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Laurent Hazard - One of the best experts on this subject based on the ideXlab platform.
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Endophytic fungus fine-tunes the persistence strategy of its alpine host grass in response to Soil Resource levels
Oikos, 2013Co-Authors: Anaïs Gibert, Daniele Magda, Laurent HazardAbstract:An understanding of hereditary endophytic fungi, and the effects on grass persistence strategies (i.e. relative investment in sexual reproduction and vegetative growth) under natural conditions may help to predict how some alpine ecosystems will respond to environmental change. Grass persistence and endophyte maintenance in host populations are closely related, but could become independent due to endophyte loss mechanisms. We used native grass and endophyte populations to test the hypothesis that fungal endophytes manipulate grass persistence strategies to secure endophyte maintenance in plant populations. Two conditions were required to verify this hypothesis: 1) the fungus caused alterations in host plant strategies; and 2) plant phenotypic changes induced by the fungal endophyte increased endophyte transmission. We compared symbiotic (S) and non-symbiotic (NS) persistence strategies of Festuca eskia (Poaceae), an alpine grass infected by the asexual form of the fungal endophyte Epichloë festucae. We characterised endophyte transmission efficiency, and described vegetative growth and sexual reproduction in a field population that naturally supports approximately 50% S plants. We built a demographic model to estimate plant vegetative growth rates. A correlation between plant persistence strategy, and fungal maintenance was evaluated by increasing Soil Resource levels. Under natural conditions, S and NS plants exploited different persistence strategies in the same population; S plants exhibited greater vegetative growth than their NS counterparts, while maintaining the same reproductive output. In response to higher Soil Resource levels, S plants shifted in persistence strategies and phenology, whereas NS plants maintained the same strategies. Therefore, results suggested the fungal endophyte fine-tuned host persistence strategies according to Soil Resource level. Finally, we found no direct relationship between the changes induced by fungal endophyte and endophyte transmission. Consequently, fungal endophytes affected host persistence strategies, but did not directly increase endophyte transmission.
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Endophytic fungus fine‐tunes the persistence strategy of its alpine host grass in response to Soil Resource levels
Oikos, 2012Co-Authors: Anaïs Gibert, Daniele Magda, Laurent HazardAbstract:An understanding of hereditary endophytic fungi, and the effects on grass persistence strategies (i.e. relative investment in sexual reproduction and vegetative growth) under natural conditions may help to predict how some alpine ecosystems will respond to environmental change. Grass persistence and endophyte maintenance in host populations are closely related, but could become independent due to endophyte loss mechanisms. We used native grass and endophyte populations to test the hypothesis that fungal endophytes manipulate grass persistence strategies to secure endophyte maintenance in plant populations. Two conditions were required to verify this hypothesis: 1) the fungus caused alterations in host plant strategies; and 2) plant phenotypic changes induced by the fungal endophyte increased endophyte transmission. We compared symbiotic (S) and non-symbiotic (NS) persistence strategies of Festuca eskia (Poaceae), an alpine grass infected by the asexual form of the fungal endophyte Epichloe festucae. We characterised endophyte transmission efficiency, and described vegetative growth and sexual reproduction in a field population that naturally supports approximately 50% S plants. We built a demographic model to estimate plant vegetative growth rates. A correlation between plant persistence strategy, and fungal maintenance was evaluated by increasing Soil Resource levels. Under natural conditions, S and NS plants exploited different persistence strategies in the same population; S plants exhibited greater vegetative growth than their NS counterparts, while maintaining the same reproductive output. In response to higher Soil Resource levels, S plants shifted in persistence strategies and phenology, whereas NS plants maintained the same strategies. Therefore, results suggested the fungal endophyte fine-tuned host persistence strategies according to Soil Resource level. Finally, we found no direct relationship between the changes induced by fungal endophyte and endophyte transmission. Consequently, fungal endophytes affected host persistence strategies, but did not directly increase endophyte transmission.
Aveliina Helm - One of the best experts on this subject based on the ideXlab platform.
