Net primary production of ectomycorrhizas in a California forest

Soils contain a large global pool of carbon. Mycorrhizal fungi comprise a large fraction of that pool but are highly dynamic. We utilized an in situ soil observatory to study fungal dynamics of a California mixed-forest ectomycorrhizal fungal (EMF) ecosystem. Across 2011, we observed fungal hyphae daily using an automated minirhizotron. Simultaneously, we made continuous temperature, precipitation, photosynthetically active radiation (PAR) and sap flow measurements. From the hyphal observations, we estimated hyphal net primary production. We then estimated total net primary production (NPP) and root NPP using DayCENT, an ecosystem model of carbon exchange parameterized for daily to annual output, for the calendar year 2011. Total NPP was 600 g C m−2 with 200 g C m−2 fine roots. The estimated NPP allocated to EMF was 162.6 g C m−2 or 27 % of the total NPP. The proportion of the total NPP allocated to EMF based on the Hobbie and Hobbie (2006) N fractionation model, was 34 %. These differing techniques provided similar estimates that can be refined with additional research and can be used to improve regional and global models of C dynamics.