Simulation of greenhouse gases following land‐use change to bioenergy crops using the <scp>ECOSSE</scp> model: a comparison between site measurements and model predictions

Abstract

Abstract This article evaluates the suitability of the ECOSSE model to estimate soil greenhouse gas (GHG) fluxes from short rotation coppice willow ( SRC ‐Willow), short rotation forestry ( SRF ‐Scots Pine) and Miscanthus after land‐use change from conventional systems (grassland and arable). We simulate heterotrophic respiration ( R h ), nitrous oxide (N 2 O) and methane ( CH 4 ) fluxes at four paired sites in the UK and compare them to estimates of R h derived from the ecosystem respiration estimated from eddy covariance ( EC ) and R h estimated from chamber ( IRGA ) measurements, as well as direct measurements of N 2 O and CH 4 fluxes. Significant association between modelled and EC ‐derived R h was found under M iscanthus , with correlation coefficient ( r ) ranging between 0.54 and 0.70. Association between IRGA ‐derived R h and modelled outputs was statistically significant at the Aberystwyth site ( r = 0.64), but not significant at the Lincolnshire site ( r = 0.29). At all SRC ‐Willow sites, significant association was found between modelled and measurement‐derived R h (0.44 ≤ r ≤ 0.77); significant error was found only for the EC ‐derived R h at the Lincolnshire site. Significant association and no significant error were also found for SRF ‐Scots Pine and perennial grass. For the arable fields, the modelled CO 2 correlated well just with the IRGA ‐derived R h at one site ( r = 0.75). No bias in the model was found at any site, regardless of the measurement type used for the model evaluation. Across all land uses, fluxes of CH 4 and N 2 O were shown to represent a small proportion of the total GHG balance; these fluxes have been modelled adequately on a monthly time‐step. This study provides confidence in using ECOSSE for predicting the impacts of future land use on GHG balance, at site level as well as at national level.