Competition can be fully hierarchical or intransitive, and this degree of hierarchy is driven by multiple factors, including environmental conditions, the functional traits of the species involved or the topology of competition networks. Studies simultaneously analysing these drivers of competition hierarchy are rare. Additionally, organisms compete either directly or via interference competition for resources or space, within a local neighbourhood or across the habitat. Therefore, the drivers of competition could change accordingly and depend on the taxa studied.
We performed the first multi\uffe2\uff80\uff90taxon study on pairwise competition across major taxonomic groups, including experiments with vascular plants, mosses, saprobic fungi, aquatic protists and soil bacteria. We evaluated how general is competition intransitivity from the pairwise competition matrix including all species and also for each possible three\uffe2\uff80\uff90species combination (triplets). We then examined which species were likely to engage in competitive loops and the effects of environmental conditions, competitive rank and functional traits on intransitive competition.
We found some degree of competition intransitivity in all taxa studied, with 38% to 5% of triplets being intransitive. Variance in competitive rank between species and more fertile conditions strongly reduced intransitivity, with triplets composed of species differing widely in their competitive ranks much less likely to be intransitive.
Including functional traits of the species involved more than doubled the variation explained compared to models including competitive rank only. Both trait means and variance within triplets affected the odds of them being intransitive. However, the traits responsible and the direction of trait effects varied widely between taxa, suggesting that traits can have a wide variety of effects on competition.
Synthesis. We evaluated the drivers of competition across multiple taxa and showed that productivity and competitive rank are fundamental drivers of intransitivity. We also showed that not only the functional traits of each species, but also those of the accompanying species, determine competition intransitivity. Intransitive competition is common across multiple taxa but can dampen under fertile conditions or for those species with large variance in their competitive abilities. This provides a first step towards predicting the prevalence of intransitive competition in natural communities.
For over three decades, low\uffe2\uff80\uff90intensity grazing has been used to maintain or increase plant species richness in European natural areas, but the effects are highly variable. Thus far, good predictors of whether grazing will have positive effects on plant species richness are limited. How does the interplay between low\uffe2\uff80\uff90intensity grazing and topographic heterogeneity affect plant species richness at different spatial scales?LocationLong\uffe2\uff80\uff90term grazed and ungrazed salt marshes of the Dutch Wadden Sea island of Schiermonnikoog.
MethodsWe selected ten plots of 2200\uffc2\uffa0m2 in grazed and ungrazed areas of our study sites, and recorded and compared plant species richness in 0.1, 1, 10, 100 and 1000\uffc2\uffa0m2 subplots. Topographic heterogeneity was quantified at the plot scale using the standard deviation of the elevation derived from a high\uffe2\uff80\uff90resolution (5\uffc2\uffa0m\uffc2\uffa0\uffc3\uff97\uffc2\uffa05\uffc2\uffa0m) digital elevation model. We calculated species\uffe2\uff80\uff93area relationships to analyse our data.
ResultsWe found that large\uffe2\uff80\uff90scale topographic heterogeneity (based on the whole plot of 2200\uffc2\uffa0m2) positively affects plant species richness at all scales (even at the smallest 0.1\uffe2\uff80\uff90m2 scale), and that grazing has a positive additive effect at the small scales (0.1 and 10\uffc2\uffa0m2). While grazing also had a positive effect on species richness at larger scales (1000\uffc2\uffa0m2), the strength of the effect was dependent on the topographic heterogeneity at that scale. The effectiveness of grazing for increased plant species richness was highest at low topographic heterogeneity, and lowest at intermediate topographic heterogeneity. Effects of intermediate heterogeneity were probably counterbalanced by the effects of grazing.
ConclusionsOur results suggest that the variation in elevation is an important predictor of whether low\uffe2\uff80\uff90intensity grazing has positive effects on plant species richness or not. Grazing appears most beneficial at low topographic heterogeneity, but whether these findings hold for other grazed ecosystems will depend on several factors, most importantly, the relationship between topographic and abiotic heterogeneity. Results of our study are highly relevant for the application of low\uffe2\uff80\uff90intensity grazing as tool for conservation management in salt marshes and other natural areas.
