PARENT SESSION
Oral Session #33: Biodiversity and Ecosystem Function: Nutrients, soils, microbes.
Presiding: K. Brown
Tuesday, August 6. 8:00 AM to 11:30 AM. Grand Ballroom Central, Radisson.
Root herbivore:microbe interactions in upland grasslands.
GRAYSTON, SUSAN*,1, DAWSON, LORNA1, MURRAY, PHILIP2, COOK, ROGER3, CURRIE, AMANDA4, GANGE, ALAN4, TREONIS, AMY1,5, 1 The Macaulay Institute, Aberdeen, U.K.2 Institute of Grassland and Environmental Research, Okehampton, U.K.3 Institute of Grassland and Environmental Research, Aberystwyth, U.K.4 Royal Holloway, University of London, Egham, U.K.5 Creighton University, Omaha, Nebraska
ABSTRACT- In upland pastures the importance of soil biota in plant nutrient acquisition is well recognised. However, the roles played by various groups of soil organisms in nutrient transformations are poorly understood and few studies have addressed interactions between them. In grasslands numerous invertebrates, including insect larvae and phytophagic nematodes accumulate. Root herbivory by invertebrates will change rhizosphere carbon flow and is, therefore, likely to have a major impact on soil microbial communities and subsequently nutrient cycling. However, few studies have linked these processes. One aim of the NERC Soil Biodiversity Programme (http://mwnta.nmw.ac.uk/soilbio) is to increase our understanding of biological diversity and functioning in soil. As part of this programme the diversity of invertebrate root herbivores and their impact on plant biomass and soil microbial communities across a range of grasslands subjected to different management treatments is being investigated (http://www.macaulay.ac.uk/hugbug). Insect larvae of the cranefly (Tipula paludosa) and a number of plant parasitic nematodes have been identified as the dominant root herbivores at the site. In microcosm experiments larval herbivory had a significant negative effect on grass growth, caused an increase in C flux to the rhizosphere and the soil microbial community structure was altered in favour of Gram-negative bacteria. The implications of these findings for understanding the effect of root herbivory on microbial communities and the consequences for nutrient cycling and vegetation dynamics are discussed.
KEY WORDS: root herbivory, soil microbial communities, nematodes, rhizosphere carbon flow