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Knut Kielland - One of the best experts on this subject based on the ideXlab platform.
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Effects of livestock grazing on the spatial Heterogeneity of net Soil nitrogen mineralization in three types of Mongolian grasslands
Journal of Soils and Sediments, 2013Co-Authors: Muneto Hirobe, Junji Kondo, Altangerel Enkhbaatar, Narantsetseg Amartuvshin, Noboru Fujita, Keiji Sakamoto, Ken Yoshikawa, Knut KiellandAbstract:Purpose Small-scale Soil Heterogeneity relates to productivity and biodiversity and is crucial to understand. Soil Heterogeneity could be affected by vegetation structure, and large mammal grazers could modify it through herbivory and excretion. The objective is to clarify the effects of livestock grazing on the small-scale (∼3 m) Soil Heterogeneity in three types of Mongolian grasslands. Materials and methods We sampled Soils from inside (ungrazed) and outside (grazed) exclosures in three vegetation types: forest-steppe, shrub-steppe, and desert-steppe. We measured laboratory rates of Soil net nitrogen (N) mineralization and net nitrification and geostatistically analyzed Heterogeneity. Results and discussion Average rates of net N mineralization and net nitrification were lower at shrub-steppe and desert-steppe and were decreased by grazing. Semivariograms showed vegetation-induced Heterogeneity in ungrazed plots, except for net nitrification at forest-steppe. We found linear change with distance under dense and uniform vegetation at forest-steppe, 1.3 m patch under patchy vegetation at shrub-steppe, and linear change, but with much smaller semivariance, under sparse and poor vegetation at desert-steppe. At forest-steppe, grazing randomized the spatial patterns of net N mineralization and net nitrification. At shrub-steppe and desert-steppe, grazing greatly decreased the semivariances of net N mineralization and net nitrification as well as their averages, and the Soil Heterogeneity was virtually disappeared. Conclusions Grazing in Mongolian grasslands homogenized the spatial patterns of net N mineralization and net nitrification, irrespective of their original spatial patterns determined by the differences in vegetation structure.
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Effects of livestock grazing on the spatial Heterogeneity of net Soil nitrogen mineralization in three types of Mongolian grasslands
Journal of Soils and Sediments, 2013Co-Authors: Muneto Hirobe, Junji Kondo, Altangerel Enkhbaatar, Narantsetseg Amartuvshin, Noboru Fujita, Keiji Sakamoto, Ken Yoshikawa, Knut KiellandAbstract:Purpose Small-scale Soil Heterogeneity relates to productivity and biodiversity and is crucial to understand. Soil Heterogeneity could be affected by vegetation structure, and large mammal grazers could modify it through herbivory and excretion. The objective is to clarify the effects of livestock grazing on the small-scale (∼3 m) Soil Heterogeneity in three types of Mongolian grasslands.
Jean H. Burns - One of the best experts on this subject based on the ideXlab platform.
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Light Heterogeneity interacts with plant-induced Soil Heterogeneity to affect plant trait expression
Plant Ecology, 2015Co-Authors: Gaston A. Del Pino, Angela J. Brandt, Jean H. BurnsAbstract:Phenotypic plasticity, the expression of traits dependent on an individual’s environment, should increase the range of communities in which a plant can establish, potentially influencing community assembly. Plasticity may be induced by either the mean or variance in conditions; however, plant responses to variance in the environment remain largely unquantified. We conducted a greenhouse experiment in northeastern Ohio using two congeneric pairs of perennial species in a design that crossed two Soil Heterogeneity and two light Heterogeneity treatments. Nested within the Soil Heterogeneity treatment were patches of congener and conspecific origin, which tests the effects of possible plant-Soil feedbacks on trait expression. We used plant biomass to measure performance and root:shoot ratio and specific leaf area (SLA) to measure resource acquisition and allocation. Plant biomass responded to the origin of the Soil, consistent with the literature demonstrating that plant-Soil feedbacks influence plant performance. Soil and light Heterogeneity interacted to significantly affect resource acquisition traits (i.e., SLA) demonstrating that plants integrated both above- and belowground resource variance. All four species showed light-dependent, non-additive effects of Soil mixture, though these effects were only marginally significant (P < 0.10). This is important in the context of community assembly because studies find the variance in environmental drivers to be as, or more, important than the means in determining community structure. This study provides some of the first evidence that plant trait expression responds to the variance of environmental drivers, including those driven by plant-Soil feedbacks, as well as the means.
