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Abstract:
Aim: Trees associating with ectomycorrhizal (ECM) fungi typically occur in infertile soils and use nutrients more conservatively than arbuscular mycorrhizal (AM) trees. We hypothesized that ECM
trees would have greater nutrient resorption (i.e., proportion of nutrients resorbed during leaf
senescence) than AM trees.
Location: Global.
Methods: We synthesized nitrogen (N) and phosphorus (P) resorption data from 378 species from
sub/tropical, temperate and boreal forests, including 43 studies where ECM and AM trees cooccurred,
and conducted a meta-analysis. Additionally, we quantified N resorption in 45 plots varying
in ECM-AM tree abundances in the temperate deciduous forests of southern Indiana, USA.
Results: Overall, resorption patterns were driven primarily by mycorrhizal type, climate zone, and
to a lesser degree, leaf habit. In the boreal forest, P resorption was 76% greater for ECM than AM
trees (p<.05). In the sub/tropics, AM trees resorbed 30% more N than ECM trees. At the sites
where AM and ECM trees co-occurred, ECM trees resorbed more N in temperate forests (15%
greater; p<.001) whereas AM trees tended to resorb more N in sub/tropical forests (by 29%;
p5.08). Besides, deciduous ECM trees resorbed more N (10%) and P (15%) than deciduous AM
trees, while evergreen ECM and AM trees did not differ. In the deciduous forests of Indiana, where
ECM and AM trees co-occurred, the relative abundance of ECM trees in a plot was positively correlated
to plot-scale N resorption (R25.25, p5.001), indicating greater nutrient conservatism with
increasing ECM-dominance.
Main conclusions: Our results indicate that mycorrhizal association – in addition to other factors
– is correlated with the degree to which trees recycle nutrients, with the strongest effects occurring
for N resorption by temperate deciduous trees.
