title: Rainfall variability counteracts N addition by promoting invasive Lonicera maackii and extending phenology in prairie.
abstract: Although encroaching woody plants have reduced the global extent of grasslands, continuing increases in soil nitrogen availability could slow this trend by favoring resident herbaceous species. At the same time, projected increases in rainfall variability could promote woody encroachment by aligning spatiotemporal patterns of soil moisture availability with the needs of woody species. We evaluated the responses of two deciduous woody species to these simulated environmental changes by planting seedlings of Quercus palustris and Lonicera maackii into tallgrass prairie communities grown under a factorial combination of increased rainfall variability and nitrogen addition. Lonicera maackii growth was reduced 20% by nitrogen addition, and increased rainfall variability led to 33% larger seedlings, despite greater competition for light and soil resources. In contrast, Q. palustris growth showed little response to either treatment. Increased rainfall variability allowed both species to retain their leaves for an additional 6.5 d in autumn, potentially in response to wetter end-of-season shallow soils. Our findings suggest increases in rainfall variability will counteract the inhibitory effect of nitrogen deposition on growth of L. maackii, extend autumn phenology, and promote the encroachment of some woody species into grasslands.
authors.affiliation: Department of Forestry and Natural Resources, Purdue University, 715 West State Street, West Lafayette, Indiana, 47907, USA.|Department of Forest Resources, University of Minnesota, 1530 Cleveland Avenue North, St. Paul, Minnesota, 55108, USA.
authors.forename: Michael J
authors.identifier: 0000-0001-8978-2608
authors.initials: MJ
authors.lastname: Schuster
authors.affiliation: Department of Forestry and Natural Resources, Purdue University, 715 West State Street, West Lafayette, Indiana, 47907, USA.|Department of Biological Sciences, Purdue University, 715 West State Street, West Lafayette, Indiana, 47907, USA.
authors.forename: Jeffrey S
authors.initials: JS
authors.lastname: Dukes
mesh_terms: D065948:Grassland; D007196:Indiana; D058865:Introduced Species; D031239:Lonicera / Q000254:growth & development* / Q000502:physiology; D009584:Nitrogen / Q000008:administration & dosage / Q000378:metabolism*; D063148:Plant Dispersal; D029963:Quercus / Q000254:growth & development* / Q000502:physiology; D011891:Rain; D036226:Seedlings / Q000254:growth & development / Q000502:physiology; D012987:Soil / Q000737:chemistry
chemical_list: D012987:Soil; D009584:Nitrogen
keywords: Lonicera maackii (Amur honeysuckle); Quercus palustris (Pin oak); biotic resistance; climate change; grassland; growth; limiting similarity; nitrogen; phenology; precipitation; woody encroachment