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Questions: 1. Are there differences among species in their preference for coniferous vs. deciduous forest? 2. Are tree and shrub species better colonizers of recent forest stands than herbaceous species? 3. Do colonization patterns of plant species groups depend on tree species composition? Location: Three deciduous and one coniferous recent forest areas in Brandenburg, NE Germany. Methods: In 34 and 21 transects in coniferous and deciduous stands, respectively, we studied the occurrence and percentage cover of vascular plants in a total of 150 plots in ancient stands, 315 in recent stands and 55 at the ecotone. Habitat preference, diaspore weight, generative dispersal potential and clonal extension were used to explain mechanisms of local migration. Regression analysis was conducted to test whether migration distance was related to species’ life-history traits. Results: 25 species were significantly associated with ancient stands and ten species were significantly more frequent in recent stands. Tree and shrub species were good colonizers of recent coniferous and deciduous stands. In the coniferous stands, all herbaceous species showed a strong dispersal limitation during colonization, whereas in the deciduous stands generalist species may have survived in the grasslands which were present prior to afforestation. Conclusions: The fast colonization of recent stands by trees and shrubs can be explained by their effective dispersal via wind and animals. This, and the comparably efficient migration of herbaceous forest specialists into recent coniferous stands, implies that the conversion of coniferous into deciduous stands adjacent to ancient deciduous forests is promising even without planting of trees.
The paper presents a simulation and parameter-estimation approach for evaluating stochastic patterns of population growth and spread of an annual forest herb, Melampyrum pratense (Orobanchaceae). The survival of a species during large-scale changes in land use and climate will depend, to a considerable extent, on its dispersal and colonisation abilities. Predictions on species migration need a combination of field studies and modelling efforts. Our study on the ability of M. pratense to disperse into so far unoccupied areas was based on experiments in secondary woodland in NE Germany. Experiments started in 1997 at three sites where the species was not yet present, with 300 seeds sown within one square meter. Population development was then recorded until 2001 by mapping of individuals with a resolution of 5 cm. Additional observations considered density dependence of seed production. We designed a spatially explicit individual-based computer simulation model to explain the spatial patterns of population development and to predict future population spread. Besides primary drop of seeds (barochory) it assumed secondary seed transport by ants (myrmecochory) with an exponentially decreasing dispersal tail. An important feature of populationpattern explanation was the simultaneous estimation of both population-growth and dispersal parameters from consistent spatio-temporal data sets. As the simulation model produced stochastic time series and random spatially discrete distributions of individuals we estimated parameters by minimising the expectation of weighted sums of squares. These sums-ofsquares criteria considered population sizes, radial population distributions around the area of origin and distributions of individuals within squares of 25*25 cm, the range of density action. Optimal parameter values, together with the precision of the estimates, were obtained from calculating sums of squares in regular grids of parameter values. Our modelling results showed that transport of fractions of seeds by ants over distances of 1…2 m was indispensable for explaining the observed population spread that led to distances of at most 8 m from population origin within 3 years. Projections of population development over 4 additional years gave a diffusion-like increase of population area without any “outposts”. This prediction generated by the simulation model gave a hypothesis which should be revised by additional field observations. Some structural deviations between observations and model output already indicated that for full understanding of population spread the set of dispersal mechanisms assumed in the model may have to be extended by additional features of plant-animal mutualism.
The paper presents a simulation and parameter-estimation approach for evaluating stochastic patterns of population growth and spread of an annual forest herb, Melampyrum pratense (Orobanchaceae). The survival of a species during large-scale changes in land use and climate will depend, to a considerable extent, on its dispersal and colonisation abilities. Predictions on species migration need a combination of field studies and modelling efforts. Our study on the ability of M. pratense to disperse into so far unoccupied areas is based on experiments in secondary woodland in NE Germany. Experiments started in 1997 at three sites where the species was not yet present, with 300 seeds sown within 1m2. Population development was then recorded until 2001 by mapping of individuals with a resolution of 5 cm. Additional observations considered density dependence of seed production. We designed a spatially explicit individual-based computer simulation model to explain the spatial patterns of population development and to predict future population spread. Besides primary drop of seeds (barochory) it assumed secondary seed transport by ants (myrmecochory) with an exponentially decreasing dispersal tail. An important feature of population-pattern explanation was the simultaneous estimation of both population-growth and dispersal parameters from consistent spatio-temporal data sets. As the simulation model produced stochastic time series and random spatially discrete distributions of individuals we estimated parameters by minimising the expectation of weighted sum of squares. These sums of squares criteria considered population sizes, radial population distributions around the area of origin and distributions of individuals within squares of 25cm×25 cm, the range of density action. Optimal parameter values, together with the precision of the estimates, were obtained from calculating sum of squares in regular grids of parameter values. Our modelling results showed that transport of fractions of seeds by ants over distances of 1-2m was indispensable for explaining the observed population spread that led to distances of at most 8mfrom population origin within 3 years. Projections of population development over four additional years gave a diffusion-like increase of population area without any "outposts". This prediction generated by the simulation model gave a hypothesis which should be revised by additional field observations. Some structural deviations between observations and model output already indicated that for full understanding of population spread the set of dispersal mechanisms assumed in the model may have to be extended by additional features of plant-animal mutualism.
1. Atmospheric nitrogen (N) deposition is expected to change forest understorey plant community composition and diversity, but results of experimental addition studies and observational studies are not yet conclusive. A shortcoming of observational studies, which are generally based on resurveys or sampling along large deposition gradients, is the occurrence of temporal or spatial confounding factors.
2. We were able to assess the contribution of N deposition versus other ecological drivers on forest understorey plant communities by combining a temporal and spatial approach. Data from 1205 (semi-)permanent vegetation plots taken from 23 rigorously selected understorey resurvey studies along a large deposition gradient across deciduous temperate forest in Europe were compiled and related to various local and regional driving factors, including the rate of atmospheric N deposition, the change in large herbivore densities and the change in canopy cover and composition.
3. Although no directional change in species richness occurred, there was considerable floristic turnover in the understorey plant community and a shift in species composition towards more shade-tolerant and nutrient-demanding species. However, atmospheric N deposition was not important in explaining the observed eutrophication signal. This signal seemed mainly related to a shift towards a denser canopy cover and a changed canopy species composition with a higher share of species with more easily decomposed litter.
4. Synthesis. Our multi-site approach clearly demonstrates that one should be cautious when drawing conclusions about the impact of atmospheric N deposition based on the interpretation of plant community shifts in single sites or regions due to other, concurrent, ecological changes. Even though the effects of chronically increased N deposition on the forest plant communities are apparently obscured by the effects of canopy changes, the accumulated N might still have a significant impact. However, more research is needed to assess whether this N time bomb will indeed explode when canopies will open up again.
Global environmental changes are expected to alter the functional characteristics of understorey herb-layer communities, potentially affecting forest ecosystem functioning. However, little is known about what drives the variability of functional traits in forest understories. Here, we assessed the role of different environmental drivers in shaping the functional trait distribution of understorey herbs in fragmented forests across three spatial scales. We focused on 708 small, deciduous forest patches located in 16 agricultural landscape windows, spanning a 2500-km macroclimatic gradient across the temperate forest biome in Europe. We estimated the relative effect of patch-scale, landscape-scale and macroclimatic variables on the community mean and variation of plant height, specific leaf area and seed mass. Macroclimatic variables (monthly temperature and precipitation extremes) explained the largest proportion of variation in community trait means (on average 77% of the explained variation). In contrast, patch-scale factors dominated in explaining community trait variation (on average 68% of the explained variation). Notably, patch age, size and internal heterogeneity had a positive effect on the community-level variability. Landscape-scale variables explained only a minor part of the variation in both trait distribution properties. The variation explained by shared combinations of the variable groups was generally negligible. These findings highlight the importance of considering multiple spatial scales in predictions of environmental-change effects on the functionality of forest understories. We propose that forest management sustainability could benefit from conserving larger, historically continuous and internally heterogeneous forest patches to maximise ecosystem service diversity in rural landscapes. (C) 2018 Gesellschaft fur Okologie. Published by Elsevier GmbH. All rights reserved.
Um Themen des Schutzes von Pflanzengemeinschaften wirksamer in der breiten Öffentlichkeit zu kommunizieren wird der Vorstand der „Floristisch-Soziologischen Arbeitsgemeinschaft (FlorSoz)“ ab 2019 eine „Pflanzengesellschaft des Jahres“ ausrufen. Damit sollen politische und administrative Entscheidungs- und Umsetzungsprozesse zur Erhaltung der Vielfalt von Ökosystemen und Pflanzengesellschaften in Deutschlands gezielt unterstützt werden. Für das Jahr 2019 wurde die Glatthaferwiese ausgewählt. Sie zählt aktuell zu den durch Artenverarmung und Flächenrückgang besonders bedrohten Pflanzengesellschaften Deutschlands. Es sind deshalb dringend Maßnahmen zum Schutz und zur Wiederherstellung notwendig. Dieser Artikel gibt einen kurzen Überblick zur naturschutzfachlichen Bedeutung von Glatthaferwiesen und deren Ökosystemleistungen sowie zur floristisch-soziologischen Erforschung, zu Ursachen ihres Rückgangs und zu geeigneten Gegenmaßnahmen.