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Experimental protocol for manipulating plant-induced Soil Heterogeneity.
Journal of visualized experiments : JoVE, 2014Co-Authors: Angela J. Brandt, Gaston A. Del Pino, Jean H. BurnsAbstract:Coexistence theory has often treated environmental Heterogeneity as being independent of the community composition; however biotic feedbacks such as plant-Soil feedbacks (PSF) have large effects on plant performance, and create environmental Heterogeneity that depends on the community composition. Understanding the importance of PSF for plant community assembly necessitates understanding of the role of Heterogeneity in PSF, in addition to mean PSF effects. Here, we describe a protocol for manipulating plant-induced Soil Heterogeneity. Two example experiments are presented: (1) a field experiment with a 6-patch grid of Soils to measure plant population responses and (2) a greenhouse experiment with 2-patch Soils to measure individual plant responses. Soils can be collected from the zone of root influence (Soils from the rhizosphere and directly adjacent to the rhizosphere) of plants in the field from conspecific and heterospecific plant species. Replicate collections are used to avoid pseudoreplicating Soil samples. These Soils are then placed into separate patches for heterogeneous treatments or mixed for a homogenized treatment. Care should be taken to ensure that heterogeneous and homogenized treatments experience the same degree of Soil disturbance. Plants can then be placed in these Soil treatments to determine the effect of plant-induced Soil Heterogeneity on plant performance. We demonstrate that plant-induced Heterogeneity results in different outcomes than predicted by traditional coexistence models, perhaps because of the dynamic nature of these feedbacks. Theory that incorporates environmental Heterogeneity influenced by the assembling community and additional empirical work is needed to determine when Heterogeneity intrinsic to the assembling community will result in different assembly outcomes compared with Heterogeneity extrinsic to the community composition.
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Soil Heterogeneity generated by plant Soil feedbacks has implications for species recruitment and coexistence
Journal of Ecology, 2013Co-Authors: Angela J. Brandt, Hans De Kroon, Heather L. Reynolds, Jean H. BurnsAbstract:Summary Most studies of Soil Heterogeneity have focused on underlying abiotic factors such as Soil nutrients. However, increasing recognition of plant–Soil feedback (PSF) effects on plant growth, combined with the observation that PSFs operate at small spatial scales, suggests that Heterogeneity due to PSF could affect plant population and community dynamics. The consequences of PSF-generated Heterogeneity for coexistence depend on Heterogeneity's effects on vital rates and how those vital rates influence population-level recruitment dynamics. We measured vital rates and recruitment dynamics of three congeneric pairs of introduced perennial plants grown as monocultures in experimental PSF-generated Soil environments. Field Soils collected from conspecifics and congeners were alternated in patches or mixed together to produce heterogeneous and homogeneous Soils, respectively. We quantified the effects of PSF-generated Heterogeneity on germination and establishment and determined how these vital rates affected recruitment. We calculated net pairwise interaction coefficients to predict whether PSFs could mediate coexistence between congeners. Soil Heterogeneity altered the relationship of vital rates to recruitment dynamics for some species. For example, Solanum dulcamara recruited later into heterogeneous than homogeneous Soils, and germination was a stronger predictor of the timing of recruitment in heterogeneous Soil, while mortality was a stronger predictor in homogeneous Soil. Contrasts between Soils of different origin suggest that mixing Soils had non-additive effects on vital rates (e.g. Rumex crispus mortality was higher in homogeneous than in conspecific or congener Soil). Interaction coefficients predicted that PSFs in heterogeneous Soils might mediate stable coexistence only of Rumex congeners. Synthesis. Heterogeneity generated by PSFs had species-specific effects on vital rates, with consequences for recruitment dynamics. Mixing Soils of different origin often resulted in non-additive effects, which may indicate an interaction between Soil abiotic and/or biotic properties and could predict non-additive responses to Soil disturbance. Finally, quantifying the reciprocal effects of PSFs on congeners suggests that PSF-generated Heterogeneity may promote coexistence of certain species, which was not evident from individual PSF responses. Future studies should determine whether such mechanisms might operate for more distantly related species.
