This is the first study quantifying total soil CO2
efflux, heterotrophic and autotrophic respiration in an old-growth kauri forest. Root biomass explained a high proportion of the spatial variation suggesting that soil CO2
efflux in this forest is not only directly affected by the amount of autotrophic respiration but also by the supply of C through roots and mycorrhiza. Our findings also suggest that biotic factors such as tree structure should be investigated in soil carbon related studies.