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  • 1.
    Bienau, Miriam J.
    et al.
    Justus-Liebig University, Giessen, Germany.
    Hattermann, Dirk
    University of Marburg, Marburg, Germany.
    Kroencke, Michael
    University of Applied Sciences Bremen, Bremen, Germany.
    Kretz, Lena
    Justus-Liebig University, Giessen, Germany.
    Otte, Annette
    Justus-Liebig University, Giessen, Germany.
    Eiserhardt, Wolf L.
    Norwegian University of Science and Technology, Trondheim, Norway.
    Milbau, Ann
    Umea University.
    Graae, Bente J.
    Norwegian University of Science and Technology, Trondheim, Norway.
    Durka, Walter
    Helmholtz Centre for Environmental Research UFZ, Halle (Saale), Germany.
    Eckstein, Rolf Lutz
    Justus-Liebig University, Giessen, Germany.
    Snow cover consistently affects growth and reproduction of Empetrum hermaphroditum across latitudinal and local climatic gradients2014In: Alpine Botany, ISSN 1664-2201, E-ISSN 1664-221X, Vol. 124, no 2, p. 115-129Article in journal (Refereed)
    Abstract [en]

    Arctic ecosystems face strong changes in snow conditions due to global warming. In contrast to habitat specialists, species occupying a wide range of microhabitats under different snow conditions may better cope with such changes. We studied how growth and reproduction of the dominant dwarf shrub Empetrum hermaphroditum varied among three habitat types differing in winter snow depth and summer irradiation, and whether the observed patterns were consistent along a local climatic gradient (sub-continental vs. sub-oceanic climates) and along a latitudinal gradient (northern Sweden vs. central Norway). Habitat type explained most of the variation in growth and reproduction. Shoots from shallow snow cover and high summer irradiation habitats had higher numbers of flowers and fruits, lower ramet heights, shorter shoot segments, lower numbers of lateral shoots and total biomass but higher leaf density and higher relative leaf allocation than shoots from habitats with higher snow depth and lower summer irradiation. In addition, biomass, leaf allocation and leaf life expectancy were strongly affected by latitude, whereas local climate had strong effects on seed number and seed mass. Empetrum showed high phenotypic trait variation, with a consistent match between local habitat conditions and its growth and reproduction. Although study areas varied strongly with respect to latitude and local climatic conditions, response patterns of growth and reproduction to habitats with different environmental conditions were consistent. Large elasticity of traits suggests that Empetrum may have the potential to cope with changing snow conditions expected in the course of climate change.

  • 2.
    Bryngelsson, Christine
    Karlstad University, Faculty of Health, Science and Technology (starting 2013).
    Diversitet av kärlväxter och mossor längs en markfuktighetsgradient2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Old forests are rich in diversity and house large numbers of plant, animal and insect species. Clear-cutting and ditching are common forestry practices in Scandinavia used to increase timber yield and production. This is done at a cost as there is often a turnover and a decrease in biodiversity as a result. Ditching reduces water levels, decreases the size of riparian zones and sometimes even dries out wetlands. Habitat change and disturbance affect the whole ecosystem, from small specialized micro-organisms to that of large grazers. The purpose of my study was to investigate the diversity of plants and mosses along a moisture gradient to identify if there is any pattern in diversity. Observations took place along the stream bank of Almarskogen, northeast of Karlstad in April, 2016. The gradient in the forest was divided into three separate categories ranging from moist soil, through an intermediate section to dry soil in the forest. A total of nine transects with three sample areas of two squaremeters each. An analysis of variance was calculated based on the effective number of species applied to Shannon-Wiener index (H´) for each sample plot. No significant difference was found, hence plant and mosses were analyzed separately, showing significance among the categories of vascularplants (P<0,05). The prediction; that the largest diversity will be found in the intermediate category was not supported by the data. For further analysis, Ellenbergs indicator values for moist was applied. No significance was shown, but the average Ellenberg value for the different species showed a pattern along a gradient from moist soils to slightly drier soils. 

  • 3.
    Burmeier, Sandra
    et al.
    Justus-Liebig-University Giessen, Germany.
    Donath, Tobias W.
    Justus Liebig University Giessen, Germany.
    Otte, Annette
    Justus-Liebig-University Giessen, Germany.
    Eckstein, Rolf Lutz
    Justus-Liebig-University Giessen, Germany.
    Rapid burial has differential effects on germination and emergence of small- and large-seeded herbaceous plant species2010In: Seed Science Research, ISSN 0960-2585, E-ISSN 1475-2735, Vol. 20, no 3, p. 189-200Article in journal (Refereed)
    Abstract [en]

    The dynamics of many plant populations essentially depend upon seed and seedling stages, and a persistent seed bank may give species an opportunity to disperse through time. Seed burial is a decisive prelude to persistence and may strongly influence seed-bank dynamics. The fate of buried seeds depends on species-specific traits, environmental conditions and possibly also burial mode. We tested seed germination, seedling emergence and growth of the co-occurring herbaceous flood-meadow species Arabis nemorensis, Galium wirtgenii, Inula salicina, Sanguisorba officinalis and Selinum carvifolia in response to the experimental manipulation of burial depth (0, 1, 2, 4, 8, 12 cm) and substrate type (sand, clay). Increasing burial depth led to decreased germination, emergence and growth in all species studied, and seedling growth differed significantly between substrate types. The responses of species differed on an individual basis, but also showed a higher-ranking pattern based on seed size. Larger-seeded species were able to emerge from greater depths and experienced less depth-mediated growth inhibition than smaller-seeded species, which, in turn, had higher survival rates during burial and were less likely to experience fatal germination. Based on these results, we suggest that herbaceous flood-meadow species have developed two different seed-size based strategies for coping with the extreme recruitment conditions prevailing in flood meadows, the balance of which seems to be maintained by disturbance events.

  • 4.
    Burmeier, Sandra
    et al.
    Justus-Liebig-University, Giessen, Germany.
    Eckstein, Rolf Lutz
    Justus-Liebig-University Giessen, Germany.
    Donath, Tobias W.
    Justus-Liebig-University, Giessen, Germany.
    Otte, Annette
    Justus-Liebig-University Giessen, Germany.
    Plant Pattern Development during Early Post-Restoration Succession in Grasslands-A Case Study of Arabis nemorensis2011In: Restoration Ecology, ISSN 1061-2971, E-ISSN 1526-100X, Vol. 19, no 5, p. 648-659Article in journal (Refereed)
    Abstract [en]

    The main objective of this study was to analyze whether plant material transfer is a suitable approach for establishing plant populations with spatial patterns and population structures resembling those of remnant populations. We studied pattern formation and population characteristics in three remnant and two restored populations of the biennial plant species Arabis nemorensis in the upper Rhine valley in southwestern Germany over a period of 2 years. We investigated spatial patterns of seedlings, juveniles, and adults as well as the small-scale horizontal and vertical distribution of seeds in the soil, followed the fate of individual plants and recorded structural habitat parameters such as vegetation and litter cover. Population dynamics differed between the study sites, but there was no pronounced difference between restored and remnant sites. Seedlings, juveniles, and adults as well as seeds in the seed bank showed aggregated spatial patterns on all study sites, with positive autocorrelation on a scale of 20-60 cm. Within sites, patterns remained approximately stable through time. Restored sites experienced rapid seed bank formation as a result of the restoration measures. Our results suggest that the restoration measures were not only successful in transferring the target species but also triggered rapid formation of spatially structured populations that, years after restoration, closely resembled those of remnant sites.

  • 5.
    Burmeier, Sandra
    et al.
    Justus-Liebig-University Giessen, Germany.
    Eckstein, Rolf Lutz
    Justus-Liebig-University Giessen, Germany.
    Otte, Annette
    Justus-Liebig-University Giessen, Germany.
    Donath, Tobias W.
    Desiccation cracks act as natural seed traps in flood-meadow systems2010In: Plant and Soil, ISSN 0032-079X, E-ISSN 1573-5036, Vol. 333, no 1-2, p. 351-364Article in journal (Refereed)
    Abstract [en]

    Desiccation cracks are a natural phenomenon of clay-rich soils that form via soil shrinkage during dry conditions. Our aim was to test the seed trapping potential of such cracks and assess its impact on seed bank formation in a flood-meadow ecosystem. We documented crack patterns on permanent plots and analysed the soil seed content along and adjacent to cracks. Seed translocation via cracks was tested with a mark-recapture experiment, and post-entrapment seed fate was tested with a burial experiment. Most cracks re-opened in the same positions in consecutive dry periods. Along cracks, most seeds were found in 10-20 cm depth, whereas adjacent to cracks most seeds were found in 0-5 cm depth. The majority of seeds found in shallow depths adjacent to cracks belonged to species that were also present in the above-ground vegetation, whereas this rate was always under 50% along desiccation cracks. The mark-recapture experiment gave evidence for vertical seed translocation through desiccation cracks. Post-entrapment seed fate differed between species and burial depth, with a trend towards increasing survival with increasing depth. We conclude that desiccation cracks act as natural seed traps, foster seed bank formation and thus influence plant community dynamics in flood meadow systems.

  • 6.
    Burmeier, Sandra
    et al.
    Justus-Liebig-University Giessen, Germany.
    Eckstein, Rolf Lutz
    Justus-Liebig-University Giessen, Germany.
    Otte, Annette
    Justus-Liebig-University, Giessen, Germany.
    Donath, Tobias W.
    Justus-Liebig-University Giessen, Germany.
    Spatially-restricted plant material application creates colonization initials for flood-meadow restoration2011In: Biological Conservation, ISSN 0006-3207, E-ISSN 1873-2917, Vol. 144, no 1, p. 212-219Article in journal (Refereed)
    Abstract [en]

    Plant material transfer is a well-established technique for overcoming dispersal limitation during grassland restoration. As restoration sites are frequently more abundant than donor sites, the plant material is often applied as patches or strips, with the assumption that these will act as colonization initials from which transferred species will spread and eventually cover the entire sites. Our aim was to test this assumption and to evaluate whether it is feasible to restore entire sites by spatially-restricted plant material application in a flood-meadow ecosystem. We established transverse transects consisting of eight 2 x 2 m plots on five plant material strips 7-8 years after plant material application. We monitored the above-ground vegetation development, analyzed the seed rain and determined the composition of the soil seed bank, i.e. we compared three different components of the emerging flood-meadow community. Transferred species were present in all three community components studied, and 88.6% of the 79 species we found in total had already spread from the plant material strips and colonized their surroundings. Detected dispersal distances differed between community components, and the share of colonizers was highest for the above-ground vegetation and lowest for the soil seed bank. We conclude that plant material transfer is a suitable technique for restoring flood-meadows as transferred species not only establish on the sites supplied with plant material, but also colonize their surroundings. (C) 2010 Elsevier Ltd. All rights reserved.