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Soil Heterogeneity generated by plant–Soil feedbacks has implications for species recruitment and coexistence
Journal of Ecology, 2013Co-Authors: Angela J. Brandt, Hans De Kroon, Heather L. Reynolds, Jean H. BurnsAbstract:Summary Most studies of Soil Heterogeneity have focused on underlying abiotic factors such as Soil nutrients. However, increasing recognition of plant–Soil feedback (PSF) effects on plant growth, combined with the observation that PSFs operate at small spatial scales, suggests that Heterogeneity due to PSF could affect plant population and community dynamics. The consequences of PSF-generated Heterogeneity for coexistence depend on Heterogeneity's effects on vital rates and how those vital rates influence population-level recruitment dynamics. We measured vital rates and recruitment dynamics of three congeneric pairs of introduced perennial plants grown as monocultures in experimental PSF-generated Soil environments. Field Soils collected from conspecifics and congeners were alternated in patches or mixed together to produce heterogeneous and homogeneous Soils, respectively. We quantified the effects of PSF-generated Heterogeneity on germination and establishment and determined how these vital rates affected recruitment. We calculated net pairwise interaction coefficients to predict whether PSFs could mediate coexistence between congeners. Soil Heterogeneity altered the relationship of vital rates to recruitment dynamics for some species. For example, Solanum dulcamara recruited later into heterogeneous than homogeneous Soils, and germination was a stronger predictor of the timing of recruitment in heterogeneous Soil, while mortality was a stronger predictor in homogeneous Soil. Contrasts between Soils of different origin suggest that mixing Soils had non-additive effects on vital rates (e.g. Rumex crispus mortality was higher in homogeneous than in conspecific or congener Soil). Interaction coefficients predicted that PSFs in heterogeneous Soils might mediate stable coexistence only of Rumex congeners. Synthesis. Heterogeneity generated by PSFs had species-specific effects on vital rates, with consequences for recruitment dynamics. Mixing Soils of different origin often resulted in non-additive effects, which may indicate an interaction between Soil abiotic and/or biotic properties and could predict non-additive responses to Soil disturbance. Finally, quantifying the reciprocal effects of PSFs on congeners suggests that PSF-generated Heterogeneity may promote coexistence of certain species, which was not evident from individual PSF responses. Future studies should determine whether such mechanisms might operate for more distantly related species.
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PLANT-Soil FEEDBACKS IN A CHANGING WORLD Soil Heterogeneity generated by plant-Soil feedbacks has implications for species recruitment and coexistence
2013Co-Authors: Angela J. Brandt, Hans De Kroon, Heather L. Reynolds, Jean H. BurnsAbstract:Summary 1. Most studies of Soil Heterogeneity have focused on underlying abiotic factors such as Soil nutrients. However, increasing recognition of plant–Soil feedback (PSF) effects on plant growth, combined with the observation that PSFs operate at small spatial scales, suggests that Heterogeneity due to PSF could affect plant population and community dynamics. The consequences of PSF-generated Heterogeneity for coexistence depend on Heterogeneity’s effects on vital rates and how those vital rates influence population-level recruitment dynamics. 2. We measured vital rates and recruitment dynamics of three congeneric pairs of introduced perennial plants grown as monocultures in experimental PSF-generated Soil environments. Field Soils collected from conspecifics and congeners were alternated in patches or mixed together to produce heterogeneous and homogeneous Soils, respectively. 3. We quantified the effects of PSF-generated Heterogeneity on germination and establishment and determined how these vital rates affected recruitment. We calculated net pairwise interaction coefficients to predict whether PSFs could mediate coexistence between congeners. 4. Soil Heterogeneity altered the relationship of vital rates to recruitment dynamics for some species. For example, Solanum dulcamara recruited later into heterogeneous than homogeneous Soils, and germination was a stronger predictor of the timing of recruitment in heterogeneous Soil, while mortality was a stronger predictor in homogeneous Soil. Contrasts between Soils of different origin suggest that mixing Soils had non-additive effects on vital rates (e.g. Rumex crispus mortality was higher in homogeneous than in conspecific or congener Soil). Interaction coefficients predicted that PSFs in heterogeneous Soils might mediate stable coexistence only of Rumex congeners. 5. Synthesis. Heterogeneity generated by PSFs had species-specific effects on vital rates, with consequences for recruitment dynamics. Mixing Soils of different origin often resulted in non-additive effects, which may indicate an interaction between Soil abiotic and/or biotic properties and could predict non-additive responses to Soil disturbance. Finally, quantifying the reciprocal effects of PSFs on congeners suggests that PSF-generated Heterogeneity may promote coexistence of certain species, which was not evident from individual PSF responses. Future studies should determine whether such mechanisms might operate for more distantly related species.
