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Christian Korner - One of the best experts on this subject based on the ideXlab platform.
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Community and species level responses to elevated CO2 in designed Calcareous Grassland communities
Acta Oecologica-international Journal of Ecology, 2006Co-Authors: Jürg Stöcklin, Paul W. Leadley, Christian KornerAbstract:We present a synthesis of two independent glasshouse experiments in which we investigated the short term response of model communities of Calcareous Grassland species to CO2-enrichment. Communities consisted of six species in the first study and of 14 species in-the second study. Communities were grown in containers filled with ca. 20 liters of natural soil. Total aboveground biomass production was increased by 14% (n.s., p=0.21) in the first study and by 8.5% (p=0.03) in the second study. This community level response was due to a significant stimulation of growth in 2 and 5 species, respectively. In each of the experiments, one species responded negatively to CO2-enrichment. The remaining species, including all legumes, remained unaffected by CO2-enrichment. Positive or negative responding species did not belong to specific functional groups, hence responses could not have been predicted from a priori knowledge of individual plant traits. Bromus erectus, which is the dominant species in Calcareous Grasslands of the Jura mountains, did not exhibit a CO2-response at the species level, but genotype-specific responses in this species varied significantly and included positive as well as negative responses. No such genotypic differentiation of CO2-response was observed in Fes tuca ovina. In the long term, we expect directional selection of positively responding genotypes and shifts in species composition to alter both population and community structure of Calcareous grass lands - a conclusion that may also hold for other diverse plant communities.
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synthesis of a six year study of Calcareous Grassland responses to in situ co2 enrichment
Ecological Monographs, 2004Co-Authors: Pascal A. Niklaus, Christian KornerAbstract:We exposed species-rich temperate Calcareous Grassland to elevated CO2 (600 μL/L) for six growing seasons and studied carbon (C) and nutrient (nitrogen [N] and phosphorus [P]) cycling, water relations, and plant community structure and diversity. CO2 enrichment stimulated leaf- and ecosystem-level daytime CO2 uptake and increased plant community productivity; relative CO2 effects on aboveground biomass were predicted with r 0.95) by precipitation prior to biomass harvests. The underlying mechanisms were water savings due to reduced leaf conductance under elevated CO2, allowing for more growth in this temporarily water-limited ecosystem; this effect was more important in dry years. At the plant-species level, no effects of [CO2] were found except for the subdominant sedges Carex flacca and C. caryophyllea, which responded positively to elevated CO2, mainly due to increased soil moisture. Bryophytes also responded to CO2 enrichment for the same reason. At a more aggregate level, elevated CO2 in...
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seed production and seed quality in a Calcareous Grassland in elevated co2
Global Change Biology, 2003Co-Authors: Barbara Thurig, Christian Korner, Jürg StöcklinAbstract:In diverse plant communities the relative contribution of species to community biomass may change considerably in response to elevated CO2. Along with species-specific biomass responses, reproduction is likely to change as well with increasing CO2 and might further accelerate shifts in species composition. Here, we ask if, after 5 years of CO2 exposure, seed production and seed quality in natural nutrient-poor Calcareous Grassland are affected by elevated CO2 (650 μL L−1 vs 360 μL L−1) and how this might affect long-term community dynamics. The effect of elevated CO2 on the number of flowering shoots (+ 24%, P < 0.01) and seeds (+ 29%, P = 0.06) at the community level was similar to above ground biomass responses in this year, suggesting that the overall allocation to sexual reproduction remained unchanged. Compared among functional groups of species we found a 42% increase in seed number (P < 0.01) of graminoids, a 33% increase (P = 0.07) in forbs, and no significant change in legumes (− 38%, n.s.) under elevated CO2. Large responses particularly of two graminoid species and smaller responses of many forb species summed up to the significant or marginally significant increase in seed number of graminoids and forbs, respectively. In several species the increase in seed number resulted both from an increase in flowering shoots and an increase in inflorescence size. In most species, seeds tended to be heavier (+ 12%, P < 0.01), and N-concentration of seeds was significantly reduced in eight out of 13 species. The fraction of germinating seeds did not differ between seeds produced in ambient and elevated CO2, but time to germination was significantly shortened in two species and prolonged in one species when seeds had been produced in elevated CO2. Results suggest that species specific increases in seed number and changes in seed quality will exert substantial cumulative effects on community composition in the long run.
