Research

Addressing how 3-D vegetation structure controls shortwave radiation transfer in Earth System Models is essential for accurate carbon-budget estimates and climate predictions. While leaf-level photosynthesis is well understood, global carbon-assimilation estimates in the literature range from 110 to 175 PgC yr⁻¹.

My work shows that neglecting canopy structure — for example vegetation clumping — leads to significant uncertainties in radiation partitioning and derived properties such as leaf area index, and systematically underestimates global photosynthesis in land-surface models. I bring these processes together in next-generation models such as CliMA Land, coupling plant traits, radiative transfer, and sun-induced fluorescence.

Most tree species associate with a single type of mycorrhizal fungi, which shapes plant nutrient acquisition and biogeochemical cycling. Yet mycorrhizal distributions are highly uncertain — current estimates disagree by up to 50% over 40% of the land area.

Using the carbon–nitrogen economics of the Community Land Model v5 (CLM5), I found that Net Primary Productivity increased ~20% through the 21st century, but as soil nitrogen became limiting, the carbon cost of nutrient acquisition rose ~60% faster — meaning nutrient uptake will increasingly demand assimilated carbon to sustain the same productivity.

In canopies with complex architecture, diffuse solar radiation can enhance photosynthesis. Across three sites in the Amazon deforestation arc, I estimated how aerosol optical depth modifies surface fluxes of carbon, heat, and water.

Results show significant aerosol effects: CO₂ uptake increased by up to 55% at some sites in the presence of aerosols, while sensible and latent heat fluxes were reduced as less energy reached the surface.

Closing the land-carbon gap means confronting models with observations at every scale — flux towers, imaging spectroscopy, and satellite constraints. In the North American Arctic-Boreal region, I showed that a projected tipping point in the carbon sink persists across new-generation Earth System Models even as inter-model uncertainty falls — a robust and concerning signal for high-latitude carbon.

From tropical forests in the Amazon to boreal peatlands in Finland, I use flux-tower observations, digital hemispherical photography, and 3-D radiative transfer modelling to characterise canopy clumping and integrate it into hyperspectral Earth System Models — linking structure to photosynthesis and vegetation indices such as NDVI, NIRv, and SIF.