  • 7.
    Böddi, Bela
    et al.
    Department of Plant Physiology, Eötvös Lóránd University, Budapest.
    Mc Ewen, Birgitta
    Botaniska institutionen, Göteborgs universitet.
    Ryberg, Margaretha
    Botaniska institutionen, Göteborgs universitet.
    Sundqvist, Christer
    Botaniska institutionen, Göteborgs universitet.
    Short-wavelength protochlorophyllide forms and their phototransformation in epicotyl of pea (Pisum sativum)1995In: Photosynthesis: From light to biosphere. Vol III / [ed] Mathis, P, Dortrecht: Kluwer Academic Publishers, 1995, p. 949-952Conference paper (Refereed)
  • 8. Cafaro, Philip
    et al.
    Butler, Tom
    Crist, Eileen
    Cryer, Paul
    Dinerstein, Eric
    Kopnina, Helen
    Noss, Reed
    Piccolo, John
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Taylor, Bron
    Vynne, Carly
    Washington, Haydn
    If we want a whole Earth, Nature Needs Half: a response to Buscher et al.2017In: Oryx, ISSN 0030-6053, E-ISSN 1365-3008, Vol. 51, no 3, p. 400-400Article in journal (Refereed)
  • 9. De Frenne, Pieter
    et al.
    Coomes, David A.
    De Schrijver, An
    Staelens, Jeroen
    Alexander, Jake M.
    Bernhardt-Roemermann, Markus
    Brunet, Jorg
    Chabrerie, Olivier
    Chiarucci, Alessandro
    den Ouden, Jan
    Eckstein, Rolf Lutz
    Justus-Liebig-University, Giessen, Germany.
    Graae, Bente J.
    Gruwez, Robert
    Hedl, Radim
    Hermy, Martin
    Kolb, Annette
    Marell, Anders
    Mullender, Samantha M.
    Olsen, Siri L.
    Orczewska, Anna
    Peterken, George
    Petrik, Petr
    Plue, Jan
    Simonson, William D.
    Tomescu, Cezar V.
    Vangansbeke, Pieter
    Verstraeten, Gorik
    Vesterdal, Lars
    Wulf, Monika
    Verheyen, Kris
    Plant movements and climate warming: intraspecific variation in growth responses to nonlocal soils2014In: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 202, no 2, p. 431-441Article in journal (Refereed)
    Abstract [en]

    Most range shift predictions focus on the dispersal phase of the colonization process. Because moving populations experience increasingly dissimilar nonclimatic environmental conditions as they track climate warming, it is also critical to test how individuals originating from contrasting thermal environments can establish in nonlocal sites. We assess the intraspecific variation in growth responses to nonlocal soils by planting a widespread grass of deciduous forests (Milium effusum) into an experimental common garden using combinations of seeds and soil sampled in 22 sites across its distributional range, and reflecting movement scenarios of up to 1600km. Furthermore, to determine temperature and forest-structural effects, the plants and soils were experimentally warmed and shaded. We found significantly positive effects of the difference between the temperature of the sites of seed and soil collection on growth and seedling emergence rates. Migrant plants might thus encounter increasingly favourable soil conditions while tracking the isotherms towards currently colder' soils. These effects persisted under experimental warming. Rising temperatures and light availability generally enhanced plant performance. Our results suggest that abiotic and biotic soil characteristics can shape climate change-driven plant movements by affecting growth of nonlocal migrants, a mechanism which should be integrated into predictions of future range shifts.

  • 10.
    Donath, T. W.
    et al.
    Justus-Liebig University, Giessen, Germany.
    Eckstein, Rolf Lutz
    Justus-Liebig-University Giessen, Germany.
    Litter effects on seedling establishment interact with seed position and earthworm activity2012In: Plant Biology, ISSN 1435-8603, E-ISSN 1438-8677, Vol. 14, no 1, p. 163-170Article in journal (Refereed)
    Abstract [en]

    Seedling establishment is influenced by litter cover and by seed predators, but little is known about interactions between these two factors. We tested their effects on emergence of five typical grassland species in a microcosm experiment. We manipulated the amounts of grass litter, seed sowing position and earthworm activity to determine whether: (i) the protective effect of litter against seed predation depends on cover amount and seed sowing position, i.e., on top or beneath litter; (ii) seed transport by earthworms changes the effect of seed sowing position on seedling emergence; and (iii) seeds transported into deeper soil layers by earthworms are still germinable. Litter cover and presence of earthworms lowered seedling emergence. The impact of seed position increased with seed size. Emergence of large-seeded species was reduced when sown on the surface. Additionally, we found an important seed position x earthworm interaction related to seed size. Emergence of large-seeded species sown on top of the litter was up to three times higher when earthworms were present than without earthworms. Earthworms also significantly altered the depth distribution of seeds in the soil and across treatments: on average 6% of seeds germinated after burial. In contrast to the seed position effect, we found no size effect on mobility and germinability of seeds after burial in the soil. Nevertheless, the fate of different-sized seeds may differ. While burial will remove large seeds from the regeneration pool, it may enhance seed bank build up in small-seeded species. Consequently, changes in the amount of litter cover and the invertebrate community play a significant role in plant community composition.

  • 11.
    Donath, Tobias W.
    et al.
    Justus-Liebig-University Giessen, Germany.
    Eckstein, Rolf Lutz
    Justus-Liebig-University Giessen, Germany.
    Effects of bryophytes and grass litter on seedling emergence vary by vertical seed position and seed size2010In: Plant Ecology, ISSN 1385-0237, E-ISSN 1573-5052, Vol. 207, no 2, p. 257-268Article in journal (Refereed)
    Abstract [en]

    Establishment of plants through seeds is often constrained by the quality of microsites, which is in part controlled by the nature and amount of ground cover. The latter consists of living shoots of vascular plants or bryophytes and/or the dead remains of the dominant species. In the present article, we report the results of a controlled pot experiment with five species characteristic of floodplain grasslands. We manipulated the amounts of grass litter and/or mosses to study (1) differences between ground cover types with respect to their effects on microenvironment and seedling emergence and (2) how these effects interact with seed size and seed sowing position. Increasing amounts of both cover types led to increasing soil humidity, whereas temperature amplitude and illumination were decreased. However, since grass litter decomposed much faster than bryophytes, light conditions for germination under grass litter improved considerably with time. Although seedling emergence varied significantly between species, ground cover types and cover amounts, seed position alone explained about 50% of the variation in the data set. Additionally, we found an important interaction between seed size, seed position and cover type: large-seeded species showed a fitness advantage when seeds were situated beneath a cover, irrespective of cover type, which disappeared when seeds were shed on top of a cover layer. We suggest that this interaction may be ecologically and evolutionarily relevant because it may lead to changes in species composition and diversity of plant communities as a consequence of changes in the amount and type of ground cover.

  • 12.
    Donath, Tobias W.
    et al.
    Justus-Liebig-University Giessen, Germany.
    Eckstein, Rolf Lutz
    Justus-Liebig-University Giessen, Germany.
    Grass and oak litter exert different effects on seedling emergence of herbaceous perennials from grasslands and woodlands2008In: Journal of Ecology, ISSN 0022-0477, E-ISSN 1365-2745, Vol. 96, no 2, p. 272-280Article in journal (Refereed)
    Abstract [en]

    1. The effects of litter on seedling emergence (e.g. during succession from grassland to woodland) may not only depend on litter amount and environmental conditions but may also be related to litter types. We tested the effect of litter types, litter cover and soil moisture on the emergence of four congeneric pairs of grassland and woodland species. 2. We carried out a controlled pot experiment (Experiment I) using litter and species from two habitats (grassland vs. woodland), three levels of litter cover (low, medium, high) and two levels of water-addition (leading to constantly humid or intermittently dry substrate). Amounts of litter were adjusted to result in the same relative light reduction for both litter types. Consequently, we applied 2 g, 4 g and 8 g of grassland litter and 0.5 g, 1 g and 2 g of woodland (oak) litter per pot. 3. To separate the shade effect of litter from its mechanical plus chemical effects we exposed additional pots with seeds of the same species to deep shade conditions (Experiment II) corresponding to 4 g and 1 g of grass and oak litter, respectively. 4. Under intermittently dry conditions both litter types increased seedling emergence. In addition, we found a significant interaction between litter type and species origin: seedling emergence of woodland species was significantly lower from beneath grass litter than from beneath oak litter, whereas grassland species emerged equally well from beneath both litter types. Compared with seed germination under a shade cloth, seedling emergence of woodland species from beneath grass litter was reduced by 44%. Litter significantly affected soil humidity and the amplitude of diurnal temperature fluctuations. Differential effects of litter types on woodland and grassland species are probably related to litter structure. 5. Synthesis. Our experimental data present evidence that ecosystem specific litter effects slow down succession from grassland to woodland and that the effect size is controlled by the litter amount present and the environmental conditions.

