Data from: Contrasting effects of ectomycorrhizal and arbuscular mycorrhizal tropical tree species on soil nitrogen cycling: the potential mechanisms and corresponding adaptive strategies

While it is increasingly recognized that ectomycorrhizal (ECM) and
arbuscular mycorrhizal (AM) tree species vary in their effects on soil
nitrogen (N) cycling, little is known about the mechanisms causing and how
ECM and AM trees adapt to this variation. Using monoculture plots of six
ECM and eight AM tropical trees planted in a common garden, we examined
whether the contrasting effects of ECM and AM trees on soil N cycling
could be explained by their differences in plant traits. Furthermore,
rhizosphere effects on soil N transformations and soil exploration by fine
roots were also measured to assess whether ECM and AM trees differed in N
acquisition capacities. Results showed that soil NH 4+N concentration, net
N mineralization and net nitrification rates were markedly lower, but soil
C:N ratio was significantly higher beneath ECM trees than beneath AM
trees. This more closed N cycling caused by ECM trees was attributed to
their resource-conservative traits, especially the poorer leaf litter
decomposability compared with AM trees. To adapt to their induced lower
soil N availability, ECM trees were found to have greater rhizosphere
effects on NO 3-N concentration, net N mineralization and net
nitrification rates to mine N, and higher soil exploration in terms of
root length density to scavenge N from soils, indicating that these two
strategies work in synergy to meet N demand of ECM trees. These findings
suggest that ECM and AM trees have contrasting effects on soil N cycling
owing to their differences in leaf litter decomposability and
correspondingly possess different N acquisition capacities.