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The prevention of biodiversity loss in agricultural landscapes to protect ecosystem stability and functions is of major importance to stabilize overall diversity. Intense agriculture leads to a loss in species richness and homogenization of species pools, but the processes behind are poorly understood due to a lack of systematic case studies: The specific impacts by agriculture in contrast to other land-use creating open habitat are not studied as such landscapes hardly exist in temperate regions. Applying systematic grids, we compared the plant species distribution at the landscape scale between an active military training areas in Europe and an adjacent rather intensively used agricultural landscape. As the study areas differ mainly in the type of disturbance regime (agricultural vs. non-agricultural), differences in species pattern can be traced back more or less directly to the management. Species trait analyses and multiple measures of beta diversity were applied to differentiate between species similarities between plots, distance-decay, or nestedness. Contrary to our expectation, overall beta diversity in the agricultural area was not reduced but increased under agricultural. This was probably the result of species nestedness due to fragmentation. The natural process of increasing dissimilarity with distance (distance-decay) was suppressed by intense agricultural land-use, generalist and long-distance dispersers gained importance, while rare species lost continuity. There are two independent processes that need to be addressed separately to halt biodiversity loss in agricultural land. There is a need to conserve semi-natural open habitat patches of diverse size to favor poor dispersers and specialist species. At the same time, we stress the importance of mediating biotic homogenization caused by the decrease of distance-decay: The spread of long-distance dispersers in agricultural fields may be acceptable, however, optimized fertilizer input and erosion control are needed to stop the homogenization of environmental gradients due to nitrogen input into semi-natural habitat. [ABSTRACT FROM AUTHOR]

Climate projections propose that drought stress will become challenging for establishing trees. The magnitude of stress is dependent on tree species, provenance, and most likely also highly influenced by soil quality. European Beech ( Fagus sylvatica) is of major ecological and economical importance in Central European forests. The species has an especially wide physiological and ecological amplitude enabling growth under various soil conditions within its distribution area in Central Europe. We studied the effects of extreme drought on beech saplings (second year) of four climatically distinct provenances growing on different soils (sandy loam and loamy sand) in a full factorial pot experiment. Foliar δ13C, δ15N, C, and N as well as above- and belowground growth parameters served as measures for stress level and plant growth. Low-quality soil enhanced the effect of drought compared with qualitatively better soil for the above- and belowground growth parameters, but foliar δ13C values revealed that plant stress was still remarkable in loamy soil. For beeches of one provenance, negative sandy soil effects were clearly smaller than for the others, whereas for another provenance drought effects in sandy soil were sometimes fatal. Foliar δ15N was correlated with plant size during the experiment. Plasticity of beech provenances in their reaction to drought versus control conditions varied clearly. Although a general trend of declining growth under control or drought conditions in sandy soil was found compared to loamy soil, the magnitude of the effect of soil quality was highly provenance specific. Provenances seemed to show adaptations not only to drought but also to soil quality. Accordingly, scientists should integrate information about climatic pre-adaptation and soil quality within the home range of populations for species distribution modeling and foresters should evaluate soil quality and climatic parameters when choosing donor populations for reforestation projects. [ABSTRACT FROM AUTHOR]

Aims: Lowland meadow irrigation used to be a widespread management practice to improve hay yield in Central European grasslands. Recently, traditional meadow irrigation is being re-established in some parts of Europe. Nevertheless, the consequences of the regular artificial flooding on vegetation of these water meadows remain poorly understood. We studied the impact of flood irrigation on the plant functional and species composition of extensively managed hay meadows. Location: Lowland of River Queich, between Landau and Lustadt, Germany. Methods: We sampled vegetation in 34 meadows that differed in irrigation status (irrigated/non-irrigated) and fertilization (unfertilized/fertilized). Plants were classified into functional groups according to growth forms, N-fixing ability and reproductive strategy. Effects of meadow irrigation on the plant functional composition were analysed using two complementary approaches. In the 'community approach', we analysed total cover of each functional group per meadow with respect to irrigation and fertilization. In the 'species approach', we analysed the mean response to irrigation among the species within the defined functional groups. Results: Total cover of rosettes and semi-rosettes increased relative to graminoids in irrigatedmeadows. Cover of legumes was three times higher in irrigated compared to non-irrigated meadows. Irrigation enhanced preferences for seed and vegetative reproduction. However, the response of individual species within the functional groups was inconsistent. Fertilization had an overall minor influence on functional composition of the meadows. Conclusions: The higher proportion of plants with basal growth organs in irrigated meadows suggests that irrigation may enhance a more complex vertical structure of the vegetation. Enhancement of rosettes, semi-rosettes and legumes at the cost of graminoids through irrigation was more significant in the community than in the species approach, indicating that the functional group response was amplified by the respective dominant species. This highlights the importance of considering species-level interactions in functional vegetation analysis. [ABSTRACT FROM AUTHOR]