The effects of habitat fragmentation and isolation on plant species richness have been verified for a wide range of anthropogenically fragmented habitats, but there is currently little information about their effects in naturally small and isolated habitats. We tested whether habitat area, heterogeneity, and isolation affect the richness of wetland vascular plant species in kettle holes, i.e., small glacially created wetlands, in an agricultural landscape of 1 km(2) in NE Germany. We compared fragmentation effects with those of forest fragments in the same landscape window. Since wetland and forest species might differ in their tolerance to isolation, and because isolation effects on plant species may be trait dependent, we asked which key life history traits might foster differences in isolation tolerance between wetland and forest plants. We recorded the flora and vegetation types in 83 isolated sites that contained 81 kettle holes and 25 forest fragments. Overall, the number of wetland species increased with increasing area and heterogeneity, i.e., the number of vegetation types, while area was not a surrogate for heterogeneity in these naturally fragmented systems. Isolation did not influence the number of wetland species but decreased the number of forest species. We also found that seeds of wetland species were on average lighter, more persistent and better adapted to epizoochory, e.g., by waterfowl, than seeds of forest species. Therefore, we suggest that wetland species are more tolerant to isolation than forest species due to their higher dispersal potential in space and time, which may counterbalance the negative effects of isolation.
The persistence of species under changed climatic conditions depends on adaptations and plastic responses to these conditions and on interactions with their local plant community resulting in direct and indirect effects of changed climatic conditions. Populations at species' range margins may be especially crucial in containing a gene pool comprising adaptations to extreme climatic conditions. Many species of northern European bog ecosystems reach their southern lowland range limit in central Europe. In a common-garden experiment, we experimentally assessed the impact of projected climatic changes on five bog-plant species (including peat moss Sphagnum magellanicum) sampled along a latitudinal gradient of 1400km from Scandinavia to the marginal lowland populations in Germany. Populations were cultivated in monocultures and in experimental communities composed of all five species from their local community, and exposed to five combinations of three climate treatments (warming, fluctuating water-tables, fertilization) in a southern common garden. Whereas most monocultures showed a decreasing biomass production from southern to northern origins under southern environmental conditions, in the experimental mixed-species communities, an increasing biomass production towards northern communities was observed together with a shift in interspecific interactions along the latitudinal gradient. While negative dominance effects prevailed in southern communities, higher net biodiversity effects were observed in northern subarctic communities. The combined effects of climate treatments increased biomass production in monocultures of most origins. In communities, however, overall the treatments did not result in significantly changed biomass production. Among individual treatments, water-table fluctuations caused a significant decrease in biomass production, but only in southern communities, indicating higher vulnerability to changed climatic conditions. Here, negative effects of climate treatments on graminoids were not compensated by the slightly increased growth of peat moss that benefited from interspecific interactions only in northern communities.Synthesis. We conclude that shifting interactions within multispecies communities caused pronounced responses to changed climatic conditions in wetland communities of temperate southern marginal, but not of northern subarctic origin. Therefore, future models investigating the impacts of climate change on plant communities should consider geographical variation in species interactions an important factor influencing community responses to changed climatic conditions.
Wie erstmals 2019 wird auch für das Jahr 2020 von der „Floristisch-soziologischen Arbeitsgemeinschaft“ (FlorSoz) für Deutschland die „Pflanzengesellschaft des Jahres“ vorgestellt. Damit soll wiederum für die Öffentlichkeit die Notwendigkeit des Schutzes gefährdeter Pflanzengesellschaften aufgezeigt werden. Für das Jahr 2020 wurden die Borstgrasrasen ausgewählt. Wie alle Pflanzengemeinschaften nährstoffarmer Standorte, sind auch die Borstgrasrasen stark gefährdet und regional sogar unmittelbar vom Aussterben bedroht. Wir konzentrieren uns vor allem auf die Bestände der planaren bis montanen Stufe (Unterverband Violenion caninae: Hundsveilchen-Borstgrasrasen). Die Standorte von Violenion caninae-Gesellschaften werden nicht gedüngt und sind auf extensive Beweidung, z.T. auch auf einschürige Mahd angewiesen. Für Borstgrasrasen bezeichnend sind eine Fülle gefährdeter Pflanzenarten wie z.B. Arnica montana (Arnika) und Antennaria dioica (Zweihäusiges Katzenpfötchen). Bei den Borstgrasrasen spielen für die zunehmend hohe Gefährdung nicht nur Flächenrückgänge durch Nutzungsaufgabe, Aufforstung, Sport- und Freizeitaktivitäten und Überbauung eine Rolle, sondern auch Änderungen der Struktur und Artenzusammensetzung durch direkte Düngung sowie atmogene Stickstoffeinträge sind von Bedeutung. Nährstoffanreicherungen führen zum Verlust der konkurrenzschwachen, gefährdeten Arten zugunsten einiger allgemein verbreiteter, häufig dominanter Gräser sowie konkurrenzkräftiger Kräuter. Wir skizzieren die Bedeutung der Borstgrasrasen als gefährdete Lebensgemeinschaften, geben Hinweise zur floristisch-soziologischen Erforschung und zu weiteren Naturschutz-Aspekten (Rückgang, Erhaltung, Möglichkeiten der Restitution). Ein wirksamer Schutz ist nur bei einem integrativen Naturschutzansatz mit geeigneter Nutzung möglich.
Large herbivores are significant vectors for the long-distance dispersal of seeds in various habitats, both attached to animals (epizoochory) and via gut passage (endozoochory). The majority of studies on epizoochory have examined dispersal in the fur of domesticated ungulates. Studies on wild ungulates are important to understand dispersal processes in many habitats, but rare due to methodological constraints. We studied epizoochory of seeds by European bison in an open-forest-mosaic (nutrient-poor grassland and heathland, mixed forest) in NW Germany, where bison had been introduced for the purpose of nature conservation. At the study site it was possible to apply a method by which hoof material of free-ranging bison was non-invasively collected. We identified a total of 1082 seeds from 32 plant species in the hoof material. The three most abundant species were Polygonum aviculare, Agrostis capillaris and Betula spp. Seed species originated from various habitat types of the study area, while the majority of seeds derived from trampled areas. Compared to the non-dispersed plant species of the study area, dispersed plant species had a higher seed longevity index, suggesting that many seeds were picked up from the soil seed bank. Epizoochory ranking indices of dispersed seed species, classifying the importance of epizoochory, revealed that transport in the fur may be of minor importance for many species, i.e. epizoochory by the hooves turned out to be negatively correlated to epizoochory in the fur. We conclude that European bison disperses a considerable number of seed species through trampling. Further research should consider epizoochory via the hooves and include integrative approaches to understand the different dispersal mechanisms by ungulates and their long-term synergetic effect on plant communities.
QuestionDoes eutrophication drive vegetation change in pine forests on nutrient deficient sites and thus lead to the homogenization of understorey species composition?
LocationForest area (1600ha) in the Lower Spreewald, Brandenburg, Germany.
MethodsResurvey of 77 semi-permanent plots after 45yr, including vascular plants, bryophytes and ground lichens. We applied multidimensional ordination of species composition, dissimilarity indices, mean Ellenberg indicator values and the concept of winner/loser species to identify vegetation change between years. Differential responses along a gradient of nutrient availability were analysed on the basis of initial vegetation type, reflecting topsoil N availability of plots.
ResultsSpecies composition changed strongly and overall shifted towards higher N and slightly lower light availability. Differences in vegetation change were related to initial vegetation type, with strongest compositional changes in the oligotrophic forest type, but strongest increase of nitrophilous species in the mesotrophic forest type. Despite an overall increase in species number, species composition was homogenized between study years due to the loss of species (mainly ground lichens) on the most oligotrophic sites.
ConclusionsThe response to N enrichment is confounded by canopy closure on the N-richest sites and probably by water limitation on N-poorest sites. The relative importance of atmospheric N deposition in the eutrophication effect is difficult to disentangle from natural humus accumulation after historical litter raking. However, the profound differences in species composition between study years across all forest types suggest that atmospheric N deposition contributes to the eutrophication, which drives understorey vegetation change and biotic homogenization in Central European Scots pine forests on nutrient deficient sites.
Ecological niches of organisms vary across geographical space, but niche shift patterns between regions and the underlying mechanisms remain largely unexplored. We studied shifts in the pH niche of 42 temperate forest plant species across a latitudinal gradient from northern France to boreo-nemoral Sweden. We asked 1) whether species restrict their niches with increasing latitude as they reach their northern range margin (environmental constraints); 2) whether species expand their niches with increasing latitude as regional plant species richness decreases (competitive release); and 3) whether species shift their niche position toward more acidic sites with increasing latitude as the relative proportion of acidic soils increases (local adaptation). Based on 1458 vegetation plots and corresponding soil pH values, we modelled species response curves using Huisman-Olff-Fresco models. Four niche measures (width, position, left and right border) were compared among regions by randomization tests. We found that with increasing latitude, neutrophilic species tended to retreat from acidic sites, indicating that these species retreat to more favorable sites when approaching their range margin. Alternatively, these species might benefit from enhanced nitrogen deposition on formerly nutrient-poor, acidic sites in southern regions or lag behind in post-glacial recolonization of potential habitats in northern regions. Most acidophilic species extended their niche toward more base-rich sites with increasing latitude, indicating competitive release from neutrophilic species. Alternatively, acidophilic species might benefit from optimal climatic conditions in the north where some have their core distribution area. Shifts in the niche position suggested that local adaptation is of minor importance. We conclude that shifts in the pH niche of temperate forest plants are the rule, but the directions of the niche shifts and possible explanations vary. Our study demonstrates that differentiating between acidophilic and neutrophilic species is crucial to identify general patterns and underlying mechanisms.
Aim Seed banks are central to the regeneration strategy of many plant species. Any factor altering seed bank density thus affects plant regeneration and population dynamics. Although seed banks are dynamic entities controlled by multiple environmental drivers, climatic factors are the most comprehensive, but still poorly understood. This study investigates how climatic variation structures seed production and resulting seed bank patterns.