Muneto Hirobe - One of the best experts on this subject based on the ideXlab platform.
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Effects of livestock grazing on the spatial Heterogeneity of net Soil nitrogen mineralization in three types of Mongolian grasslands
Journal of Soils and Sediments, 2013Co-Authors: Muneto Hirobe, Junji Kondo, Altangerel Enkhbaatar, Narantsetseg Amartuvshin, Noboru Fujita, Keiji Sakamoto, Ken Yoshikawa, Knut KiellandAbstract:Purpose Small-scale Soil Heterogeneity relates to productivity and biodiversity and is crucial to understand. Soil Heterogeneity could be affected by vegetation structure, and large mammal grazers could modify it through herbivory and excretion. The objective is to clarify the effects of livestock grazing on the small-scale (∼3 m) Soil Heterogeneity in three types of Mongolian grasslands. Materials and methods We sampled Soils from inside (ungrazed) and outside (grazed) exclosures in three vegetation types: forest-steppe, shrub-steppe, and desert-steppe. We measured laboratory rates of Soil net nitrogen (N) mineralization and net nitrification and geostatistically analyzed Heterogeneity. Results and discussion Average rates of net N mineralization and net nitrification were lower at shrub-steppe and desert-steppe and were decreased by grazing. Semivariograms showed vegetation-induced Heterogeneity in ungrazed plots, except for net nitrification at forest-steppe. We found linear change with distance under dense and uniform vegetation at forest-steppe, 1.3 m patch under patchy vegetation at shrub-steppe, and linear change, but with much smaller semivariance, under sparse and poor vegetation at desert-steppe. At forest-steppe, grazing randomized the spatial patterns of net N mineralization and net nitrification. At shrub-steppe and desert-steppe, grazing greatly decreased the semivariances of net N mineralization and net nitrification as well as their averages, and the Soil Heterogeneity was virtually disappeared. Conclusions Grazing in Mongolian grasslands homogenized the spatial patterns of net N mineralization and net nitrification, irrespective of their original spatial patterns determined by the differences in vegetation structure.
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Effects of livestock grazing on the spatial Heterogeneity of net Soil nitrogen mineralization in three types of Mongolian grasslands
Journal of Soils and Sediments, 2013Co-Authors: Muneto Hirobe, Junji Kondo, Altangerel Enkhbaatar, Narantsetseg Amartuvshin, Noboru Fujita, Keiji Sakamoto, Ken Yoshikawa, Knut KiellandAbstract:Purpose Small-scale Soil Heterogeneity relates to productivity and biodiversity and is crucial to understand. Soil Heterogeneity could be affected by vegetation structure, and large mammal grazers could modify it through herbivory and excretion. The objective is to clarify the effects of livestock grazing on the small-scale (∼3 m) Soil Heterogeneity in three types of Mongolian grasslands.
Heather L. Reynolds - One of the best experts on this subject based on the ideXlab platform.
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Soil Heterogeneity generated by plant Soil feedbacks has implications for species recruitment and coexistence
Journal of Ecology, 2013Co-Authors: Angela J. Brandt, Hans De Kroon, Heather L. Reynolds, Jean H. BurnsAbstract:Summary Most studies of Soil Heterogeneity have focused on underlying abiotic factors such as Soil nutrients. However, increasing recognition of plant–Soil feedback (PSF) effects on plant growth, combined with the observation that PSFs operate at small spatial scales, suggests that Heterogeneity due to PSF could affect plant population and community dynamics. The consequences of PSF-generated Heterogeneity for coexistence depend on Heterogeneity's effects on vital rates and how those vital rates influence population-level recruitment dynamics. We measured vital rates and recruitment dynamics of three congeneric pairs of introduced perennial plants grown as monocultures in experimental PSF-generated Soil environments. Field Soils collected from conspecifics and congeners were alternated in patches or mixed together to produce heterogeneous and homogeneous Soils, respectively. We quantified the effects of PSF-generated Heterogeneity on germination and establishment and determined how these vital rates affected recruitment. We calculated net pairwise interaction coefficients to predict whether PSFs could mediate coexistence between congeners. Soil Heterogeneity altered the relationship of vital rates to recruitment dynamics for some species. For example, Solanum dulcamara recruited later into heterogeneous than homogeneous Soils, and germination was a stronger predictor of the timing of recruitment in heterogeneous Soil, while mortality was a stronger predictor in homogeneous Soil. Contrasts between Soils of different origin suggest that mixing Soils had non-additive effects on vital rates (e.g. Rumex crispus mortality was higher in homogeneous than in conspecific or congener Soil). Interaction coefficients predicted that PSFs in heterogeneous Soils might mediate stable coexistence only of Rumex congeners. Synthesis. Heterogeneity generated by PSFs had species-specific effects on vital rates, with consequences for recruitment dynamics. Mixing Soils of different origin often resulted in non-additive effects, which may indicate an interaction between Soil abiotic and/or biotic properties and could predict non-additive responses to Soil disturbance. Finally, quantifying the reciprocal effects of PSFs on congeners suggests that PSF-generated Heterogeneity may promote coexistence of certain species, which was not evident from individual PSF responses. Future studies should determine whether such mechanisms might operate for more distantly related species.