  • 13.
    Drechsler, Michal
    Karlstad University, Faculty of Technology and Science.
    Syror och baser i gymnasieskolan2012In: Skola och naturvetenskap: - politik, praktik, problematik i belysning av ämnesdidaktisk forskning / [ed] Helge Strömdahl & Lena Tibell, Lund, 2012Chapter in book (Other academic)
  • 14.
    Eckstein, Rolf Lutz
    Justus-Liebig-University Giessen, Germany.
    Differential effects of interspecific interactions and water availability on survival, growth and fecundity of three congeneric grassland herbs2005In: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 166, no 2, p. 525-536Article in journal (Refereed)
    Abstract [en]

    Fitness of individual plants and of populations depends on the rates of survival, growth and fecundity. This study tested whether vital rates were differentially affected by biotic interactions and water availability. The effects of manipulations of above-ground competition (through clipping) and water availability (through water addition) on the vital rates of seedlings of three species (Viola elatior Fries, Viola pumila Chaix and Viola stagnina Kit.) were analysed in dry, mesic and wet grasslands. Water addition and grassland type had the largest effects on survival (accounting for 41 and 24% of total variation, respectively) across species. Height growth rate was positively affected by grassland type (19%) and water addition (12%) and varied among species (8%), while leaf accumulation rates and reproduction were affected by grassland type and clipping. The data suggested facilitative effects of the canopy on seedling survival in the dry grassland. This study presents evidence that environmental conditions and biotic interactions may have differential effects on seedling survival, growth and reproduction. The findings highlight the complex interplay between spatial and temporal environmental variation and biotic interactions in structuring plant communities.

  • 15.
    Eckstein, Rolf Lutz
    Uppsala University.
    Nitrogen retention by Hylocomium splendens in a subarctic birch woodland2000In: Journal of Ecology, ISSN 0022-0477, E-ISSN 1365-2745, Vol. 88, no 3, p. 506-515Article in journal (Refereed)
  • 16.
    Eckstein, Rolf Lutz
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences. Uppsala University.
    Danihelka, J
    Masaryk University, Czech republic.
    Holzel, N
    Justus-Liebig-University Giessen, Germany.
    Otte, A
    Justus-Liebig-University Giessen, Germany.
    The effects of management and environmental variation on population stage structure in three river-corridor violets2004In: Acta Oecologica, ISSN 1146-609X, E-ISSN 1873-6238, Vol. 25, no 1-2, p. 83-91Article in journal (Refereed)
  • 17.
    Eckstein, Rolf Lutz
    et al.
    Justus-Liebig-University Giessen, Germany.
    Danihelka, Jiri
    Czech republic.
    Otte, Annette
    Variation in life-cycle between three rare and endangered floodplain violets in two regions: implications for population viability and conservation2009In: Biologia (Bratislava), ISSN 0006-3088, E-ISSN 1336-9563, Vol. 64, no 1, p. 69-80Article in journal (Refereed)
    Abstract [en]

    We studied the demography of Viola elatior, V. pumila, and V. stagnina, three rare and endangered Central European floodplain species, to (i) analyse variation in life-cycles among congeners and between regions (Dyje-Morava floodplains, Czech Republic; Upper Rhine, Germany), (ii) to define sensitive stages in the life-cycles, and (iii) to identify possible threats for population viability and species conservation. Matrix models were based on the fate of marked individuals from a total of 27 populations over two years. We analysed population growth rate (lambda), stage distribution, net reproductive rate (R (0)), generation time, age at first reproduction, and elasticity and calculated a life table response experiment (LTRE). Most populations were declining and lambda did not differ between species or regions during the observed interval. Despite higher probabilities for survival and flowering in the Dyje populations, R (0) was higher in the Rhine populations. Also other demographic traits showed consistent differences between regions and/or species. Complex life-cycles and large variation in lambda precluded unequivocal identification of sensitive stages or vital rates for conservation. Variation between regions may be a consequence of differences in habitat quality. Our results suggest that deterministic processes such as reduced management, succession, habitat destruction, and lack of disturbance through reduced or eliminated flooding present the strongest threat for the viability and persistence of populations of the three floodplain violets as compared with stochastic processes. However, the persistent seed bank of the species may buffer populations against environmental variation and represents a reservoir for recovery after resumption of suitable land-use management.

  • 18.
    Eckstein, Rolf Lutz
    et al.
    Justus-Liebig-University Giessen, Germany.
    Donath, T W
    Justus-Liebig-University Giessen, Germany.
    Interactions between litter and water availability affect seedling emergence in four familial pairs of floodplain species2005In: Journal of Ecology, ISSN 0022-0477, E-ISSN 1365-2745, Vol. 93, no 4, p. 807-816Article in journal (Refereed)
    Abstract [en]

    We studied seedling emergence in four familial pairs of floodplain herbs in response to the experimental manipulation of soil moisture and litter cover to analyse (i) whether the effect of litter changes from negative under humid to positive under dry conditions, and (ii) whether the response to changing water and light conditions with increasing litter cover varies among species and plant families. We carried out a controlled pot experiment using four levels of litter cover (0 g, 2 g, 4 g and 8 g litter per pot, corresponding to 0 kg m(-2), 0.2 kg m(-2), 0.4 kg m(-2) and 0.8 kg m(-2)) and two levels of water-addition, leading to constantly humid substrate or intermittently dry topsoil. Across water-additions, percentage emergence reached a peak at low levels of litter cover (0.2 kg m(-2) and 0.4 kg m(-2)). There was a significant litter x water-addition interaction in six species, with positive effects of litter under intermittently dry conditions and negative or neutral effects under constantly humid conditions. Litter lowered maximum temperature as well as amplitude, and alleviated soil humidity under low water supply, while imposing increasingly shaded conditions. Analysis of species- and family-specific responses suggested that germination under a litter cover of 0.8 kg m(-2) was significantly reduced in smaller-seeded species (i.e. those that tend to have higher light demands for germination). Our results suggest that transfer of seed-containing plant litter can aid restoration projects if applied at 0.2-0.4 kg m(-2). Below these levels, establishment of most species may be inhibited by drought, while higher amounts will increasingly suppress seedling emergence, especially of small-seeded species. In addition to facilitation effects observed between living plants, dead plant remains may also exert positive effects on establishment. The sign of the litter effect on seedling emergence depends on soil humidity, with negative effects seen above a threshold amount, which is species- and family-specific and is closely related to seed size. Whether positive litter effects in grasslands are a consequence of coevolution remains to be examined.

  • 19.
    Eckstein, Rolf Lutz
    et al.
    Justus-Liebig-University Giessen, Germany.
    Hoelzel, Norbert
    Justus-Liebig-University Giessen, Germany.
    Danihelka, Jiri
    Czech Republic.
    Biological flora of central Europe: Viola elatior, V. pumila and V. stagnina2006In: Perspectives in plant ecology, evolution and systematics, ISSN 1433-8319, E-ISSN 1618-0437, Vol. 8, no 1, p. 45-66Article, review/survey (Refereed)
    Abstract [en]

    Viola elatior, V pumila and V stagnina (syn. V persicifolia) are very rare in central and western Europe and red-listed in many central European countries. To improve their conservation and to base management efforts on sound scientific knowledge, we here review the available information on their biology. A comparative approach is adopted to identify similarities and differences between the species. Special emphasis will be on taxonomy, community ecology and population biology. All three species belong to the section Viola, subsection Rostratae. Since they are morphologically rather similar and have often been misidentified, we supply the most important characters for separating the three taxa. The species share a continental distribution with a centre of occurrence in the temperate zone of eastern Europe and western Siberia, and reach their western range margin in central and western Europe. They have become rare and endangered through melioration and fragmentation of their habitats. All three species are iteroparous hemicryptophytes with a complex life cycle, a mixed mating system with chasmogamous and cleistogamous flowers, and a persistent seed bank. Viola pumila and V. stagnina occur in floodplain meadows and wet grasslands, whereas V. elatior is a typical species of alluvial woodland fringes and other ecotonal habitats bordering floodplain meadows. Viola elatior and V pumila are confined to calcareous or at least base-rich substrates, whereas V stagnina may also occur on strongly acidic soils. The violets are able to occupy a broad range of site conditions in terms of soil nutrient status and productivity. However, on fertile sites the species depend on regular disturbances that weaken competitors and enhance the germination of dormant seeds. Current information about mycorrhizal colonisation, biochemical and physiological data, and herbivores and pathogens is scarce or lacking, probably due to the rarity of the three species in central Europe. (c) 2006 Rubel Foundation, ETH Zurich. Published by Elsevier GmbH. All rights reserved.

  • 20.
    Eckstein, Rolf Lutz
    et al.
    Uppsala University.
    Karlsson, P S
    Uppsala University.
    Variation in nitrogen-use efficiency among and within subarctic graminoids and herbs2001In: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 150, no 3, p. 641-651Article in journal (Refereed)
  • 21.
    Eckstein, Rolf Lutz
    et al.
    Uppsala University.
    Karlsson, P S
    Uppsala University.
    Weih, M
    Uppsala University.
    Leaf life span and nutrient resorption as determinants of plant nutrient conservation in temperate-arctic regions1999In: New phytologist, Vol. 143, no 1, p. 177-189Article in journal (Refereed)
  • 22.
    Eckstein, Rolf Lutz
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences. Uppsala University.
    Karlsson, P S
    Uppsala University.
    Weih, M
    Uppsala University.
    The significance of resorption of leaf resources for shoot growth in evergreen and deciduous woody plants from a subarctic environment1998In: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 81, no 3, p. 567-575Article in journal (Refereed)
  • 23.
    Eckstein, Rolf Lutz
    et al.
    Uppsala University.
    Karlsson, P. Staffan
    Abisko Scientific Research Station.
    The effect of reproduction on nitrogen use-efficiency of three species of the carnivorous genus Pinguicula2001In: Journal of Ecology, ISSN 0022-0477, E-ISSN 1365-2745, Vol. 89, no 5, p. 798-806Article in journal (Refereed)
    Abstract [en]

    Life history theory predicts that reproduction incurs costs in terms of future growth and survival. In infertile environments reproductive events may accelerate nutrient turnover such that losses of limiting nutrients cannot be replenished by uptake from the soil. 

    We compared the effect of reproduction on nitrogen (N) turnover and N use-efficiency, i.e. the annual dry matter produced per unit N lost, of three carnivorous species of the genus Pinguicula on an infertile subarctic heath. We hypothesized that reproduction should increase N turnover, unless a larger N pool or improved N resorption can compensate for the losses associated with reproduction.