Location Temperate forests along a 1900km latitudinal gradient in north-western (NW) Europe.
Methods Seed production and seed bank density were quantified in 153 plots along the gradient for four forest herbs with different seed longevity: Geum urbanum, Milium effusum, Poa nemoralis and Stachys sylvatica. We tested the importance of climatic and local environmental factors in shaping seed production and seed bank density.
Results Seed production was determined by population size, and not by climatic factors. G.urbanum and M.effusum seed bank density declined with decreasing temperature (growing degree days) and/or increasing temperature range (maximum-minimum temperature). P.nemoralis and S.sylvatica seed bank density were limited by population size and not by climatic variables. Seed bank density was also influenced by other, local environmental factors such as soil pH or light availability. Different seed bank patterns emerged due to differential seed longevities. Species with long-lived seeds maintained constant seed bank densities by counteracting the reduced chance of regular years with high seed production at colder northern latitudes.
Main conclusions Seed bank patterns show clear interspecific variation in response to climate across the distribution range. Not all seed banking species may be as well equipped to buffer climate change via their seed bank, notably in short-term persistent species. Since the buffering capacity of seed banks is key to species persistence, these results provide crucial information to advance climatic change predictions on range shifts, community and biodiversity responses.
QuestionBelow-ground processes are key determinants of above-ground plant population and community dynamics. Still, our understanding of how environmental drivers shape plant communities is mostly based on above-ground diversity patterns, bypassing below-ground plant diversity stored in seed banks. As seed banks may shape above-ground plant communities, we question whether concurrently analysing the above- and below-ground species assemblages may potentially enhance our understanding of community responses to environmental variation. LocationTemperate deciduous forests along a 2000km latitudinal gradient in NW Europe. MethodsHerb layer, seed bank and local environmental data including soil pH, canopy cover, forest cover continuity and time since last canopy disturbance were collected in 129 temperate deciduous forest plots. We quantified herb layer and seed bank diversity per plot and evaluated how environmental variation structured community diversity in the herb layer, seed bank and the combined herb layer-seed bank community. ResultsSeed banks consistently held more plant species than the herb layer. How local plot diversity was partitioned across the herb layer and seed bank was mediated by environmental variation in drivers serving as proxies of light availability. The herb layer and seed bank contained an ever smaller and ever larger share of local diversity, respectively, as both canopy cover and time since last canopy disturbance decreased. Species richness and -diversity of the combined herb layer-seed bank community responded distinctly differently compared to the separate assemblages in response to environmental variation in, e.g. forest cover continuity and canopy cover. ConclusionsThe seed bank is a below-ground diversity reservoir of the herbaceous forest community, which interacts with the herb layer, although constrained by environmental variation in e.g. light availability. The herb layer and seed bank co-exist as a single community by means of the so-called storage effect, resulting in distinct responses to environmental variation not necessarily recorded in the individual herb layer or seed bank assemblages. Thus, concurrently analysing above- and below-ground diversity will improve our ecological understanding of how understorey plant communities respond to environmental variation.
The contemporary state of functional traits and species richness in plant communities depends on legacy effects of past disturbances. Whether temporal responses of community properties to current environmental changes are altered by such legacies is, however, unknown. We expect global environmental changes to interact with land-use legacies given different community trajectories initiated by prior management, and subsequent responses to altered resources and conditions. We tested this expectation for species richness and functional traits using 1814 survey-resurvey plot pairs of understorey communities from 40 European temperate forest datasets, syntheses of management transitions since the year 1800, and a trait database. We also examined how plant community indicators of resources and conditions changed in response to management legacies and environmental change. Community trajectories were clearly influenced by interactions between management legacies from over 200 years ago and environmental change. Importantly, higher rates of nitrogen deposition led to increased species richness and plant height in forests managed less intensively in 1800 (i.e., high forests), and to decreases in forests with a more intensive historical management in 1800 (i.e., coppiced forests). There was evidence that these declines in community variables in formerly coppiced forests were ameliorated by increased rates of temperature change between surveys. Responses were generally apparent regardless of sites’ contemporary management classifications, although sometimes the management transition itself, rather than historic or contemporary management types, better explained understorey responses. Main effects of environmental change were rare, although higher rates of precipitation change increased plant height, accompanied by increases in fertility indicator values. Analysis of indicator values suggested the importance of directly characterising resources and conditions to better understand legacy and environmental change effects. Accounting for legacies of past disturbance can reconcile contradictory literature results and appears crucial to anticipating future responses to global environmental change.
Many bryophytes may depend on epizoochorous dispersal by large mammals for maintaining their populations and colonizing new habitats. On dry grassland we investigated the transport of bryophyte diaspores by sheep, which are known to be effective epizoochorous dispersal vectors of seed plants. Twelve sheep of two breeds were examined by collecting gametophyte fragments from their fleece and hooves. Furthermore, microscopic diaspores from the soil adhering to the hooves were grown in a greenhouse. Species frequency and composition were compared to bryophyte vegetation on the pasture. Considerable amounts of unspecialized gametophyte fragments from 16 moss species, 40% of the species growing on the pasture, were transported by sheep, especially on the belly and the tail. Additionally, we provide first evidence of epizoochorous dispersal of thallus fragments from fruticose lichens. Sheep breeds differed in species spectrum and frequency, i.e. sheep with dense, curly fleece carried more fragments and larger species than those with smooth and fine hair. Among the dispersed bryophytes pleurocarps, certain taxa, sizes (small species) and life forms (mats) were overrepresented compared to the vegetation of the pasture, while large species, acrocarps, wefts and turfs were underrepresented, reflecting fragmentation and adhesion features of the species. In the hooves mostly acrocarpous colonist species were transported. We conclude that sheep are important dispersal vectors with the potential of long-range dispersal for bryophytes, especially for species without sexual reproduction, and that epizoochorous dispersal of microscopic diaspores might be underestimated in its importance so far.
Environmental drivers interactively affect individual tree growth across temperate European forests
(2018)
Forecasting the growth of tree species to future environmental changes requires abetter understanding of its determinants. Tree growth is known to respond to global‐change drivers such as climate change or atmospheric deposition, as well as to localland‐use drivers such as forest management. Yet, large geographical scale studiesexamining interactive growth responses to multiple global‐change drivers are relativelyscarce and rarely consider management effects. Here, we assessed the interactiveeffects of three global‐change drivers (temperature, precipitation and nitrogen deposi-tion) on individual tree growth of three study species (Quercus robur/petraea, Fagus syl-vatica and Fraxinus excelsior). We sampled trees along spatial environmental gradientsacross Europe and accounted for the effects of management for Quercus. We collectedincrement cores from 267 trees distributed over 151 plots in 19 forest regions andcharacterized their neighbouring environment to take into account potentially confounding factors such as tree size, competition, soil conditions and elevation. Wedemonstrate that growth responds interactively to global‐change drivers, with species ‐specific sensitivities to the combined factors. Simultaneously high levels of precipita-tion and deposition benefited Fraxinus, but negatively affected Quercus’ growth, high-lighting species‐specific interactive tree growth responses to combined drivers. ForFagus, a stronger growth response to higher temperatures was found when precipita-tion was also higher, illustrating the potential negative effects of drought stress underwarming for this species. Furthermore, we show that past forest management canmodulate the effects of changing temperatures on Quercus’ growth; individuals in plotswith a coppicing history showed stronger growth responses to higher temperatures.Overall, our findings highlight how tree growth can be interactively determined by glo-bal‐change drivers, and how these growth responses might be modulated by past for-est management. By showing future growth changes for scenarios of environmentalchange, we stress the importance of considering multiple drivers, including past man-agement and their interactions, when predicting tree growth.
Topsoil conditions in temperate forests are influenced by several soil-forming factors, such as canopy composition (e.g. through litter quality), land-use history, atmospheric deposition, and the parent material. Many studies have evaluated the effects of single factors on physicochemical topsoil conditions, but few have assessed the simultaneous effects of multiple drivers. Here, we evaluate the combined effects of litter quality, land-use history (past land cover as well as past forest management), and atmospheric deposition on several physicochemical topsoil conditions of European temperate deciduous forest soils: bulk density, proportion of exchangeable base cations, carbon/nitrogen-ratio (C/N), litter mass, bio-available and total phosphorus, pH(KCI)and soil organic matter. We collected mineral soil and litter layer samples, and measured site characteristics for 190 20 x 20 m European mixed forest plots across gradients of litter quality (derived from the canopy species composition) and atmospheric deposition, and for different categories of past land cover and past forest management. We accounted for the effects of parent material on topsoil conditions by clustering our plots into three soil type groups based on texture and carbonate concentration. We found that litter quality was a stronger driver of topsoil conditions compared to land-use history or atmospheric deposition, while the soil type also affected several topsoil conditions here. Plots with higher litter quality had soils with a higher proportion of exchangeable base cations, and total phosphorus, and lower C/N-ratios and litter mass. Furthermore, the observed litter quality effects on the topsoil were independent from the regional nitrogen deposition or the soil type, although the soil type likely (co)-determined canopy composition and thus litter quality to some extent in the investigated plots. Litter quality effects on topsoil phosphorus concentrations did interact with past land cover, highlighting the need to consider land-use history when evaluating canopy effects on soil conditions. We conclude that forest managers can use the canopy composition as an important tool for influencing topsoil conditions, although soil type remains an important factor to consider.
