| 1. |
- Mayor, Jordan, et al.
(författare)
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Elevation alters ecosystem properties across temperate treelines globally
- 2017
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Ingår i: Nature. - : NATURE PUBLISHING GROUP. - 0028-0836 .- 1476-4687. ; 542:7639, s. 91-95
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Tidskriftsartikel (refereegranskat)abstract
- Temperature is a primary driver of the distribution of biodiversity as well as of ecosystem boundaries(1,2). Declining temperature with increasing elevation in montane systems has long been recognized as a major factor shaping plant community biodiversity, metabolic processes, and ecosystem dynamics(3,4). Elevational gradients, as thermoclines, also enable prediction of long-term ecological responses to climate warming(5-7). One of the most striking manifestations of increasing elevation is the abrupt transitions from forest to treeless alpine tundra(8). However, whether there are globally consistent above-and belowground responses to these transitions remains an open question(4). To disentangle the direct and indirect effects of temperature on ecosystem properties, here we evaluate replicate treeline ecotones in seven temperate regions of the world. We find that declining temperatures with increasing elevation did not affect tree leaf nutrient concentrations, but did reduce ground-layer community-weighted plant nitrogen, leading to the strong stoichiometric convergence of ground-layer plant community nitrogen to phosphorus ratios across all regions. Further, elevation-driven changes in plant nutrients were associated with changes in soil organic matter content and quality (carbon to nitrogen ratios) and microbial properties. Combined, our identification of direct and indirect temperature controls over plant communities and soil properties in seven contrasting regions suggests that future warming may disrupt the functional properties of montane ecosystems, particularly where plant community reorganization outpaces treeline advance.
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| 2. |
- Mayor, Jordan
(författare)
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Parasites dominate hyperdiverse soil protist communities in Neotropical rainforests
- 2017
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Ingår i: Nature ecology & evolution. - : Springer Science and Business Media LLC. - 2397-334X. ; 1
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Tidskriftsartikel (refereegranskat)abstract
- High animal and plant richness in tropical rainforest communities has long intrigued naturalists. It is unknown if similar hyper-diversity patterns are reflected at the microbial scale with unicellular eukaryotes (protists). Here we show, using enwironmental metabarcoding of soil samples and a phylogeny-aware cleaning step, that protist communities in Neotropical rainforests are hyperdiverse and dominated by the parasitic Apicomplexa, which infect arthropods and other animals. These host-specific parasites potentially contribute to the high animal diversity in the forests by reducing population growth in a density-dependent manner. By contrast, too few operational taxonomic units (OTUs) of Oomycota were found to broadly drive high tropical tree diversity in a host-specific manner under the Janzen-Connell model. Extremely high OTU diversity and high heterogeneity between samples within the same forests suggest that protists, not arthropods, are the most diverse eukaryotes in tropical rainforests. Our data show that protists play a large role in tropical terrestrial ecosystems long viewed as being dominated by macroorganisms.
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| 3. |
- Mayor, Jordan
(författare)
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Yeasts dominate soil fungal communities in three lowland Neotropical rainforests
- 2017
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Ingår i: Environmental Microbiology Reports. - : Wiley. - 1758-2229. ; 9, s. 668-675
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Tidskriftsartikel (refereegranskat)abstract
- Forest soils typically harbour a vast diversity of fungi, but are usually dominated by filamentous (hyphae-forming) taxa. Compared to temperate and boreal forests, though, we have limited knowledge about the fungal diversity in tropical rainforest soils. Here we show, by environmental metabarcoding of soil samples collected in three Neotropical rainforests, that Yeasts dominate the fungal communities in terms of the number of sequencing reads and OTUs. These unicellular forms are commonly found in aquatic environments, and their hyperdiversity may be the result of frequent inundation combined with numerous aquatic microenvironments in these rainforests. Other fungi that are frequent in aquatic environments, such as the abundant Chytridiomycotina, were also detected. While there was low similarity in OTU composition within and between the three rainforests, the fungal communities in Central America were more similar to each other than the communities in South America, reflecting a general biogeographic pattern also seen in animals, plants and protists.
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