely,Red-List species mainly inhabit snags,withβdiversity being more similar to snags and forest stand space.Notably,both the conservation value(weighted average by conservation status)and beetle biomass are significantly highest in snags,whereas stand space shows the lowest values across all measured saproxylic beetle indices.Furthermore,the use of traps set on the poles in forest stand space resulted in an underestimation of the actual stand richness by 20%-25%.Our results support the conclusion that snags are indispensable features in beech forests,playing a key role in promoting high species diversity,especially among Red-List species,and supporting the biomass of saproxylic beetles.Consequently,it becomes crucial to incorporate a higher percentage of standing deadwood in managed forests or actively create equivalent environments by introducing high stumps.
基金funded by the Bavarian Ministry for Food,Agriculture and Forestry (Grant No.F053)support by the Open Access Publication Funds/transformative agreements of the Gottingen University
文摘In Central Europe,anthropogenic coniferous monocultures have been subject to conversion to more diverse mixed forests since the 1990s,however,they are still abundant across many forest landscapes.Artificial and natural tree regeneration both play a key role during conversion by determining the species composition and structure of the future forests.Many abiotic and biotic factors can potentially influence the regeneration process and its specific combinations or interactions may be different among tree species and its developmental stages.Here,we aimed to identify and quantify the effect of the most important drivers on the density of the most abundant regenerating tree species(i.e.,Norway spruce and European beech),as well as on species and structural diversity of the tree regeneration.We studied tree regeneration in four former monospecific coniferous stand types(i.e.,Norway spruce,Scots pine,European larch,and Douglas fir)in Southwest Germany that have been under conversion to mixed forests since the 1990s.We sampled tree regeneration in four growth height classes together with a variety of potentially influencing factors on 108 sampling plots and applied multivariate analyses.We identified light availability in the understorey,stand structural attributes,browsing pressure,and diaspore source abundance as the most important factors for the density and diversity of tree regeneration.Particularly,we revealed speciesspecific differences in drivers of regeneration density.While spruce profited from increasing light availability and decreasing stand basal area,beech benefited either from a minor reduction or more strikingly from an increase in overstorey density.Increasing diaspore source abundance positively and a high browsing pressure negatively affected both species equally.Our results suggest that humus and topsoil properties were modified during conversion,probably due to changes in tree species composition and silvicultural activities.The species and structural diversity of the tree regeneration benefitted from increasing light availability,decreasing stand basal area,and a low to moderate browsing pressure.We conclude that forest managers may carefully equilibrate among the regulation of overstorey cover,stand basal area,and browsing pressure to fulfil the objectives of forest conversion,i.e.,establishing and safeguarding a diverse tree regeneration to promote the development of mature mixed forests in the future.
基金the collaborative research project SFB 433("Buchendominierte Laubwalder unter dem Einfluβ von Klima und Bewirtschaftung:Okologische,waldbauliche und sozialwissenschaftliche Analysen"-Beech dominated deciduous forests under the influence of climate and forest management)funded by the project Bu Klim within Waldklimafods program of BMEL/BMUB("Gefordert durch Bundesministerium für Ernahrung und Landwirtschaft und das Bundesministerium für Umwelt,Naturschutz,Bau und Reaktorsicherheit aufgrund eines Beschlusses des Deutschen Bundestages")
文摘Background： Wood density is considered to be the most important predictor of wood quality but despite its importance, diffuse-porous tree species have been the subject of only a limited number of studies. The importance of European beech forests for Central Europe calls for profound research to examine the potential impact of a warmer climate on the quality of beech timber. Methods： In this study we analysed the influence of tree-ring width and tree-ring age on the wood density of beech, and whether the wood density response to these two parameters is modified by aspect. A linear mixed-effects model for wood density was constructed for mean density data measured with high frequency densitometry on stem discs from 72 beech trees sampled from two different aspects （northeast -NE and southwest -SW） of a valley in southwestern Germany. Results： Part of the variability of mean annual wood density was explained by cambial age： an increase in cambial age resulted in an increase in mean wood density. Tree-ring width and aspect had only a small influence on wood density, Wood density on the SW aspect was lower than on the NE with a difference of approximately 0.006 g/cm3. The between-tree variability was very high. Conclusions： The significant interaction between cambial age and aspect reflects the importance of site conditions at older tree ages： with increasing cambial age the difference between aspects becomes stronger. Our results give a better understanding of the importance of site conditions on the wood quality of beech.
基金funded by the Federal Ministry for Education and Research(BMBF)through a grant to CL(project number:01LC1314B).