Meta-communities of habitat islands may be essential to maintain biodiversity in anthropogenic landscapes allowing rescue effects in local habitat patches. To understand the species-assembly mechanisms and dynamics of such ecosystems, it is important to test how local plant-community diversity and composition is affected by spatial isolation and hence by dispersal limitation and local environmental conditions acting as filters for local species sorting.We used a system of 46 small wetlands (kettle holes)natural small-scale freshwater habitats rarely considered in nature conservation policiesembedded in an intensively managed agricultural matrix in northern Germany. We compared two types of kettle holes with distinct topographies (flat-sloped, ephemeral, frequently plowed kettle holes vs. steep-sloped, more permanent ones) and determined 254 vascular plant species within these ecosystems, as well as plant functional traits and nearest neighbor distances to other kettle holes.Differences in alpha and beta diversity between steep permanent compared with ephemeral flat kettle holes were mainly explained by species sorting and niche processes and mass effect processes in ephemeral flat kettle holes. The plant-community composition as well as the community trait distribution in terms of life span, breeding system, dispersal ability, and longevity of seed banks significantly differed between the two habitat types. Flat ephemeral kettle holes held a higher percentage of non-perennial plants with a more persistent seed bank, less obligate outbreeders and more species with seed dispersal abilities via animal vectors compared with steep-sloped, more permanent kettle holes that had a higher percentage of wind-dispersed species. In the flat kettle holes, plant-species richness was negatively correlated with the degree of isolation, whereas no such pattern was found for the permanent kettle holes.Synthesis: Environment acts as filter shaping plant diversity (alpha and beta) and plant-community trait distribution between steep permanent compared with ephemeral flat kettle holes supporting species sorting and niche mechanisms as expected, but we identified a mass effect in ephemeral kettle holes only. Flat ephemeral kettle holes can be regarded as meta-ecosystems that strongly depend on seed dispersal and recruitment from a seed bank, whereas neighboring permanent kettle holes have a more stable local species diversity.
Meta‐communities of habitat islands may be essential to maintain biodiversity in anthropogenic landscapes allowing rescue effects in local habitat patches. To understand the species‐assembly mechanisms and dynamics of such ecosystems, it is important to test how local plant‐community diversity and composition is affected by spatial isolation and hence by dispersal limitation and local environmental conditions acting as filters for local species sorting. We used a system of 46 small wetlands (kettle holes)—natural small‐scale freshwater habitats rarely considered in nature conservation policies—embedded in an intensively managed agricultural matrix in northern Germany. We compared two types of kettle holes with distinct topographies (flatsloped, ephemeral, frequently plowed kettle holes vs. steep‐sloped, more permanent ones) and determined 254 vascular plant species within these ecosystems, as well as plant functional traits and nearest neighbor distances to other kettle holes. Differences in alpha and beta diversity between steep permanent compared with ephemeral flat kettle holes were mainly explained by species sorting and niche processes and mass effect processes in ephemeral flat kettle holes. The plant‐community composition as well as the community trait distribution in terms of life span, breeding system, dispersal ability, and longevity of seed banks significantly differed between the two habitat types. Flat ephemeral kettle holes held a higher percentage of non‐perennial plants with a more persistent seed bank, less obligate outbreeders and more species with seed dispersal abilities via animal vectors compared with steep‐sloped, more permanent kettle holes that had a higher percentage of wind‐dispersed species. In the flat kettle holes, plant‐species richness was negatively correlated with the degree of isolation, whereas no such pattern was found for the permanent kettle holes. Synthesis: Environment acts as filter shaping plant diversity (alpha and beta) and plant‐community trait distribution between steep permanent compared with ephemeral flat kettle holes supporting species sorting and niche mechanisms as expected, but we identified a mass effect in ephemeral kettle holes only. Flat ephemeral kettle holes can be regarded as meta‐ecosystems that strongly depend on seed dispersal and recruitment from a seed bank, whereas neighboring permanent kettle holes have a more stable local species diversity.
Meta‐communities of habitat islands may be essential to maintain biodiversity in anthropogenic landscapes allowing rescue effects in local habitat patches. To understand the species‐assembly mechanisms and dynamics of such ecosystems, it is important to test how local plant‐community diversity and composition is affected by spatial isolation and hence by dispersal limitation and local environmental conditions acting as filters for local species sorting. We used a system of 46 small wetlands (kettle holes)—natural small‐scale freshwater habitats rarely considered in nature conservation policies—embedded in an intensively managed agricultural matrix in northern Germany. We compared two types of kettle holes with distinct topographies (flatsloped, ephemeral, frequently plowed kettle holes vs. steep‐sloped, more permanent ones) and determined 254 vascular plant species within these ecosystems, as well as plant functional traits and nearest neighbor distances to other kettle holes. Differences in alpha and beta diversity between steep permanent compared with ephemeral flat kettle holes were mainly explained by species sorting and niche processes and mass effect processes in ephemeral flat kettle holes. The plant‐community composition as well as the community trait distribution in terms of life span, breeding system, dispersal ability, and longevity of seed banks significantly differed between the two habitat types. Flat ephemeral kettle holes held a higher percentage of non‐perennial plants with a more persistent seed bank, less obligate outbreeders and more species with seed dispersal abilities via animal vectors compared with steep‐sloped, more permanent kettle holes that had a higher percentage of wind‐dispersed species. In the flat kettle holes, plant‐species richness was negatively correlated with the degree of isolation, whereas no such pattern was found for the permanent kettle holes. Synthesis: Environment acts as filter shaping plant diversity (alpha and beta) and plant‐community trait distribution between steep permanent compared with ephemeral flat kettle holes supporting species sorting and niche mechanisms as expected, but we identified a mass effect in ephemeral kettle holes only. Flat ephemeral kettle holes can be regarded as meta‐ecosystems that strongly depend on seed dispersal and recruitment from a seed bank, whereas neighboring permanent kettle holes have a more stable local species diversity.
Tree-ring chronologies of Pinus sylvestris L. from latitudinal and altitudinal limits of the species distribution have been widely used for climate reconstructions, but there are many sites within the temperate climate zone, as is the case in northeastern Germany, at which there is little evidence of a clear climate signal in the chronologies. In this study, we developed long chronologies of several cell structure variables (e. g., average lumen area and cell wall thickness) from P. sylvestris growing in northeastern Germany and investigated the influence of climate on ring widths and cell structure variables. We found significant correlations between cell structure variables and temperature, and between tree-ring width and relative humidity and vapor pressure, respectively, enabling the development of robust reconstructions from temperate sites that have not yet been realized. Moreover, it has been shown that it may not be necessary to detrend chronologies of cell structure variables and thus low-frequency climate signals may be retrieved from longer cell structure chronologies. The relatively extensive resource of archaeological material of P. sylvestris covering approximately the last millennium may now be useful for climate reconstructions in northeastern Germany and other sites in the temperate climate zone.
A novel procedure has been developed to conduct cell structure measurements on increment core samples of conifers. The procedure combines readily available hardware and software equipment. The essential part of the procedure is the application of a confocal laser scanning microscope (CLSM) which captures images directly from increment cores surfaced with the advanced WSL core-microtome. Cell wall and lumen are displayed with a strong contrast due to the monochrome black and green nature of the images. Consecutive images are merged into long images representing entire increment cores which are then analysed for cell structures in suitable software.
Patterns of phenotypic trait variation in two temperate forest herbs along a broad climatic gradient
(2015)
Phenotypic trait variation plays a major role in the response of plants to global environmental change, particularly in species with low migration capabilities and recruitment success. However, little is known about the variation of functional traits within populations and about differences in this variation on larger spatial scales. In a first approach, we therefore related trait expression to climate and local environmental conditions, studying two temperate forest herbs, Milium effusum and Stachys sylvatica, along a similar to 1800-2500 km latitudinal gradient. Within each of 9-10 regions in six European countries, we collected data from six populations of each species and recorded several variables in each region (temperature, precipitation) and population (light availability, soil parameters). For each plant, we measured height, leaf area, specific leaf area, seed mass and the number of seeds and examined environmental effects on within-population trait variation as well as on trait means. Most importantly, trait variation differed both between and within populations. Species, however, differed in their response. Intrapopulation variation in Milium was consistently positively affected by higher mean temperatures and precipitation as well as by more fertile local soil conditions, suggesting that more productive conditions may select for larger phenotypic variation. In Stachys, particularly light availability positively influenced trait variation, whereas local soil conditions had no consistent effects. Generally, our study emphasises that intra-population variation may differ considerably across larger scales-due to phenotypic plasticity and/or underlying genetic diversity-possibly affecting species response to global environmental change.
The recent decline of Lepidoptera species strongly correlates with the increasing intensification of agriculture in Western and Central Europe. However, the effects of changed host-plant quality through agricultural fertilization on this insect group remain largely unexplored. For this reason, we tested the response of six common butterfly and moth species to host-plant fertilization using fertilizer quantities usually applied in agriculture. The larvae of the study species Coenonympha pamphilus, Lycaena phlaeas, Lycaena tityrus, Pararge aegeria, Rivula sericealis and Timandra comae were distributed according to a split-brood design to three host-plant treatments comprising one control treatment without fertilization and two fertilization treatments with an input of 150 and 300kgNha(-1)year(-1), respectively. In L.tityrus, we used two additional fertilization treatments with an input of 30 and 90kgNha(-1)year(-1), respectively. Fertilization increased the nitrogen concentration of both host-plant species, Rumex acetosella and Poa pratensis, and decreased the survival of larvae in all six Lepidoptera species by at least one-third, without clear differences between sorrel- and grass-feeding species. The declining survival rate in all species contradicts the well-accepted nitrogen-limitation hypothesis, which predicts a positive response in species performance to dietary nitrogen content. In contrast, this study presents the first evidence that current fertilization quantities in agriculture exceed the physiological tolerance of common Lepidoptera species. Our results suggest that (1) the negative effect of plant fertilization on Lepidoptera has previously been underestimated and (2) that it contributes to the range-wide decline of Lepidoptera.
