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Ann Milbau - One of the best experts on this subject based on the ideXlab platform.
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plant community type and small scale disturbances but not altitude influence the Invasibility in subarctic ecosystems
New Phytologist, 2013Co-Authors: Ann Milbau, Anna Shevtsova, Nora Osler, Maria Mooshammer, Bente J. GraaeAbstract:Little of our knowledge about Invasibility comes from arctic and alpine ecosystems, despite increasing plant migration and invasion in those regions. Here, we examine how community type, altitude, and small-scale disturbances affect Invasibility in a subarctic ecosystem. Over a period of 4 yr, we studied seedling emergence and establishment in 17 species sown in gaps or undisturbed vegetation in four subarctic community types (Salix scrub, meadow, rich heath, poor heath) along an elevation gradient. Invasibility was lowest in rich heath and highest in Salix scrub. Small disturbances significantly increased the Invasibility in most communities, thereby showing the importance of biotic resistance to invasion in subarctic regions. Unexpectedly, Invasibility did not decrease with increasing elevation, and it was also not related to summer temperature. Our data suggest that biotic resistance might be more important than abiotic stress for Invasibility in subarctic tundra and that low temperatures do not necessarily limit seedling establishment at high altitudes. High elevations are therefore potentially more vulnerable to invasion than was originally thought. Changes in community composition as a result of species migration or invasion are most likely to occur in Salix scrub and meadow, whereas Empetrum-dominated rich heath will largely remain unchanged.
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Plant community type and small‐scale disturbances, but not altitude, influence the Invasibility in subarctic ecosystems
The New phytologist, 2012Co-Authors: Ann Milbau, Anna Shevtsova, Nora Osler, Maria Mooshammer, Bente J. GraaeAbstract:Little of our knowledge about Invasibility comes from arctic and alpine ecosystems, despite increasing plant migration and invasion in those regions. Here, we examine how community type, altitude, and small-scale disturbances affect Invasibility in a subarctic ecosystem. Over a period of 4 yr, we studied seedling emergence and establishment in 17 species sown in gaps or undisturbed vegetation in four subarctic community types (Salix scrub, meadow, rich heath, poor heath) along an elevation gradient. Invasibility was lowest in rich heath and highest in Salix scrub. Small disturbances significantly increased the Invasibility in most communities, thereby showing the importance of biotic resistance to invasion in subarctic regions. Unexpectedly, Invasibility did not decrease with increasing elevation, and it was also not related to summer temperature. Our data suggest that biotic resistance might be more important than abiotic stress for Invasibility in subarctic tundra and that low temperatures do not necessarily limit seedling establishment at high altitudes. High elevations are therefore potentially more vulnerable to invasion than was originally thought. Changes in community composition as a result of species migration or invasion are most likely to occur in Salix scrub and meadow, whereas Empetrum-dominated rich heath will largely remain unchanged.
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The Role of Species Traits (Invasiveness) and Ecosystem Characteristics (Invasibility) in Grassland Invasions: A Framework1
Weed Technology, 2004Co-Authors: Ann Milbau, Ivan NijsAbstract:A framework was created based on the results of two experimental studies on invasiveness and Invasibility. It shows us that grassland ecosystems are more invasible if the availability of nitrogen and light is high, whereas high aboveground biomass and high species richness reduce their Invasibility. To restrict invasions, increasing the species richness of grasslands seems to be an ap- propriate management practice. A combined study of invader and ecosystem traits is needed to successfully predict invasions.