The invasion success of plants into new regions and ecosystems is assumed to depend on certain constellations of species traits. Often, effective sexual reproduction and the generation of high performance genotypes allow invaders to rapidly colonize even unfavourable sites by demonstrating high plasticity. Interspecific hybridisation, can produce such high performance genotypes, which may serve as an evolutionary stepping stone for invaders of limited genetic variability. A very aggressive invader with particularly limited genetic variability is the Japanese Knotweed ( Fallopia japonica ). Hybridisation with the Giant Knotweed Fallopia sachalinensis in recent years, however, has created the hybrid Bohemian Knotweed ( Fallopia × bohemica ) presenting new opportunities for the species complex. An accelerated invasion process could be the result. We assessed whether or not different taxa of the F. japonica species complex would exhibit different growth potential depending on site conditions. After taxon identification for over 100 samples using genetic markers (microsatellite DNA), we combined the data with observations on Fallopia stand growth, horizontal spreading behaviour, flowering and seed set in relation to different environmental site conditions across an ecologically diverse region in Germany (Rhineland Palatinate). The majority of the samples were interspecific hybrids, which is an outstanding finding compared to earlier studies. The hybrids were genetically diverse exhibiting a high number of multilocus genotypes, suggesting that sexual reproduction is a major strategy for generating new genotypes and for dispersal. Hybrids that were closely related to F. japonica exhibited the highest potential for aggressive growth in terms of horizontal spreading and reduction of competitor plants within stands. Site conditions, especially N-supply, contributed to the aggressive growth found but were less relevant than taxonomic characteristics. Moreover, several hybrids set a lot of seeds that germinated very well. We demonstrated that hybridisation is able to generate new high performance genotypes and enables the taxa to accelerate and increase the invasion potential. Our study provides new insights into the invasiveness of alien plants in general and for the taxa F. japonica s. l. in particular. [ABSTRACT FROM AUTHOR]

Species that frequently regenerate sexually after fire were not found in soil seed banks of previous studies in south-eastern Spain (Province of Murcia) and this led to the idea of studying seed longevity in the species concerned. A seed burial field experiment was carried out over a period of 30 months to examine the seed longevity of eight species that mainly reproduce sexually during early postfire succession. In addition, longevity was determined for seeds stored at room temperature and the results were compared to those obtained for buried seeds. Seeds of the study species showed very different patterns of persistence. Water-impermeable seeds of Cistus albidus, Cistus clusii, Fumana laevipes, Convolvulus lanuginosus and Calicotome intermedia survived at least 1 year of burial in high numbers. However, seeds of Calicotome intermedia did not survive a second year, and only approximately 20% of the Fumana laevipes and Convolvulus lanuginosus seeds were alive after 30 months of burial. The longevity of buried water-permeable seeds of Asterolinum linum-stellatum, Teucrium pseudochamaepitys and Stipa tenacissima did not exceed 2 years. When buried for 30 months in a coastal and a mountain population site, the number of viable seeds of Convolvulus lanuginosus and Stipa tenacissima did not differ significantly between the two sites. Seeds of most species showed better survival under room temperature than under burial conditions. We concluded that the seed longevity of some species in soil might have previously been overestimated. [ABSTRACT FROM AUTHOR]

Abstract: Species of Mediterranean vegetation are known to regenerate directly after fire. The phenomenon of autosuccession (direct regeneration) has been found to be often combined with an increase of species richness during the first years after fire due to the high abundance of short-lived herbaceous plants facilitated by plentiful nutrients and light. The high degree of vegetation resilience, which is expressed in terms of autosuccession, has been explained by the selective pressure of fire in historic times. According to existing palaeoecological data, however, the Pinus halepensis forests in the Ricote Mountains (Province of Murcia, SE Spain) did not experience substantial fire impact before the presence of man nor are they especially fire-prone today. Therefore, we studied post-fire regeneration to find out if direct succession is present or if species from pre-fire vegetation are absent during the post-fire regeneration stages. Patterns of succession were deduced from observations made in sample plots on sites of a known regeneration age as well as in adjacent unburnt areas. The results of the vegetation analyses, including a Detrended Correspondence Analysis, indicate that Pinus halepensis forest regeneration after fire resembles autosuccession. As regards the presence of woody species, there is a high percentage similarity on north (83%) and south (70%) facing slopes during the first year after fire vs. reference areas which is due, for example, to direct regeneration of the resprouting Quercus coccifera or seeders like Pinus halepensis or Fumana laevipes. However, if herbaceous species are included in the comparison, the similarity on north-facing sites decreases (to 53%) with the presence of additional species, mainly ruderals like Anagallis arvensis or Reseda phyteuma, and even woody species on the burnt plots. This effect indicates “enhanced autosuccession”, which was not found on south-facing sites where overall species richness was very high irrespective of the impact of fire. Locally we found limited regeneration of some species, for example Pinus halepensis at high altitudes (1000 m), even 22 years after fire. As we assume that historical fires did not play an important role in the area and direct succession is present nevertheless, our results support the theory that autosuccession is not a process restricted to fire-prone areas. Fire has been only one of several selective forces since human settlement that probably led to a set of species pre-adapted against recurrent disturbance. [Copyright &y& Elsevier]