Butterflies rank among the most threatened animal groups throughout Europe. However, current population trends differ among species. The nettle-feeding butterflies Aglais io and Aglais urticae cope successfully with the anthropogenic land-use change. Both species are assumed to be pre-adapted to higher nitrogen contents in their host plant, stinging nettle (Urtica dioica). However, it is currently unknown, whether this pre-adaptation enables both Aglais species to cope successfully or even to benefit from the excessive nitrogen availabilities in nettles growing in modern farmlands. For this reason, this study focused on the response of both Aglais species to unfertilized nettles compared to nettles receiving 150 or 300 kg N ha(-1) yr(-1) (i.e., common fertilizer quantities of modern-day agriculture). Fertilized nettles were characterized by higher nitrogen concentrations and lower C:N ratios compared to the control group. In both Aglais species, the individuals feeding on fertilized nettles had higher survival rates, shorter larval periods and heavier pupae and, in A. urticae also longer forewings. All these trait shifts are beneficial for the individuals, lowering their risk to die before reproduction and increasing their reproductive potential. These responses agree with the well-accepted nitrogen-limitation hypothesis predicting a positive relationship between the nitrogen content of the diet and the performance of herbivorous insects. Furthermore, our findings suggest that the increasing abundance of both Aglais species may result not only from the increasing spread of nettles into the farmland but also from changes in their quality due to the eutrophication of the landscape during recent decades.
The intensification of agricultural practices has led to a severe decrease in grassland biodiversity. Although there is strong evidence that organic farming can reduce the negative impacts of land use, knowledge regarding the most beneficial management system for species richness on organic grasslands is still scarce. This study examines differences in the biodiversity of plants and butterflies on rotationally and continuously grazed pastures as well as on meadows cut twice per year on two large organic suckler cow farms in NE Germany. Vegetation and flower abundance, as factors likely to influence butterfly abundance and diversity, were compared and used to explain the differences. The data attained by vegetation assessments and monthly transect inspections from May to August were analyzed using descriptive statistics and nonparametric methods. The abiotic site conditions of the studied plots had more influence on plant species numbers than the management method. Dry and nutrient-poor areas (mainly poor types of Cynosurion) and undrained wet fens (Calthion) were important for phytodiversity, measured by the absolute number of species, indicator species for ecologically valuable grasslands and the Shannon Index. Meadows tended to have more indicator species than pastures, where small-scale special sites such as wet depressions were crucial for plant diversity. Butterfly diversity was very low, and 90% of the recorded butterflies were individuals of the generalist species Pieris napi. Butterfly abundance depended mainly on occurrence of specific habitat types and specific larval host plants. Supply of flowers was crucial only in certain time periods. Differences in butterfly abundance between the management systems could be explained by the site conditions of the studied grasslands. We conclude that meadows are more favorable to support ecologically valuable plant species; however, their extension is contradictory to the organic farming method of suckler cows maintained outside of stables. Rotationally grazed pastures could be a compromise that would enhance the temporal heterogeneity of flower abundance and vegetation structure. The plant diversity on pastures should be improved by less intensive grazing on special sites and plant species enrichment by means of hay transfer. For enhancing butterfly diversity we suggest to reduce land use intensity especially on poor soils. Considering the economic perspective of the farms, small parts of the agricultural area could be sufficient if connectivity to other suitable habitats is assured. Flower abundance and diversity of larval host plants could be promoted by high diversity of farming practices as well as preserving small uncut strips of meadows.
Structure and reactivity of a biological soil crust from a xeric sandy soil in Central Europe
(2004)
The investigation was designed to explore the structure, composition and activity of a biological soil crust on an acidic, sandy soil from a temperate climate. The crust covers several hundreds of square meters on the hilltop of a large terminal moraine. The conjugate alga Zygogonium ericetorum forms the essential matrix for the crust, a dense web of algal filaments with interspersed lichens and mosses. The crust is composed of three layers, with an uppermost layer consisting nearly entirely of a dense algal mat. In lower layers, a parasitic fungus, penetrating the algal cells, is another important component of the crust community. In this soil crust, photosynthetic and respiratory activity is stabilized at low water activities.
In northeastern German pine forests we studied re-colonization patterns of experimental gaps by four dominant bryophyte species (Dicranum scoparium, Hypnum jutlandicum, Pleurozium schreberi and Scleropodium purum) over three years. Both vegetation and litter layer were removed on 1 m(2) plots within +/- pure colonies of the experimental species, while the humus layer was left intact. All plots were vegetatively re-colonized by the species which was dominant before gap creation. Three mechanisms of re-colonization occurred and interacted: (1) advance of surrounding shoots from the edge into the gaps by clonal growth, (2) dispersal of detached single shoots as well as larger clumps of multiple shoots into the plots, resulting in new colonies by continuing growth, and (3) regeneration from a soil diaspore bank consisting of seemingly dead stem fragments in the humus layer of the gaps. Scleropodium purum, which occurs at locations with good water and nutrient supply, displayed the most rapid growth. Here, some plots were completely recovered after three years. Despite lower rates of advance from the edge, colonization of Hypnum jutlandicum was faster than and of Dicranum scoparium as fast than that of Pleurozium schreberi because of a larger diaspore bank. Thus, each bryophyte species was characterized by a different habitat occupation strategy. The different clonal colonization strategies account for the high competitive capacity and regeneration potential of the investigated bryophyte species in pine forests despite of the lack of generative reproduction. Experimental disturbance resulted in a temporary increase of bryophyte diversity, because short-lived Colonists with a low competitive capacity colonized the gaps, before they will be overgrown by the dominant Perennials
Myrmecochory, i.e. dispersal of seeds by ants towards and around their nests, plays an important role in temperate forests. Yet hardly any study has examined plant population spread over several years and the underlying joint contribution of a hierarchy of dispersal modes and plant demography. We used a seed-sowing approach with three replicates to examine colonization patterns of Melampyrum pratense, an annual myrmecochorous herb, in a mixed Scots pine forest in northeastern Germany. Using a spatially explicit individualbased (SEIB) model population patterns over 4 years were explained by short-distance transport of seeds by small ant species with high nest densities, resulting in random spread. However, plant distributions in the field after another 4 years were clearly deviating from model predictions. Mean annual spread rate increased from 0.9 m to 5.1 m per year, with a clear inhomogeneous component. Obviously, after a lag-phase of several years, non-random seed dispersal by large red wood ants (Formica rufa) was determining the species’ spread, thus resulting in stratified dispersal due to interactions with different-sized ant species. Hypotheses on stratified dispersal, on dispersal lag, and on non-random dispersal were verified using an extended SEIB model, by comparison of model outputs with field patterns (individual numbers, population areas, and maximum distances). Dispersal towards red wood ant nests together with seed loss during transport and redistribution around nests were essential features of the model extension. The observed lag-phase in the initiation of non-random, medium-distance transport was probably due to a change of ant behaviour towards a new food source of increasing importance, being a meaningful example for a lag-phase in local plant species invasion. The results demonstrate that field studies should check model predictions wherever possible. Future research will show whether or not the M. pratense–ant system is representative for migration patterns of similar animal dispersal systems after having crossed range edges by long-distance dispersal events.
Habitat fragmentation is one of the most important causes for the decline of plant species. However, plants differing in phylogeny, habitat requirements and biology are likely to respond differently to habitat fragmentation. We ask whether case studies on the effects of habitat fragmentation conducted so far allow generalizations about its effects on the fitness and genetic diversity of populations of endangered plant species. We compared the characteristics of plant species endangered in Germany whose sensitivity to habitat fragmentation had been studied with those of the endangered species that had not been studied. We found strong discrepancies between the two groups with regard to their taxonomy and traits relevant to their sensitivity to habitat fragmentation. Monocots, graminoids, clonal, abiotically pollinated and self compatible species were underrepresented among the studied species, and most study species were from a few habitat types, in particular grasslands. We conclude that our current knowledge of the effects of habitat fragmentation on plant populations is not sufficient to provide widely applicable guidelines for species management. The selection of species studied so far has been biased toward species from certain habitats and species exhibiting traits that probably make them vulnerable to habitat fragmentation. Future studies should include community-wide approaches in different habitats, e.g. re-visitation studies in which the species pool is assessed at different time intervals, and population-biological studies of species from a wide range of habitats, and of different life forms and growth strategies. A more representative picture of the effects of habitat fragmentation would allow a better assessment of threats and more specific recommendations for optimally managing populations of endangered plants.
Im Norddeutschen Tiefland wurde die Ausbreitung von Gefäßpflanzen durch Rehe, Dam- und Rothirsche sowie Wildschweine untersucht. Diese Tiere transportieren zahlreiche Pflanzenarten in teilweise erheblichen Mengen über größere Distanzen, sowohl durch den Kot nach Darmpassage (Endozoochorie) als auch durch Anheftung an Fell und Schalen (Epizoochorie). Besondere Bedeutung kommt dabei Wildschweinen zu, die potenziell fast alle Pflanzenarten ausbreiten können. Bevorzugt werden im Wald wie im Offenland vorkommende Pflanzen und Arten des Offenlands ausgebreitet, während Arten mit enger Waldbindung nur in geringem Maße transportiert werden. Zoochorie durch Schalenwild bietet Erklärungsansätze sowohl für Ausbreitungsphänomene wie auch für das weitgehend fehlende Ausbreitungspotenzial vieler Pflanzenarten. Der Einfluss des Schalenwilds auf die Artenzusammensetzung und Gefäßpflanzen-Diversität in der mitteleuropäischen Kulturlandschaft sollte in seine naturschutzfachliche Neubewertung miteinbezogen werden. Die Einschränkung von Aktionsradien der Tiere durch die Zerschneidung von Lebensräumen sowie die Wildfütterung können für Ausbreitungsprozesse bisher kaum beachtete Konsequenzen haben.