    These carnivorous herbs showed a nitrogen use strategy similar to that of non-carnivorous plants (herbs and grasses) with a relatively low mean residence time (MRT) of N and a large dry matter productivity per unit N in the plant (annual N productivity). N pool size and the efficiency of N resorption from senescent leaves were similar in reproductive and non-reproductive individuals. Reproductive individuals had significantly larger annual N losses and thus a lower average MRT (0.8 vs. 1.8 years), with values < 1 indicating that the annual N losses are greater than the annual average N pool. Unless plants can enhance their nutrient acquisition, flowering may therefore impact on future growth and survival.

    This study presents evidence for a direct link between reproduction, reflected in a higher relative allocation to inflorescences, turnover and N use-efficiency; the latter being reduced because of increased N turnover. The ranking of species in terms of reproductive allocation was the reverse of their ranking in terms of their N use-efficiency.

  • 24.
    Eckstein, Rolf Lutz
    et al.
    Justus-Liebig-University Giessen, Germany.
    O'Neill, R. A.
    Justus-Liebig-University Giessen, Germany.
    Danihelka, J.
    Justus-Liebig-University Giessen, Germany.
    Otte, A.
    Justus-Liebig-University Giessen, Germany.
    Koehler, W.
    Justus-Liebig-University Giessen, Germany.
    Genetic structure among and within peripheral and central populations of three endangered floodplain violets2006In: Molecular Ecology, ISSN 0962-1083, E-ISSN 1365-294X, Vol. 15, no 9, p. 2367-2379Article in journal (Refereed)
    Abstract [en]

    Understanding the partitioning of genetic variance in peripheral and central populations may shed more light on the effects of genetic drift and gene flow on population genetic structure and, thereby, improve attempts to conserve genetic diversity. We analysed genetic structure of peripheral and central populations of three insect-pollinated violets (Viola elatior, Viola pumila, Viola stagnina) to evaluate to what extent these patterns can be explained by gene flow and genetic drift. Amplified fragment length polymorphism was used to analyse 930 individuals of 50 populations. Consistent with theoretical predictions, peripheral populations were smaller and more isolated, differentiation was stronger, and genetic diversity and gene flow lower in peripheral populations of V. pumila and V. stagnina. In V. elatior, probably historic fragmentation effects linked to its specific habitat type were superimposed on the plant geographic (peripheral-central) patterns, resulting in lower relative importance of gene flow in central populations. Genetic variation between regions (3-6%), among (30-37%) and within populations (60-64%) was significant. Peripheral populations lacked markers that were rare and localized in central populations. Loss of widespread markers in peripheral V. stagnina populations indicated genetic erosion. Autocorrelation within populations was statistically significant up to a distance of 10-20 m. Higher average genetic similarity in peripheral populations than in central ones indicated higher local gene flow, probably owing to management practices. Peripheral populations contributed significantly to genetic variation and contained unique markers, which made them valuable for the conservation of genetic diversity.

  • 25.
    Eckstein, Rolf Lutz
    et al.
    Justus-Liebig-University Giessen.
    Otte, A
    Justus-Liebig-University Giessen.
    Effects of cleistogamy and pollen source on seed production and offspring performance in three endangered violets2005In: Basic and Applied Ecology, ISSN 1439-1791, E-ISSN 1618-0089, Vol. 6, no 4, p. 339-350Article in journal (Refereed)
    Abstract [en]

    In rare plants that often occur in small or isolated populations the probability of selfing between close relatives is increased as a consequence of demographic stochasticity. The mode of pollination (selfing, outcrossing) may have considerable effects on seed traits and offspring performance and hence potential viability. Since current efforts aiming at the restoration of floodplain grasslands through the transfer of plant material from species-rich source stands may lead to the establishment of initially small populations consisting of founders from different populations, the present paper experimentally investigated the effects of pollen source and floral types (i.e. chasmogamous (CH) and cleistogamous (CL) flowers) on seed traits and offspring performance in three highly endangered violet species (Viola elatior, V. pumila, V. stagnina) of these grasslands. We estimated inbreeding depression and tested the performance of selfed and outcrossed offspring in two microbial environments, i.e. in soil inoculated with (i) non-sterile substrate from the same species ('home'-conditions) and (ii) sterilised substrate. Plants produced more CL capsules than CH flowers. Pollinator exclusion had only small effects on CH seed production. CL seeds had a significantly lower mass per seed than CH seeds. This may be related to constraints in allocation or environmental conditions. Seedling growth was reduced in plants grown under 'home'-conditions as compared to control soils. Under 'home'-conditions, relative fitness of selfed seedlings of V. stagnina was significantly higher than that of crossed progeny. Our results suggest that high genetic differentiation among populations as a consequence of isolation may result in outbreeding depression, e.g., through biochemical or physiological incompatibilities between genes or the breaking of coadapted gene complexes. In V. stagnina, offspring fitness differed considerably between environments, but in general we found no indications for inbreeding depression in these rare species. (c) 2005 Gesellschaft fur Okologie. Published by Elsevier GmbH. All rights reserved.

  • 26.
    Eckstein, Rolf Lutz
    et al.
    Justus-Liebig-University Giessen.
    Otte, Annette
    Justus-Liebig-University Giessen.
    Evidence for consistent trait-habitat relations in two closely related violets of contiguous habitat types from a fertilisation experiment2004In: Flora: Morphologie, Geobotanik, Oekophysiologie, ISSN 0367-2530, E-ISSN 1618-0585, Vol. 199, no 3, p. 234-246Article in journal (Refereed)
    Abstract [en]

    Most studies on the adaptive significance of plant traits compared species that differed in inherent growth rate or species of habitats at the extremes of environmental gradients. In the present paper, we compared the response of Viola elatior and V. pumila, two closely related and morphologically similar violets to the experimental variation of nitrogen availability. The species occur in adjacent habitat types, viz. alluvial forest fringes (V. elatior) and floodplain meadows (V. pumila), that differ in resource availability and disturbance across a relatively small gradient. We tested the hypotheses that, according to their typical habitat, V. elatior should show more traits of a stress tolerant competitive plant, while V. pumila should exhibit more ruderal traits. We carried out a two-year common garden experiment with two levels of fertiliser addition (N5, 5 g N m(-2) yr(-1); N20, 20 g N m(-2) yr(-1)), and analysed a number of traits related to relative growth rate (RGR), allocation, and nutrient use. We further did an experiment with seeds from the experimental plants to study variation in germination rate. We found considerable ontogenetic drift in the species during two years of growth. In the first year, both species showed similar mass and growth rate but these were achieved through different trait combinations. In the second year, V. elatior had a higher RGR, produced more biomass per unit nutrient and developed more leaf area per unit plant mass than V. pumila, while the latter produced thinner leaves. V. pumila had a higher capacity for nutrient acquisition, but a large proportion of the captured nutrients were used for reproduction. Germination rate was higher in V. pumila than in V. elatior, independent of the nutrient status of the mother plant, while seeds of V. elatior from N20 plants had a significantly higher germination rate (67%) than seeds from N5 plants (35%). Our data suggested that many of the analysed trait differences seem to be consistent with the requirements of the different habitat types.

  • 27.
    Eckstein, Rolf Lutz
    et al.
    Justus-Liebig-University Giessen, Germany.
    Pereira, Eva
    Justus-Liebig-University, Giessen, Germany.
    Milbau, Ann
    Justus-Liebig-University, Giessen, Germany.
    Graae, Bente Jessen
    Justus-Liebig-University, Giessen, Germany.
    Predicted changes in vegetation structure affect the susceptibility to invasion of bryophyte-dominated subarctic heath2011In: Annals of Botany, ISSN 0305-7364, E-ISSN 1095-8290, Vol. 108, no 1, p. 177-183Article in journal (Refereed)
    Abstract [en]

    Background and Aims A meta-analysis of global change experiments in arctic tundra sites suggests that plant productivity and the cover of shrubs, grasses and dead plant material (i.e. litter) will increase and the cover of bryophytes will decrease in response to higher air temperatures. However, little is known about which effects these changes in vegetation structure will have on seedling recruitment of species and invasibility of arctic ecosystems. Methods A field experiment was done in a bryophyte-dominated, species-rich subarctic heath by manipulating the cover of bryophytes and litter in a factorial design. Three phases of seedling recruitment (seedling emergence, summer seedling survival, first-year recruitment) of the grass Anthoxanthum alpinum and the shrub Betula nana were analysed after they were sown into the experimental plots. Key Results Bryophyte and litter removal significantly increased seedling emergence of both species but the effects of manipulations of vegetation structure varied strongly for the later phases of recruitment. Summer survival and first-year recruitment were significantly higher in Anthoxanthum. Although bryophyte removal generally increased summer survival and recruitment, seedlings of Betula showed high mortality in early August on plots where bryophytes had been removed. Conclusions Large species-specific variation and significant effects of experimental manipulations on seedling recruitment suggest that changes in vegetation structure as a consequence of global warming will affect the abundance of grasses and shrubs, the species composition and the susceptibility to invasion of subarctic heath vegetation.

  • 28.
    Eckstein, Rolf Lutz
    et al.
    Justus-Liebig-University Giessen, Germany.
    Ruch, Diana
    Otte, Annette
    Justus-Liebig-University, Giessen, Germany.
    Donath, Tobias W.
    Justus-Liebig University, Giessen, Germany.
    Invasibility of a Nutrient-Poor Pasture through Resident and Non-Resident Herbs Is Controlled by Litter, Gap Size and Propagule Pressure2012In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 7, no 7, article id e41887Article in journal (Refereed)
    Abstract [en]

    Since inference concerning the relative effects of propagule pressure, biotic interactions, site conditions and species traits on the invasibility of plant communities is limited, we carried out a field experiment to study the role of these factors for absolute and relative seedling emergence in three resident and three non-resident confamilial herb species on a nutrient-poor temperate pasture. We set up a factorial field experiment with two levels each of the factors litter cover (0 and 400 g m(-2)), gap size (0.01 and 0.1 m(2)) and propagule pressure (5 and 50 seeds) and documented soil temperature, soil water content and relative light availability. Recruitment was recorded in spring and autumn 2010 and in spring 2011 to cover initial seedling emergence, establishment after summer drought and final establishment after the first winter. Litter alleviated temperature and moisture conditions and had positive effects on proportional and absolute seedling emergence during all phases of recruitment. Large gaps presented competition-free space with high light availability but showed higher temperature amplitudes and lower soil moisture. Proportional and absolute seedling recruitment was significantly higher in large than in small gaps. In contrast, propagule pressure facilitated absolute seedling emergence but had no effects on proportional emergence or the chance for successful colonisation. Despite significantly higher initial seedling emergence of resident than non-resident species, seed mass and other species-specific traits may be better predictors for idiosyncratic variation in seedling establishment than status. Our data support the fluctuating resource hypothesis and demonstrate that the reserve effect of seeds may facilitate seedling emergence. The direct comparison of propagule pressure with other environmental factors showed that propagule pressure affects absolute seedling abundance, which may be crucial for species that depend on other individuals for sexual reproduction. However, propagule batch size did not significantly affect the chance for successful colonisation of disturbed plots.