文摘Background:Organic carbon stored in forest soils(SOC)represents an important element of the global C cycle.It is thought that the C storage capacity of the stable pool can be enhanced by increasing forest productivity,but empirical evidence in support of this assumption from forests differing in tree species and productivity,while stocking on similar substrate,is scarce.Methods:We determined the stocks of SOC and macro-nutrients(nitrogen,phosphorus,calcium,potassium and magnesium)in nine paired European beech/Scots pine stands on similar Pleistocene sandy substrates across a precipitation gradient(560–820mm∙yr−1)in northern Germany and explored the influence of tree species,forest history,climate,and soil pH on SOC and nutrient pools.Results:While the organic layer stored on average about 80%more C under pine than beech,the pools of SOC and total N in the total profile(organic layer plus mineral soil measured to 60 cm and extrapolated to 100 cm)were greater under pine by about 40%and 20%,respectively.This contrasts with a higher annual production of foliar litter and a much higher fine root biomass in beech stands,indicating that soil C sequestration is unrelated to the production of leaf litter and fine roots in these stands on Pleistocene sandy soils.The pools of available P and basic cations tended to be higher under beech.Neither precipitation nor temperature influenced the SOC pool,whereas tree species was a key driver.An extended data set(which included additional pine stands established more recently on former agricultural soil)revealed that,besides tree species identity,forest continuity is an important factor determining the SOC and nutrient pools of these stands.Conclusion:We conclude that tree species identity can exert a considerable influence on the stocks of SOC and macronutrients,which may be unrelated to productivity but closely linked to species-specific forest management histories,thus masking weaker climate and soil chemistry effects on pool sizes.
文摘A novel but simple approach for describing stand structure in natural and managed forests driven by small-scaled disturbances is introduced. A primeval beech forest reserve in Slovakia and two beech stands in Germany with different management histories were studied, and their forest stand texture was analysed in terms of tree coordinates, stem diameter, and crown radius. Neigh-bouring trees of similar size with estimated contact of their crowns were assigned to tree groups. The study goal was to estimate the number and size of such homogeneous patches. In all cases, the number of tree groups in a particular diameter class decreased exponentially as group size increased. Single trees were predominant. Compared to simulated random tree distributions, the natural stand exhibited a more clumped distribution of small trees and more regular distribution of larger ones. The natural forest generally had smaller groups than the managed even aged stand, but the smallest group sizes were found in the uneven-aged selection forest. The simple analytical approach provided new spatial insights into neighbourhood relations of trees. The continuous scale from single trees to larger tree groups is an important achievement compared to other analytical methods applied in this field. The findings may even indicate a certain degree of self-organization in natural forests. Due to the limitations associated with each method or statistical models, a joint consideration of 1) gap dynamics, 2) forest developmental stages, and 3) size classes of homogeneous tree groups is recommended. Relevant to forest practitioners, the size class distributions enhance an understanding of the complex stand structures in natural forests and therewith support an emulation of natural forest dynamics in managed beech forests.
文摘Equilibrium moisture contents (EMC) of wood species are very necessary in the utilization of these in service. This study investigated the EMC of five lesser utilized species of Ghana and compared it with that of three European species. Sixteen randomly sampled specimens of each of the eight species (heartwood and sapwood) with dimensions 3 cm × 3 cm × 3 cm were exposed at various relative humidity conditions of 30%, 45%, 60%, 75% and 90% in a temperature and humidity-controlled climate chamber at a temperature of 25°C in accordance to German standard DIN 52182. The species are Albies alba, Fagus sylvatica and Picea abies which are European species and Amphimas pterocarpoides, Antiaris toxicaria, Canarium schweinfurthii, Celtis zenkeri and Cola gigantea are wood species from Ghana. Internal wood temperature and humidity were measured with datalogger. Samples were considered to have reached equilibrium at any given humidity when the daily weight changes were less than 0.1 mg according to German standard DIN 52183. After the last measurements of the weight changes, the samples were dried at 103°C until there was a constant weight. The five tropical hardwoods had low sorption values recorded and high sorption values for the European species and this could be attributed to differences in the microstructure of these woods.