Soil seed banks near rubbing trees indicate dispersal of plant species into forests by wild boar
(2006)
Current knowledge about processes that generate long-distance dispersal of plants is still limited despite its importance for persistence of populations and colonization of new potential habitats. Today wild Large mammals are presumed to be important vectors for long-distance transport of diaspores within and between European temperate forest patches, and in particular wild boars recently came into focus. Here we use a specific habit of wild boar, i.e. wallowing in mud and subsequent rubbing against trees, to evaluate epizoochorous dispersal of vascular plant diaspores. We present soil seed bank data from 27 rubbing trees versus 27 control trees from seven forest areas in Germany. The mean number of viable seeds and the plant species number were higher in soil samples near rubbing trees compared with control trees. Ten of the 20 most frequent species were more frequent, and many species exclusively appeared in the soil samples near rubbing trees. The large number of plant species and seeds - more than 1000 per tree - in the soils near rubbing trees is difficult to explain unless the majority were dispersed by wild boar. Hooked and bristly diaspores, i.e. those adapted to epizoochory, were more frequent; however, many species with unspecialized diaspores occurred exclusively near rubbing trees. As opposed to plant species closely tied to forests species which occur both in forest and open vegetation and non-forest species were more frequent near rubbing trees compared with controls. These findings are consistent with previous studies on diaspore loads in the coats and hooves of shot wild boars. However, our method allows to identify the transport of diaspores from the open landscape into forest stands, where they might especially emerge after disturbance, and a clustered distribution of epizoochorically dispersed seeds. Moreover, accumulation of seeds of wetness indicators near rubbing trees demonstrates directed dispersal of plant species inhabiting wet places among remote wallows.
Soil seed banks near rubbing trees indicate dispersal of plant species into forests by wild boar
(2006)
Current knowledge about processes that generate long-distance dispersal of plants is still limited despite its importance for persistence of populations and colonization of new potential habitats. Today wild large mammals are presumed to be important vectors for long-distance transport of diaspores within and between European temperate forest patches, and in particular wild boars recently came into focus. Here we use a specific habit of wild boar, i.e. wallowing in mud and subsequent rubbing against trees, to evaluate epizoic dispersal of vascular plant diaspores. We present soil seed bank data from 27 rubbing trees versus 27 control trees from seven forest areas in Germany. The mean number of viable seeds and the plant species number were higher in soil samples near rubbing trees compared with control trees. Ten of the 20 most frequent species were more frequent, and many species exclusively appeared in the soil samples near rubbing trees. The large number of plant species and seeds – approximated > 1000 per tree – in the soils near rubbing trees is difficult to explain unless the majority were dispersed by wild boar. Hooked and bristly diaspores, i.e. those adapted to epizoochory, were more frequent, above that many species with unspecialised diaspores occurred exclusively near rubbing trees. Different to plant species closely tied to forest species which occur both in forest and open vegetation, and non-forest species were more frequent near rubbing trees compared with controls. These findings are consistent with previous studies on diaspore loads in the coats and hooves of shot wild boars. However, our method allows to identify the transport of diaspores from the open landscape into forest stands where they might especially emerge after disturbance, and a clustered distribution of epizoochorically dispersed seeds. Moreover, accumulation of seeds of wetness indicators near rubbing trees demonstrates directed dispersal of plant species inhabiting wet places between remote wallows.
Gametophyte and thallus fragments, respectively, may be an important or even the only mode of reproduction for many bryophytes and lichens species. Until now especially birds and mammals have been identifi ed as potential animal dispersal vectors of fragments. This study investigates the dispersal of bryophyte and lichen fragments by red wood ants which build large nest mounds from plant material and are abundant in European coniferous forests. We sampled nest material from 25 nest mounds in fi ve different pine and spruce forest types in Germany and found numerous fragments of 20 bryophyte and ten lichen species. As they occurred on almost all studied mounds and often in large numbers we conclude that collecting cryptogam fragments as nest material is a characteristic feature for the Formica rufa group in coniferous forests. Species number and composition of fragments on mounds coincided with the epigeic vegetation around ant nests to a large extent: Almost all collected species were present in the vegetation, and dominant fragment species occurred in large amounts in the vicinity of ant nests. Lichen fragments were larger than bryophyte fragments. Certain life forms (weft-forming bryophytes, reindeer lichens) were accumulated on mounds, while others (tall turfs, cup-type Cladonia species) were discriminated, refl ecting fragmentation features of species. Collected fragments may regenerate to mature plants if nest mounds are abandoned, and especially if they are lost during transport over several metres. We conclude that dispersal of fragments by red wood ants contributes to maintain epigeic bryophyte and lichen diversity of coniferous forests by supporting colonisation after disturbances, which occur on different spatial and temporal scales.
The external dispersal ("epizoochory") of vascular plant diaspores (seeds and fruits) by roe deer and wild boar, i.e. the most common wild large mammals with a large home range in central Europe, was investigated in a 6.5-km² forest area in NE Germany dominated by mesic deciduous forests. The study involved brushing out the diaspores from the coats and hooves of 25 shot roe deer and nine wild boar. The results were compared with the forest vegetation of the study area. Whilst wild boar transported large amounts of various diaspores in the coat, the significance of roe deer for epizoochory was low due to their sleek fur and different behaviour compared to wild boar. Altogether, 55 vascular plant species were transported externally. Since only a limited number of seeds came from woodland habitats, the open landscape was at least as important as a source of attached seeds as the forest vegetation. Thus, most plant species occurring in the studied forest area, especially characteristic woodland herbs, showed no adaptations to epizoochorous dispersal, although being very abundant in the herb layer. We conclude that hoofed game play a particular role concerning the dispersal of ruderal and grassland species in the agricultural landscape of central Europe. However, the actual spread of some herb species in forests of northern Germany, e.g. Agrostis capillaris, Brachypodium sylvaticum, Deschampsia flexuosa, Galium aparine and Urtica dioica, may be mainly facilitated by wild ungulates. Though dispersal by large mammals is an important mechanism for long-distance dispersal of plants in general, our results suggest that most of the characteristic herb species of mesic deciduous forests have only low epizoochorous dispersal potentials. The implications for nature conservation and silviculture are discussed.
Natürliche Standorte der Waldkiefer gibt es in Deutschland nur kleinflächig. Während Kiefernforste anstelle natürlicher Laubwälder heute oft landschaftsprägend sind, bildet die konkurrenzschwache und lichtbedürftige Kiefer ausschließlich auf extrem trockenen oder nassen, nährstoffarmen Standorten naturnahe Schlusswaldgesellschaften. Regionale Schwerpunkte liegen in subkontinentalen Regionen wie dem nordostdeutschen Tiefland und Bayern, ein „natürliches Kiefernareal" lässt sich aber kaum abgrenzen. An der Trockengrenze des Waldes finden sich auf Kalk- und Dolomitgesteinen artenreiche Karbonat-Trockenkiefernwälder mit Elementen der alpinen Rasen und Kalkmagerrasen in der Bodenvegetation. Diese Wälder besiedeln steile, südexponierte Felsen und morphodynamisch aktive Bereiche wie Rutschhänge und FlussSchotterböden im Umkreis der Alpen, kommen aber auch in den Mittelgebirgen vor. Ihr Gegenstück auf sauren Standorten sind die Sand- und Silikat-Kiefernwälder der Quarzsande und Sandstein-Verwitterungsböden, deren Bodenvegetation durch Zwergsträucher, Moose und Strauchflechten geprägt ist. Hier siedelt die Kiefer in den Tieflagen besonders auf Binnendünen und Sandern, aber auch auf Küstendünen der Ostsee, in den Mittelgebirgen z. B. auf den Sandsteinriffen der Sächsischen Schweiz. Der dritte Wuchsbereich natürlicher Kiefernwälder sind saure, nährstoffarme Moore, die ganz überwiegend von Regenwasser gespeist werden. Auch die Kiefern-Moorwälder sind in Nordostdeutschland und Bayern am häufigsten. Von diesen Standorten ausgehend, wo ihr Platz kaum von anderen Baumarten streitig gemacht wird, tritt die Waldkiefer immer wieder als Pionier auf weniger extremen Standorten auf. In der Naturlandschaft kam dies etwa nach Waldbränden oder Stürmen vor, doch der Mensch förderte die Kiefer durch Auflichtung der Wälder, Waldweide und Streunutzung stark. Auch die damit verbundene Nährstoffverarmung macht eine exakte Abgrenzung natürlicher Kiefernstandorte unmöglich. Die schlechtwüchsigen und forstwirtschaftlich nicht interessanten, ästhetisch aber sehr ansprechenden natürlichen Kiefernbestände sind heute vor allem durch Stickstoff-Immissionen gefährdet. Trotz ihrer oft kargen Erscheinung besitzen sie einen hohen Wert für die Biodiversität und den Artenschutz. Neben bodenbewohnenden Flechten und regionalen Relikt-Endemiten ist vor allem die in den letzten Jahrzehnten zunehmend gefährdete Vielfalt an Mykorrhiza-Pilzen hervorzuheben, die der Kiefer das Leben auf extrem nährstoffarmen Standorten überhaupt ermöglichen. Abschließend werden mögliche Schutz- bzw. Regenerationsmaßnahmen wie das Abplaggen flechtenreicher Kiefernstandorte vorgestellt.