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Soil Heterogeneity generated by plant–Soil feedbacks has implications for species recruitment and coexistence
Journal of Ecology, 2013Co-Authors: Angela J. Brandt, Hans De Kroon, Heather L. Reynolds, Jean H. BurnsAbstract:Summary Most studies of Soil Heterogeneity have focused on underlying abiotic factors such as Soil nutrients. However, increasing recognition of plant–Soil feedback (PSF) effects on plant growth, combined with the observation that PSFs operate at small spatial scales, suggests that Heterogeneity due to PSF could affect plant population and community dynamics. The consequences of PSF-generated Heterogeneity for coexistence depend on Heterogeneity's effects on vital rates and how those vital rates influence population-level recruitment dynamics. We measured vital rates and recruitment dynamics of three congeneric pairs of introduced perennial plants grown as monocultures in experimental PSF-generated Soil environments. Field Soils collected from conspecifics and congeners were alternated in patches or mixed together to produce heterogeneous and homogeneous Soils, respectively. We quantified the effects of PSF-generated Heterogeneity on germination and establishment and determined how these vital rates affected recruitment. We calculated net pairwise interaction coefficients to predict whether PSFs could mediate coexistence between congeners. Soil Heterogeneity altered the relationship of vital rates to recruitment dynamics for some species. For example, Solanum dulcamara recruited later into heterogeneous than homogeneous Soils, and germination was a stronger predictor of the timing of recruitment in heterogeneous Soil, while mortality was a stronger predictor in homogeneous Soil. Contrasts between Soils of different origin suggest that mixing Soils had non-additive effects on vital rates (e.g. Rumex crispus mortality was higher in homogeneous than in conspecific or congener Soil). Interaction coefficients predicted that PSFs in heterogeneous Soils might mediate stable coexistence only of Rumex congeners. Synthesis. Heterogeneity generated by PSFs had species-specific effects on vital rates, with consequences for recruitment dynamics. Mixing Soils of different origin often resulted in non-additive effects, which may indicate an interaction between Soil abiotic and/or biotic properties and could predict non-additive responses to Soil disturbance. Finally, quantifying the reciprocal effects of PSFs on congeners suggests that PSF-generated Heterogeneity may promote coexistence of certain species, which was not evident from individual PSF responses. Future studies should determine whether such mechanisms might operate for more distantly related species.
