title: Root morphology and mycorrhizal symbioses together shape nutrient foraging strategies of temperate trees.
abstract: Photosynthesis by leaves and acquisition of water and minerals by roots are required for plant growth, which is a key component of many ecosystem functions. Although the role of leaf functional traits in photosynthesis is generally well understood, the relationship of root functional traits to nutrient uptake is not. In particular, predictions of nutrient acquisition strategies from specific root traits are often vague. Roots of nearly all plants cooperate with mycorrhizal fungi in nutrient acquisition. Most tree species form symbioses with either arbuscular mycorrhizal (AM) or ectomycorrhizal (EM) fungi. Nutrients are distributed heterogeneously in the soil, and nutrient-rich "hotspots" can be a key source for plants. Thus, predicting the foraging strategies that enable mycorrhizal root systems to exploit these hotspots can be critical to the understanding of plant nutrition and ecosystem carbon and nutrient cycling. Here, we show that in 13 sympatric temperate tree species, when nutrient availability is patchy, thinner root species alter their foraging to exploit patches, whereas thicker root species do not. Moreover, there appear to be two distinct pathways by which thinner root tree species enhance foraging in nutrient-rich patches: AM trees produce more roots, whereas EM trees produce more mycorrhizal fungal hyphae. Our results indicate that strategies of nutrient foraging are complementary among tree species with contrasting mycorrhiza types and root morphologies, and that predictable relationships between below-ground traits and nutrient acquisition emerge only when both roots and mycorrhizal fungi are considered together.
authors.affiliation: Intercollege Graduate Degree Program in Ecology, The Pennsylvania State University, University Park, PA 16802; Department of Ecosystem Science and Management, The Pennsylvania State University, University Park, PA 16802;
authors.forename: Weile
authors.initials: W
authors.lastname: Chen
authors.affiliation: Intercollege Graduate Degree Program in Ecology, The Pennsylvania State University, University Park, PA 16802; Department of Biology, Brigham Young University, Provo, UT 84602;
authors.forename: Roger T
authors.initials: RT
authors.lastname: Koide
authors.affiliation: Intercollege Graduate Degree Program in Ecology, The Pennsylvania State University, University Park, PA 16802; Department of Ecosystem Science and Management, The Pennsylvania State University, University Park, PA 16802;
authors.forename: Thomas S
authors.initials: TS
authors.lastname: Adams
authors.affiliation: Department of Environmental and Plant Biology, Ohio University, Athens, OH 45701;
authors.forename: Jared L
authors.initials: JL
authors.lastname: DeForest
authors.affiliation: Intercollege Graduate Degree Program in Ecology, The Pennsylvania State University, University Park, PA 16802; College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Cheng
authors.affiliation: Intercollege Graduate Degree Program in Ecology, The Pennsylvania State University, University Park, PA 16802; Department of Ecosystem Science and Management, The Pennsylvania State University, University Park, PA 16802; dme9@psu.edu.
authors.forename: David M
authors.initials: DM
authors.lastname: Eissenstat
mesh_terms: D002244:Carbon / Q000378:metabolism*; D017753:Ecosystem; D038821:Mycorrhizae / Q000378:metabolism* / Q000502:physiology; D009584:Nitrogen / Q000378:metabolism*; D018517:Plant Roots / Q000254:growth & development / Q000378:metabolism* / Q000382:microbiology; D012987:Soil / Q000737:chemistry; D012988:Soil Microbiology; D013559:Symbiosis; D014197:Trees / Q000254:growth & development / Q000378:metabolism* / Q000382:microbiology
chemical_list: D012987:Soil; D002244:Carbon; D009584:Nitrogen
keywords: mycorrhizal fungi; plant traits; root proliferation; soil heterogeneity; symbioses