  • 29.
    Hensgen, Frank
    et al.
    Justus-Liebig-University, Giessen, Germany.
    Albrecht, Christian
    Justus-Liebig-University, Giessen, Germany.
    Donath, Tobias W.
    Justus-Liebig-University Giessen, Germany.
    Otte, Annette
    Justus-Liebig-University Giessen, Germany.
    Eckstein, Rolf Lutz
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences. Justus-Liebig-University Giessen, Germany.
    Distribution of gastropods in floodplain compartments and feeding preferences for river corridor plant species: Is there an effect of gastropod herbivory on the distribution of river corridor plants?2011In: Flora: Morphologie, Geobotanik, Oekophysiologie, ISSN 0367-2530, E-ISSN 1618-0585, Vol. 206, no 6, p. 534-543Article in journal (Refereed)
    Abstract [en]

    Herbivory through gastropods has among others been proposed as a potential factor responsible for the river corridor distribution of plant species, which is a well known but poorly understood ecological pattern. Since floodplains are characterised by seasonally changing abiotic conditions, viz, floods during winter and spring and severe summer drought that are unsuitable for gastropods they may present safe habitats for highly palatable plant species. In the present study we compared species composition of gastropods and vegetation of twelve grassland sites situated within three floodplain compartments along the Upper Rhine. Additionally, we studied the palatability of 7 days and 25 days old seedlings of five typical floodplain plant species and five mesic grassland species to the slug Deroceras reticulatum in laboratory experiments. Our results showed that both vegetation and gastropod community composition but not gastropod diversity and abundance differed between floodplain compartments. Owing to omnivory of most gastropods the similarity structure of sites based on plants and gastropods was not significantly correlated. In general, slug herbivory significantly reduced survival and biomass of 7 days old seedlings, but responses were species-specific. In contrast, with the exception of Arabis nemorensis, Viola pumila and Taraxacum sect. Ruderalia biomass of 25 days old seedlings was not significantly affected by slug herbivory. Although the response of floodplain plant species as a group to slug herbivory did not differ from common grassland species, our results suggest that gastropods may potentially influence the distribution pattern of the highly palatable river corridor species Arabis nemorensis and Viola pumila. However, further research is needed to estimate the damage to river corridor plants through gastropod herbivory and its effect on competitive relationships under natural conditions.

  • 30.
    Huels, Joerg
    et al.
    Justus-Liebig-University Giessen, Germany.
    Otte, Annette
    Justus Liebig University Giessen, Germany.
    Eckstein, R. Lutz
    Justus-Liebig-University Giessen, Germany.
    Population life-cycle and stand structure in dense and open stands of the introduced tall herb Heracleum mantegazzianum2007In: Biological Invasions, ISSN 1387-3547, E-ISSN 1573-1464, Vol. 9, no 7, p. 799-811Article in journal (Refereed)
    Abstract [en]

    Populations of the introduced Heracleum mantegazzianum consist of dense central stands, which gradually give way to open stands towards the margins. To analyse whether open stands are due to unsuitable conditions or represent the invading front for further spread, we studied life-cycle, population dynamics, stand structure and soil conditions of open and dense stands over two transition periods. Populations decreased during the first interval but increased after the extremely dry and warm summer of 2003 during the second interval. Open stands had shorter generation times, lower height, smaller proportions of small individuals and were less in equilibrium with the environment than dense stands. In open stands, growth to higher stages was most important, while in dense stands delayed development (self-loops) had a strong effect on population growth; stasis and fecundity contributed most to the difference in lambda between stand types. By petiole extension H. mantegazzianum may raise its leaves just above the resident vegetation. Therefore, younger stages develop faster in open stands, whereas strong competition by conspecific adults leads to longer generation times and a higher proportion of small individuals in dense stands. Disturbance due to extreme climatic conditions in summer 2003 equalised population dynamics of both stand types. Life-cycle variation between stand types makes it difficult to infer simple management rules. However, our data suggest that small and/or open stands of H. mantegazzianum may eventually serve as initials for further spread after land-use changes, whereas dense stands are stable and may represent sources of propagules.

  • 31.
    Jelk, Caroline
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Skillnader i inomartsvariation i morfologiska karaktärer av Empetrum hermaphroditum mellan habitat2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This study is based on data of a previous study investigating whether snow depth affects average growth and reproduction of Empetrum hermaphroditum over a latitudinal and climatic gradient (Bienau et al. 2014). I tested the effects region and snow depth on intraspecific variation of growth-related variables instead, to clarify whether the species has the potential to cope with changes in snow depth and increased growing season in the future. Earlier research results led to the hypothesis that intraspecific variation depends on resources in the habitat and raises the question of whether there is higher variation in Empetrum in favorable habitats such as birch forests and habitats with deep snow cover than in adverse habitats such as those with a shallow snow cover. My analyses suggest that there were significant differences in variability between habitats in some morphological characters. However, not all of these characters follow the expected pattern that the favorable habitats would have a greater variety. Overall, significant differences were found in variation in the length of the main and the lateral shoots, leaf vitality on the main shoots and the dry weight of the stem. These results imply that the above hypothesis is correct for some growth-related variables. 

  • 32.
    Jung, L. S.
    et al.
    Justus-Liebig-University, Giessen, Germany.
    Eckstein, Rolf Lutz
    Justus-Liebig-University Giessen, Germany.
    Otte, A.
    Justus-Liebig-University, Giessen, Germany.
    Donath, T. W.
    Justus-Liebig University, Giessen, Germany.
    Above- and below-ground nutrient and alkaloid dynamics in Colchicum autumnale: optimal mowing dates for population control or low hay toxicity2012In: Weed research (Print), ISSN 0043-1737, E-ISSN 1365-3180, Vol. 52, no 4, p. 348-357Article in journal (Refereed)
    Abstract [en]

    Jung LS, Eckstein RL, Otte A & Donath TW (2012). Above- and below-ground nutrient and alkaloid dynamics in Colchicum autumnale: indications for optimal mowing dates for population control or low hay toxicity. Weed Research52, 348-357. Summary In some Central European regions, the conservation of seminatural grasslands is jeopardised by management intensification or abandonment, caused by high densities of the toxic weed Colchicum autumnale. We investigated two possibilities to deal with C. autumnale: (i) reducing population densities by mowing when nutrient contents are high in leaves and capsules and low in the storage organs, that is, when the ratio between both is highest, or (ii) reducing alkaloid content in hay by mowing when alkaloid content of leaves and capsules of C. autumnale is low. To identify the optimal mowing point, we analysed the dynamics of nutrients, starch and alkaloids of naturally grown plants in two biogeographical regions. In the colder region, the maximum nutrient ratio between above-ground and storage organs, as well as alkaloid content in leaves and capsules, occurred significantly later. Compared with the common first mowing date (15 June), alkaloid content decreased significantly until 5 July in both regions. On both dates, it was on average 1.8 times higher in the colder region. Our results suggest the following time for the two management options: (i) mowing at about 25 cm plant height (late April/early May) to reduce C. autumnale densities or (ii) delayed mowing in late June/early July when the plant has turned brown and dry and alkaloid content has declined.

  • 33.
    Jung, Linda S.
    et al.
    Justus-Liebig-University, Giessen, Germany.
    Winter, Silvia
    University of Natural Resources and Life Sciences, Vienna, Austria.
    Eckstein, Rolf Lutz
    Justus-Liebig-University Giessen, Germany.
    Kriechbaum, Monika
    University of Natural Resources and Life Sciences, Vienna, Austria.
    Karrer, Gerhard
    Welk, Erik
    Martin-Luther-University, Halle, Germany.
    Elsaesser, Martin
    Education and Knowledge Centre Aulendorf-Livestock Farming, Germany.
    Donath, Tobias W.
    Justus-Liebig-University Giessen, Germany.
    Otte, Annette
    Justus-Liebig-University Giessen, Germany.
    Colchicum autumnale L.2011In: Perspectives in plant ecology, evolution and systematics, ISSN 1433-8319, E-ISSN 1618-0437, Vol. 13, no 3, p. 227-244Article in journal (Refereed)
    Abstract [en]

    Colchicum autumnale is a perennial hysteranthous geophyte, which is native to Europe. It is characteristic of periodically wet to moderately moist grasslands but also occurs in alluvial forests. This article gives an overview of the taxonomy, distribution, life cycle, and population biology of C. autumnale and puts special emphasis on its morphology, germination and its response to competition and management.

