Representing the Dynamic Response of Vegetation to Nitrogen Limitation via Biological Nitrogen Fixation in the CLASSIC Land Model

Despite its pivotal feedback to carbon cycling, representing the dynamic response of vegetation nitrogen limitation is a key challenge for simulating terrestrial sink with land models. Here, we explore representation this novel biological fixation and cycling in Canadian Land Surface Scheme Including Biogeochemical Cycles. First, assess how incorporating via influences CO2 fertilization experiments, comparing simulations against observation-based estimates from meta-analyses. This evaluates whether underlying mechanisms are realistically represented. Second, affects simulated sequestration over 20th early 21st century, examining effects global change drivers (CO2, deposition, climate, land-use change) acting both individually concurrently. reduces driven by elevated historical period. Representing increases estimate present-day 0.2 Pg C yr?1 (because intensifies limitation, which drives upregulation fixation, alleviating limitation). Our results highlight importance projecting future under