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Disentangling invasiveness and Invasibility during invasion in synthesized grassland communities
New Phytologist, 2003Co-Authors: Ann Milbau, Ivan Nijs, Liesbeth Van Peer, Dirk Reheul, Benny De CauwerAbstract:Summary • An experiment with synthesized grassland communities was performed to identify plant traits that contribute to invasiveness and community traits that promote Invasibility, and to study the relationship between, and the relative importance of, invasiveness and Invasibility. • Eight perennial grass species were used both as invasible monocultures and as potential invaders in gaps in these monocultures. Invasion success in the establishment phase, and invader and monoculture traits were assessed. • Invasion success expressed as germination correlated significantly with germination time (invader trait), light penetration in the gaps and N acquisition by the edge plants (monoculture traits). Success expressed as leaf length correlated with seed mass, germination time (invader traits) and light penetration. Forty-six per cent of the variation in germination was explained by invader identity and 8% by monoculture identity, whereas, for leaf length, they explained 15% and 18%, respectively. • Regenerative traits (seed mass and germination time) correlated with invasiveness, and resource availability (light and nitrogen) with Invasibility. The results suggest that species characteristics would largely determine the extent of an invasion event (number of seedlings), while the success of individual invaders (growth and survival) is determined by both species and ecosystem characteristics.
Bente J. Graae - One of the best experts on this subject based on the ideXlab platform.
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plant community type and small scale disturbances but not altitude influence the Invasibility in subarctic ecosystems
New Phytologist, 2013Co-Authors: Ann Milbau, Anna Shevtsova, Nora Osler, Maria Mooshammer, Bente J. GraaeAbstract:Little of our knowledge about Invasibility comes from arctic and alpine ecosystems, despite increasing plant migration and invasion in those regions. Here, we examine how community type, altitude, and small-scale disturbances affect Invasibility in a subarctic ecosystem. Over a period of 4 yr, we studied seedling emergence and establishment in 17 species sown in gaps or undisturbed vegetation in four subarctic community types (Salix scrub, meadow, rich heath, poor heath) along an elevation gradient. Invasibility was lowest in rich heath and highest in Salix scrub. Small disturbances significantly increased the Invasibility in most communities, thereby showing the importance of biotic resistance to invasion in subarctic regions. Unexpectedly, Invasibility did not decrease with increasing elevation, and it was also not related to summer temperature. Our data suggest that biotic resistance might be more important than abiotic stress for Invasibility in subarctic tundra and that low temperatures do not necessarily limit seedling establishment at high altitudes. High elevations are therefore potentially more vulnerable to invasion than was originally thought. Changes in community composition as a result of species migration or invasion are most likely to occur in Salix scrub and meadow, whereas Empetrum-dominated rich heath will largely remain unchanged.
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Plant community type and small‐scale disturbances, but not altitude, influence the Invasibility in subarctic ecosystems
The New phytologist, 2012Co-Authors: Ann Milbau, Anna Shevtsova, Nora Osler, Maria Mooshammer, Bente J. GraaeAbstract:Little of our knowledge about Invasibility comes from arctic and alpine ecosystems, despite increasing plant migration and invasion in those regions. Here, we examine how community type, altitude, and small-scale disturbances affect Invasibility in a subarctic ecosystem. Over a period of 4 yr, we studied seedling emergence and establishment in 17 species sown in gaps or undisturbed vegetation in four subarctic community types (Salix scrub, meadow, rich heath, poor heath) along an elevation gradient. Invasibility was lowest in rich heath and highest in Salix scrub. Small disturbances significantly increased the Invasibility in most communities, thereby showing the importance of biotic resistance to invasion in subarctic regions. Unexpectedly, Invasibility did not decrease with increasing elevation, and it was also not related to summer temperature. Our data suggest that biotic resistance might be more important than abiotic stress for Invasibility in subarctic tundra and that low temperatures do not necessarily limit seedling establishment at high altitudes. High elevations are therefore potentially more vulnerable to invasion than was originally thought. Changes in community composition as a result of species migration or invasion are most likely to occur in Salix scrub and meadow, whereas Empetrum-dominated rich heath will largely remain unchanged.
Andreas Y. Troumbis - One of the best experts on this subject based on the ideXlab platform.
