title: Teasing apart plant community responses to N enrichment: the roles of resource limitation, competition and soil microbes.
abstract: Although ecologists have documented the effects of nitrogen enrichment on productivity, diversity and species composition, we know little about the relative importance of the mechanisms driving these effects. We propose that distinct aspects of environmental change associated with N enrichment (resource limitation, asymmetric competition, and interactions with soil microbes) drive different aspects of plant response. We test this in greenhouse mesocosms, experimentally manipulating each factor across three ecosystems: tallgrass prairie, alpine tundra and desert grassland. We found that resource limitation controlled productivity responses to N enrichment in all systems. Asymmetric competition was responsible for diversity declines in two systems. Plant community composition was impacted by both asymmetric competition and altered soil microbes, with some contributions from resource limitation. Results suggest there may be generality in the mechanisms of plant community change with N enrichment. Understanding these links can help us better predict N response across a wide range of ecosystems.
authors.affiliation: Department of Ecology and Evolutionary Biology, Tulane University, New Orleans, LA, 70118, USA. efarrer@tulane.edu.|Institute of Arctic and Alpine Research, University of Colorado Boulder, Boulder, CO, 80303, USA. efarrer@tulane.edu.
authors.forename: Emily C
authors.initials: EC
authors.lastname: Farrer
authors.affiliation: Institute of Arctic and Alpine Research, University of Colorado Boulder, Boulder, CO, 80303, USA.
authors.forename: Katharine N
authors.initials: KN
authors.lastname: Suding
mesh_terms: D001419:Bacteria / Q000145:classification*; D044822:Biodiversity; D002244:Carbon / Q000378:metabolism; D005308:Fertilizers; D065948:Grassland; D009584:Nitrogen / Q000378:metabolism*; D018521:Plant Physiological Phenomena; D010944:Plants / Q000145:classification* / Q000378:metabolism*; D011156:Population Density; D012988:Soil Microbiology; D065929:Tundra
chemical_list: D005308:Fertilizers; D002244:Carbon; D009584:Nitrogen
keywords: Alpine tundra; asymmetric competition; desert grassland; diversity; fertilisation; global change; greenhouse experiment; inoculum; nitrogen; tallgrass prairie