Denitrification in humid tropical forests: Mass balance constraints and global change

Total N gas losses from humid tropical forest ecosystems are estimated using small watershed budgeting of plant N uptake and turnover and hydrologic N losses. Globally, denitrification in tropical forests is likely equivalent to or higher than hydrologic losses, but these loss fractions depend on the degree to which denitrifiers and plants compete for a common nitrate pool. Relaxing steady state assumptions reveals the sensitivity of denitrification to net forest biomass change and the abundance and dynamics of N fixing legumes. Climate change and CO₂ fertilization could affect the balance of microbial denitrification and fixation and thus forest productivity.