  • 34.
    Karlsson, P S
    et al.
    Uppsala University.
    Eckstein, Rolf Lutz
    Uppsala University.
    Weih, M
    Uppsala University.
    Seasonal variation in N-15 natural abundance in subarctic plants of different life-forms2000In: Ecoscience, ISSN 1195-6860, Vol. 7, no 3, p. 365-369Article in journal (Refereed)
  • 35. Loydi, A.
    et al.
    Donath, T. W.
    Eckstein, Rolf Lutz
    Justus-Liebig University, Giessen, Germany.
    Otte, A.
    Non-native species litter reduces germination and growth of resident forbs and grasses: allelopathic, osmotic or mechanical effects?2015In: Biological Invasions, ISSN 1387-3547, E-ISSN 1573-1464, Vol. 17, no 2, p. 581-595Article in journal (Refereed)
    Abstract [en]

    Non-native plant species may contain allelopathic substances that might help to out-compete native vegetation. These allelochemicals may be released from live or dead plant tissues and be accumulated in the soil. We tested whether non-native species leaf litter and their leachates reduced seedling establishment and growth of native species. We subjected seeds of six native species to the effect of litter leachates of three of the most important invasive plants in Europe and to mannitol solutions with similar osmotic potential in germination chamber experiments. Additionally, we measured the effect of the same litter on emergence and growth of the native species in an outdoor pot experiment. Litter leachates delayed and reduced germination and affected initial root growth of all native species. The effects of leachates were significantly higher than those of mannitol, indicating the action of toxic, most probably allelochemical substances. Emergence of seedlings in pots was also reduced, but total biomass per pot was not affected and biomass per seedling increased. Allelochemicals may affect germination and early stages of seedling recruitment. However, these negative effects seem to cease shortly after germination, when other mechanisms such as competition may be more important. Consequently, litter-borne allelochemicals are unlikely to drive the invasion of the studied non-native species, but they may contribute to maintain mono-dominant stands reinforcing invasion success.

  • 36. Loydi, A.
    et al.
    Donath, T. W.
    Otte, A.
    Eckstein, Rolf Lutz
    Justus-Liebig University Giessen, Giessen, Germany.
    Negative and positive interactions among plants: effects of competitors and litter on seedling emergence and growth of forest and grassland species2015In: Plant Biology, ISSN 1435-8603, E-ISSN 1438-8677, Vol. 17, no 3, p. 667-675Article in journal (Refereed)
    Abstract [en]

    Living plant neighbours, but also their dead aboveground remains (i.e. litter), may individually exert negative or positive effects on plant recruitment. Although living plants and litter co-occur in most ecosystems, few studies have addressed their combined effects, and conclusions are ambivalent. Therefore, we examined the response in terms of seedling emergence and growth of herbaceous grassland and forest species to different litter types and amounts and the presence of competitors. We conducted a pot experiment testing the effects of litter type (grass, oak), litter amount (low, medium, high) and interspecific competition (presence or absence of four Festuca arundinacea individuals) on seedling emergence and biomass of four congeneric pairs of hemicryptophytes from two habitat types (woodland, grassland). Interactions between litter and competition were weak. Litter presence increased competitor biomass. It also had positive effects on seedling emergence at low litter amounts and negative effects at high litter amounts, while competition had no effect on seedling emergence. Seedling biomass was negatively affected by the presence of competitors, and this effect was stronger in combination with high amounts of litter. Litter affected seedling emergence while competition determined the biomass of the emerged individuals, both affecting early stages of seedling recruitment. High litter accumulation also reduced seedling biomass, but this effect seemed to be additive to competitor effects. This suggests that live and dead plant mass can affect species recruitment in natural systems, but the mechanisms by which they operate and their timing differ

  • 37.
    Loydi, Alejandro
    et al.
    Justus-Liebig-University, Giessen, Germany.
    Eckstein, Rolf Lutz
    Justus-Liebig-University, Giessen, Germany.
    Otte, Annette
    Justus-Liebig-University, Giessen, Germany.
    Donath, Tobias W.
    Justus-Liebig University, Giessen, Germany.
    Effects of litter on seedling establishment in natural and semi-natural grasslands: a meta-analysis2013In: Journal of Ecology, ISSN 0022-0477, E-ISSN 1365-2745, Vol. 101, no 2, p. 454-464Article in journal (Refereed)
    Abstract [en]

    1. Plant litter is a key component in terrestrial ecosystems. It plays a major role in nutrient cycles and community organization. Land use and climate change may change the accumulation of litter in herbaceous ecosystems and affect plant community dynamics. Additionally, the transfer of seeds containing plant material (i.e. litter) is a widespread technique in grassland restoration.

    2. Ecosystem responses to litter represent the outcome of interactions, whose sign and strength will depend on many variables (e. g. litter amount, seed size). A previous meta-analysis (from 1999) reported that litter had an overall negative effect on seed germination and seedling establishment in different ecosystems. However, recent studies indicated that this might not be the case in grassland ecosystems.

    3. We used 914 data from 46 independent studies to analyse the effects of litter on seedling (i) emergence, (ii) survival and (iii) biomass, employing meta-analytical techniques. Each data set was stratified according to methodology, grassland type, irrigation conditions, litter amount and seed size.

    4. We found an overall neutral effect of litter presence on seedling emergence and survival and a positive effect on seedling biomass. However, whereas for field experiments the response remained neutral, it was positive for common garden studies. In glasshouse experiments, litter effects were negative for emergence and positive for biomass.

    5. Litter may have a positive effect on seedling recruitment in dry grasslands or under water-limited conditions, or in the presence of low to medium litter amounts (< 500 g m(-2)). However, high litter amounts (> 500 g m(-2)) will inhibit seedling recruitment. Large seeds showed a more positive response to litter presence with respect to seedling emergence and survival, but not concerning biomass.

    6. Synthesis. Under dry conditions (e. g. dry grasslands or dry periods) or with low to medium litter amounts, litter presence has a positive effect on seedling establishment. However, climate and land use change may promote litter accumulation and reduce seedling establishment, affecting grasslands composition and ecosystem functions.

  • 38.
    Loydi, Alejandro
    et al.
    Justus-Liebig-University, Giessen, Germany.
    Lohse, Kerstin
    Justus-Liebig-University, Giessen, Germany.
    Otte, Annette
    Justus-Liebig-University, Giessen, Germany.
    Donath, Tobias W.
    Justus-Liebig-University, Giessen, Germany.
    Eckstein, Rolf Lutz
    Justus-Liebig-University, Giessen, Germany.
    Distribution and effects of tree leaf litter on vegetation composition and biomass in a forest-grassland ecotone2014In: Journal of Plant Ecology, ISSN 1752-9921, E-ISSN 1752-993X, Vol. 7, no 3, p. 264-275Article in journal (Refereed)
    Abstract [en]

    Aims

    After abandonment of grasslands, secondary succession leads to the invasion by woody species. This process begins with the accumulation of tree litter in the forest-grassland ecotone. Our objectives were to determine the relationships between litter amounts and vegetation composition and cover along natural forest-grassland ecotones and to experimentally study the initial effects of tree litter accumulation on grassland vegetation and on microsite conditions.

    Methods

    We established 11 transects varying from 12 to 15 m in length in different forest-grassland ecotones in the Lahn-Dill highlands, Germany, and measured the mass and cover of tree litter and the cover and composition of vegetation at five sequential positions along each transect by using 1 m(2) plots with five replications. In a field experiment, we established plots subjected to different litter amounts (0, 200 and 600 g m(-2)) and evaluated changes in grassland vegetation, soil temperature and soil nutrient availability below the litter layer.

    Important Findings

    Tree litter amounts decrease from 650 to 65 g m(-2) across the forest-grassland ecotone. Vegetation changed from shrubs and annual species (adapted to more stressful conditions) in the forests edge to grasses, rosettes and hemirosette species (with higher competitive abilities) in the grassland. These anthropogenic forest-grassland ecotones showed abrupt edges, and the two adjacent ecosystems were characterized by different species pools and functional groups. In the field experiment, the presence of a litter layer reduced vegetation biomass and cover; the species richness was only reduced in the treatment with high litter (600 g m(-2)). Additionally, adding litter on top of vegetation also reduced thermal amplitude and the number of frost days, while increasing the availability of some nutrients, such as nitrogen and aluminium, the latter being an indicator of soil acidification. Adding a tree litter layer of 600 g m(-2) in grassland areas had strong effects on the composition and diversity of grassland vegetation by reducing the cover of several key grassland species. In, or near, forest edges, litter accumulation rapidly changes established vegetation, microsite conditions and soil nutrients.

  • 39. Ludewig, Kristin
    et al.
    Donath, Tobias W.
    Zelle, Bianka
    Eckstein, Rolf Lutz
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences. nstitute of Landscape Ecology and Resource Managementnstitute of Landscape Ecology and Resource Management, Giessen, Germany.
    Mosner, Eva
    Otte, Annette
    Jensen, Kai
    Effects of Reduced Summer Precipitation on Productivity and Forage Quality of Floodplain Meadows at the Elbe and the Rhine River2015In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 10, no 5, article id e0124140Article in journal (Refereed)
    Abstract [en]

    Floodplain meadows along rivers are semi-natural habitats and depend on regular land use. When used non-intensively, they offer suitable habitats for many plant species including rare ones. Floodplains are hydrologically dynamic ecosystems with both periods of flooding and of dry conditions. In German floodplains, dry periods may increase due to reduced summer precipitation as projected by climate change scenarios. Against this background, the question arises, how the forage quantity and quality of these meadows might change in future.

    Methods

    We report results of two field trials that investigated effects of experimentally reduced summer precipitation on hay quantity and quality of floodplain meadows at the Rhine River (2011-2012) and at two Elbe tributaries (2009-2011). We measured annual yield, the amount of hay biomass, and contents of crude protein, crude fibre, energy, fructan, nitrogen, phosphorus, and potassium.

    Results

    The annual yield decreased under precipitation reduction at the Rhine River. This was due to reduced productivity in the second cut hay at the Rhine River in which, interestingly, the contents of nitrogen and crude protein increased. The first cut at the Rhine River was unaffected by the treatments. At the Elbe tributaries, the annual yield and the hay quantity and quality of both cuts were only marginally affected by the treatments.

    Conclusion

    We conclude that the yield of floodplain meadows may become less reliable in future since the annual yield decreased under precipitation reduction at the Rhine River. However, the first and agriculturally more important cut was almost unaffected by the precipitation reduction, which is probably due to sufficient soil moisture from winter/spring. As long as future water levels of the rivers will not decrease during spring, at least the use of the hay from the first cut of floodplain meadows appears reliable under climate change.

