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  • Print publication year: 2006
  • Online publication date: December 2009

5 - Integrating ectomycorrhizal fungi into quantitative frameworks of forest carbon and nitrogen cycling

Summary

Introduction

Ecosystem ecologists have calculated carbon and nitrogen budgets for a variety of forest ecosystems. Despite a growing awareness of the importance of mycorrhizal fungi in nitrogen uptake, as carbon sinks for photosynthate and as conduits for carbon from plants to the below-ground community, few ecosystem ecologists have incorporated mycorrhizal fungi in their conceptual models of how forests function. Longstanding difficulties in assessing the presence and quantity of mycorrhizal fungi in soil, in identifying mycorrhizal fungi to species, and in assessing the mycorrhizal role in carbon and nitrogen cycling, have probably limited the willingness and ability of ecosystem ecologists to incorporate mycorrhizal fungi into their research. In particular, ecosystem models have not yet included mycorrhizal fungi, despite the key role of mycorrhizal fungi at the interface of plants, the soil and microbial communities below-ground.

In this review we will focus on ectomycorrhizal fungi that form symbioses with many of the dominant trees of temperate and boreal forests, particularly in trees of the Pinaceae, Fagaceae, Betulaceae and Salicaceae. Ectomycorrhizal fungi also form symbioses with many tropical trees, including the Dipterocarpaceae of southeast Asia and Eucalyptus of Australia. We will lay out the current state of knowledge of the functioning of ectomycorrhizal fungi in carbon and nitrogen cycling of forest ecosystems as inferred from field and laboratory studies. Finally, we will discuss progress in integrating mycorrhizal fungi into quantitative frameworks of forest ecosystem function.

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