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Effects of six years atmospheric CO2 enrichment on plant, soil, and soil microbial C of a Calcareous Grassland
Plant and Soil, 2001Co-Authors: Pascal A. Niklaus, Monika Wohlfender, Rolf Siegwolf, Christian KornerAbstract:Stimulated plant production and often even larger stimulation of photosynthesis at elevated CO_2 raise the possibility of increased C storage in plants and soils. We analysed ecosystem C partitioning and soil C fluxes in Calcareous Grassland exposed to elevated CO_2 for 6 years. At elevated CO_2, C pools increased in plants (+23%) and surface litter (+24%), but were not altered in microbes and soil organic matter. Soils were fractionated into particle size and density separates. The amount of low-density macroorganic C, an indicator of particulate soil C inputs from root litter, was not affected by elevated CO_2. Incorporation of C fixed during the experiment (C_new) was tracked by C isotopic analysis of soil fractions which were labelled due to ^13C depletion of the commercial CO_2 used for atmospheric enrichment. This data constrains estimates of C sequestration (absolute upper bound) and indicates where in soils potentially sequestered C is stored. C_new entered soils at an initial rate of 210±42 g C m^−2 year^−1, but only 554±39 g C_new m^−2 were recovered after 6 years due to the low mean residence time of 1.8 years. Previous process-oriented measurements did not indicate increased plant–soil C fluxes at elevated CO_2 in the same system (^13C kinetics in soil microbes and fine roots after pulse labelling, and minirhizotron observations). Overall experimental evidence suggests that C storage under elevated CO_2 occurred only in rapidly turned-over fractions such as plants and detritus, and that potential extra soil C inputs were rapidly re-mineralised. We argue that this inference does not conflict with the observed increases in photosynthetic fixation at elevated CO_2, because these are not good predictors of plant growth and soil C fluxes for allometric reasons. C sequestration in this natural system may also be lower than suggested by plant biomass responses to elevated CO_2 because C storage may be limited by stabilisation of C_new in slowly turned-over soil fractions (a prerequisite for long-term storage) rather than by the magnitude of C inputs per se.
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carbon allocation in Calcareous Grassland under elevated co2 a combined 13c pulse labelling soil physical fractionation study
Functional Ecology, 2001Co-Authors: Pascal A. Niklaus, Rolf Siegwolf, E Glockler, Christian KornerAbstract:Summary 1 To test whether plant–soil C fluxes in natural Grassland increase under elevated atmospheric CO2 concentration, intact Calcareous Grassland monoliths exposed to ambient or elevated CO2 were pulse-labelled and the dynamics of the 13C label followed throughout the rest of the growing season. 2 The experiment revealed no increased fluxes of C to soils at elevated CO2. The only changes found were relatively small shifts towards increased C allocation to roots by the end of the growing season. This effect was probably because wetter soil under elevated CO2 prolonged the growing period. At elevated CO2, plant C pools increased below ground (+28%) at the end of the season, resulting in slightly increased root : shoot ratios. Plant 13C pools increased significantly below ground. There were no effects of CO2 enrichment on 13C in soil microbes, fine roots or earthworms. 3 Elevated CO2 caused a shift in soil particle size distribution towards smaller aggregate sizes, but had no effect on the total C and 13C content of low- and high-density soil fractions. 4 The absence of effects of CO2 on the labelling of soil microbial biomass, and of C and 13C accumulation in low-density macro-organic fractions, suggest that there is no significant effect of elevated CO2 on root exudation or turnover, agreeing with published labelling studies, but conflicting with CO2-exchange budgets.
Pascal A. Niklaus - One of the best experts on this subject based on the ideXlab platform.
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effects of long term co2 enrichment on microbial community structure in Calcareous Grassland
Plant and Soil, 2004Co-Authors: Diana Ebersberger, Pascal A. Niklaus, Nicola Wermbter, Ellen KandelerAbstract:Elevated CO2 generally increases plant productivity, and has been found to alter plant community composition in many ecosystems. Because soil microbes depend on plant-derived C and are often associated with specific plant species, elevated CO2 has the potential to alter structure and functioning of soil microbial communities. We investigated soil microbial community structure of a species-rich semi-natural Calcareous Grassland that had been exposed to elevated CO2 (600 μL L−1) for 6 growing seasons. We analysed microbial community structure using phospholipid fatty acid (PLFA) profiles and DNA fingerprints obtained by Denaturing Gradient Gel Electrophoresis (DGGE) of 16S rDNA fragments amplified by the Polymerase Chain Reaction (PCR).