Sand- und Silikat-Kiefernwälder (Dicrano-Pinion) in Deutschland : Gliederungskonzept und Ökologie
(2007)
In preparation for the „Synopsis of plant communities of Germany“ a comprehensive classification concept for the Scots pine forests on sandy and silicate soils is presented. On the basis of 2699 relevés from all natural provinces with important occurrences this classification for the first time integrates both northern and southern German forest stands. Pine forests are stable (“climax”) communities on three distinct habitat types at the drought and wetness limits of forest growth. In the phytosociological system these are reflected by the clearly separated syntaxa Erico-Pinetea (dry-calcareous), Dicrano-Pinion (dry-acidic) and Vaccinio uliginosi- Pinetea (wet-acidic). However, Pulsatillo-Pinetea (dry-moderate basicity) described in earlier publications cannot be separated floristically. In addition to the stable communities on extreme habitats pine forests of the mentioned syntaxa are widespread on potential mixed deciduous forest stands, especially after anthropogenic devastation and even beyond their original range. Six communites of the Dicrano-Pinion which also includes such secondary pine forest stands are occurring in Germany. They are presented in detail and classified according to their dynamic and edaphic differentiation. Lichen-rich pine forests (Cladonio- Pinetum) which grow on extremely dry and nutrient-poor sites are ecologically and floristically well-defined, though closely connected with other Dicrano-Pinion communities by forest succession. After separation of the Cladonio-Pinetum the Leucobryo-Pinetum is a speciespoor “central association” within the alliance. The Deschampsia flexuosa-Pinus-sylvestriscommunity is the most widespread forest type and dynamically and floristically passes into the mixed oak forests on acidic soils (Quercion roboris). On base-rich habitats the Empetro- Pinetum as endemic community of the southern Baltic Sea coasts, and the Peucedano-Pinetum in the northeastern and southern German inland are distinguished. The latter is found both on calcareous sands and primarily acidic sands which are secondary limed by calciferous pollutions. Finally, differences and similarities between the geographically separated northern and southern German Dicrano-Pinion forests are discussed in a biogeographic context, emphasising the advantages of the presented nation-wide classification concept.
A seed sowing experiment was conducted in a mixed secondary woodland on acidic soils in NE Germany with Melampyrum pratense, an annual ant-dispersed forest herb which lacks a natural population in the study area, but is abundant in similar habitats. Each set of 300 seeds was sown within one square metre at three sites in 1997, and the development of the populations was recorded from 1998 onward. Additionally, seed fall patterns were studied in a natural population by means of adhesive cardboard. All trials resulted in the recruitment of populations, which survived and increased in both individual number and area, up to the year 2001. Thus, local distribution of Melampyrum pratense is dispersallimited. Total individual number increased from 105 to 3,390, and total population area from 2.07 to 109.04 m². Migration occurred in all directions. Mean migration rate was 0.91 m per year, and the highest migration rate was 6.48 m. No individual was recorded beyond 7.63 m from the centres of the sawn squares after three years, suggesting exclusive short-distance dispersal. As primary dispersal enables only distances of up to 0.25 m, ants are presumed to be the main dispersal vectors. Despite differences in individual number and colonization patterns, migration rates did not differ significantly between the populations, but were significantly higher in 2001 due to an increased population size. Colonization patterns were characterized by a rapid, negative exponential decrease of population density with increasing distance from the sown plot, suggesting a colonization by establishment of more or less isolated outposts of individuals and a subsequent gradual infill of the gaps between. My results resemble myrmecochorous dispersal distances in temperate woodlands, and migration rates and patterns across ecotones from ancient to recent deciduous forests. They may function as a colonization model of Melampyrum pratense after accidental long-distance dispersal.
Vegetation und Standort bodensaurer Buchenwälder am Arealrand : am Beispiel Mittelbrandenburgs
(2008)
Different from NW Germany, the northern part of NE Germany and the "Hohe Flaeming" region, central Brandenburg is considered as being largely devoid of natural beech forests because of its subcontinental, dry climate. In the present study the vegetation ecology of beech forests of the region is comprehensively documented for the first time, and they are compared with NW German stands in Lower Saxony. In the study area beech forests are concentrated in the Berlin-Potsdam region along the Havel river lakes which is characterised by relatively high precipitation and a specific land use history. All belong to the Luzulo-Fagetum growing on acid soils. Four subtypes are distinguished according to nutrient availability and soil moisture. The central Brandenburg Luzulo-Fagetum does not markedly deviate from other beech forests in the northern German lowlands with respect to vegetation structure and edaphic subtypes. However, numerous indicator species for humid or moist conditions are less frequent than under atlantic climate conditions in the lowlands of Lower Saxony, a pattern occurring also in other forest communities. On the other hand, nitrogen and disturbance indicators are more frequent in central Brandenburg. As expected, podzolisation of the soils and humus accumulation is lower in beech forests under subcontinental climate, but surprisingly the soils are more sandy and thus drier. However, beech forests are lacking on south-exposed slopes, and they are notably occurring in northern exposition. A combined analysis of distribution patterns and climatic data, postglacial vegetation history and forest use history, and actual rejuvenation dynamics reveals that the present-day beech forests in central Brandenburg have to be considered as near-natural relics, which are currently spreading. The range of potentially natural beech forests is larger than assumed until now, but further on it is not clearly to define.
Besides habitat loss, population-biological and genetic consequences of habitat fragmentation are thought to be a major threat to species since the 1990's and thus are now in the focus of plant species conservation. Using examples, this article gives an overview on the state of the art. It aims to evaluate the relevance habitat fragmentation and the resulting small size and isolation of populations may have for Central European plant populations. Stochasticity, edge effects, pollinator limitation, genetic drift and inbreeding depression are identified as important and very widespread negative effects. Together with changed habitat quality due to eutrophication, drainage or altered land use they negatively affect the fitness of individuals and populations, resulting in an increased risk of extinction. This negative effect of small populations on the fitness of individuals is called the Allee-effect, irrespective of the underlying causes, which can only be identified by scientific experiments. Metapopulation dynamics that are supported by a habitat network may prevent a permanent extinction of plant populations and minimize the negative genetic effects of habitat fragmentation by increasing gene flow via pollen and seeds. However, existing studies from Central Europe mainly concentrated on certain plant families (Gentianaceae, Primulaceae), habitats (species- rich grasslands), insect-pollinated and outcrossing species, and species mainly relying on sexual reproduction. On the other hand, few insights exist about grasses, ruderal plants and weeds, non-indigenous, wind- and self-pollinated species, and species mainly reproducing vegetatively or via apomictic seeds. However, according to the present state of knowledge especially these plant species, and those with a high dispersal potential, have to be considered as less sensitive to habitat fragmentation. Based on these findings, habitat types are classified with regard to their sensitivity to fragmentation, and ecological characters and species traits of sensitive and less sensitive species are compared. Finally, general consequences for conservation practice are presented with regard to target species and habitats for the formation of habitat networks, minimum viable population sizes, genetic rescue of populations, and deploying plants from ex-situ conservation to natural habitats.
Neben dem Habitatverlust gelten Konsequenzen der Habitatfragmentierung seit den 1990er Jahren als wesentliche Ursache der Gefaehrdung von Pflanzen und stehen damit nun auch im Fokus des botanischen Artenschutzes. Der vorliegende Beitrag gibt einen ueberblick ueber den Stand der populationsbiologischen und genetischen Forschung und versucht abzuschaetzen, welche Bedeutung Habitatfragmentierung und die dadurch entstehenden kleinen, isolierten Populationen auf heimische Pflanzenarten haben koennen. Als wesentliche und offenbar sehr weit verbreitete negative Effekte werden Zufallsereignisse, Randeffekte, Bestaeuberlimitierung, Gendrift und Inzuchtdepression identifiziert. Zusammen mit verringerter Habitatqualitaet durch Eutrophierung, Entwaesserung oder Nutzungsaenderung wirken sie zumeist negativ auf die Fitness der Individuen und Populationen und erhoehen so deren Aussterberisiko. Dieser negative Effekt kleiner Populationen auf die individuelle Fitness wird unabhaengig von der Ursache als Allee-Effekt bezeichnet. Eine durch einen Biotopverbund gefoerderte Metapopulationsdynamik kann das dauerhafte Aussterben von Pflanzenpopulationen verhindern und mindert die negativen genetischen Effekte der Habitatfragmentierung ueber einen erhoehten Genfluss durch Pollen und Samen. Die bisherigen wissenschaftlichen Studien in Mitteleuropa beruhen allerdings in ueberproportionaler Weise auf bestimmten Pflanzenfamilien (Gentianaceae, Primulaceae), Habitaten (Trocken- und Magerrasen, Wirtschaftsgruenland), insekten- und obligat fremdbestaeubten sowie weitgehend auf sexuelle Fortpflanzung angewiesenen Arten, waehrend etwa ueber Grasartige, Ruderalpflanzen, wind- und selbstbestaeubte sowie an vegetative Fortpflanzung angepasste Arten nur wenige Erkenntnisse vorliegen. Gerade diese und Pflanzenarten mit hohem Ausbreitungspotenzial muessen aber nach derzeitigem Wissensstand als weniger sensitiv gegenueber Habitatfragmentierung eingestuft werden. Auf diesen Befunden aufbauend werden fuer die Naturschutzpraxis Biotoptypen hinsichtlich ihrer Sensitivitaet gegenueber Habitatfragmentierung klassifiziert und ein auf biologischen Merkmalen basierender Kriterienkatalog zur Auswahl von Zielarten des Biotopverbunds vorgestellt. Schließlich wird eroertert, was bei Maßnahmen zur Regeneration kleiner bzw. bereits ausgestorbener Populationen zu beachten ist, und es werden allgemeine Folgerungen zur Ausgestaltung eines Biotopverbundskonzepts fuer Pflanzen gezogen.
