| 1. |
- Loydi, Alejandro, et al.
(författare)
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Opposite effects of litter and hemiparasites on a dominant grass under different water regimes and competition levels
- 2018
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Ingår i: Plant Ecology. - : Springer Science and Business Media LLC. - 1385-0237 .- 1573-5052. ; 219:2, s. 133-144
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Tidskriftsartikel (refereegranskat)abstract
- Direct and indirect biotic interactions may affect plant growth and development, but the magnitude of these effects may vary depending on environmental conditions. In grassland ecosystems, competition is a strong structuring force. Nonetheless, if hemiparasitic plant species are introduced the competition intensity caused by the dominant species may be affected. However, the outcome of these interactions may change between wet or dry periods. In order to study this, we performed a pot experiment with different densities of the dominant species Schedonorus arundinaceus (1, 2 or 4 individuals) under constantly moist or intermittently dry conditions. The different Schenodorus densities were crossed with presence or absence of hemiparasites (either Rhinanthus minor or R. alectorolophus). Additionally, pots remained with bare ground or received a grass litter layer (400 g m(-2)). We expected that indirect litter effects on vegetation (here Schedonorus or Rhinanthus) vary depending on soil moisture. We measured Schedonorus and Rhinanthus aboveground biomass and C stable isotope signature (delta C-13) as response variables. Overall, Schedonorus attained similar biomass under moist conditions with Rhinanthus as in pots under dry conditions without Rhinanthus. Presence of Rhinanthus also increased delta C-13 in moist pots, indicating hemiparasite-induced water stress. Litter presence increased Schedonorus biomass and reduced delta C-13, indicating improved water availability. Plants under dry conditions with litter showed similar biomass as under wet conditions without litter. Hemiparasites and litter had opposite effects: hemiparasites reduced Schedonorus biomass while litter presence facilitated grass growth. Contrary to our expectations, litter did not compensate Schedonorus biomass when Rhinanthus was present.
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| 2. |
- Ludewig, Kristin, et al.
(författare)
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Phenology and morphology of the invasive legume Lupinus polyphyllus along a latitudinal gradient in Europe
- 2022
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Ingår i: NeoBiota. - : Pensoft Publishers. - 1619-0033 .- 1314-2488. ; 78
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Tidskriftsartikel (refereegranskat)abstract
- Plant phenology, i. e. the timing of life cycle events, is related to individual fitness and species distributionranges. Temperature is one of the most important drivers of plant phenology together with day length.The adaptation of their phenology may be important for the success of invasive plant species. The presentstudy aims at understanding how the performance and the phenology of the invasive legume Lupinuspolyphyllus vary with latitude. We sampled data across a >2000 km latitudinal gradient from Centralto Northern Europe. We quantified variation in phenology of flowering and fruiting of L. polyphyllususing >1600 digital photos of inflorescences from 220 individual plants observed weekly at 22 sites. Theday of the year at which different phenological phases were reached, increased 1.3–1.8 days per degreelatitude, whereas the growing degree days (gdd) required for these phenological phases decreased 5–16 gddper degree latitude. However, this difference disappeared, when the day length of each day included inthe calculation of gdd was considered. The day of the year of the earliest and the latest climatic zone toreach any of the three studied phenological phases differed by 23–30 days and temperature requirementsto reach these stages differed between 62 and 236 gdd. Probably, the invasion of this species will furtherincrease in the northern part of Europe over the next decades due to climate warming. For invasive speciescontrol, our results suggest that in countries with a large latitudinal extent, the mowing date should shiftby ca. one week per 500 km at sites with similar elevations.
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| 3. |
- Ludewig, Kristin, et al.
(författare)
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Phenology of Lupinus polyphyllus from Central to Northern Europe
- 2022
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Annan publikationabstract
- Plant phenology, i. e. the timing of life cycle events, is related to individual fitness and species distribution ranges. Among the environmental factors, phenology is mostly driven by temperature and day length. Rapid adaptation of their phenology may also be important for the success of invasive plant species. Our main aim was to understand how the performance, timing, and temperature dependence of the phenology of the invasive legume Lupinus polyphyllus varies with latitude. L. polyphyllus is one of the most frequent invasive species in Europe, and the gained information may help to make management more effective by adjustments to latitude and phenology.Methods:We quantified variation in phenology across a >2000 km latitudinal gradient from Central to Northern Europe. We sampled data of flowering and fruiting of L. polyphyllus using >1600 digital photos of inflorescences from 220 individual plants observed weekly at 22 locations. We calculated the accumulated growing degree days for each observation date at each site from the temperature data of the meteorological stations, which are listed in the metadata of the dataset.
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| 4. |
- Burmeier, Sandra, et al.
(författare)
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Desiccation cracks act as natural seed traps in flood-meadow systems
- 2010
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Ingår i: Plant and Soil. - : Springer Science and Business Media LLC. - 0032-079X .- 1573-5036. ; 333:1-2, s. 351-364
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 5. |
- Burmeier, Sandra, et al.
(författare)
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Plant Pattern Development during Early Post-Restoration Succession in Grasslands-A Case Study of Arabis nemorensis
- 2011
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Ingår i: Restoration Ecology. - 1061-2971 .- 1526-100X. ; 19:5, s. 648-659
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 6. |
- Burmeier, Sandra, et al.
(författare)
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Rapid burial has differential effects on germination and emergence of small- and large-seeded herbaceous plant species
- 2010
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Ingår i: Seed Science Research. - 0960-2585 .- 1475-2735. ; 20:3, s. 189-200
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 7. |
- Burmeier, Sandra, et al.
(författare)
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Spatially-restricted plant material application creates colonization initials for flood-meadow restoration
- 2011
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Ingår i: Biological Conservation. - : Elsevier BV. - 0006-3207 .- 1873-2917. ; 144:1, s. 212-219
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 8. |
- Donath, Tobias W., et al.
(författare)
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Effects of bryophytes and grass litter on seedling emergence vary by vertical seed position and seed size
- 2010
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Ingår i: Plant Ecology. - : Springer Science and Business Media LLC. - 1385-0237 .- 1573-5052. ; 207:2, s. 257-268
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 9. |
- Donath, Tobias W., et al.
(författare)
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Grass and oak litter exert different effects on seedling emergence of herbaceous perennials from grasslands and woodlands
- 2008
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Ingår i: Journal of Ecology. - : Wiley. - 0022-0477 .- 1365-2745. ; 96:2, s. 272-280
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 10. |
- Eckstein, Rolf Lutz, et al.
(författare)
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Invasibility of a Nutrient-Poor Pasture through Resident and Non-Resident Herbs Is Controlled by Litter, Gap Size and Propagule Pressure
- 2012
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 7:7
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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