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synthesis of a six year study of Calcareous Grassland responses to in situ co2 enrichment
Ecological Monographs, 2004Co-Authors: Pascal A. Niklaus, Christian KornerAbstract:We exposed species-rich temperate Calcareous Grassland to elevated CO2 (600 μL/L) for six growing seasons and studied carbon (C) and nutrient (nitrogen [N] and phosphorus [P]) cycling, water relations, and plant community structure and diversity. CO2 enrichment stimulated leaf- and ecosystem-level daytime CO2 uptake and increased plant community productivity; relative CO2 effects on aboveground biomass were predicted with r 0.95) by precipitation prior to biomass harvests. The underlying mechanisms were water savings due to reduced leaf conductance under elevated CO2, allowing for more growth in this temporarily water-limited ecosystem; this effect was more important in dry years. At the plant-species level, no effects of [CO2] were found except for the subdominant sedges Carex flacca and C. caryophyllea, which responded positively to elevated CO2, mainly due to increased soil moisture. Bryophytes also responded to CO2 enrichment for the same reason. At a more aggregate level, elevated CO2 in...
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long term co2 enrichment stimulates n mineralisation and enzyme activities in Calcareous Grassland
Soil Biology & Biochemistry, 2003Co-Authors: Diana Ebersberger, Pascal A. Niklaus, Ellen KandelerAbstract:Elevated concentration of atmospheric carbon dioxide will affect carbon cycling in terrestrial ecosystems. Possible effects include increased carbon input into the soil through the rhizosphere, altered nutrient concentrations of plant litter and altered soil moisture. Consequently, the ongoing rise in atmospheric carbon dioxide might indirectly influence soil biota, decomposition and nutrient transformations. N-mineralisation and activities of the enzymes invertase, xylanase, urease, protease, arylsulfatase, and alkaline phosphatase were investigated in spring and summer in Calcareous Grassland, which had been exposed to ambient and elevated CO2 concentrations (365 and 600 μl l−1) for six growing seasons. In spring, N-mineralisation increased significantly by 30% at elevated CO2, while there was no significant difference between treatments in summer (+3%). The response of soil enzymes to CO2 enrichment was also more pronounced in spring, when alkaline phosphatase and urease activities were increased most strongly by 32 and 21%. In summer, differences of activities between CO2 treatments were greatest in the case of urease and protease (+21 and +17% at elevated CO2). The stimulation of N-mineralisation and enzyme activities at elevated CO2 was probably caused by higher soil moisture and/or increased root biomass. We conclude that elevated CO2 will enhance below-ground C- and N-cycling in Grasslands.
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Effects of six years atmospheric CO2 enrichment on plant, soil, and soil microbial C of a Calcareous Grassland
Plant and Soil, 2001Co-Authors: Pascal A. Niklaus, Monika Wohlfender, Rolf Siegwolf, Christian KornerAbstract:Stimulated plant production and often even larger stimulation of photosynthesis at elevated CO_2 raise the possibility of increased C storage in plants and soils. We analysed ecosystem C partitioning and soil C fluxes in Calcareous Grassland exposed to elevated CO_2 for 6 years. At elevated CO_2, C pools increased in plants (+23%) and surface litter (+24%), but were not altered in microbes and soil organic matter. Soils were fractionated into particle size and density separates. The amount of low-density macroorganic C, an indicator of particulate soil C inputs from root litter, was not affected by elevated CO_2. Incorporation of C fixed during the experiment (C_new) was tracked by C isotopic analysis of soil fractions which were labelled due to ^13C depletion of the commercial CO_2 used for atmospheric enrichment. This data constrains estimates of C sequestration (absolute upper bound) and indicates where in soils potentially sequestered C is stored. C_new entered soils at an initial rate of 210±42 g C m^−2 year^−1, but only 554±39 g C_new m^−2 were recovered after 6 years due to the low mean residence time of 1.8 years. Previous process-oriented measurements did not indicate increased plant–soil C fluxes at elevated CO_2 in the same system (^13C kinetics in soil microbes and fine roots after pulse labelling, and minirhizotron observations). Overall experimental evidence suggests that C storage under elevated CO_2 occurred only in rapidly turned-over fractions such as plants and detritus, and that potential extra soil C inputs were rapidly re-mineralised. We argue that this inference does not conflict with the observed increases in photosynthetic fixation at elevated CO_2, because these are not good predictors of plant growth and soil C fluxes for allometric reasons. C sequestration in this natural system may also be lower than suggested by plant biomass responses to elevated CO_2 because C storage may be limited by stabilisation of C_new in slowly turned-over soil fractions (a prerequisite for long-term storage) rather than by the magnitude of C inputs per se.
