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The nutrient concentration in seeds determines many aspects of potential success of the sexual reproductive phase of plants, including the seed predation probability, efficiency of seed dispersal and seedling performance. Despite considerable research interest in latitudinal gradients of foliar nutrients, a similar gradient for seeds remains unexplored. We investigated a potential latitudinal gradient in seed nutrient concentrations within the widespread European understorey forest herb Anemone nemorosa L. We sampled seeds of A. nemorosa in 15 populations along a 1900-km long latitudinal gradient at three to seven seed collection dates post-anthesis and investigated the relative effects of growing degree-hours > 5 degrees C, soil characteristics and latitude on seed nutrient concentrations. Seed nitrogen, nitrogen:phosphorus ratio and calcium concentration decreased towards northern latitudes, while carbon:nitrogen ratios increased. When taking differences in growing degree-hours and measured soil characteristics into account and only considering the most mature seeds, the latitudinal decline remained particularly significant for seed nitrogen concentration. We argue that the decline in seed nitrogen concentration can be attributed to northward decreasing seed provisioning due to lower soil nitrogen availability or greater investment in clonal reproduction. This pattern may have large implications for the reproductive performance of this forest herb as the degree of seed provisioning ultimately co-determines seedling survival and reproductive success.
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.
We measured LHS traits in 41 Anemone nemorosa and 44 Milium effusum populations along a 1900-2300 km latitudinal gradient from N France to N Sweden. We then applied multilevel models to identify the effects of regional (temperature, latitude) and local (soil fertility and acidity, overstorey canopy cover) environmental factors on LHS traits.
Both species displayed a significant 4% increase in plant height with every degree northward shift (almost a two-fold plant height difference between the southernmost and northernmost populations). Neither seed mass nor SLA showed a significant latitudinal cline. Temperature had a large effect on the three LHS traits of Anemone. Latitude, canopy cover and soil nutrients were related to the SLA and plant height of Milium. None of the investigated variables appeared to be related to the seed mass of Milium.
The variation in LHS traits indicates that the ecological strategy determined by the position of each population in this three-factor triangle is not constant along the latitudinal gradient. The significant increase in plant height suggests greater competitive abilities for both species in the northernmost populations. We also found that the studied environmental factors affected the LHS traits of the two species on various scales: spring-flowering Anemone was affected more by temperature, whereas early-summer flowering Milium was affected more by local and other latitude-related factors. Finally, previously reported cross-species correlations between LHS traits and latitude were generally unsupported by our within-species approach.
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.
Atmospheric nitrogen deposition on petals enhances seed quality of the forest herb Anemone nemorosa
(2018)
Elevated atmospheric input of nitrogen (N) is currently affecting plant biodiversity and ecosystem functioning. The growth and survival of numerous plant species is known to respond strongly to N fertilisation. Yet, few studies have assessed the effects of N deposition on seed quality and reproductive performance, which is an important life-history stage of plants. Here we address this knowledge gap by assessing the effects of atmospheric N deposition on seed quality of the ancient forest herb Anemone nemorosa using two complementary approaches. By taking advantage of the wide spatiotemporal variation in N deposition rates in pan-European temperate and boreal forests over 2years, we detected positive effects of N deposition on the N concentration (percentage N per unit seed mass, increased from 2.8% to 4.1%) and N content (total N mass per seed more than doubled) of A.nemorosa seeds. In a complementary experiment, we applied ammonium nitrate to aboveground plant tissues and the soil surface to determine whether dissolved N sources in precipitation could be incorporated into seeds. Although the addition of N to leaves and the soil surface had no effect, a concentrated N solution applied to petals during anthesis resulted in increased seed mass, seed N concentration and N content. Our results demonstrate that N deposition on the petals enhances bioaccumulation of N in the seeds of A.nemorosa. Enhanced atmospheric inputs of N can thus not only affect growth and population dynamics via root or canopy uptake, but can also influence seed quality and reproduction via intake through the inflorescences.
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.
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.
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.
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.
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.
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.