  • 40.
    Ludewig, Kristin
    et al.
    ustus Liebig University Giessen, 35392 Giessen, Germany;.
    Zelle, Bianka
    ustus Liebig University Giessen, 35392 Giessen, Germany;.
    Eckstein, Rolf Lutz
    ustus Liebig University Giessen, 35392 Giessen, Germany;.
    Mosner, Eva
    Otte, Annette
    ustus Liebig University Giessen, 35392 Giessen, Germany;.
    Donath, Tobias W.
    ustus Liebig University Giessen, 35392 Giessen, Germany;.
    Differential effects of reduced water potential on the germination of floodplain grassland species indicative of wet and dry habitats2014In: Seed Science Research, ISSN 0960-2585, E-ISSN 1475-2735, Vol. 24, no 1, p. 49-61Article in journal (Refereed)
    Abstract [en]

    Floodplain meadow ecosystems are characterized by high water level fluctuations and highly variable soil water potentials. Additionally, climate change scenarios indicate an increasing risk for summer drought along the northern Upper Rhine and the Middle Elbe River, Germany. While adult plants often persist even after strong changes in water availability, early life phases, such as seed germination and seedling establishment, might be more vulnerable. Therefore we tested whether reduced soil water potentials will affect the germination of meadow species and whether the response varies between (1) forbs indicative of wet and dry habitats and (2) seeds originating from sites along the rivers Elbe and Rhine. We exposed seeds of 20 floodplain meadow species with different moisture requirements from five plant families to a water potential gradient ranging from 0 to -1.5MPa. While across species germination percentage and synchrony decreased, germination time increased at reduced water potentials. Germination of the species indicative of dry habitats decreased more strongly, was slower and less synchronous at reduced water potentials than that of species indicative of wet habitats. Seeds from sites along the rivers Elbe and Rhine did not differ in their germination characteristics. We propose that species of wet sites follow an all-or-nothing-strategy with fast and synchronous germination to maximize competitive advantages, betting on a high probability of moist conditions for establishment (optimists). In contrast, species from dry sites appear to follow a bet-hedging strategy with a moisture-sensing mechanism for unsuitable conditions (pessimists), resulting in a slower and less synchronous germination.

  • 41.
    Mc Ewen, Birgitta
    et al.
    Karlstad University, Division for Environmental Sciences.
    Welander, Margaretha
    Faculty of Landscape Planning, Horticulture and Agricultural Science, Swedish University of Agricultural Sciences, Alnarp.
    The role of thidiazuron and beta-naphtalene acetic acid in transformation of birch, Betula pendula, with help of Agrobacterium tumefaciens1999Conference paper (Other academic)
  • 42. Ruehl, A. Theresa
    et al.
    Eckstein, Rolf Lutz
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences. Justus Liebig University Giessen, Germany.
    Otte, Annette
    Donath, Tobias W.
    Future challenge for endangered arable weed species facing global warming: Low temperature optima and narrow moisture requirements2015In: Biological Conservation, ISSN 0006-3207, E-ISSN 1873-2917, Vol. 182, p. 262-269Article in journal (Refereed)
    Abstract [en]

    As a result of the intensification of agriculture in Central Europe, many arable weed species have declined. Global climate change may further challenge the adaptability of arable weeds since plants may be more often subjected to higher temperatures and lower soil moisture during the germination period.

    A climate chamber experiment analysed the response of four familial pairs of common and endangered arable weeds from Germany. To this end we used a large range of temperatures and water potentials to assess specific traits defining their germination requirements. Using a simple response surface approach, we predicted germination response under three climate change scenarios.Results supported our expectation that endangered species, owing to their narrow germination requirements, may be more negatively affected by global warming than common species. Endangered species germinated significantly less than the common arable weeds, except at very low temperatures (3 °C and 5 °C). The preference of endangered arable weed species for low germination temperatures was confirmed by their low optimal germination temperature (15.8 °C ± 0.4). In contrast, common species germinated at significant higher temperatures (optimal temperature 18.4 °C ± 0.2), had a significantly wider range of germination temperature (endangered: 24 °C ± 3.5, common: 31 °C ± 0.5) and were also more flexible towards changes in water potential.Calculations based on response surfaces for three climate change scenarios indicated that endangered arable weed species may benefit less from climate warming than common species.

  • 43.
    Ruprecht, Eszter
    et al.
    Romania.
    Donath, Tobias W.
    Justus Liebig University Giessen, Germany.
    Otte, Annette
    Justus-Liebig-University Giessen, Germany.
    Eckstein, Rolf Lutz
    Justus-Liebig-University Giessen, Germany.
    Chemical effects of a dominant grass on seed germination of four familial pairs of dry grassland species2008In: Seed Science Research, ISSN 0960-2585, E-ISSN 1475-2735, Vol. 18, no 4, p. 239-248Article in journal (Refereed)
    Abstract [en]

    Community composition and ecosystem processes during succession may be driven partly by traits of plant species that attain dominance. Here, we addressed the hypothesis that Stipa pulcherrima, the dominant grass of abandoned continental grasslands, controls seedling recruitment of co-occurring species through chemical effects of its litter. Eight species with successful and unsuccessful recruitment under field conditions were selected (four familial pairs) to study experimentally the effects of leaf leachate under four temperature regimes. Since fungi developed in leachate-treated Petri dishes, in another experiment seeds were surface sterilized to remove confounding effects of fungi on recruitment. Leachate affected various stages of seedling recruitment: it significantly reduced seed germination (by 33-94%) and radicle elongation, and it delayed germination of seedlings of all species. In two families, species with unsuccessful field recruitment were more negatively affected than the successful ones. In a third family, the species with successful recruitment was more negatively affected, and in the fourth there were no differences. Similar germination responses after exclusion of fungi through seed-surface sterilization suggested that leachate was responsible for the observed effects on recruitment. Besides other traits and physical/microclimatic effects of accumulating litter, S. pulcherrima influences plant community dynamics and may potentially affect ecosystem processes through its secondary compounds.

  • 44.
    Ruprecht, Eszter
    et al.
    Romania.
    Enyedi, Marton Z.
    Romania.
    Eckstein, Rolf Lutz
    Justus-Liebig-University Giessen, Germany.
    Donath, Tobias W.
    Justus-Liebig-University Giessen, Germany.
    Restorative removal of plant litter and vegetation 40 years after abandonment enhances re-emergence of steppe grassland vegetation2010In: Biological Conservation, ISSN 0006-3207, E-ISSN 1873-2917, Vol. 143, no 2, p. 449-456Article in journal (Refereed)
    Abstract [en]

    The accumulation of biomass and of dead plant remains is a direct consequence of grassland abandonment. Litter can occupy potential microsites for seed germination and seedling establishment, and thus decrease species diversity in the long-term. This effect can be more accentuated in dry grassland of open structure where species are adapted to excessive light and bare surfaces during the recruitment phase. We conducted a field experiment with litter removal alone or in combination with vegetation cutting and studied germination and seedling survival during 2 years in two abandoned steppe sites. With our experimental treatments we intended to create microsites and to activate the seed bank, with the aim to enhance recruitment of dry-grassland species; potentially also those already absent from the established vegetation. Our results show, that while both treatments significantly increased recruitment by enhancing seed germination in the first year of the study, only litter removal combined with vegetation cutting significantly promoted seedling survival during both years. Our experiment demonstrated that even after 40 years of abandonment the applied measures favoured the re-emergence of target species that were very rare or absent from the above-ground vegetation of continental steppe-like grassland. Thus, management prescriptions which comprise removal of dead and even living biomass, such as mowing or grazing, are considered beneficial for this habitat type of high nature conservation priority. (C) 2009 Elsevier Ltd. All rights reserved.

  • 45.
    Schmiede, Ralf
    et al.
    Justus-Liebig-University, Giessen, Germany.
    Ruprecht, Eszter
    Babeş-Bolyai University, Romania.
    Eckstein, Rolf Lutz
    Justus-Liebig-University, Giessen, Germany.
    Otte, Annette
    Justus-Liebig University, Giessen, Germany.
    Donath, Tobias W.
    Justus-Liebig-University, Giessen, Germany.
    Establishment of rare flood meadow species by plant material transfer: Experimental tests of threshold amounts and the effect of sowing position2013In: Biological Conservation, ISSN 0006-3207, E-ISSN 1873-2917, Vol. 159, p. 222-229Article in journal (Refereed)
    Abstract [en]

    The transfer of freshly cut seed-containing plant material is a widely applied method to re-establish grassland of high biodiversity. Still, the amount of plant material applied varies greatly across restoration projects. Therefore, we set up a two-year common garden experiment where we assessed the effect of plant material amount (0, 400, 800, 1600, 3200 g m2 and relative seed position (on top and beneath a litter layer) on seedling establishment, seedling fate and seedling fitness of eight target species for restoration of alluvial meadows. Most seedlings (85.6%) emerged within the first year. Cumulative seedling emergence and final seedling establishment across all species were highest on control plots and low litter plots but were very low or failed completely, at 1600 and 3200 g m2, respectively. In general, large-seeded species were significantly more successful than smaller seeded species. Relative seed position had only a small impact on seedling emergence and establishment but was decisive for seedling survival at high litter quantities. Across all species, seedlings that died had a significantly lower relative height than surviving seedlings. Interestingly, co-occurring resident grassland vegetation had a neutral rather than negative impact on the response variables. Our results suggest an upper threshold of 1000 g m2 for the amount of plant material applied in grassland restoration, since higher amounts will inhibit seedling establishment. The prompt emergence of most seedlings during the first vegetation period highlights the importance of creating optimal conditions for seedling establishment already in the early phase of vegetation development on restoration sites.