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Invasion of woody species into temperate grasslands: Relationship with abiotic and biotic Soil Resource heterogeneity
Journal of Vegetation Science, 2007Co-Authors: Meelis Pärtel, Aveliina HelmAbstract:Question: Invasion of woody species into grasslands is a global phenomenon. This is also topical in semi-natural temperate grasslands that are no longer profitable for agricultural management. Trees and grasses interact through harsh root competition, but below-ground processes have been neglected in the dynamics of semi-natural grasslands. Trees are thought to have a competitive advantage in Resource-rich and heterogeneous Soils. We tested whether Soil Resource quantity and heterogeneity differ between paired temperate semi-natural grasslands and forests (former grasslands), and whether this was caused abiotically by varying Soil depth or biotically by fine roots. Location: Thin-Soil calcareous alvar grasslands with overgrown parts (young Pinus sylvestris forests) in W. Estonia. Methods: The quantity and spatial heterogeneity of Soil Resources (moisture and nutrients), Soil depth, and root parameters (mass, length and specific length) were measured in 1-m transects of 11 samples in 26 paired grasslands and forests. The quantity and heterogeneity of Soil Resources were compared between vegetation types and related to Soil depth and root parameters. Results: Soil Resources were lower and more heterogeneous in forests than in grasslands. The invasion of woody species was enhanced abiotically by deeper Soil. Root mass was larger in the forests, but root length was longer in the grasslands. Both root mass and specific root length were more heterogeneous in the forests. Forest root length was negatively correlated with transient Soil moisture patches and positively correlated with more persistent nutrient-rich patches. No such relationship was found in grasslands. Conclusions: Abiotic Soil heterogeneity (local deep-Soil patches) supports woody species invasion, but the trees themselves also biotically make Soils more heterogeneous, which further enhances woody species invasion. Large trees use Soil Resources patchily, making Soils biotically poorer and more heterogeneous in Resources. The dynamics of temperate semi-natural grasslands are strongly linked to below-ground ecological processes, and high Soil heterogeneity can be both the cause and the outcome of woody species invasion.
Scott D. Wilson - One of the best experts on this subject based on the ideXlab platform.
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Fine root response to Soil Resource heterogeneity differs between grassland and forest
Plant Ecology, 2013Co-Authors: Bradley D. Pinno, Scott D. WilsonAbstract:Soil Resource heterogeneity has clear effects on plant root development and overall plant performance. Here we test whether contrasting vegetation types have similar or different responses to Soil patches of differing Resource availability. We examined the fine root responses of grassland and forest vegetation at the northern edge of the Great Plains to transplanted patches of Resource-poor and Resource-rich Soils, using rhizotron imaging. Every aspect of measured root behavior, including root length, production, mortality, turnover, variability and size distribution, varied significantly between patch types, and most aspects also varied between vegetation types. Most importantly, differential responses to patches between grassland and forest were shown by significant interactions between patch type and vegetation for two response variables. First, root length variability was significantly lower in Resource-rich compared to Resource-poor patches in forest but not grassland. Second, the proportion of very fine roots was significantly greater in Resource-rich than Resource-poor patches in forests but not grassland. Thus, compared to grassland, forest more fully occupied Resource-rich patches relative to Resource-poor patches by allocating more growth to very fine roots. We report the first example of significant differences between vegetation types (grassland and forest) in root responses to Soil Resource heterogeneity measured in a field experiment. The relatively high ability of forest roots to more fully occupy Resource-rich patches is consistent with the global expansion of woody vegetation and associated increases in Soil heterogeneity.
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Vegetation Effects on Soil Resource Heterogeneity in Prairie And Forest
The American naturalist, 1997Co-Authors: Heather R. Kleb, Scott D. WilsonAbstract:Abstract A current, widespread example of vegetation change is the invasion of grassland by woody plants. This is associated with an increase in Soil heterogeneity, and it has been argued that woody plants both cause and benefit from high heterogeneity. We know of no experimental demonstrations of differences between grasses and woody plants in their effects on heterogeneity. Here we compare heterogeneity between mixed‐grass prairie and aspen forest, and we report the results of a Soil transplant experiment that tested for differences between these vegetation types in their effects on Soil Resource heterogeneity. We measured the heterogeneity of Resources and plant mass along 10 transects in both prairie and aspen forest in spring and summer. Light and available nitrogen (N; sum of ammonium and nitrate) were significantly more variable in forest than prairie, as were root and understory shoot mass. The variability of Soil moisture and topography did not differ between prairie and forest. In our experiment...
Anaïs Gibert - One of the best experts on this subject based on the ideXlab platform.
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Endophytic fungus fine-tunes the persistence strategy of its alpine host grass in response to Soil Resource levels
Oikos, 2013Co-Authors: Anaïs Gibert, Daniele Magda, Laurent HazardAbstract:An understanding of hereditary endophytic fungi, and the effects on grass persistence strategies (i.e. relative investment in sexual reproduction and vegetative growth) under natural conditions may help to predict how some alpine ecosystems will respond to environmental change. Grass persistence and endophyte maintenance in host populations are closely related, but could become independent due to endophyte loss mechanisms. We used native grass and endophyte populations to test the hypothesis that fungal endophytes manipulate grass persistence strategies to secure endophyte maintenance in plant populations. Two conditions were required to verify this hypothesis: 1) the fungus caused alterations in host plant strategies; and 2) plant phenotypic changes induced by the fungal endophyte increased endophyte transmission. We compared symbiotic (S) and non-symbiotic (NS) persistence strategies of Festuca eskia (Poaceae), an alpine grass infected by the asexual form of the fungal endophyte Epichloë festucae. We characterised endophyte transmission efficiency, and described vegetative growth and sexual reproduction in a field population that naturally supports approximately 50% S plants. We built a demographic model to estimate plant vegetative growth rates. A correlation between plant persistence strategy, and fungal maintenance was evaluated by increasing Soil Resource levels. Under natural conditions, S and NS plants exploited different persistence strategies in the same population; S plants exhibited greater vegetative growth than their NS counterparts, while maintaining the same reproductive output. In response to higher Soil Resource levels, S plants shifted in persistence strategies and phenology, whereas NS plants maintained the same strategies. Therefore, results suggested the fungal endophyte fine-tuned host persistence strategies according to Soil Resource level. Finally, we found no direct relationship between the changes induced by fungal endophyte and endophyte transmission. Consequently, fungal endophytes affected host persistence strategies, but did not directly increase endophyte transmission.
