Robust Ecosystem Demography (RED version 1.0): a parsimonious approach to modelling vegetation dynamics in Earth system models
<p>A significant proportion of the uncertainty in climate projections arises from uncertainty in the representation of land carbon uptake. Dynamic global vegetation models (DGVMs) vary in their representations of regrowth and competition for resources, which results in differing responses to c...
| Main Authors: | , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2020-09-01
|
| Series: | Geoscientific Model Development |
| Online Access: | https://gmd.copernicus.org/articles/13/4067/2020/gmd-13-4067-2020.pdf |
| _version_ | 1811291776900661248 |
|---|---|
| author | A. P. K. Argles J. R. Moore C. Huntingford A. J. Wiltshire A. B. Harper C. D. Jones P. M. Cox |
| author_facet | A. P. K. Argles J. R. Moore C. Huntingford A. J. Wiltshire A. B. Harper C. D. Jones P. M. Cox |
| author_sort | A. P. K. Argles |
| collection | DOAJ |
| description | <p>A significant proportion of the uncertainty in climate projections arises from uncertainty in the representation of land carbon uptake. Dynamic global vegetation models (DGVMs) vary in their representations of regrowth and competition for resources, which results in differing responses to changes in atmospheric <span class="inline-formula">CO<sub>2</sub></span> and climate. More advanced cohort-based patch models are now becoming established in the latest DGVMs. These models typically attempt to simulate the size distribution of trees as a function of both tree size (mass or trunk diameter) and age (time since disturbance). This approach can capture the overall impact of stochastic disturbance events on the forest structure and biomass – but at the cost of increasing the number of parameters and ambiguity when updating the probability density function (pdf) in two dimensions. Here we present the Robust Ecosystem Demography (RED), in which the pdf is collapsed onto the single dimension of tree mass. RED is designed to retain the ability of more complex cohort DGVMs to represent forest demography, while also being parameter sparse and analytically solvable for the steady state. The population of each plant functional type (PFT) is partitioned into mass classes with a fixed baseline mortality along with an assumed power-law scaling of growth rate with mass. The analytical equilibrium solutions of RED allow the model to be calibrated against observed forest cover using a single parameter – the ratio of mortality to growth for a tree of a reference mass (<span class="inline-formula"><i>μ</i><sub>0</sub></span>). We show that RED can thus be calibrated to the ESA LC_CCI (European Space Agency Land Cover Climate Change Initiative) coverage dataset for nine PFTs. Using net primary productivity and litter outputs from the UK Earth System Model (UKESM), we are able to diagnose the spatially varying disturbance rates consistent with this observed vegetation map. The analytical form for RED circumnavigates the need to spin up the numerical model, making it attractive for application in Earth system models (ESMs). This is especially so given that the model is also highly parameter sparse.</p> |
| first_indexed | 2024-04-13T04:34:34Z |
| format | Article |
| id | doaj.art-c35fe21b09ac406e8dc44d6b4f813633 |
| institution | Directory Open Access Journal |
| issn | 1991-959X 1991-9603 |
| language | English |
| last_indexed | 2024-04-13T04:34:34Z |
| publishDate | 2020-09-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Geoscientific Model Development |
| spelling | doaj.art-c35fe21b09ac406e8dc44d6b4f8136332022-12-22T03:02:13ZengCopernicus PublicationsGeoscientific Model Development1991-959X1991-96032020-09-01134067408910.5194/gmd-13-4067-2020Robust Ecosystem Demography (RED version 1.0): a parsimonious approach to modelling vegetation dynamics in Earth system modelsA. P. K. Argles0J. R. Moore1C. Huntingford2A. J. Wiltshire3A. B. Harper4C. D. Jones5P. M. Cox6College of Engineering, Mathematics, and Physical Sciences, University of Exeter, Exeter EX4 4QF, UKCollege of Engineering, Mathematics, and Physical Sciences, University of Exeter, Exeter EX4 4QF, UKUK Centre for Ecology and Hydrology, Wallingford OX10 8BB, UKMet Office Hadley Centre, Fitzroy Road, Exeter EX1 3PB, UKCollege of Engineering, Mathematics, and Physical Sciences, University of Exeter, Exeter EX4 4QF, UKMet Office Hadley Centre, Fitzroy Road, Exeter EX1 3PB, UKCollege