SCIENTIST SAYS / NGC MONTHLY SERIES / SEPTEMBER 2026

Jessica Needham – Land surface modeller and co-developer of the FATES vegetation model 

Tue 29 September 2026,  NGC Communication Team

Dr Jessica Needham. Photo: Jessica Needham

SCIENTIST SAYS – OUR MONTHLY INTERVIEW SERIES  Dr Jessica Needham is a Senior Researcher at CICERO Centre for International Climate Research in Norway. She is a land surface modeler, with a focus on forest dynamics, and a co-developer of the FATES vegetation model. Jessica has experience working with forest inventory data and is interested in benchmarking forest demography in land surface models. As part of NextGenCarbon she will be working on Work Package 4, Vegetation Demographics Observations & Modeling, constraining forest regrowth in land surface models. 

Hi Jessica, please tell us about yourself briefly! 

I became interested in forest ecology while studying biology as an undergraduate. During my PhD, I worked on methods for modeling the population and community dynamics of trees, which led to my current work as a land surface modeler. Vegetation plays a critical role in the Earth System, cycling huge amounts of carbon, water and energy. My work broadly focuses on how vegetation responses to changes in climate and CO2 will feedback to impact future climate.

What is FATES vegetation model and how it is used in NextGenCarbon? 

FATES – the Functionally Assembled Terrestrial Ecosystem Simulator – is a vegetation demography model that exists as a module within land surface models. FATES models competition for light and other resources among cohorts, groups of trees of the same size and plant functional type (e.g. evergreen or deciduous, broadleaf or needleleaf).

We can use FATES to model forest disturbance and regrowth which is essential for our understanding of the land carbon sink, given the increasing pressure forests face from land use and more frequent climate extremes. Within NextGenCarbon we are benchmarking FATES and other demographic land surface models with observations of forest age structure to ensure models can recreate the past impact of land use and regrowth on contemporary forest structure.

We can use FATES to model forest disturbance and regrowth which is essential for our understanding of the land carbon sink, given the increasing pressure forests face from land use and more frequent climate extremes. 

What are the main challenges in modelling forest regrowth? 

One challenge is ensuring that when we compare model results with observations we are making an ‘apples to apples’ comparison. For example, in FATES the age of a forest patch corresponds to the time since last disturbance, with disturbances including large scale processes like fires and land use, but also smaller scale processes such as the death of a large canopy tree. Observations of forest age usually do not account for these smaller scale disturbances and so FATES patches may appear younger than observed forests unless we correct for this discrepancy.   

Who do you think would find the results interesting? 

The results from the NextGenCarbon project will be interesting to the land surface modelling community as well as forest ecologists and remote sensing experts. In addition, results regarding forest response to differing management strategies will be of interest to forest managers and land owners, while an overall improved understanding of the land carbon sink is important for policy makers.

Where can our readers find you and your work?

You can read more about the NorESM-FATES team at CICERO here: Rosieafisher.com/network