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Long-term Invasibility patterns in Mediterranean grasslands of varying initial diversities
Journal of Biological Research, 2012Co-Authors: Alexandros Galanidis, Andreas Y. Troumbis, Panayiotis G. DimitrakopoulosAbstract:This paper reports the findings of a long-term natural Invasibility field study, in experimental Mediterranean grasslands of varying initial diversities and compositions. The study aims to explore the relationship between the initial planted species richness and composition, and the various Invasibility components five years after the cessation of weeding of communities. During our experiment, the local species pools of communities with 1, 2, 4, 8, and 18 plant species were kept closed for three years and subsequently opened to natural invasion. Species richness, density and biomass of initial and invading species were monitored in the communities. Values of the Jaccard similarity index of all species in communities decreased over time and their turnover rate increased. External invader cohorts became more similar over time, with their similarity significantly reduced in high species richness plots. Invasibility components significantly declined across the initial species richness gradient. Invasion patterns across the initial richness gradient were constant during the time of the experiment as no significant ‘initial species richness x year’ interactions were observed. Initial species richness significantly affected external invader biomass. Canopy height eliminated the effect of initial species richness on external invader biomass. Invasion significantly declined with an increase in initial species dominance (i.e. their absolute and fractional biomass). Differences in initial species dominance across the experimental speciesrichness gradient fully explained the effect of initial species richness on Invasibility. Consequently, species-rich communities supporting a taller and denser canopy and a higher initial species biomass than species-poor ones are less prone to invasions as they represent stronger competitive environments.
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Short-term Invasibility patterns in burnt and unburnt experimental Mediterranean grassland communities of varying diversities.
Oecologia, 2005Co-Authors: Panayiotis G. Dimitrakopoulos, Alexandros Galanidis, A.-s. D. Siamantziouras, Andreas Y. TroumbisAbstract:This paper reports the findings of a short-term natural Invasibility field study in constructed Mediterranean herbaceous communities of varying diversities, under a fire treatment. Three components of Invasibility, i.e. species richness, density and biomass of invaders, have been monitored in burnt and unburnt experimental plots with resident diversity ranging from monocultures to 18-species mixtures. In general, species richness, density and biomass of invaders decreased significantly with the increase of resident species richness. Furthermore, the density and biomass of invading species were significantly influenced by the species composition of resident communities. Although aboveground biomass, leaf area index, canopy height and percent bare ground of the resident communities explained a significant part of the variation in the success of invading species, these covariates did not fully explain the effects of resident species richness. Fire mainly influenced Invasibility via soil nutrient levels. The effect of fire on observed Invasibility patterns seems to be less important than the effects of resident species richness. Our results demonstrate the importance of species richness and composition in controlling the initial stages of plant invasions in Mediterranean grasslands but that there was a lack of interaction with the effects of fire disturbance.
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Components of short-term Invasibility in experimental Mediterranean grasslands
Oikos, 2002Co-Authors: Andreas Y. Troumbis, Alexis Galanidis, Giorgos D. KokkorisAbstract:Troumbis, A. Y., Galanidis, A. and Kokkoris, G. D. 2002. Components of short-term Invasibility in experimental Mediterranean grasslands. – Oikos 98: 239–250.The paper reports findings of a natural Invasibility study in constructed Mediter-ranean grasslands, located in the Greek site of the BIODEPTH project. Threedifferent components of Invasibility, i.e. species richness, abundance and rarity ofinvaders, have been monitored in experimental plots where the resident diversityranged from monocultures to 18-species mixtures. Invaders’ richness and abundancewere negatively correlated to the resident diversity, while the occurrence of rareinvaders was strongly positively correlated to the resident diversity. Standing biomassexplained also a significant part of the variation of communities’ Invasibility. Soilnutrients and structural traits of the constructed vegetation such as the space-fillingshowed no influence in the definition of the overall pattern of Invasibility in thesecommunities. A verbal model of selection of invaders at the neighbourhood scale isproposed to explain these diverging trends of Invasibility.
Anke Jentsch - One of the best experts on this subject based on the ideXlab platform.