Seminatural grasslands provide habitats for various species and are important for biodiversity conservation. The understanding of the diverse responses of species and traits to different grassland management methods is therefore urgently needed. We disentangled the role of grassland management (fertilization and irrigation), vegetation structure (biomass, sward height) and plant quality (protein and fiber content) for Orthoptera communities in lowland hay meadows in Germany. We found vegetation structure to be the most important environmental category in explaining community structure of Orthoptera (species richness, total individuals, functional diversity and species composition). Intensively used meadows (fertilized, irrigated, high plant biomass) were characterized by assemblages with few species, low functional diversity, and low conservation value. Thereby, the relatively moderate fertilizer inputs in our study system of up to ∼75 kg N/ha/year reduced functional diversity of Orthoptera, while this negative effect of fertilization was not detectable when solely considering taxonomic aspects. We found strong support for a prominent role of plant quality in shaping Orthoptera communities and especially the trait composition. Our findings demonstrate the usefulness of considering both taxonomic and functional components (functional diversity) in biodiversity research and we suggest a stronger involvement of plant quality measures in Orthoptera studies. [ABSTRACT FROM AUTHOR]

The highly invasive Fallopia complex ( Fallopia japonica s.l., Fallopia japonica var. japonica, Fallopia sachalinensis and the hybrid Fallopia × bohemica) is known to spread primarily vegetatively by rhizomes and stem fragments in its adventive range. Sexual reproduction has rarely been shown in Europe, despite a high production of germinable seeds. To elucidate this contradiction the aim of the present study was to determine which environmental conditions prevent seed germination or seedling establishment. Several laboratory experiments were conducted focusing on water and light supply as well as the influence of frost. According to morphological and cytological analyses of the parental plants paired with morphological analyses of the seedlings, the seeds used for these experiments were assumed to belong predominantly to the hybrid Fallopia × bohemica. Laboratory experiments revealed that seedling establishment is hampered by severe drought or strong late frost, which are, however, rare events in the study region and could not be crucial in explaining the rarity of seedlings in the field. We discuss the possible role of weather conditions that might lead to a loss of seeds or seedlings under field conditions and include a comparison of several other cited studies carried out in the adventive range of Fallopia japonica s.l. that observed either the presence or the absence of Fallopia seedlings in the field. [ABSTRACT FROM AUTHOR]

The species in the Japanese knotweed complex ( Fallopia japonica s.l. and its hybrids) are among the most invasive plants on earth. Their expansion and reproduction in the introduced range have been mostly due to vegetative reproduction, but observations of low seedling numbers and hybridization processes exist. Knowledge of factors affecting germination characteristics is essential if the risk of sexual reproduction is to be assessed, and its impact on the ability of the species to spread and adapt to different environments. This study aims to examine the germination success of Fallopia japonica s.l. seeds of different ages, quality, and storage conditions. Irrespective of age and even after natural overwintering in the soil, seeds germinated quite well (48-79%). Ungerminated seeds collected in autumn of 2008 were characterized by a low weight/length ratio ( W/ L), low nutrient concentrations, and a greenish tepal coloration. These differences may be due to alternative male taxa participating in the pollination process. Spring collected seeds were subject to strong predation by birds. In contrast to the high germination observed under laboratory conditions, seed germination or early establishment in the field was inhibited and only a few seedlings were observed. Although the factors that inhibit the establishment of mature seeds in the field remain unknown, there is a clear risk that sexual reproduction could gain importance in the future as a result of changing environmental conditions or genetic adaptation. Not only would this facilitate expansive dispersal by wind, but it might also increase the potential for further adaptation of the species complex. [ABSTRACT FROM AUTHOR]

