El ciclo global del nitrógenoUna visión para el ecólogo terrestre

Resumo

The nitrogen (N) availability in the biosphere, the alteration of the global cycle, and its impact on the ecosystem are given by three key functional characteristics of the N cycle. First, the atmospheric N abundance allows both the biological and industrial fixation through the Haber-Bosch process, doubling the atmospheric N total inputs. Thus, the atmospheric N reservoir is the main source of the N cycle alteration, being the easiness to return to its original compartment the principal difference with the carbon (C) and phosphorus (P) cycles. Second, low concentrations of N in rock and soil minerals determines that in the long-term N limitation is mainly regulated by the biological fixation rate, being also dependent on the soil development and the presence of organic sedimentary rocks. Finally, an essential property of the N cycle in the biosphere is the high mobility of N across ecosystem boundaries through N-fixation, nitrification, denitrification and ammonification processes. All these properties cause that the fixed N molecule have multiples effects along its movement across different ecosystems, leading to acidification, eutrophication, alteration of albedo among other processes, and contributing substantially to climate change.