XVI International Botanical Congess
Pasture abandonment leads to new ecosystems that may affect emissions of nitrous and nitric oxide, two globally important N-oxide gases. We measured N-oxide fluxes and rates of soil N cycling in active pastures and successional forests in 2 regions of Puerto Rico. Tree dbh and species were noted in all forests. Fluxes of N-oxides were greatest where leguminous tree species were dominant, i.e., on sites where former coffee production was indicated (subtropical wet) or that had succeeded to a legume (subtropical dry). Soil nitrate and rates of N cycling were also greatest at these sites. Human activities have altered fluxes of N-oxides in previously unrecognized ways. Future studies of N-oxide emissions would benefit from noting plant species composition.