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carbon allocation in Calcareous Grassland under elevated co2 a combined 13c pulse labelling soil physical fractionation study
Functional Ecology, 2001Co-Authors: Pascal A. Niklaus, Rolf Siegwolf, E Glockler, Christian KornerAbstract:Summary 1 To test whether plant–soil C fluxes in natural Grassland increase under elevated atmospheric CO2 concentration, intact Calcareous Grassland monoliths exposed to ambient or elevated CO2 were pulse-labelled and the dynamics of the 13C label followed throughout the rest of the growing season. 2 The experiment revealed no increased fluxes of C to soils at elevated CO2. The only changes found were relatively small shifts towards increased C allocation to roots by the end of the growing season. This effect was probably because wetter soil under elevated CO2 prolonged the growing period. At elevated CO2, plant C pools increased below ground (+28%) at the end of the season, resulting in slightly increased root : shoot ratios. Plant 13C pools increased significantly below ground. There were no effects of CO2 enrichment on 13C in soil microbes, fine roots or earthworms. 3 Elevated CO2 caused a shift in soil particle size distribution towards smaller aggregate sizes, but had no effect on the total C and 13C content of low- and high-density soil fractions. 4 The absence of effects of CO2 on the labelling of soil microbial biomass, and of C and 13C accumulation in low-density macro-organic fractions, suggest that there is no significant effect of elevated CO2 on root exudation or turnover, agreeing with published labelling studies, but conflicting with CO2-exchange budgets.
Johannes Kollmann - One of the best experts on this subject based on the ideXlab platform.
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impacts of visitor trampling on the taxonomic and functional community structure of Calcareous Grassland
Applied Vegetation Science, 2015Co-Authors: Timo Conradi, Katharina Strobl, Anna-lena Wurfer, Johannes KollmannAbstract:Question: Does long-term visitor trampling close to hiking trails affect the taxonomic and functional composition and diversity of a Calcareous Grassland, thus reducing its nature conservation value? Location: Ancient Calcareous Grassland (nature reserve Garchinger Heide) in the Munich Gravel Plain, south Germany. Methods: We sampled plant species composition at four distance classes representing different trampling intensities along replicated transects running perpendicular to 20-yr-old hiking trails in the nature reserve. We used a combination of distance-based multivariate methods and a series of univariate tests to study the effects of trampling on a number of conservation-relevant aspects of taxonomic and functional plant community composition and diversity. Results: The different trampling intensities led to a significant variation in plant species composition that was driven by trait-mediated responses, mainly of traits related to dispersal and regeneration, but these patterns only occurred close to the trails (<1.5 m). Except directly on the trails, species richness, the number of habitat specialists and threatened species, as well as Functional Richness were not or marginally affected by trampling. Multivariate dispersion within levels of trampling intensities and evenness, the latter measured for either species or traits, remained constant across the gradient of trampling intensity. Conclusions: Even after 20 yr of exposure to different intensities of trampling, Calcareous Grassland vegetation showed only few and spatially limited compositional responses, while its nature conservation value was not affected. Therefore, marked hiking trails are a good compromise between meeting the needs for recreation and environmental education, and the conservation of threatened habitat specialists and should be preferred to alternatives such as undirected access that would result in spatially extensive changes in community structure.
