title: Species decline under nitrogen fertilization increases community-level competence of fungal diseases.
abstract: The artificial fertilization of soils can alter the structure of natural plant communities and exacerbate pathogen emergence and transmission. Although the direct effects of fertilization on disease resistance in plants have received some research attention, its indirect effects of altered community structure on the severity of fungal disease infection remain largely uninvestigated. We designed manipulation experiments in natural assemblages of Tibetan alpine meadow vegetation along a nitrogen-fertilization gradient over 5 years to compare the relative importance of direct and indirect effects of fertilization on foliar fungal infections at the community level. We found that species with lower proneness to pathogens were more likely to be extirpated following fertilization, such that community-level competence of disease, and thus community pathogen load, increased with the intensity of fertilization. The amount of nitrogen added (direct effect) and community disease competence (indirect effect) provided the most parsimonious combination of parameters explaining the variation in disease severity. Our experiment provides a mechanistic explanation for the dilution effect in fertilized, natural assemblages in a highly specific pathogen-host system, and thus insights into the consequences of human ecosystem modifications on the dynamics of infectious diseases.
authors.affiliation: Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, School of Life Sciences, Fudan University, 2005 Songhu Road, Shanghai 200438, China.
authors.forename: Xiang
authors.initials: X
authors.lastname: Liu
authors.affiliation: Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, School of Life Sciences, Fudan University, 2005 Songhu Road, Shanghai 200438, China.
authors.forename: Shengman
authors.initials: S
authors.lastname: Lyu
authors.affiliation: Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, School of Life Sciences, Fudan University, 2005 Songhu Road, Shanghai 200438, China.
authors.forename: Dexin
authors.initials: D
authors.lastname: Sun
authors.affiliation: School of Biological Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001, Australia.
authors.forename: Corey J A
authors.initials: CJ
authors.lastname: Bradshaw
authors.affiliation: Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, School of Life Sciences, Fudan University, 2005 Songhu Road, Shanghai 200438, China zhshrong@fudan.edu.cn.
authors.forename: Shurong
authors.identifier: 0000-0002-7093-1703
authors.initials: S
authors.lastname: Zhou
mesh_terms: D005308:Fertilizers; D005658:Fungi / Q000472:pathogenicity; D065948:Grassland; D009584:Nitrogen; D010935:Plant Diseases / Q000382:microbiology*; D012987:Soil
chemical_list: D005308:Fertilizers; D012987:Soil; D009584:Nitrogen
keywords: alpine meadow; community competence; dilution effect; diversity–disease relationship; foliar fungal disease; nitrogen addition