", "keywords": ["0106 biological sciences", "2. Zero hunger", "Topography", "Livestock", "IMPACT", "Vascular plants", "Spatial scale", "DIVERSITY", "Nature management", "Biodiversity", "Conservation", "15. Life on land", "01 natural sciences", "SOIL", "Grazing lawns", "HERBIVORES", "BIODIVERSITY", "Herbivory", "VEGETATION", "14. Life underwater", "Plant-herbivore interactions", "GRASSLANDS", "RESTORATION", "RESPONSES", "ENVIRONMENTS"]}, "links": [{"href": "https://doi.org/10.1111/avsc.12107"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Applied%20Vegetation%20Science", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1111/avsc.12107", "name": "item", "description": "10.1111/avsc.12107", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1111/avsc.12107"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2014-05-02T00:00:00Z"}}, {"id": "10.1111/j.1365-2486.2011.02585.x", "type": "Feature", "geometry": null, "properties": {"updated": "2026-05-25T16:18:49Z", "type": "Journal Article", "created": "2011-10-24", "title": "High Nitrogen Deposition Alters The Decomposition Of Bog Plant Litter And Reduces Carbon Accumulation", "description": "AbstractBogs are globally important sinks of atmospheric carbon (C) due to the accumulation of partially decomposed litter that forms peat. Because bogs receive their nutrients from the atmosphere, the world\uffe2\uff80\uff90wide increase of nitrogen (N) deposition is expected to affect litter decomposition and, ultimately, the rate of C accumulation. However, the mechanism of such biogeochemical alteration remains unclear and quantification of the effect of N addition on litter accumulation has yet to be done. Here, we show that 7\uffc2\uffa0years of N addition to a bog decreased the C\uffc2\uffa0:\uffc2\uffa0N ratio, increased the bacterial biomass and stimulated the activity of hydrolytic and oxidative enzymes in surface peat. Furthermore, N addition modified nutrient limitation of microbes during litter decomposition so that phosphorus became a primary limiting nutrient. Alteration of N release from decomposing litter affected bog water chemistry and the competitive balance between peat\uffe2\uff80\uff90forming mosses and vascular plants. We estimate that deposition of about 4 g\uffc2\uffa0N\uffc2\uffa0m\uffe2\uff88\uff922\uffc2\uffa0yr\uffe2\uff88\uff921 will cause a mean annual reduction of fresh litter C accumulation of about 40\uffc2\uffa0g\uffc2\uffa0m\uffe2\uff88\uff922 primarily as a consequence of decreased litter production from peat\uffe2\uff80\uff90forming mosses. Our findings show that N deposition interacts with both above and below ground components of biodiversity to threaten the ability of bogs to act as N\uffe2\uff80\uff90sinks, which may offset the positive effects of N on C accumulation seen in other ecosystems.
", "keywords": ["570", "Decomposition; litter accumulation modelling; microbial diversity; peatland; primary production; soil enzymatic activity; Sphagnum; vascular plants", "decomposition", "04 agricultural and veterinary sciences", "litter accumulation modelling", "soil enzymatic activity", "15. Life on land", "S phagnum", "13. Climate action", "microbial diversity", "0401 agriculture", " forestry", " and fisheries", "peatland", "vascular plants", "primary production"]}, "links": [{"href": "https://doi.org/10.1111/j.1365-2486.2011.02585.x"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Global%20Change%20Biology", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1111/j.1365-2486.2011.02585.x", "name": "item", "description": "10.1111/j.1365-2486.2011.02585.x", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1111/j.1365-2486.2011.02585.x"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2011-11-23T00:00:00Z"}}, {"id": "10.1139/x78-044", "type": "Feature", "geometry": null, "properties": {"updated": "2026-05-25T16:19:12Z", "type": "Journal Article", "created": "2007-11-26", "title": "Biomass And Nutrient Distribution In Aspen, Pine, And Spruce Stands On The Same Soil Type In Minnesota", "description": "Vegetation and soils were sampled in adjacent 40-year-old stands of red pine (Pinusresinosa Ait.), jack pine (Pinusbanksiana Lamb.), white spruce (Piceaglauca (Moench.) Voss), and aspen (Populustremuloides Michx., P. grandidentata Michx.) on a very fine sandy loam soil in north-central Minnesota. Total tree biomass was greatest for red pine followed by aspen, spruce, and jack pine. Nutrient weights (N, P, K, Ca, Mg) in the trees were greatest in aspen followed generally by spruce, red pine, and jack pine. Particularly large proportions of biomass and nutrients were found in aspen bark and spruce foliage and branches. Understory biomass contributed less than 1.2% of the total organic matter in the vegetation\uffe2\uff80\uff93soil complex but contributed up to 5.0% of the nutrients. Exchangeable Ca in the surface soil was much lower under aspen and spruce than under the pines. No significant soil differences between species were detected below 36\uffe2\uff80\uff82cm. Harvesting the entire aboveground portion of the tree would remove up to three times more nutrients from the site than would harvesting only the bole.