  • 46.
    Schulz, Benjamin
    et al.
    Justus-Liebig-University, Giessen, Germany.
    Eckstein, Rolf Lutz
    Justus-Liebig-University, Giessen, Germany.
    Durka, Walter
    Justus-Liebig-University, Giessen, Germany.
    Epigenetic variation reflects dynamic habitat conditions in a rare floodplain herb2014In: Molecular Ecology, ISSN 0962-1083, E-ISSN 1365-294X, Vol. 23, no 14, p. 3523-3537Article in journal (Refereed)
    Abstract [en]

    Variation of DNA methylation is thought to play an important role for rapid adjustments of plant populations to dynamic environmental conditions, thus compensating for the relatively slow response time of genetic adaptations. However, genetic and epigenetic variation of wild plant populations has not yet been directly compared in fast changing environments. Here, we surveyed populations of Viola elatior from two adjacent habitat types along a successional gradient characterized by strong differences in light availability. Using amplified fragment length polymorphisms (AFLP) and methylation-sensitive amplification polymorphisms (MSAP) analyses, we found relatively low levels of genetic (H-gen' = 0.19) and epigenetic (H-epi' = 0.23) diversity and high genetic (phi(ST) = 0.72) and epigenetic (phi(ST) = 0.51) population differentiation. Diversity and differentiation were significantly correlated, suggesting that epigenetic variation partly depends on the same driving forces as genetic variation. Correlation-based genome scans detected comparable levels of genetic (17.0%) and epigenetic (14.2%) outlier markers associated with site specific light availability. However, as revealed by separate differentiation-based genome scans for AFLP, only few genetic markers seemed to be actually under positive selection (0-4.5%). Moreover, principal coordinates analyses and Mantel tests showed that overall epigenetic variation was more closely related to habitat conditions, indicating that environmentally induced methylation changes may lead to convergence of populations experiencing similar habitat conditions and thus may play a major role for the transient and/or heritable adjustment to changing environments. Additionally, using a new MSAP-scoring approach, we found that mainly the unmethylated (phi(ST) = 0.60) and CG-methylated states (phi(ST) = 0.46) of epiloci contributed to population differentiation and putative habitat-related adaptation, whereas CHG-hemimethylated states (phi(ST) = 0.21) only played a marginal role.

  • 47.
    Schulz, Benjamin
    et al.
    Justus-Liebig-University Giessen, Germany.
    Eckstein, Rolf Lutz
    Justus-Liebig-University Giessen, Germany.
    Durka, Walter
    Helmholtz Centre for Environmental Research.
    Scoring and analysis of methylation-sensitive amplification polymorphisms for epigenetic population studies2013In: Molecular Ecology Resources, ISSN 1755-098X, E-ISSN 1755-0998, Vol. 13, no 4, p. 642-653Article in journal (Refereed)
    Abstract [en]

    DNA methylation is an important, heritable epigenetic modification in most eukaryotic organisms that is connected with numerous biological processes. To study the impact of natural epigenetic variation in an ecological or evolutionary context, epigenetic studies are increasingly using methylation-sensitive amplification polymorphism (MSAP) for surveys at the population or species level. However, no consensus exists on how to interpret and score the multistate information obtained from the MSAP banding patterns. Here, we review the previously used scoring approaches for population epigenetic studies and develop new alternatives. To assess effects of the different approaches on parameters of epigenetic diversity and differentiation, we applied eight scoring schemes to a case study of three populations of the plant species Viola elatior. For a total number of 168 detected polymorphic MSAP fragments, the number of ultimately scored polymorphic epiloci ranged between 78 and 286 depending on the particular scoring scheme. Both, estimates of epigenetic diversity and differentiation varied strongly between scoring approaches. However, linear regression and PCoA revealed qualitatively similar patterns, suggesting that the scoring approaches are largely consistent. For single-locus analyses of MSAP data, for example the search for loci under selection, we advocate a new scoring approach that separately takes into account different methylation types and thus seems appropriate for drawing more detailed conclusions in ecological or evolutionary contexts. An R script (MSAP_score.r) for scoring and basic data analysis is provided.

  • 48.
    Shakeri, Zahed
    et al.
    Iran.
    Mohadjer, Mohammad Reza Marvie
    Iran.
    Simberloff, Daniel
    USA.
    Etemad, Vahid
    Iran.
    Assadi, Mostafa
    Iran.
    Donath, Tobias W.
    Germany.
    Otte, Annette
    Germany.
    Eckstein, Rolf Lutz
    Germany.
    Plant community composition and disturbance in Caspian Fagus orientalis forests: which are the main driving factors?2012In: Phytocoenologia, ISSN 0340-269X, Vol. 41, no 4, p. 247-263Article in journal (Refereed)
    Abstract [en]

    The oriental beech forests along the southern Caspian Sea shores of Iran are characterized by high biodiversity and high ecological value. However, there is little information concerning factors governing community composition and the presence and abundance of invasive plants. In the present study we aimed to evaluate the main drivers of community composition, diversity, and establishment of invasive plants in disturbed and undisturbed Fagus orientalis communities. We sampled 104 vegetation releves in undisturbed and disturbed sites of the "Kheiroud Investigation Forest" in northern Iran and collected data on a large number of environmental variables concerning soil properties, light conditions, and topography. Data analysis consisted of a forward selection of significant explanatory variables followed by partial CCA analyses. Additionally, we carried out indicator species analysis of groups of releves affected by different disturbance types and analyzed effects of disturbance on species richness, diversity, and evenness using general linear models. CCA results showed that disturbance, soil properties, light conditions and elevation explained 22.6% of the total variation in floristic composition. Gap and gap + grazing were the most important disturbance types affecting community composition. Disturbance had significant but rather weak effects on species richness, evenness, and the Shannon index. The most obvious effect of disturbance was on species composition, as revealed by significant groups of indicator species for different disturbance types. Most of the indicator species in grazed sites were unpalatable, poisonous, and creeping species, which are avoided by cattle. Grazing led to decreased abundance of indicator species and species characteristic of old-growth Fagus forests. The most intensive disturbance type "harvesting + gap + grazing" was associated with invasion by native vascular plant species not typically found in beech forests (apophytes).

  • 49.
    Voss, Nicole
    et al.
    Justus-Liebig-University Giessen, Germany.
    Eckstein, Rolf Lutz
    Justus-Liebig-University Giessen, Germany.
    Durka, Walter
    UFZ, Halle, Germany.
    Range expansion of a selfing polyploid plant despite widespread genetic uniformity2012In: Annals of Botany, ISSN 0305-7364, E-ISSN 1095-8290, Vol. 110, no 3, p. 585-593Article in journal (Refereed)
    Abstract [en]

    Ongoing and previous range expansions have a strong influence on population genetic structure of plants. In turn, genetic variation in the new range may affect the population dynamics and the expansion process. The annual Ceratocapnos claviculata (Papaveraceae) has expanded its Atlantic European range in recent decades towards the north and east. Patterns of genetic diversity were investigated across the native range to assess current population structure and phylogeographical patterns. A test was then made as to whether genetic diversity is reduced in the neophytic range and an attempt was made to identify source regions of the expansion. Samples were taken from 55 populations in the native and 34 populations in the neophytic range (Sweden, north-east Germany). Using amplified fragment length polymorphism markers an analysis was made of genetic variation and population structure (Bayesian statistical modelling) and population differentiation was quantified. Pollen/ovule ratio was analysed as a proxy for the breeding system. Genetic diversity at population level was very low (mean H-e 0004) and two multilocus genotypes dominated large parts of the new range. Population differentiation was strong (F-ST 0812). These results and a low pollen/ovule ratio are consistent with an autogamous breeding system. Genetic variation decreased from the native to the neophytic range. Within the native range, H-e decreased towards the north-east, whereas population size increased. According to the Bayesian cluster analysis, the putative source regions of the neophytic range are situated in north-west Germany and adjacent regions. Ceratocapnos claviculata shows a cline of genetic variation due to postglacial recolonization from putative Pleistocene refugia in south-west Europe. Nevertheless, the species has expanded successfully during the past 40 years to southern Sweden and north-east Germany where it occurs as an opportunistic neophyte. Recent expansion was mainly human-mediated by single long-distance diaspore transport and was facilitated by habitat modification.

  • 50. Voss, Nicole
    et al.
    Simmering, Dietmar
    Peppler-Lisbach, Cord
    Carl von Ossietzky University Oldenburg.
    Durka, Walter
    Helmholtz Centre for Environmental Research, Halle, Germany.
    Eckstein, Rolf Lutz
    Justus-Liebig-University Giessen, Germany.
    Vegetation databases as a tool to analyse factors affecting the range expansion of the forest understory herb Ceratocapnos claviculata2011In: Journal of Vegetation Science, ISSN 1100-9233, E-ISSN 1654-1103, Vol. 22, no 4, p. 726-740Article in journal (Refereed)
    Abstract [en]

    Question: The eu-atlantic forest herb Ceratocapnos claviculata showed a recent increase in frequency within its native range and an eastward and northward range expansion in Central Europe. To gain deeper understanding of factors affecting the range expansion of the species, we analyzed vegetation releves at three different scales and asked the following questions: As the species occurs in a wide range of vegetation types, is variation in community composition across the entire range related to climatic environmental zones and tree cover? Are there differences in species composition and habitat characteristics between the native range and the two invaded regions (S Sweden and NE Germany)? Did community composition and habitat characteristics within the native range (The Netherlands) change between 'before 1970' and '1990 to 2006'? Location: W, C and N Europe. Methods: We analysed vegetation-plot data with C. claviculata from various databases and own surveys using partial CCA, partial DCA, Indicator Species Analysis, MANCOVA and multiple regression. Results: Using vegetation plots from the entire distribution range, climatic environmental zones explained 68.9% of the total canonical Eigenvalue. Differences in floristic composition and habitat characteristics between the two invaded regions were as large as between native and invaded range sites. However, releves from the invaded range were generally characterized by anthropogenic disturbance. Accordingly, abundance of C. claviculata was positively linked to silvicultural intensity. New releves from 1990 to 2006 were characterized by higher Ellenberg nutrient indicator values, lower species diversity, higher proportions of neophytic and hemerobic species and showed a lower cover of the study species than old releves from before 1970. Conclusions: Across the range of C. claviculata, climatic environmental zones determine vegetation composition. Accordingly, the species is characterized by a broad macroclimatic amplitude. Vegetation composition and structure differ significantly between the two regions of the new range. Thus, the species has successfully established under various biotic and abiotic environmental conditions. Beyond potential positive effects of soil eutrophication and mild winters, anthropogenic impact may directly facilitate seed dispersal and provide sites and resource conditions suitable for germination and establishment of C. claviculata, whereas a decrease of forest management may constrain the species.

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