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Endophytic fungus fine‐tunes the persistence strategy of its alpine host grass in response to Soil Resource levels
Oikos, 2012Co-Authors: Anaïs Gibert, Daniele Magda, Laurent HazardAbstract:An understanding of hereditary endophytic fungi, and the effects on grass persistence strategies (i.e. relative investment in sexual reproduction and vegetative growth) under natural conditions may help to predict how some alpine ecosystems will respond to environmental change. Grass persistence and endophyte maintenance in host populations are closely related, but could become independent due to endophyte loss mechanisms. We used native grass and endophyte populations to test the hypothesis that fungal endophytes manipulate grass persistence strategies to secure endophyte maintenance in plant populations. Two conditions were required to verify this hypothesis: 1) the fungus caused alterations in host plant strategies; and 2) plant phenotypic changes induced by the fungal endophyte increased endophyte transmission. We compared symbiotic (S) and non-symbiotic (NS) persistence strategies of Festuca eskia (Poaceae), an alpine grass infected by the asexual form of the fungal endophyte Epichloe festucae. We characterised endophyte transmission efficiency, and described vegetative growth and sexual reproduction in a field population that naturally supports approximately 50% S plants. We built a demographic model to estimate plant vegetative growth rates. A correlation between plant persistence strategy, and fungal maintenance was evaluated by increasing Soil Resource levels. Under natural conditions, S and NS plants exploited different persistence strategies in the same population; S plants exhibited greater vegetative growth than their NS counterparts, while maintaining the same reproductive output. In response to higher Soil Resource levels, S plants shifted in persistence strategies and phenology, whereas NS plants maintained the same strategies. Therefore, results suggested the fungal endophyte fine-tuned host persistence strategies according to Soil Resource level. Finally, we found no direct relationship between the changes induced by fungal endophyte and endophyte transmission. Consequently, fungal endophytes affected host persistence strategies, but did not directly increase endophyte transmission.
John P. Gerlach - One of the best experts on this subject based on the ideXlab platform.
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Intraspecific growth and functional leaf trait responses to natural Soil Resource gradients for conifer species with contrasting leaf habit.
Tree physiology, 2013Co-Authors: Michael B. Walters, John P. GerlachAbstract:Interspecific relationships among species mean leaf traits, performance and species Resource/climate distributions help provide the foundation for a predictive, functionally based plant ecology. Intraspecific responses of leaf traits and performance to Resource gradients and how these vary among species may be equally important but have received less attention. Here, we examine relationships between proxies of Soil Resource availability, leaf traits and growth (height at 25 years, SI25) for winter deciduous Larix decidua Mill. and evergreen Pinus resinosa Ait. trees distributed over Soil Resource gradients in the Great Lakes region of North America. We predicted that (i) leaf trait responses to Soil Resources within species will be similar to reported distributions of mean leaf traits over Soil Resource gradients among species; (ii) Soil Resource-related variation in leaf traits can help explain SI25; and (iii) SI25 will be greater for Larix than Pinus at higher Soil Resources and greater for Pinus than Larix at lower Soil Resources and this pattern will be associated with species differences in leaf trait responses to Soil Resources. Among the measured leaf traits (live N, Mg, Ca, K, P, and Mn, litter N, N resorption, carbon isotope discrimination, specific leaf area, lifespan), Soil Resources only impacted live and litter N for both species and K for Pinus. In turn, only the leaf traits responsive to Soil Resources affected SI25 in the expected manner. Larix had greater SI25 than Pinus across Soil Resource gradients and both species had similar growth and leaf trait sensitivities to Resources. In summary: (i) several leaf traits reported to be associated with performance and edaphic distributions across species were, within species, unresponsive to nitrogen and water availability and unrelated to growth; (ii) leaf N showed high plasticity to Soil Resources and this plasticity was functionally relevant to growth over its entire range of response; (iii) large species-level differences in leaf traits between Larix and Pinus did not translate into different leaf trait and growth responses to Soil Resources.