Large, infrequent fires (LIFs) can have substantial impacts on both ecosystems and the economy. To better understand LIFs and to better predict the effects of human management and climate change on their occurrence, we must first determine the factors that produce them. Here, we review local and regional literature investigating the drivers of LIFs. The emerging conceptual model proposes that ecosystems can be typified based on climatic conditions that determine both fuel moisture and fuel amount. The concept distinguishes three ecosystem types: (1) biomass-rich, rarely dry ecosystems where fuel moisture rather than fuel amount limits LIFs; (2) biomass-poor, at least seasonally dry ecosystems where fuel amount rather than fuel moisture limits LIFs; and (3) biomass-poor, rarely dry ecosystems where both fuel amount and fuel moisture limit the occurrence of LIFs. Our main goal in this paper is to discuss the drivers of LIFs and the three mentioned ecosystem types in a global context. Further, we will discuss the drivers that are not included within the ‘fuels’ versus ‘climate’ discussion. Finally, we will address the question: what kinds of additional information are needed if models predicting LIFs are to be coupled with global climate models? As with all generalizations, there are local deviations and modifications due to processes such as disturbance interaction or human impact. These processes tend to obscure the general patterns of the occurrence of LIFs and are likely to cause much of the observed controversy and confusion in the literature. [ABSTRACT FROM AUTHOR]

Aim: Distribution ranges of temperate tree species are shifting poleward and upslope into cooler environments due to global warming. Successful regeneration is crucial for population persistence and range expansion. Thus, we aimed to identify environmental variables that affect germination and seedling establishment of Europe's dominant forest tree, to compare the importance of plasticity and genetic variation for regeneration, and to evaluate the regeneration potential at and beyond the southern and northern distribution margins. Location: Europe. Time period: 2016–2018. Major taxa studied: European beech (Fagus sylvatica (L.)). Methods: We investigated how germination, establishment and juvenile survival change across a reciprocal transplantation experiment using over 9,000 seeds of beech from 7 populations from its southern to its northern distribution range margins. Results: Germination and establishment at the seedling stage were highly plastic in response to environmental conditions. Germination success increased with warmer and declined with colder air temperature, whereas establishment and survival were hampered under warmer and drier conditions. Germination differed among populations and was positively influenced by seed weight. However, there was no evidence of local adaptation in any trait. Main conclusions: The high plasticity in the early life‐history traits found irrespective of seed origin may allow for short‐term acclimatization. However, our results also indicate that this plasticity might not be sufficient to ensure the regeneration of beech in the future due to the low survival found under dry and hot conditions. The future climatic conditions in parts of the distribution centre and at the rear edge might thus become limiting for natural regeneration, as the likelihood of extreme heat and drought events will increase. By contrast, at the cold distribution margin, the high plasticity in the early life‐history traits may allow for increasing germination success with increasing temperatures and may thus facilitate natural regeneration in the future. [ABSTRACT FROM AUTHOR]

Climate extremes are expected to increase in frequency and magnitude as a consequence of global warming, threatening the functioning, services and goods of forest ecosystems. Across Europe, the ecologically and economically important tree species Fagus sylvatica is expected to suffer particularly under such conditions. The regional introduction of provenances from drier and warmer climates is one option to adapt beech forest ecosystems to these adverse effects of climate change. Marginal populations from the drought-prone southern and north-eastern edges of the species' distribution come into focus in search of suitable candidates for Central European deciduous forests. Here, we test three marginal provenances (Spain, Bulgaria and Poland) and three provenances from the centre of the distribution range (Germany) for their response to drought in two different soil types (sand, loam) in a full factorial common garden experiment in Landau, Germany. Drought impacted all growth parameters negatively (leaf damage +22 % (percentage points), height −40 % and diameter increment −41 %), and the sandy substrate exacerbated this effect. However, provenances differed in their response to drought and soil type. Evidence for a local adaptation to summer drought was detected, especially in terms of mortality rates. The Bulgarian and Spanish provenance showed a stable performance under drought conditions (BG −27 % in diameter increment; ES −32 %), compared to the Polish (−48 %) or the most sensitive German provenances (−57 %), yet for Bulgaria on a low level of total increment. This may indicate a trade-off between drought tolerance and growth. Therefore, a sole focus on drought-resistant marginal provenances seems to not be conducive, as they might be less adapted to other climatic factors, e.g. frost, as well. However, intermixed with local Central European provenances, these may act as functional insurance in future drought-prone forest stands. [ABSTRACT FROM AUTHOR]