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Impacts of visitor trampling on the taxonomic and functional community structure of Calcareous Grassland
Applied Vegetation Science, 2015Co-Authors: Timo Conradi, Katharina Strobl, Anna-lena Wurfer, Johannes KollmannAbstract:Question: Does long-term visitor trampling close to hiking trails affect the taxonomic and functional composition and diversity of a Calcareous Grassland, thus reducing its nature conservation value? Location: Ancient Calcareous Grassland (nature reserve Garchinger Heide) in the Munich Gravel Plain, south Germany. Methods: We sampled plant species composition at four distance classes representing different trampling intensities along replicated transects running perpendicular to 20-yr-old hiking trails in the nature reserve. We used a combination of distance-based multivariate methods and a series of univariate tests to study the effects of trampling on a number of conservation-relevant aspects of taxonomic and functional plant community composition and diversity. Results: The different trampling intensities led to a significant variation in plant species composition that was driven by trait-mediated responses, mainly of traits related to dispersal and regeneration, but these patterns only occurred close to the trails (
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mixed evidence for the cultivar vigour hypothesis the case of Calcareous Grassland forbs in a matrix of festuca rubra
Ecological Engineering, 2014Co-Authors: Emer A Walker, Harald Meimberg, Johannes KollmannAbstract:According to the cultivar vigour hypothesis, cultivars are frequently selected for traits such as increased biomass and resource capture, which may hinder the establishment of non-cultivars. Despite this concern, cultivar seed material is still used in Grassland restoration. An alternative is wild plant material, which is commercially produced and used in the respective region (‘regional seed’). We established a greenhouse experiment to examine the performance of cultivar and regional forb species with and without competition from cultivar and regional dominant grass species. This was conducted in order to understand the potential effects of sowing cultivar seed in Grassland restoration projects. Three Calcareous Grassland forb species (Buphthalmum salicifolium, Dianthus carthusianorum and Linum perenne) and one dominant grass species (Festuca rubra ssp. commutata) were selected. One forb species was sown in the centre of each pot and either zero, two or four F. rubra ssp. commutata individuals were planted around it. Above-ground biomass, plant height, leaf length, leaf width, number of leaves and stems were measured. When grown without competitors, each forb species performed differently with only L. perenne exhibiting cultivar vigour. Cultivar forbs were less negatively affected by competition with F. rubra ssp. commutata than their regional counterparts, thus supporting the cultivar vigour hypothesis. Overall, regional F. rubra ssp. commutata suppressed the above-ground biomass of the forbs species more than the cultivar F. rubra ssp. commutata, thus highlighting the potential competitiveness of regional seed. Ultimately, the goals of the restoration project will determine the source of seed material to be used in the project. Due to the complex nature of the issues involved in restoration, it should be considered that the reliance on simple guidelines in relation to the source of seed material used in Grassland restoration has its limitations.
Ellen Kandeler - One of the best experts on this subject based on the ideXlab platform.
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effects of long term co2 enrichment on microbial community structure in Calcareous Grassland
Plant and Soil, 2004Co-Authors: Diana Ebersberger, Pascal A. Niklaus, Nicola Wermbter, Ellen KandelerAbstract:Elevated CO2 generally increases plant productivity, and has been found to alter plant community composition in many ecosystems. Because soil microbes depend on plant-derived C and are often associated with specific plant species, elevated CO2 has the potential to alter structure and functioning of soil microbial communities. We investigated soil microbial community structure of a species-rich semi-natural Calcareous Grassland that had been exposed to elevated CO2 (600 μL L−1) for 6 growing seasons. We analysed microbial community structure using phospholipid fatty acid (PLFA) profiles and DNA fingerprints obtained by Denaturing Gradient Gel Electrophoresis (DGGE) of 16S rDNA fragments amplified by the Polymerase Chain Reaction (PCR).
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long term co2 enrichment stimulates n mineralisation and enzyme activities in Calcareous Grassland
Soil Biology & Biochemistry, 2003Co-Authors: Diana Ebersberger, Pascal A. Niklaus, Ellen KandelerAbstract:Elevated concentration of atmospheric carbon dioxide will affect carbon cycling in terrestrial ecosystems. Possible effects include increased carbon input into the soil through the rhizosphere, altered nutrient concentrations of plant litter and altered soil moisture. Consequently, the ongoing rise in atmospheric carbon dioxide might indirectly influence soil biota, decomposition and nutrient transformations. N-mineralisation and activities of the enzymes invertase, xylanase, urease, protease, arylsulfatase, and alkaline phosphatase were investigated in spring and summer in Calcareous Grassland, which had been exposed to ambient and elevated CO2 concentrations (365 and 600 μl l−1) for six growing seasons. In spring, N-mineralisation increased significantly by 30% at elevated CO2, while there was no significant difference between treatments in summer (+3%). The response of soil enzymes to CO2 enrichment was also more pronounced in spring, when alkaline phosphatase and urease activities were increased most strongly by 32 and 21%. In summer, differences of activities between CO2 treatments were greatest in the case of urease and protease (+21 and +17% at elevated CO2). The stimulation of N-mineralisation and enzyme activities at elevated CO2 was probably caused by higher soil moisture and/or increased root biomass. We conclude that elevated CO2 will enhance below-ground C- and N-cycling in Grasslands.