of Engineering, Mathematics, and Physical Sciences, University of Exeter, Exeter EX4 4QF, UK<p>A significant proportion of the uncertainty in climate projections arises from uncertainty in the representation of land carbon uptake. Dynamic global vegetation models (DGVMs) vary in their representations of regrowth and competition for resources, which results in differing responses to changes in atmospheric <span class="inline-formula">CO<sub>2</sub></span> and climate. More advanced cohort-based patch models are now becoming established in the latest DGVMs. These models typically attempt to simulate the size distribution of trees as a function of both tree size (mass or trunk diameter) and age (time since disturbance). This approach can capture the overall impact of stochastic disturbance events on the forest structure and biomass – but at the cost of increasing the number of parameters and ambiguity when updating the probability density function (pdf) in two dimensions. Here we present the Robust Ecosystem Demography (RED), in which the pdf is collapsed onto the single dimension of tree mass. RED is designed to retain the ability of more complex cohort DGVMs to represent forest demography, while also being parameter sparse and analytically solvable for the steady state. The population of each plant functional type (PFT) is partitioned into mass classes with a fixed baseline mortality along with an assumed power-law scaling of growth rate with mass. The analytical equilibrium solutions of RED allow the model to be calibrated against observed forest cover using a single parameter – the ratio of mortality to growth for a tree of a reference mass (<span class="inline-formula"><i>μ</i><sub>0</sub></span>). We show that RED can thus be calibrated to the ESA LC_CCI (European Space Agency Land Cover Climate Change Initiative) coverage dataset for nine PFTs. Using net primary productivity and litter outputs from the UK Earth System Model (UKESM), we are able to diagnose the spatially varying disturbance rates consistent with this observed vegetation map. The analytical form for RED circumnavigates the need to spin up the numerical model, making it attractive for application in Earth system models (ESMs). This is especially so given that the model is also highly parameter sparse.</p>https://gmd.copernicus.org/articles/13/4067/2020/gmd-13-4067-2020.pdf |
| spellingShingle | A. P. K. Argles J. R. Moore C. Huntingford A. J. Wiltshire A. B. Harper C. D. Jones P. M. Cox Robust Ecosystem Demography (RED version 1.0): a parsimonious approach to modelling vegetation dynamics in Earth system models Geoscientific Model Development |
| title | Robust Ecosystem Demography (RED version 1.0): a parsimonious approach to modelling vegetation dynamics in Earth system models |
| title_full | Robust Ecosystem Demography (RED version 1.0): a parsimonious approach to modelling vegetation dynamics in Earth system models |
| title_fullStr | Robust Ecosystem Demography (RED version 1.0): a parsimonious approach to modelling vegetation dynamics in Earth system models |
| title_full_unstemmed | Robust Ecosystem Demography (RED version 1.0): a parsimonious approach to modelling vegetation dynamics in Earth system models |
| title_short | Robust Ecosystem Demography (RED version 1.0): a parsimonious approach to modelling vegetation dynamics in Earth system models |
| title_sort | robust ecosystem demography red version 1 0 a parsimonious approach to modelling vegetation dynamics in earth system models |
| url | https://gmd.copernicus.org/articles/13/4067/2020/gmd-13-4067-2020.pdf |
| work_keys_str_mv | AT apkargles robustecosystemdemographyredversion10aparsimoniousapproachtomodellingvegetationdynamicsinearthsystemmodels AT jrmoore robustecosystemdemographyredversion10aparsimoniousapproachtomodellingvegetationdynamicsinearthsystemmodels AT chuntingford robustecosystemdemographyredversion10aparsimoniousapproachtomodellingvegetationdynamicsinearthsystemmodels AT ajwiltshire robustecosystemdemographyredversion10aparsimoniousapproachtomodellingvegetationdynamicsinearthsystemmodels AT abharper robustecosystemdemographyredversion10aparsimoniousapproachtomodellingvegetationdynamicsinearthsystemmodels AT cdjones robustecosystemdemographyredversion10aparsimoniousapproachtomodellingvegetationdynamicsinearthsystemmodels AT pmcox robustecosystemdemographyredversion10aparsimoniousapproachtomodellingvegetationdynamicsinearthsystemmodels |