", "keywords": ["0106 biological sciences", "Yield", "Spermatophyta", "Angiosperms", "Nitrogen", "Sandy Loam", "plant nutrition", "Coniferopsida: Gymnospermae", "Gymnosperms", "magnesium", "Pinus Banksiana", "01 natural sciences", "nitrogen", "Dicots", "forest soils", "temperate zones", "Picea Glauca", "Populus Tremuloides", "nutrients", "Spermatophytes", "Magnesium", "phosphorus", "Plantae", "Pinus Resinosa", "Forest Sciences", "soil types ecological", "calcium", "Vascular Plants", "Salicaceae: Dicotyledones", "potassium", "Populus Grandidentata", "Phosphorus", "Plants", "15. Life on land", "nutrition", "Angiospermae", "Tracheophyta: Plantae", "Potassium", "Calcium"], "contacts": [{"organization": "Alban, David H., Perala, Donald A., Schlaegel, Bryce E.,", "roles": ["creator"]}]}, "links": [{"href": "https://digitalcommons.usu.edu/context/aspen_bib/article/5834/viewcontent/Alban412.pdf"}, {"href": "https://doi.org/10.1139/x78-044"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Canadian%20Journal%20of%20Forest%20Research", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1139/x78-044", "name": "item", "description": "10.1139/x78-044", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1139/x78-044"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "1978-09-01T00:00:00Z"}}, {"id": "10.1139/x88-221", "type": "Feature", "geometry": null, "properties": {"updated": "2026-05-25T16:19:13Z", "type": "Journal Article", "created": "2007-12-19", "title": "Biomass And Nutrients In Regenerating Woody Vegetation Following Whole-Tree And Conventional Harvest In A Northern Mixed Forest", "description": "Biomass and nutrient contents of regenerating woody plants and litter fall were measured after a northern mixed conifer\uffe2\uff80\uff93hardwood forest was harvested by conventional and whole-tree methods. Before harvest, the central Ontario study site was occupied by a 95-year-old pine (Pinusresinosa, P. strobus) and aspen (Populustremuloides, P. grandidentata) stand growing on gently rolling, gravel-free outwash sands. Four years after harvest, aspen abundance increased 100-fold in both harvested areas, with higher densities after whole-tree harvest (WTH) (4.1\uffe2\uff80\uff82stems/m2) than after conventional harvest (CH) (2.7\uffe2\uff80\uff82stems/m2). No self-thinning of aspen occurred between 2 and 4 years after harvest. Total aboveground woody biomass accumulated at 2.0\uffe2\uff80\uff82t\uffe2\uff80\uffa2ha\uffe2\uff88\uff921\uffe2\uff80\uffa2year\uffe2\uff88\uff921 in the WTH area and 1.5\uffe2\uff80\uff82t\uffe2\uff80\uffa2ha\uffe2\uff88\uff921\uffe2\uff80\uffa2year\uffe2\uff88\uff921 in the CH area; the preharvest rate was 2.0\uffe2\uff80\uff82t\uffe2\uff80\uffa2ha\uffe2\uff88\uff921\uffe2\uff80\uffa2year\uffe2\uff88\uff921. Peak autumn litter production occurred earlier in the harvested areas than in an adjacent uncut area. Cycling of N and K in litter fall returned to preharvest rates after 4 years. Cycling of Ca in litter fall was lower after WTH than after CH. Vegetation uptake of N and K (litter fall plus woody biomass) in the harvested areas in year 4 exceeded the preharvest value. Increased N accumulation in woody biomass (3.0\uffe2\uff80\uff82kg\uffe2\uff80\uffa2ha\uffe2\uff88\uff921\uffe2\uff80\uffa2year\uffe2\uff88\uff921 before harvest, 10.6\uffe2\uff80\uff82kg\uffe2\uff80\uffa2ha\uffe2\uff88\uff921\uffe2\uff80\uffa2year\uffe2\uff88\uff921 after WTH) would place a relatively greater demand on forest floor N pools in the WTH than in the CH area owing to lack of N input in logging slash. Although WTH did not reduce initial rates of biomass production, Populus spp. had lower concentrations of N, Ca, and Mg in the WTH area than in the CH area. There may be a danger that WTH on less fertile sites in the region will produce dense, unproductive aspen stands with low rates of self-thinning.