In einem rund 2.200 ha großen Waldgebiet bei Magdeburgerforth (Fläming, Sachsen-Anhalt) wurden 1948 bis 1950 von Harro Passarge 120 Vegetationsaufnahmen sowie eine Vegetationskartierung erstellt. Das Gebiet zeichnet sich durch eine große Vielfalt an Waldtypen aus den Verbänden Agrostio-Quercion petraeae, Alnion glutinosae, Alnion incanae, Carpinion betuli, Dicrano-Pinion und Quercion roboris aus. Daher und weil viele der heute in Wäldern wirksamen Prozesse (z. B. Stickstoffeintrag,
Klimawandel) vor 60 Jahren noch nicht spürbar waren, bietet sich das Gebiet für eine Wiederholungsuntersuchung besonders an. Da die Aufnahmeflächen von Passarge nicht punktgenau verortet waren, wurden im Jahr 2014 in einem über die Forstabteilungen und die Vegetationskarte definierten Suchraum immer die der Erstaufnahme ähnlichsten Waldbestände erfasst. Insgesamt konnten 97 (81 %) der Aufnahmen wiederholt werden. Vegetationsveränderungen werden mithilfe einer NMDS-Ordination, der Gegenüberstellung von α -Diversität, Zeigerwerten und Waldbindungskategorien für die beiden
Aufnahmezeitpunkte sowie über die Identifikation von Gewinner- und Verlierer-Arten analysiert.
Auch wenn methodenbedingt bei der Wiederholungsuntersuchung nur die jeweils geringstmögliche
Vegetationsveränderung abgebildet wird, konnten Ergebnisse erzielt werden, die mit denen quasi permanenter Plots übereinstimmen. Die beobachteten allgemeinen Trends (Eutrophierung, Sukzession nach Nutzungswandel, Verlust lichtliebender und magerkeitszeigender Arten, Ausbreitung von stickstoffliebenden Arten und mesophilen Waldarten, Einwanderung von Neophyten, keine generelle Abnahme der Artenzahl) stimmen gut mit den in zahlreichen Studien aus mitteleuropäischen Wäldern festgestellten überein. Durch das von nassen bis trockenen sowie von bodensauer-nährstoffarmen bis zu relativ basenreichen Böden reichende Standortsspektrum innerhalb des Untersuchungsgebietes konnte aber – deutlicher als in den meisten bisherigen Fallstudien – gezeigt werden, dass sich die Resilienz der
Wälder gegenüber Vegetationsveränderung je nach Ausgangsgesellschaft stark unterscheidet und jeweils unterschiedliche Treiber wirksam sind. Stellario-Carpinetum und Luzulo-Quercetum erwiesen
sich als relativ stabil, und auch in den Feuchtwäldern des Circaeo-Alnetum gab es trotz eines Artenwechsels wenig Hinweise auf Umweltveränderungen. Dagegen wiesen die Wälder nährstoffarmer Standorte (Sphagno-Alnetum, Betulo-Quercetum, Dicrano-Pinion) viele Verliererarten und eine starke Eutrophierungstendenz auf. Die in besonderem Maße von historischen Waldnutzungsformen abhängigen thermophilen Wälder und die Flechten-Kiefernwälder gingen weitgehend verloren.
In einem rund 2.200 ha großen Waldgebiet bei Magdeburgerforth (Fläming, Sachsen-Anhalt) wur-den 1948 bis 1950 von Harro Passarge 120 Vegetationsaufnahmen sowie eine Vegetationskartierung erstellt. Das Gebiet zeichnet sich durch eine große Vielfalt an Waldtypen aus den Verbänden Agrostio-Quercion petraeae, Alnion glutinosae, Alnion incanae, Carpinion betuli, Dicrano-Pinion und Quercion roboris aus. Daher und weil viele der heute in Wäldern wirksamen Prozesse (z. B. Stickstoffeintrag, Klimawandel) vor 60 Jahren noch nicht spürbar waren, bietet sich das Gebiet für eine Wiederholungs-untersuchung besonders an. Da die Aufnahmeflächen von Passarge nicht punktgenau verortet waren, wurden im Jahr 2014 in einem über die Forstabteilungen und die Vegetationskarte definierten Such-raum immer die der Erstaufnahme ähnlichsten Waldbestände erfasst. Insgesamt konnten 97 (81 %) der Aufnahmen wiederholt werden. Vegetationsveränderungen werden mithilfe einer NMDS-Ordination, der Gegenüberstellung von α-Diversität, Zeigerwerten und Waldbindungskategorien für die beiden Aufnahmezeitpunkte sowie über die Identifikation von Gewinner- und Verlierer-Arten analysiert.Auch wenn methodenbedingt bei der Wiederholungsuntersuchung nur die jeweils geringstmögliche Vegetationsveränderung abgebildet wird, konnten Ergebnisse erzielt werden, die mit denen quasi-permanenter Plots übereinstimmen. Die beobachteten allgemeinen Trends (Eutrophierung, Sukzession nach Nutzungswandel, Verlust lichtliebender und magerkeitszeigender Arten, Ausbreitung von stick-stoffliebenden Arten und mesophilen Waldarten, Einwanderung von Neophyten, keine