Independent roles of ectomycorrhizal and saprotrophic communities in soil organic matter decomposition |
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| Institution: | 1. Department of Biology, Stanford University, Stanford, CA 94305, USA;2. Department of Plant and Microbial Biology, University of California Berkeley, Berkeley, CA 94702, USA;3. Department of Biology, Duke University, Durham, NC 27708, USA;1. Aix Marseille Univ, Univ Avignon, CNRS, IRD, IMBE, Marseille, France;2. Université Rennes 1 – OSUR, UMR CNRS 6553 ECOBIO, Avenue du Général Leclerc, 35042 Rennes, France;3. Centre d’Ecologie Fonctionnelle et Evolutive (CEFE), UMR CNRS 5175, Campus CNRS/CEFE, 1919 route de Mende, 34293 Montpellier Cedex 05, France;6. Forest Science and Technology Centre of Catalonia (CTFC), Ctra de Sant Llorenç de Morunys, km 2, E-25280 Solsona, Lleida, Spain;1. Department of Forest Ecology, Swedish University of Agricultural Sciences, SLU, SE-901 83 Umeå, Sweden;2. Environmental Science and Technology Department, University of Maryland, College Park, MD 20742, USA;3. Department of Microbiology, Oregon State University, Corvallis, OR 97331, USA;4. Department of Crop and Soil Science, Oregon State University, Corvallis, OR 97331, USA;1. Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, No. 11A, Datun Road, Chaoyang District, Beijing 100101,China;2. University of Chinese Academy of Sciences, Beijing 100049, China;3. School of Life Sciences, Beijing Normal University, Beijing 100875, China;4. College of Geographical Science, Southwest University, Chongqing 400715, China |
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| Abstract: | The relative roles of ectomycorrhizal (ECM) and saprotrophic communities in controlling the decomposition of soil organic matter remain unclear. We tested the hypothesis that ECM community structure and activity influences the breakdown of nutrient-rich biopolymers in soils, while saprotrophic communities primarily regulate the breakdown of carbon-rich biopolymers. To test this hypothesis, we used high-throughput techniques to measure ECM and saprotrophic community structure, soil resource availability, and extracellular enzyme activity in whole soils and on ECM root tips in a coastal pine forest. We found that ECM and saprotroph richness did not show spatial structure and did not co-vary with any soil resource. However, species richness of ECM fungi explained variation in the activity of enzymes targeting recalcitrant N sources (protease and peroxidase) in bulk soil. Activity of carbohydrate- and organic P- targeting enzymes (e.g. cellobiohydrolase, β-glucosidase, α-glucosidase, hemicellulases, N-acetyl-glucosaminidase, and acid phosphatase) was correlated with saprotroph community structure and soil resource abundance (total soil C, N, and moisture), both of which varied along the soil profile. These observations suggest independent roles of ECM fungi and saprotrophic fungi in the cycling of N-rich, C-rich, and P-rich molecules through soil organic matter. Enzymatic activity on ECM root tips taken from the same soil cores used for bulk enzyme analysis did not correlate with the activity of any enzyme measured in the bulk soil, suggesting that ECM contributions to larger-scale soil C and nutrient cycling may occur primarily via extramatrical hyphae outside the rhizosphere. |
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