", "keywords": ["0106 biological sciences", "Spermatophyta", "Angiosperms", "Broadleaves", "Forest litter", "Microorganisms", "Coniferopsida: Gymnospermae", "Gymnosperms", "01 natural sciences", "logging", "Dicots", "pines", "nutrients", "Spermatophytes", "Natural regeneration", "Plant nutrition", "Plantae", "Forest Sciences", "Vascular Plants", "biomass", "Stand characteristics", "Salicaceae: Dicotyledones", "thinning", "Soil morphology", "Cycling", "Forestry", "Pinus Resinosa Pinus Strobus Populus Tremuloides Populus Grandidentata Forest Biomass Energy Forest Products", "Plants", "15. Life on land", "Conifers", "Angiospermae", "composition", "whole tree logging", "nutrient reserves", "natural thinning", "measurement", "ecology"], "contacts": [{"organization": "Hendrickson, O.Q.", "roles": ["creator"]}]}, "links": [{"href": "https://doi.org/10.1139/x88-221"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Canadian%20Journal%20of%20Forest%20Research", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1139/x88-221", "name": "item", "description": "10.1139/x88-221", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1139/x88-221"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "1988-11-01T00:00:00Z"}}, {"id": "10.1139/x89-213", "type": "Feature", "geometry": null, "properties": {"updated": "2026-05-25T16:19:13Z", "type": "Journal Article", "created": "2008-01-08", "title": "The Effect Of Wildfire On Soil Chemistry In 4 Forest Types In Interior Alaska", "description": "Soil chemical properties were studied after a wildfire in stands of white spruce (Piceaglauca (Moench) Voss), black spruce (Piceamariana (Mill.) B.S.P.), paper birch (Betulapapyrifera Marsh.), and quaking aspen (Populustremuloides Michx.). Samples of the forest floor and surface 5\uffe2\uff80\uff82cm of mineral soil were collected from burned sites and unburned controls and analyzed soon after the fire. With the exception of soil pH, effects of the fire on soil chemistry differed among the four forest types. Generally, amounts of exchangeable K, Ca, and Mg did not appreciably increase in the forest floor and surface mineral soil except in heavily burned areas in white spruce and black spruce. Fire reduced amounts of N by about 50% in white spruce, aspen, and birch forest floors. In black spruce, quantities of N were slightly higher in heavily burned locations. Forest floor C:N ratios were substantially lower in heavily burned locations in white spruce and black spruce than in unburned controls. Burning did not have a marked influence on supplies of available P in the forest floor, except in heavily burned black spruce, where average amounts were 12.50\uffe2\uff80\uff82g/m2 versus only 0.46\uffe2\uff80\uff82g/m2 in the control. Burning caused more moderate gains in available P in surface mineral soils under aspen and white spruce. We concluded that fire caused marked short-term changes in soil chemistry in the four forest types. How long these changes will persist is unknown.