Wildfires affect biodiversity at multiple levels. While vegetation is directly changed by fire events, animals are often indirectly affected through changes in habitat and food availability. Globally, fire frequency and the extent of fires are predicted to increase in the future. The impact of fire on the biodiversity of temperate wetlands has gained little attention so far. We compared species richness and abundance of plants and birds in burnt and unburnt areas in the Amur floodplain/Russian Far East in the year of fire and 1 year after. We also analysed vegetation recovery in relation to time since fire over a period of 18 years. Plant species richness was higher in burnt compared to unburnt plots in the year of the fire, but not in the year after. This suggests that fire has a positive short-term effect on plant diversity. Bird species richness and abundance were lower on burnt compared to unburnt plots in the year of the fire, but not in the year after. Over a period of 18 years, high fire frequency led to an increase in herb cover and a decrease in grass cover. We show that the effects on biodiversity are taxon- and species-specific. Fire management strategies in temperate wetlands should consider fire frequency as a key driving force of vegetation structure, with carry-over effects on higher trophic levels. Designing fire refuges, i.e., areas that do not burn annually, might locally be necessary to maintain high species richness.
Waldökosysteme unterliegen vielfältigen Einflüssen wie forstlicher Bewirtschaftung, Stickstoffdeposition, Veränderung des Grundwasserspiegels oder der Einwanderung invasiver Arten. Die Wiederholung historischer Vegetationsaufnahmen ist ein wichtiges Mittel, um Veränderungen der Pflanzengesellschaften zu dokumentieren und mögliche Hauptursachen (Treiber) zu bestimmen. Wir haben 2015 den Vegetationswandel auf 140 semi-permanenten Plots in Wirtschaftswäldern der Elbtalniederung im Nordostdeutschen Tiefland (Sachsen-Anhalt, Brandenburg) untersucht. Die Erstaufnahme erfolgte von 1956 bis 1963. Die Vegetationsaufnahmen decken ein fast einzigartig breites Spektrum unterschiedlicher Waldstandorte ab, das von Feuchtwäldern (Au-, Bruch- und Moorwäldern des Alnion incanae, Alnion glutinosae und Betulion pubescentis) über bodensaure Eichen-Mischwälder (Quercion roboris) bis hin zu bodensauren, meist trockenen Kiefernwäldern mit unterschiedlicher Nährstoffausstattung (Dicrano-Pinion) reicht.
Die Veränderungen der Vegetation haben wir mit Hilfe von Bestandesdaten, Gewinner- und Verliererarten, der α- und β -Diversität sowie der Ellenberg-Zeigerwerte für Stickstoff, Reaktion, Feuchte und Licht analysiert. Dabei wurden, anders als in den meisten bisherigen Wiederholungsuntersuchungen, auch Flächen berücksichtigt, auf denen bis zur Zweitaufnahme ein vollständiger Bestandeswechsel stattgefunden hatte.
Insbesondere in den Feuchtwäldern und den bodensauren Wäldern mit mäßig guter Nährstoffversorgung sind Wechsel der Hauptbaumarten zu verzeichnen; außerdem wurden viele Kiefernbestände zwischenzeitlich neu begründet. Die Artenzahl hat insgesamt und in fast allen Waldtypen abgenommen, die β-Diversität ist jedoch unverändert geblieben bzw. hat sich erhöht. Die Zeigerwerte deuten auf eine Abnahme der Bodenfeuchte in den Au-, Bruch-, und Moorwäldern hin, während insbesondere die bodensauren Kiefernwälder dunkler, nährstoffreicher und feuchter geworden sind. Die Anzahl der Verlierer-Arten ist mehr als doppelt so hoch wie die der Gewinner-Arten, jedoch mit unterschiedlicher Entwicklung in den einzelnen Waldtypen. Insbesondere die nassen und feuchten Wälder, die bodensauren Eichen-Mischwälder und die Flechten-Kiefernwälder haben die meisten ihrer charakteristischen Arten verloren.
Veränderungen der Vegetation in den Feuchtwäldern gehen v. a. auf lokal gesunkene Grundwasserspiegel und eine dadurch gestiegene Nährstoffverfügbarkeit zurück; die Artenzusammensetzung der Auwälder wurde zudem sehr stark durch forstliche Eingriffe beeinflusst. Ursachen für den Trend zu feuchteren und nährstoffreicheren Bedingungen in ehemals trockenen bodensauren Kiefern- und Eichenwäldern sind Stickstoffeinträge sowie eine Sukzession nach Aufgabe historischer Waldnutzungs-formen (Streunutzung, Waldweide). Obwohl sich die einzelnen Waldtypen unterschiedlich entwickelt haben, sind Eutrophierung, sinkende Grundwasserspiegel und Waldbaumaßnahmen insgesamt die wichtigsten Ursachen für die beobachteten Vegetationsveränderungen. Forstliche Eingriffe wie Kahlschlag und Bestandesumbau mit Baumartenwechsel sind zugleich die Hauptursache dafür, dass es trotz Nivellierung des Standortsgradienten, gemessen an der β-Diversität, nicht zu einer Homogenisierung der Vegetation gekommen ist.
Predictions on displacement of suitable habitats due to climate change suggest that plant species with poor colonization ability may be unable to move fast enough to match forecasted climate-induced changes in habitat distribution. However, studies on early Holocene plant migration show fast migration of many plant species that are poor colonizers today. We hypothesize that warmer temperatures during the early Holocene yielded higher seed quality, contributing to explaining the fast migration. We studied how the 3 seed quality variables, seed mass, germinability, and requirements for break of seed dormancy, vary for seeds of 11 forest herb species with varying colonization capacity collected along a 1400-km latitudinal gradient. Within species, seed mass showed a positive correlation with latitude, whereas germinability was more positively correlated with temperature (growing degree hours obtained at time of seed collection). Only slow-colonizing species increased germinability with temperature, whereas only fast-colonizing species increased germinability with latitude. These interactions were only detectable when analyzing germinability of the seeds, even though this trait and seed mass were correlated. The requirement for dormancy break did not correlate with latitude or temperature. The results indicate that seed development of slow colonizers may be favoured by a warmer climate, which in turn may be important for their migration capacity.
Global warming has created a need for studies along climatic gradients to assess the effects of temperature on ecological processes. Altitudinal and latitudinal gradients are often used as such, usually in combination with air temperature data from the closest weather station recorded at 1.52 m above the ground. However, many ecological processes occur in, at, or right above the soil surface. To evaluate how representative the commonly used weather station data are for the microclimate relevant for soil surface biota, we compared weather station temperatures for an altitudinal (500900 m a.s.l.) and a latitudinal gradient (4968 degrees N) with data obtained by temperature sensors placed right below the soil surface at five sites along these gradients. The mean annual temperatures obtained from weather stations and adjusted using a lapse rate of -5.5 degrees C km-1 were between 3.8 degrees C lower and 1.6 degrees C higher than those recorded by the temperature sensors at the soil surface, depending on the position along the gradients. The monthly mean temperatures were up to 10 degrees C warmer or 5 degrees C colder at the soil surface. The within-site variation in accumulated temperature was as high as would be expected from a 300 m change in altitude or from a 4 degrees change in latitude or a climate change scenario corresponding to warming of 1.63.8 degrees C. Thus, these differences introduced by the decoupling are significant from a climate change perspective, and the results demonstrate the need for incorporating microclimatic variation when conducting studies along altitudinal or latitudinal gradients. We emphasize the need for using relevant temperature data in climate impact studies and further call for more studies describing the soil surface microclimate, which is crucial for much of the biota.
Die in Deutschland gegenwärtig durch Nährstoffeinträge und ausbleibenden Nährstoffentzug stark im Rückgang begriffenen Flechten-Kiefernwälder werden als Biotoptyp wie auch als Lebensraumtyp "Mitteleuropäische Flechten-Kiefernwälder" (Code 91T0) diskutiert. Die bisherige, sehr uneinheitliche Differenzierung von Flechten-Kiefernwäldern auf der Ebene von Biotoptypen wird dargestellt. Auf der Grundlage neuerer vegetationskundlicher übersichten werden Vorschläge für eine einheitliche Abgrenzung des Biotoptyps "Flechten-Kiefernwald" und des Lebensraumtyps 91T0 unterbreitet. Im niedersächsischen Naturwaldreservat "Kaarßer Sandberge" (Niedersachsen) wurde die Anwendung des Konzeptes erfolgreich erprobt. Nicht nur hier, sondern auch deutschlandweit wird der Rückgang der Erdflechten in den Kieferwäldern zugunsten von Drahtschmiele und/ oder pleurokarpen Moosen deutlich. Nach der derzeitigen Definition des Lebensraumtyps 91T0 besteht auf der Grundlage der FFH-Richtlinie nicht für alle Flechten-Kiefernwälder eine Chance der Verbesserung. Der Ausschluss von außerhalb des natürlichen Verbreitungsgebietes der Wald-Kiefer gelegenen sowie von durch Aufforstung angepflanzten Beständen bringt Probleme mit sich, die diskutiert werden. Für den Erhalt und die Wiederherstellung der größtenteils nutzungsbedingt entstandenen Flechten-Kiefernwälder sind praktikable Pflegemaßnahmen notwendig, die im Rahmen von Streunutzungsversuchen erprobt werden müssen.