TY - GEN A1 - Wilcke, Wolfgang A1 - Leimer, Sophia A1 - Peters, Thorsten A1 - Emck, Paul A1 - Rollenbeck, Rütger A1 - Trachte, Katja A1 - Valarezo, Carlos T1 - The nitrogen cycle of tropical montane forest in Ecuador turns inorganic under environmental change T2 - Global Biogeochemical Cycles N2 - [1] Water‐bound nitrogen (N) cycling in temperate terrestrial ecosystems of the Northern Hemisphere is today mainly inorganic because of anthropogenic release of reactive N to the environment. In little‐industrialized and remote areas, in contrast, a larger part of N cycling occurs as dissolved organic N (DON). In a north Andean tropical montane forest in Ecuador, the N cycle changed markedly during 1998–2010 along with increasing N deposition and reduced soil moisture. The DON concentrations and the fractional contribution of DON to total N significantly decreased in rainfall, throughfall, and soil solutions. This inorganic turn of the N cycle was most pronounced in rainfall and became weaker along the flow path of water through the system until it disappeared in stream water. Decreasing organic contributions to N cycling were caused not only by increasing inorganic N input but also by reduced DON production and/or enhanced DON decomposition. Accelerated DON decomposition might be attributable to less waterlogging and higher nutrient availability. Significantly increasing NO3‐N concentrations and NO3‐N/NH4‐N concentration ratios in throughfall and litter leachate below the thick organic layers indicated increasing nitrification. In mineral soil solutions, in contrast, NH4‐N concentrations increased and NO3‐N/NH4‐N concentration ratios decreased significantly, suggesting increasing net ammonification. Our results demonstrate that the remote tropical montane forests on the rim of the Amazon basin experienced a pronounced change of the N cycle in only one decade. This change likely parallels a similar change which followed industrialization in the temperate zone of the Northern Hemisphere more than a century ago. KW - nitrogen deposition KW - climate change KW - dissolved organic nitrogen KW - nitrogen turnover KW - ecosystem solutions Y1 - 2013 U6 - https://doi.org/10.1002/2012GB004471 VL - 27 IS - 4 SP - 1194 EP - 1204 ER -