Peter Poschlod - One of the best experts on this subject based on the ideXlab platform.
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Surrounding landscape structures, rather than habitat age, drive genetic variation of typical Calcareous Grassland plant species
Landscape Ecology, 2020Co-Authors: Theresa Anna Lehmair, Peter Poschlod, Ellen Pagel, Christoph ReischAbstract:Land use change reduced Calcareous Grasslands throughout Europe during the last decades. Subsequent fragmentation and habitat deterioration led, moreover, to a massive biodiversity decline. To counteract this alarming development, a clear understanding of genetic variation patterns, as fundamental level of biodiversity, becomes inevitable. The aim of our study was to identify the drivers of genetic variation in common Calcareous Grassland plant species. More specifically, we tested whether genetic diversity or differentiation of Asperula cynanchica, Campanula rotundifolia, and Linum catharticum depend on habitat age, landscape structure, habitat quality, and/or population size. We investigated 912 individuals, 304 per study species, from 19 Calcareous Grasslands across the Swabian Alb in Baden-Wurttemberg (Germany) using AFLP analyses. We observed no significant influence of habitat age on genetic diversity and differentiation. Habitat quality also had no impact on genetic diversity and population size only showed weak effects. However, genetic diversity strongly depended on landscape structure represented by distance to the nearest settlement, total area of surrounding Calcareous Grasslands, and their connectivity. Migratory sheep herding is considered as main land use in Calcareous Grasslands on the Swabian Alb and thus, landscape structures in the study region may describe movement patterns of grazing livestock. In this study, genetic variation in Calcareous Grassland populations was strongly affected by surrounding landscape structures and subsequent grazing patterns. Therefore, we assume that moderate grazing intensities over the long term may increase levels of genetic diversity, whereas periods of overgrazing or abandonment could lower genetic diversity.
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Surrounding landscape structures, rather than habitat age, drive genetic variation of typical Calcareous Grassland plant species
Landscape Ecology, 2020Co-Authors: Theresa Anna Lehmair, Peter Poschlod, Ellen Pagel, Christoph ReischAbstract:Context Land use change reduced Calcareous Grasslands throughout Europe during the last decades. Subsequent fragmentation and habitat deterioration led, moreover, to a massive biodiversity decline. To counteract this alarming development, a clear understanding of genetic variation patterns, as fundamental level of biodiversity, becomes inevitable. Objectives The aim of our study was to identify the drivers of genetic variation in common Calcareous Grassland plant species. More specifically, we tested whether genetic diversity or differentiation of Asperula cynanchica , Campanula rotundifolia , and Linum catharticum depend on habitat age, landscape structure, habitat quality, and/or population size. Methods We investigated 912 individuals, 304 per study species, from 19 Calcareous Grasslands across the Swabian Alb in Baden-Württemberg (Germany) using AFLP analyses. Results We observed no significant influence of habitat age on genetic diversity and differentiation. Habitat quality also had no impact on genetic diversity and population size only showed weak effects. However, genetic diversity strongly depended on landscape structure represented by distance to the nearest settlement, total area of surrounding Calcareous Grasslands, and their connectivity. Conclusions Migratory sheep herding is considered as main land use in Calcareous Grasslands on the Swabian Alb and thus, landscape structures in the study region may describe movement patterns of grazing livestock. In this study, genetic variation in Calcareous Grassland populations was strongly affected by surrounding landscape structures and subsequent grazing patterns. Therefore, we assume that moderate grazing intensities over the long term may increase levels of genetic diversity, whereas periods of overgrazing or abandonment could lower genetic diversity.
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Dormancy and endosperm presence influence the ex situ conservation potential in central European Calcareous Grassland plants.
