Simulating climate change and land use effects on soil nitrous oxide emissions in Mediterranean conditions using the Daycent model

In Mediterranean agroecosystems, limited information exists about possible impacts of climate change on soil N2O emissions under different land uses. This paper presents a modelling study with a dual objective. Firstly, the biogeochemical Daycent model was evaluated to predict soil N2O emissions in different land uses in a typical Mediterranean agroecosystem. Secondly, the study aimed to determine the impact of climate change on soil N2O emissions in different Mediterranean land uses over an 85-year period. Soil N2O emissions were measured in three land uses (cropland, abandoned land and afforested land) over 18 months (December 2011 to June 2013) in a characteristic Mediterranean site in Spain. For climate change simulations, Daycent was run with and without atmospheric CO2 enrichment using climate data from the CGCM2-A2 model. The cumulative N2O emissions predicted by the Daycent model agreed well with the observed values. The lack of fit (LOFIT) and the relative error (E) statistics determined that the model error was not greater than the error in the measurements and that the bias in the simulation values was lower than the 95% confidence interval of the measurements. For the different land uses and climate scenarios, annual cumulative N2O emissions ranged from 126 to 642 g N2O-N ha−1 yr−1. Over the simulated 85-year period, climate change decreased soil N2O emissions in all three land uses. At the same time, under climate change, water filled pore space (WFPS) values decreased between 4% and 15% depending on the land use and climate change scenario considered. This study demonstrated the ability of the Daycent model to simulate soil N2O emissions in different land uses. According to model predictions, in Mediterranean conditions, climate change would lead to reduced N2O emissions in a range of land uses.