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PLANT-Soil FEEDBACKS IN A CHANGING WORLD Soil Heterogeneity generated by plant-Soil feedbacks has implications for species recruitment and coexistence
2013Co-Authors: Angela J. Brandt, Hans De Kroon, Heather L. Reynolds, Jean H. BurnsAbstract:Summary 1. Most studies of Soil Heterogeneity have focused on underlying abiotic factors such as Soil nutrients. However, increasing recognition of plant–Soil feedback (PSF) effects on plant growth, combined with the observation that PSFs operate at small spatial scales, suggests that Heterogeneity due to PSF could affect plant population and community dynamics. The consequences of PSF-generated Heterogeneity for coexistence depend on Heterogeneity’s effects on vital rates and how those vital rates influence population-level recruitment dynamics. 2. We measured vital rates and recruitment dynamics of three congeneric pairs of introduced perennial plants grown as monocultures in experimental PSF-generated Soil environments. Field Soils collected from conspecifics and congeners were alternated in patches or mixed together to produce heterogeneous and homogeneous Soils, respectively. 3. We quantified the effects of PSF-generated Heterogeneity on germination and establishment and determined how these vital rates affected recruitment. We calculated net pairwise interaction coefficients to predict whether PSFs could mediate coexistence between congeners. 4. Soil Heterogeneity altered the relationship of vital rates to recruitment dynamics for some species. For example, Solanum dulcamara recruited later into heterogeneous than homogeneous Soils, and germination was a stronger predictor of the timing of recruitment in heterogeneous Soil, while mortality was a stronger predictor in homogeneous Soil. Contrasts between Soils of different origin suggest that mixing Soils had non-additive effects on vital rates (e.g. Rumex crispus mortality was higher in homogeneous than in conspecific or congener Soil). Interaction coefficients predicted that PSFs in heterogeneous Soils might mediate stable coexistence only of Rumex congeners. 5. Synthesis. Heterogeneity generated by PSFs had species-specific effects on vital rates, with consequences for recruitment dynamics. Mixing Soils of different origin often resulted in non-additive effects, which may indicate an interaction between Soil abiotic and/or biotic properties and could predict non-additive responses to Soil disturbance. Finally, quantifying the reciprocal effects of PSFs on congeners suggests that PSF-generated Heterogeneity may promote coexistence of certain species, which was not evident from individual PSF responses. Future studies should determine whether such mechanisms might operate for more distantly related species.
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Soil fertility, Heterogeneity, and microbes: towards an integrated understanding of grassland structure and dynamics.
Applied Vegetation Science, 2009Co-Authors: Heather L. Reynolds, Karen A. HaubensakAbstract:Objective: To highlight the need and the potential for an integrated understanding of three key Soil-based drivers of plant community structure and dynamics – Soil fertility, Soil Heterogeneity, and microbes. Location: European and North American grasslands. Methods: Review and discussion of conceptual models and empirical literature, including examples of observational and manipulative studies from both natural and restored grassland communities. Results and Conclusions: In general, the results of empirical studies on Soil fertility, Soil Heterogeneity, and Soil microbes in grassland communities do not support expectations of common conceptual models. Ecological theory assumes a unimodal relationship between Soil fertility and plant community diversity, yet empirical relationships from grassland communities are variable, the mechanisms underlying these variable patterns are not yet well understood, and there is mixed success at manipulating Soil fertility to facilitate restorations. While theory predicts that increased Soil Heterogeneity will lead to increased plant community diversity, results of experimental manipulations of Soil Heterogeneity often show the opposite. Of two major conceptual models proposed for how microbes structure plant communities, there is little support for the hypothesis of microbially mediated niche partitioning. Plant-microbe feedbacks do have significant empirical support to date and there is increasing application of positive feedback dynamics in restoration, yet field tests of feedback dynamics remain limited. We suggest that an understanding of interactions between these Soil drivers may help to resolve discrepancies between conceptual models and empirical results, improving our understanding of grasslands and our ability to restore them.
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Soil Heterogeneity AND PLANT COMPETITION IN ANANNUAL GRASSLAND
Ecology, 1997Co-Authors: Heather L. Reynolds, Bruce A. Hungate, F. S. Chapin, Carla M. D'antonioAbstract:Variation in competitive ability due to variation in Soil characteristics is one possible mechanism allowing the local coexistence of plant species. We measured Soil water, depth, and nitrogen pools and fluxes in distinct patches of three serpentine grassland species to determine whether Soil Heterogeneity existed and was correlated with plant species abundance. Through experimental manipulation of species’ abundances, we also examined the relative importance of inherent site characteristics vs. plant species’ effects in generating Heterogeneity in the measured Soil characteristics; and measured species’ competitive abilities in different patch types. The three common grassland annuals, Calycadenia multiglandulosum, Plantago erecta, and Lasthenia californica, were segregated with respect to the measured Soil characteristics. Differences in Soil water, Soil depth, Soil microbial nitrogen, and Soil carbon to nitrogen ratio were due to inherent site characteristics, while differences in nitrate availability ...
Meelis Pärtel - One of the best experts on this subject based on the ideXlab platform.