Aob Plants, 2019Co-Authors: Simone Tausch, Christoph Reisch, Martin Leipold, Peter PoschlodAbstract:The preservation of plant species under ex situ conditions in seed banks strongly depends on seed longevity. However, detailed knowledge on this seed ecological aspect is limited and comparative studies from central European habitats are scarce. Therefore, we investigated the seed longevity of 39 Calcareous Grassland species in order to assess the prospects of ex situ storage of seeds originating from a single, strongly threatened habitat. Seed longevity (p50 ) was determined by artificially ageing the seeds under rapid ageing conditions (45 °C and 60 % eRH (equilibrium relative humidity)), testing for germination and calculating survival curves. We consulted seed and germination traits that are expected to be related to seed longevity. P50 values strongly varied within Calcareous Grassland species. The p50 values ranged between 3.4 and 282.2 days. We discovered significantly positive effects of physical dormancy and endosperm absence on p50 . Physiological dormancy was associated to comparatively short longevity. These relationships remained significant when accounting for phylogenetic effects. Seed mass, seed shape, and seed coat thickness were not associated with longevity. We therefore recommend more frequent viability assessments of stored endospermic, non-physically and physiologically dormant seeds.
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Molecular markers provide evidence for a broad-fronted recolonisation of the widespread Calcareous Grassland species Sanguisorba minor from southern and cryptic northern refugia.
Plant Biology, 2017Co-Authors: Simone Tausch, Martin Leipold, Peter Poschlod, Christoph ReischAbstract:Calcareous Grasslands belong to the most species-rich and endangered habitats in Europe. However, little is known about the origin of the species typically occurring in these Grasslands. In this study we analysed the glacial and post-glacial history of Sanguisorba minor, a typical plant species frequently occurring in Calcareous Grasslands. The study comprised 38 populations throughout the whole distribution range of the species across Europe. We used molecular markers (AFLP) and applied Bayesian cluster analysis as well as spatial principal components analysis (sPCA) to identify glacial refugia and post-glacial migration routes to Central Europe. Our study revealed significant differences in the level of genetic variation and the occurrence of rare fragments within populations of S. minor and a distinct separation of eastern and western lineages. The analyses uncovered traditional southern but also cryptic northern refugia and point towards a broad fronted post-glacial recolonisation. Based on these results we postulate that incomplete lineage sorting may have contributed to the detected pattern of genetic variation and that S. minor recolonised Central Europe post-glacially from Iberia and northern glacial refugia in France, Belgium or Germany. Our results highlight the importance of refugial areas for the conservation of intraspecific variation in Calcareous Grassland species.
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Mycorrhizal infection indicates the suitability of different management treatments for nature conservation in Calcareous Grassland
Botanica Helvetica, 2009Co-Authors: Markus Bernhardt-römermann, Hans-jörg Brauckmann, Gabriele Broll, Karl-friedrich Schreiber, Peter PoschlodAbstract:The vegetation composition of Calcareous Grasslands in Central Europe is mainly determined by the applied management treatments and the nutrient status of the ecosystems, but these factors cannot clearly be separated. Recently several authors reported a shift in growth-limiting plant nutrients from nitrogen to phosphate. Therefore, we tested the interaction between management and plant available phosphate in a long-term experiment in Southern Germany with different management treatments applied to Calcareous Grassland. We measured mycorrhization rates, which are assumed to be high at low phosphate availability, to explore the interaction between management, phosphate availability and vegetation composition. By correlating mycorrhization rates to vegetation and soil data we found that treatments involving nutrient removal show a greater degree of mycorrhization than treatments leading to nutrient enrichment. According to decreasing suitability for Grassland conservation, the six different management treatments could be ranked as mowing, followed by mulching (twice a year, once a year and every second year), burning and undisturbed succession. It was shown, that mycorrhizal infection rates (1) can be used to evaluate different management treatments for their suitability to conserve the initial vegetation composition, and (2) may provide information about the processes of adaptation to the current management, namely to differences in plant available phosphate. However, as discussed for the undisturbed succession treatment, it might not be sufficient to look at the degree of mycorrhization only. These are related to phosphate availability, but to detect adaptation processes to management, the degree of mycorrhization should be analysed together with plant’s internal nutrient relocation patterns.