title: Effects of Increased Nitrogen Availability on C and N Cycles in Tropical Forests: A Meta-Analysis.
abstract: Atmospheric N deposition is predicted to increase four times over its current status in tropical forests by 2030. Our ability to understand the effects of N enrichment on C and N cycles is being challenged by the large heterogeneity of the tropical forest biome. The specific response will depend on the forest's nutrient status; however, few studies of N addition appear to incorporate the nutrient status in tropical forests, possibly due to difficulties in explaining how this status is maintained. We used a meta-analysis to explore the consequences of the N enrichment on C and N cycles in tropical montane and lowland forests. We tracked changes in aboveground and belowground plant C and N and in mineral soil in response to N addition. We found an increasing trend of plant biomass in montane forests, but not in lowland forests, as well as a greater increase in NO emission in montane forest compared with lowland forest. The N2O and NO emission increase in both forest; however, the N2O increase in lowland forest was significantly even at first time N addition. The NO emission increase showed be greater at first term compared with long term N addition. Moreover, the increase in total soil N, ammonium, microbial N, and dissolved N concentration under N enrichment indicates a rich N status of lowland forests. The available evidence of N addition experiments shows that the lowland forest is richer in N than montane forests. Finally, the greater increase in N leaching and N gas emission highlights the importance of study the N deposition effect on the global climate change.
authors.affiliation: Pronatura Sur, A.C. Pedro Moreno 1, 29250, San Cristóbal de Las Casas, Mexico.
authors.forename: Marylin
authors.initials: M
authors.lastname: Bejarano-Castillo
authors.affiliation: Instituto de Ecología, Universidad Nacional Autónoma de México, México D.F., Mexico.
authors.forename: Julio
authors.initials: J
authors.lastname: Campo
authors.affiliation: Centro del Cambio Global y la Sustentabilidad en el Sureste, A.C., Villahermosa, Mexico.
authors.forename: Lilia L
authors.initials: LL
authors.lastname: Roa-Fuentes
mesh_terms: D002244:Carbon / Q000378:metabolism*; D057231:Climate Change; D017753:Ecosystem; D065928:Forests; D009584:Nitrogen / Q000378:metabolism*; D012987:Soil / Q000737:chemistry*; D014197:Trees; D014329:Tropical Climate
chemical_list: D012987:Soil; D002244:Carbon; D009584:Nitrogen