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Co-occurring grassland species vary in their responses to fine-scale Soil Heterogeneity
Journal of Vegetation Science, 2016Co-Authors: Riin Tamme, Antonio Gazol, Jodi N. Price, Inga Hiiesalu, Meelis PärtelAbstract:Questions How does fine-scale Soil Heterogeneity impact on co-occurring species? Which species are advantaged in heterogeneous Soils? Location Greenhouse experiment using European grassland species, University of Tartu, Estonia. Methods We grew plant assemblages consisting of 15 species in five Soil treatments – comprising three spatially uniform fertility levels (low, medium or high) and two heterogeneous conditions created using checkerboard combinations of low- and high-fertility patches at two spatial scales (6.25 × 6.25 cm or 12.5 × 12.5 cm patches, overall medium fertility). We compared species responses (above-ground biomass) between heterogeneous and homogeneous treatments. Additionally, we compared species responses within low-fertility patches in heterogeneous treatments to the homogeneous treatment of the same fertility. Results Larger, dominant species were advantaged in heterogeneous compared to homogeneous conditions (with the same or lower overall fertility), whereas the growth and survival of smaller, subordinate species was reduced. Larger, dominant species also had increased above-ground biomass within the low-fertility patches in heterogeneous compared to homogeneous low-fertility conditions, but the opposite was true for smaller, subordinate species. In general, species responses in heterogeneous conditions did not differ from the homogeneous high-fertility treatment, although the heterogeneous conditions had lower overall fertility. Conclusions In our experimental grasslands, species differed in their responses to fine-scale Soil Heterogeneity. Patchy resource distribution directly benefits larger, dominant species that can forage among patches and produce more above-ground biomass compared to conditions where the same amount of resources is distributed homogeneously. Smaller, subordinate species that are more likely confined to a uniform Soil patch are disadvantaged by Heterogeneity due to increased root and shoot competition from neighbouring species. These species-specific responses to fine-scale Soil Heterogeneity and altered competitive interactions have important implications for plant community structure and productivity.
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Soil nitrogen and carbon Heterogeneity in woodlands and grasslands: contrasts between temperate and tropical regions
Global Ecology and Biogeography, 2007Co-Authors: Meelis Pärtel, Lauri Laanisto, Scott D. WilsonAbstract:Aim Soil resource Heterogeneity is linked to several ecological processes including invasion of woody species into grasslands. Studies from the temperate zone have demonstrated greater Soil Heterogeneity beneath woody vegetation than beneath grasslands. Woody species have a more widespread and coarser root system than herbaceous species, and may have a competitive advantage in relatively heterogeneous Soils. We tested the global generality of greater Soil Heterogeneity beneath woody vegetation. Location Global. Methods We used data from published literature for Soil nitrogen and carbon Heterogeneity from paired woodland and grassland sites around the world. Results Woodland and grassland Soil heterogeneities from paired observations were strongly correlated. There was, however, significant geographical variability in the relationship. Soils were more heterogeneous in woodlands than grasslands in temperate areas, but the opposite was true for tropical habitats. Grassland Soils were more heterogeneous at lower than higher latitudes. Woodland Soil Heterogeneity did not vary with latitude. Main conclusions The previously described high Soil Heterogeneity in woody vegetation compared to grasslands holds only for temperate regions. Consequently, the relationship between Soil resource Heterogeneity and vegetation type is dependent on the study region. Macroecological studies should test the generality of relationships between Soil and vegetation at the global scale.
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Root and leaf production, mortality and longevity in response to Soil Heterogeneity
Functional Ecology, 2001Co-Authors: Meelis Pärtel, Scott D. WilsonAbstract:Summary 1 Patches of fertile Soil support concentrations of roots, but whether this reflects increased production or increased longevity is not known. We examined the production and longevity of roots of the grass Festuca rubra in response to Soil Heterogeneity. We also explored the extent to which root dynamics reflect shoot responses to heterogeneous Soils. 2 Root and leaf dynamics were followed in pots of heterogeneous or homogeneous Soils containing the same total amount of nutrients. Digital minirhizotron images of roots and leaves were collected weekly. 3 Root length was significantly greater in homogeneous than heterogeneous Soils. This was caused by significantly larger root production but shorter life span. In contrast, Soil Heterogeneity had no effect on leaf production or longevity. 4 Within heterogeneous pots, root and leaf production were strongly concordant, both being significantly greater in fertilized patches. More roots died in fertilized patches, but leaf mortality was not affected. Longevity of neither roots nor leaves was affected by the location of a fertile patch. 5 Spatial variation in production of roots and shoots in response to nutrient patches was concordant. Roots and shoots, however, showed independent responses to the presence of within-pot Heterogeneity. A decrease in total root length in heterogeneous Soils was a counterintuitive result of decreased production and increased longevity.