RED DGVM: simple approach to modelling vegetation with novel implications.
Abstract
The modelled global vegetation for the end of the 21st century is currently is insufficiently constrainedby climate models. A significant proportion of that uncertainty has been attributed to the limitationsof current Dynamic Global Vegetation Models (DGVMs), and the misrepresentation of mortality, dis-turbance and regrowth within forests. Improving the simulation of the underlying processes of de-mographic change is of primary importance in the development of predictors of future climate.Here we present the Robust Ecosystem Demography (RED), a new dynamical vegetation model whichsimulates the size-structure of forests by partitioning the population of a Plant Functional Type (PFT)into mass classes. Allometric scaling of mortality and growth across mass classes allows for a varietyof complex demographic processes to be captured, such as disturbances and regrowth. Competitionamong PFTs is done purely through restricting the recruitment of new vegetation to unshaded space.RED represents a reduction of complexity from more numerically unwieldy cohort DGVMs whichsimulate both size and patch dimensions. The limited number of dimensions and simple competitiveregime allows the equilibrium state to be solved for analytically, providing two potential functions - (i)Avoiding-spinning up by providing an equilibrium state for intilisation. (ii) Insights into the demog-raphy of vegetated areas, arising from parameter tuning to fit observation, such as coverage or carbonmass. When paired with a rate of mortality or carbon assimilate rate gives, respectfully, required as-similate or mortality rates.We demonstrate the model functionality using offline UKESM PFT carbon assimilate rates, pairedwith observed vegetation cover from the ESA LC_CCI datasets for the 9 different PFTs. From thisdataset we calibrate a novel global equilibrium mortality map for each PFT and show the competitiveand successional behaviour of dynamical runs with convergence to the fitted equilibrium. Finally, weexplore underlying ecological questions that emerge from the equilibrium solutions.
- Publication:
-
EGU General Assembly Conference Abstracts
- Pub Date:
- May 2020
- DOI:
- 10.5194/egusphere-egu2020-16276
- Bibcode:
- 2020EGUGA..2216276A