Modelling Herbivory Impacts on Vegetation Structure and Productivity

Abstract. Animal herbivory can have large and diverse impacts on vegetation and hence on the state and function of ecosystems. Despite this, quantitative understanding of vegetation responses to consumption of green leaf tissue by herbivores is currently lacking and presents a critical gap. More and more species are becoming endangered or extinct, whereas ecosystem restoration and rewilding are also increasingly moving into the focus of the scientific community. The large-scale impacts of changes in herbivore abundance on ecosystem function have yet to be investigated. Process-based modelling can help to quantify how animals affect important processes, such as ecosystem carbon cycling. To do so, we linked the dynamic global vegetation model LPJ-GUESS with the Madingley model, a model of multi-trophic functional diversity. This implementation allows us to simulate feedbacks between the availability of green vegetation biomass, herbivory and the whole trophic chain and vice versa. In the coupled model system, we see an overall reduction in ecosystem productivity, leaf area index and carbon mass, compared to the stand-alone version of LPJ-GUESS. The impact of herbivory is most prominently visible in the boreal ecosystems. We evaluated LPJ-GUESS output against remote sensing datasets and flux measurements and find that the coupled LPJ-GUESS/Madingley model preserves LPJ-GUESS’s ability to predict realistic biome distributions and carbon pools.