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Invasibility of grassland and heath communities exposed to extreme weather events additive effects of diversity resistance and fluctuating physical environment
Oikos, 2008Co-Authors: Juergen Kreyling, Carl Beierkuhnlein, Laura C. Ellis, Anke JentschAbstract:Understanding the resistance of plant communities to invasion is urgent in times of changes in the physical environment due to climate change and changes in the resident communities due to biodiversity loss. Here, we test the interaction between repeated drought or heavy rainfall events and functional diversity of grassland and heath communities on Invasibility, measured as the number of plant individuals invading from the matrix vegetation. Invasibility of experimental plant communities was influenced by extreme weather events, although no change in above-ground productivity of the resident communities was observed. Drought decreased Invasibility while heavy rainfall increased Invasibility, a pattern that is consistent with the fluctuating resource hypothesis. Higher community diversity generally decreased Invasibility, which can be explained by a combination of the fluctuating resource hypothesis and niche theory. The effects of the physical environment (extreme weather events) and diversity resistance (community composition) were additive, as they were independent from each other. Differences in the composition of invading species sets were found, and Indicator Species Analysis revealed several invading species with significant affinity to one particular extreme weather event or community composition. This finding supports niche theory and contradicts neutral species assembly. Our data supports theories which predict decreased resistance of plant communities due to both increased climate variability and biodiversity loss. The effects of these two factors, however, appear to be independent from each other.
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Invasibility of grassland and heath communities exposed to extreme weather events – additive effects of diversity resistance and fluctuating physical environment
Oikos, 2008Co-Authors: Juergen Kreyling, Carl Beierkuhnlein, Laura C. Ellis, Anke JentschAbstract:Understanding the resistance of plant communities to invasion is urgent in times of changes in the physical environment due to climate change and changes in the resident communities due to biodiversity loss. Here, we test the interaction between repeated drought or heavy rainfall events and functional diversity of grassland and heath communities on Invasibility, measured as the number of plant individuals invading from the matrix vegetation. Invasibility of experimental plant communities was influenced by extreme weather events, although no change in above-ground productivity of the resident communities was observed. Drought decreased Invasibility while heavy rainfall increased Invasibility, a pattern that is consistent with the fluctuating resource hypothesis. Higher community diversity generally decreased Invasibility, which can be explained by a combination of the fluctuating resource hypothesis and niche theory. The effects of the physical environment (extreme weather events) and diversity resistance (community composition) were additive, as they were independent from each other. Differences in the composition of invading species sets were found, and Indicator Species Analysis revealed several invading species with significant affinity to one particular extreme weather event or community composition. This finding supports niche theory and contradicts neutral species assembly. Our data supports theories which predict decreased resistance of plant communities due to both increased climate variability and biodiversity loss. The effects of these two factors, however, appear to be independent from each other.
Giorgos D. Kokkoris - One of the best experts on this subject based on the ideXlab platform.
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Components of short-term Invasibility in experimental Mediterranean grasslands
Oikos, 2002Co-Authors: Andreas Y. Troumbis, Alexis Galanidis, Giorgos D. KokkorisAbstract:Troumbis, A. Y., Galanidis, A. and Kokkoris, G. D. 2002. Components of short-term Invasibility in experimental Mediterranean grasslands. – Oikos 98: 239–250.The paper reports findings of a natural Invasibility study in constructed Mediter-ranean grasslands, located in the Greek site of the BIODEPTH project. Threedifferent components of Invasibility, i.e. species richness, abundance and rarity ofinvaders, have been monitored in experimental plots where the resident diversityranged from monocultures to 18-species mixtures. Invaders’ richness and abundancewere negatively correlated to the resident diversity, while the occurrence of rareinvaders was strongly positively correlated to the resident diversity. Standing biomassexplained also a significant part of the variation of communities’ Invasibility. Soilnutrients and structural traits of the constructed vegetation such as the space-fillingshowed no influence in the definition of the overall pattern of Invasibility in thesecommunities. A verbal model of selection of invaders at the neighbourhood scale isproposed to explain these diverging trends of Invasibility.