generelle Ab-nahme der Artenzahl) stimmen gut mit den in zahlreichen Studien aus mitteleuropäischen Wäldern festgestellten überein. Durch das von nassen bis trockenen sowie von bodensauer-nährstoffarmen bis zu relativ basenreichen Böden reichende Standortsspektrum innerhalb des Untersuchungsgebietes konnte aber – deutlicher als in den meisten bisherigen Fallstudien – gezeigt werden, dass sich die Resilienz der Wälder gegenüber Vegetationsveränderung je nach Ausgangsgesellschaft stark unterscheidet und jeweils unterschiedliche Treiber wirksam sind. Stellario-Carpinetum und Luzulo-Quercetum erwiesen sich als relativ stabil, und auch in den Feuchtwäldern des Circaeo-Alnetum gab es trotz eines Arten-wechsels wenig Hinweise auf Umweltveränderungen. Dagegen wiesen die Wälder nährstoffarmer Standorte (Sphagno-Alnetum, Betulo-Quercetum, Dicrano-Pinion) viele Verliererarten und eine starke Eutrophierungstendenz auf. Die in besonderem Maße von historischen Waldnutzungsformen abhängi-gen thermophilen Wälder und die Flechten-Kiefernwälder gingen weitgehend verloren.
Changing temperature and precipitation can strongly influence plant reproduction. However, also biotic interactions might indirectly affect the reproduction and recruitment success of plants in the context of climate change. Information about the interactive effects of changes in abiotic and biotic factors is essential, but still largely lacking, to better understand the potential effects of a changing climate on plant populations. Here we analyze the regeneration from seeds of Acer platanoides and Acer pseudoplatanus, two currently secondary forest tree species from seven regions along a 2200 km-wide latitudinal gradient in Europe. We assessed the germination, seedling survival and growth during two years in a common garden experiment where temperature, precipitation and competition with the understory vegetation were manipulated. A. platanoides was more sensitive to changes in biotic conditions while A. pseudoplatanus was affected by both abiotic and biotic changes. In general, competition reduced (in A. platanoides) and warming enhanced (in A. pseudoplatanus) germination and survival, respectively. Reduced competition strongly increased the growth of A. platanoides seedlings. Seedling responses were independent of the conditions experienced by the mother tree during seed production and maturation. Our results indicate that, due to the negative effects of competition on the regeneration of A. platanoides, it is likely that under stronger competition (projected under future climatic conditions) this species will be negatively affected in terms of germination, survival and seedling biomass. Climate-change experiments including both abiotic and biotic factors constitute a key step forward to better understand the response of tree species' regeneration to climate change. (C) 2015 Elsevier B.V. All rights reserved.
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 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.
Global biodiversity is affected by numerous environmental drivers. Yet, the extent to which global environmental changes contribute to changes in local diversity is poorly understood. We investigated biodiversity changes in a meta-analysis of 39 resurvey studies in European temperate forests (3988 vegetation records in total, 17-75years between the two surveys) by assessing the importance of (i) coarse-resolution (i.e., among sites) vs. fine-resolution (i.e., within sites) environmental differences and (ii) changing environmental conditions between surveys. Our results clarify the mechanisms underlying the direction and magnitude of local-scale biodiversity changes. While not detecting any net local diversity loss, we observed considerable among-site variation, partly explained by temporal changes in light availability (a local driver) and density of large herbivores (a regional driver). Furthermore, strong evidence was found that presurvey levels of nitrogen deposition determined subsequent diversity changes. We conclude that models forecasting future biodiversity changes should consider coarse-resolution environmental changes, account for differences in baseline environmental conditions and for local changes in fine-resolution environmental conditions.