Resource control over abundance, structure and functional diversity of soil microbial communities is a key determinant of soil processes and related ecosystem functioning. Copiotrophic organisms tend to be found in environments which are rich in nutrients, particularly carbon, in contrast to oligotrophs, which survive in much lower carbon concentrations.
We hypothesized that microbial biomass, activity and community structure in nutrient\uffe2\uff80\uff90poor soils of an Amazonian rain forest are limited by multiple elements in interaction. We tested this hypothesis with a fertilization experiment by adding C (as cellulose), N (as urea) and P (as phosphate) in all possible combinations to a total of 40 plots of an undisturbed tropical forest in French Guiana.
After 2\uffc2\uffa0years of fertilization, we measured a 47% higher biomass, a 21% increase in substrate\uffe2\uff80\uff90induced respiration rate and a 5\uffe2\uff80\uff90fold higher rate of decomposition of cellulose paper discs of soil microbial communities that grew in P\uffe2\uff80\uff90fertilized plots compared to plots without P fertilization. These responses were amplified with a simultaneous C fertilization suggesting P and C colimitation of soil micro\uffe2\uff80\uff90organisms at our study site.
Moreover, P fertilization modified microbial community structure (PLFAs) to a more copiotrophic bacterial community indicated by a significant decrease in the Gram\uffe2\uff80\uff90positive\uffc2\uffa0:\uffc2\uffa0Gram\uffe2\uff80\uff90negative ratio. The Fungi\uffc2\uffa0:\uffc2\uffa0Bacteria ratio increased in N fertilized plots, suggesting that fungi are relatively more limited by N than bacteria. Changes in microbial community structure did not affect rates of general processes such as glucose mineralization and cellulose paper decomposition. In contrast, community level physiological profiles under P fertilization combined with either C or N fertilization or both differed strongly from all other treatments, indicating functionally different microbial communities.
While P appears to be the most critical from the three major elements we manipulated, the strongest effects were observed in combination with either supplementary C or N addition in support of multiple element control on soil microbial functioning and community structure.
We conclude that the soil microbial community in the studied tropical rain forest and the processes it drives is finely tuned by the relative availability in C, N and P. Any shifts in the relative abundance of these key elements may affect spatial and temporal heterogeneity in microbial community structure, their associated functions and the dynamics of C and nutrients in tropical ecosystems.
", "keywords": ["tropical forest", "2. Zero hunger", "570", "phospholipid fatty acids (PLFA)", "[SDE.MCG]Environmental Sciences/Global Changes", "functional significance", "[SDV.EE.IEO] Life Sciences [q-bio]/Ecology", " environment/Symbiosis", "04 agricultural and veterinary sciences", "15. Life on land", "16. Peace & justice", "[SDE.BE] Environmental Sciences/Biodiversity and Ecology", "[SDE.MCG] Environmental Sciences/Global Changes", "13. Climate action", "microbial community structure", "ecosystem functioning", "environment/Symbiosis", "[SDV.EE.ECO]Life Sciences [q-bio]/Ecology", "[SDV.EE.ECO] Life Sciences [q-bio]/Ecology", " environment/Ecosystems", "[SDV.EE.IEO]Life Sciences [q-bio]/Ecology", "0401 agriculture", " forestry", " and fisheries", "multiple resource limitation", "[SDE.BE]Environmental Sciences/Biodiversity and Ecology", "phosphorus", "environment/Ecosystems", "soil functioning"]}, "links": [{"href": "https://doi.org/10.1111/1365-2435.12329"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Functional%20Ecology", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1111/1365-2435.12329", "name": "item", "description": "10.1111/1365-2435.12329", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1111/1365-2435.12329"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2014-09-29T00:00:00Z"}}, {"id": "10.3389/fpls.2021.682142", "type": "Feature", "geometry": null, "properties": {"license": "Open Access", "updated": "2026-05-31T07:01:33Z", "type": "Journal Article", "created": "2021-07-21", "title": "Shifts in the Abundances of Saprotrophic and Ectomycorrhizal Fungi With Altered Leaf Litter Inputs", "description": "Ectomycorrhizal (EcM) and saprotrophic fungi interact in the breakdown of organic matter, but the mechanisms underlying the EcM role on organic matter decomposition are not totally clear. We hypothesized that the ecological relations between EcM and saprotroph fungi are modulated by resources availability and accessibility, determining decomposition rates. We manipulated the amount of leaf litter inputs (No-Litter, Control Litter, Doubled Litter) on Trenched (root exclusion) and Non-Trenched plots (with roots) in a temperate deciduous forest of EcM-associated trees. Resultant shifts in soil fungal communities were determined by phospholipid fatty acids and DNA sequencing after 3 years, and CO2 fluxes were measured throughout this period. Different levels of leaf litter inputs generated a gradient of organic substrate availability and accessibility, altering the composition and ecological relations between EcM and saprotroph fungal communities. EcM fungi dominated at low levels of fresh organic substrates and lower organic matter quality, where short-distances exploration types seem to be better competitors, whereas saprotrophs and longer exploration types of EcM fungi tended to dominate at high levels of leaf litter inputs, where labile organic substrates were easily accessible. We were, however, not able to detect unequivocal signs of competition between these fungal groups for common resources. These results point to the relevance of substrate quality and availability as key factors determining the role of EcM and saprotroph fungi on litter and soil organic matter decay and represent a path forward on the capacity of organic matter decomposition of different exploration types of EcM fungi.Ectomycorrhizal (EcM) and saprotrophic fungi interact in the breakdown of organic matter, but the mechanisms underlying the EcM role on organic matter decomposition are not totally clear. We hypothesized that the ecological relations between EcM and saprotroph fungi are modulated by resources availability and accessibility, determining decomposition rates. We manipulated the amount of leaf litter inputs (No-Litter, Control Litter, Doubled Litter) on Trenched (root exclusion) and Non-Trenched plots (with roots) in a temperate deciduous forest of EcM-associated trees. Resultant shifts in soil fungal communities were determined by phospholipid fatty acids and DNA sequencing after 3 years, and CO2 fluxes were measured throughout this period. Different levels of leaf litter inputs generated a gradient of organic substrate availability and accessibility, altering the composition and ecological relations between EcM and saprotroph fungal communities. EcM fungi dominated at low levels of fresh organic substrates and lower organic matter quality, where short-distances exploration types seem to be better competitors, whereas saprotrophs and longer exploration types of EcM fungi tended to dominate at high levels of leaf litter inputs, where labile organic substrates were easily accessible. We were, however, not able to detect unequivocal signs of competition between these fungal groups for common resources. These results point to the relevance of substrate quality and availability as key factors determining the role of EcM and saprotroph fungi on litter and soil organic matter decay and represent a path forward on the capacity of organic matter decomposition of different exploration types of EcM fungi.