", "keywords": ["Spermatophyta", "Angiosperms", "PH", "Coniferopsida: Gymnospermae", "Betula Papyrifera", "Gymnosperms", "01 natural sciences", "Dicots", "Picea Mariana", "Picea Glauca", "Populus Tremuloides", "Betulaceae: Dicotyledones", "Spermatophytes", "Magnesium", "Plantae", "Forest Sciences", "0105 earth and related environmental sciences", "Plant Carbon Nitrogen Ratio", "Vascular Plants", "Salicaceae: Dicotyledones", "Phosphorus", "Forestry", "04 agricultural and veterinary sciences", "Plants", "15. Life on land", "Angiospermae", "Potassium", "0401 agriculture", " forestry", " and fisheries", "Calcium"], "contacts": [{"organization": "Dyrness, D.T., Van Cleve, K., Levison, J.D.,", "roles": ["creator"]}]}, "links": [{"href": "https://doi.org/10.1139/x89-213"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Canadian%20Journal%20of%20Forest%20Research", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1139/x89-213", "name": "item", "description": "10.1139/x89-213", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1139/x89-213"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "1989-11-01T00:00:00Z"}}, {"id": "10.1139/x92-146", "type": "Feature", "geometry": null, "properties": {"updated": "2026-05-25T16:19:13Z", "type": "Journal Article", "created": "2009-12-18", "title": "Carbon Storage In Lake States Aspen Ecosystems", "description": "Total ecosystem carbon in the soil and vegetation was measured for a range of aspen (Populustremuloides Michx.) ecosystems, including a chronosequence on the same soil ranging in age from 0 to 80 years. Soil carbon stayed relatively constant throughout the stand's life and was not affected by timber harvesting. Changes in ecosystem carbon closely paralleled the changes in standing biomass. Aspen grown on 40-year rotations on good soils will sequester several times as much carbon per year as old-growth forests.
", "keywords": ["Management Options", "0106 biological sciences", "Michigan", "Spermatophyta", "Angiosperms", "Broadleaves", "wisconsin", "aspen", "Minnesota", "01 natural sciences", "Dicots", "forest succession", "Spermatophytes", "Populus tremuloides", "Biomass", "Plantae", "Forest Sciences", "USA", "Vascular Plants", "Salicaceae: Dicotyledones", "carbon", "Rotation Length", "age of trees", "Forestry", "Carbon cycle", "plant succession", "Plants", "Timber Harvest", "forest ecosystem", "carbon storage", "15. Life on land", "Angiospermae", "Chronosequence Soil Carbon", "ecosystems"], "contacts": [{"organization": "Alban, David H., Perala, D.A.,", "roles": ["creator"]}]}, "links": [{"href": "https://doi.org/10.1139/x92-146"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Canadian%20Journal%20of%20Forest%20Research", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1139/x92-146", "name": "item", "description": "10.1139/x92-146", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1139/x92-146"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "1992-08-01T00:00:00Z"}}, {"id": "10045/75093", "type": "Feature", "geometry": null, "properties": {"updated": "2026-05-25T16:24:24Z", "type": "Journal Article", "created": "2018-04-16", "title": "Intransitive competition is common across five major taxonomic groups and is driven by productivity, competitive rank and functional traits", "description": "AbstractCompetition can be fully hierarchical or intransitive, and this degree of hierarchy is driven by multiple factors, including environmental conditions, the functional traits of the species involved or the topology of competition networks. Studies simultaneously analysing these drivers of competition hierarchy are rare. Additionally, organisms compete either directly or via interference competition for resources or space, within a local neighbourhood or across the habitat. Therefore, the drivers of competition could change accordingly and depend on the taxa studied.
We performed the first multi\uffe2\uff80\uff90taxon study on pairwise competition across major taxonomic groups, including experiments with vascular plants, mosses, saprobic fungi, aquatic protists and soil bacteria. We evaluated how general is competition intransitivity from the pairwise competition matrix including all species and also for each possible three\uffe2\uff80\uff90species combination (triplets). We then examined which species were likely to engage in competitive loops and the effects of environmental conditions, competitive rank and functional traits on intransitive competition.
We found some degree of competition intransitivity in all taxa studied, with 38% to 5% of triplets being intransitive. Variance in competitive rank between species and more fertile conditions strongly reduced intransitivity, with triplets composed of species differing widely in their competitive ranks much less likely to be intransitive.
Including functional traits of the species involved more than doubled the variation explained compared to models including competitive rank only. Both trait means and variance within triplets affected the odds of them being intransitive. However, the traits responsible and the direction of trait effects varied widely between taxa, suggesting that traits can have a wide variety of effects on competition.
Synthesis. We evaluated the drivers of competition across multiple taxa and showed that productivity and competitive rank are fundamental drivers of intransitivity. We also showed that not only the functional traits of each species, but also those of the accompanying species, determine competition intransitivity. Intransitive competition is common across multiple taxa but can dampen under fertile conditions or for those species with large variance in their competitive abilities. This provides a first step towards predicting the prevalence of intransitive competition in natural communities.