Soil nitrogen levels are linked to decomposition enzyme activities along an urban-remote tropical forest gradient

► Urban versus remote tropical forest soils had suppressed ammonium:nitrate ratios. ► Nitrogen was enriched relative to carbon in urban versus remote forest soils. ► Soil enzyme activities were significantly lower in urban versus remote forests. ► Nitrogen levels were the strongest predictors of decomposition enzyme activities. ► These results suggest a strong urban influence on soil nitrogen and carbon cycling.