文摘Background： An examination of the distribution of ancient charcoal kiln sites in the forest landscape seems to be worthwhile, since general trends in the selection of suitable kiln site locations in the past might become obvious. In this way forest landscape elements with a more intense usage by charcoal burning can be identified. By doing this, we can expect to gain information on the former condition and tree species composition of woodland. Investigations on the spatial distribution of charcoal kiln sites in relation to landscape attributes are sparse, however, probably due to the high on-site mapping effort. The outstanding suitability of LiDAR-derived digital terrain models （DTMs） for the detection of charcoal kiln sites has been recently proved. Hence, DTM-based surveys of charcoal kiln sites represent a promising attempt to fill this research gap. Methods： Based on DTM-based surveys, we analyzed the spatial distribution of charcoal kiln sites in two forest landscapes in the German federal state of Hesse： Reinhardswald and Kellerwald-Edersee National Park. In doing so, we considered the landscape attibutes ＂tree species composition＂, ＂water supply status＂, ＂nutrient supply status＂, ＂soil complex classes＂, ＂altitude＂, ＂exposition＂, and ＂inclination＂. Results： We found that charcoal kiln sites were established preferably on hillside locations that provided optimal growing and regeneration conditions for European beech （Fagus sylvatico） due to their acidic brown soils and sufficient water supply. These results are in line with instructions for the selection of appropriate kiln site locations, found in literature from the 18th to the 19th century. Conclusions： We conclude that there were well-stocked, beech-dominated deciduous forest stands in northern Hesse before 1800, particularly at poorly accessible hillside locations. These large stocks of beech wood were utilized by the governments of the different Hessian territories through the establishment of ironworks and hammer mills. Our argumentation is well in line with findings which underline that not all Hessian forests were overexploited in the 18th century. Frequently repeated complaints about ＂wood shortage＂ seemed to be more a political instrument than reality, not only in Hesse, but all over Europe. Consequently, a differentiated assessment of woodland conditions in proto-industrial times is strictly advised, even if contemporary sources draw a dark picture of the historic situation.
基金German Research Foundation within the framework of the Research Training Group(GRK 1086:‘The role of biodiversity for biogeochemical cycles and biotic interactions in temperate deciduous forests’).
文摘Aims Forest fragmentation and the associated augmentation of forest edge zones are increasing worldwide.Forest edges are characterized by altered plant species richness and community composition.As the tree layer and its species composition has been shown to influence herb layer composition,changes in tree species composition or richness may weaken or strengthen edge effects in forest ecosystems.We studied effects of the edge-center transition,tree species composition and their potential interaction on the understory vegetation in the Hainich National Park,Germany’s largest connected deciduous forest,allowing to cover large edge-center transects.Methods We established 12 transects in an area of 75 km^(2) of continuous forest,6 beech-dominated and 6 in multispecies forest stands.Each transect reached from the forest edge up to 500 m into the forest interior.Vegetation relevés were conducted in regular,logarithmic distances along each transect.Important Findings Herb species richness was influenced by an interaction of edge effects and tree diversity level.With increasing distance from the forest edge,herb species richness remained constant in multispecies forest stands but rapidly decreased in beech-dominated forest stands.Further,herb richness was higher in the interior of multispecies forest stands.Percent forest specialists increased and percent generalists decreased with distance from the edge and this contrasting pattern was much more pronounced in beech-dominated transects.By using structural equation modeling,we identified litter depth mediated by tree species composition as the most important driver of herb layer plant species richness.
基金supported by the“Sonatina”grant no.2020/36/C/NZ8/00013M.Z.by the“Preludium”grant no.2016/21/N/NZ8/01059R.Z.by the“Harmonia”grant no.2018/30/M/NZ8/0052。
文摘Mast seeding causes strongfluctuations in populations of forest animals.Thus,this phenomenon can be used as a natural experiment to examine how variation in host abundance affects parasite loads.We investigatedfleas infesting yellow-necked mice in beech forest after 2 mast and 2 non-mast years.We tested 2 mutually exclusive scenarios:(1)as predicted by classical models of density-dependent transmission,an increase in host density will cause an increase in ectoparasite abundance(defined as the number of parasites per host),versus(2)an increase in host density will cause a decline inflea abundance(“dilution,”which is thought to occur when parasite population growth is slower than that of the host).In addition,we assessed whether masting alters the relationship between host traits(sex and body mass)andflea abundance.We found a hump-shaped relationship between host andflea abundance.Thus,the most basic predictions are too simple to describe ectoparasite dynamics in this system.In addition,masting modified seasonal dynamics offlea abundance,but did not affect the relationship between host traits andflea abundance(individuals with the highest body mass hosted the mostfleas;after controlling for body mass,parasite abundance did not vary between sexes).Our results demonstrate that pulses of tree reproduction can indirectly,through changes in host densities,drive patterns of ectoparasite infestation.
