Solution Attempts For additional information, contact: Jennifer Holm Research Scientist Lawrence Berkeley National Laboratory (510) 495-8083 [email protected] climatemodeling.science.energy.gov/acme Issues concerning dynamic vegetation modeling Solution Attempts Ideas and future evaluation & testing PFT1% PFT1% PFT2% PFT2% PFT3% PFT2% PFT3% PFT1% PFT2% PFT3% PFT2% PFT3% Spa+ally% average% the%direct% and%diffuse% radia+on% transmi=ed%onto% the%understory% layer.%% Reflectance,% absorp+on% and% transmi= ance% calculated% for%mul+ple% leaf% layers% for%each%PFT.%% Direct% Diffu e% Light% transmi=ed%onto% soil/snow% reflected%back%up% through% canopy% (itera+ve% solu+on)%% Individual tree stomata response (FLCgs) (prev timestep) Individual tree canopy-level transpiration (E) (current timestep) Plant traits: wood + leaf economics (WD, LMA, N L , P L ) Tree size: height, total leaf area HOST LAND SURFACE MODEL – FATES PLANT HYDRAULICS MODULE TRAIT TRADE-OFFS FOR PFT PARAMETERIZATION (from meta-analysis) Model prediction Field data Mortality Rate (yr -1 ) DBH Size Class (cm) (1) Testing radiative transfer schemes: Discretized Perfect Plasticity Approximation (PPA) (4) Processes underlying demographic structure Manaus Case Study – testing current plant mortality • ED2 = over-estimates mortality (4.2%) • FATES = over-estimates mortality (3.2%) • ZELIG-TROP = similar to observed (1.2%) (2) Testing competition for water/plant hydraulics and integration with trait based forest model: Examples of near-term development priorities for FATES and progress towards demographic ESMs: FATES model (Functionally-Assembled Terrestrial Ecosystem Simulator) 2 • Carbon pools, fluxes, allocation; litter fluxes; phenology; regeneration, growth, mortality represented by ED (Ecosystem Demography Model). • Canopy physics, soil BGC, land surface hydrology, photosynthesis, respiration represented by ALM. • Incorporates discretized PPA for canopy structure. • ‘Some’ current development foci: - Introduction of plant hydrodynamics and competitive plant water uptake - Librarification of ED code to allow multi-model compatibility (ACME/CESM/ARCOS) - Sensitivity analysis to input parameters - Multi-assumption photosynthesis module testing - Mechanistic mortality algorithms vs. static turnover Vegetation demographics in ACME: Capturing structural forest dynamics, plant co-existence, and plant functional shifts Jennifer Holm 1 , Ryan Knox 1 , Charlie Koven 1 , William Riley 1 , Chonggang Xu 2 , Elias Massoud 2 1 Lawrence Berkeley National Laboratory, 2 Los Alamos National Laboratory The inclusion of vegetation demography into Earth System Models (ESMs) will better represent plant ecology, and vegetation processes that govern fluxes of carbon, energy, water. • However, incorporating dynamic vegetation demography poses huge challenges owing to their increased model complexity. • Current issue = global application of dynamic vegetation in ALM Global vegetation demography developments and science impacts: • Investigate current and future outcomes of FATES as a result of various drought scenarios and climate change in California, over the 21 st century. • We hypothesize that under drought conditions in California the mortality of all trees will increase, but there will be higher mortality for large trees. • Secondly, we hypothesize that changing climates in the 21 st century will cause the climate of southern California to migrate to northern California. V c,max25 Interactions All others parameters V c,max25 Growth respiration fraction Target storage carbon GPP NPP Total LAI Total Biomass Leaf maintenance respiration Leaf allometry Target storage carbon V c,max25 Specific leaf area Stem allometry coef c Target storage carbon V c,max25 Leaf maintenance respiration Target storage carbon (3) Sensitivity analysis of 66 input parameters into FATES 3 • FATES has >200 parameters • Single site testing in Brazil • Using Fourier Amplitude Sensitivity Testing (FAST) = variance based sensitivity analysis. • Repeatedly found to be important for carbon dynamics = Vcmax,25; target storage carbon, stem allometry coef. 0 10 20 30 40 50 60 70 80 10-15 15-20 20-30 30-40 40-50 50-60 60-70 70-80 80-90 90-100 >100 Basal Area (m2/ha) Old parameter file Total BA = 84.2 m2/ha 100 yrs 200 yrs 0 2 4 6 8 10 12 10-15 15-20 20-30 30-40 40-50 50-60 60-70 70-80 80-90 90-100 >100 Basal Area (m2/ha) New parameter file Total BA = 30.6 m2/ha 100 yrs 200 yrs 300 yrs 400 yrs 500 yrs DBH Size Class (cm) DBH Size Class (cm) Changes to FATES parameter file The role of ecosystem heterogeneity and diversity 1 : Aggregated “big-leaf” ecosystem vs. demographic; structured ecosystem means ability to capture differences in biomass with dry season length. ED2 – Ecosystem Demography ED2- BL (“Big-leaf” analog) The Ecosystem Demography (ED) model vegetation structure, the basis for ALM-FATES. Tracks age and size of tree “cohorts”, incorporates disturbance , and dynamic turnover. But these processes can lead to more model variability. Testing variations in allometry equations for Western US evergreen trees 4 (currently 1 global allometric equation for all PFTs) References = 1. Levine NM, Zhang K, Longo M et al. (2016) Ecosystem heterogeneity determines the ecological resilience of the Amazon to climate change. Proceedings of the National Academy of Sciences, 113, 793-797. 2. Fisher, R. A., et al. Taking off the training wheels: the properties of a dynamic vegetation model without climate envelopes, CLM4.5(ED), Geosci. Model Dev., 8, 3593-3619, 2015. 3. Massoud, E.C., C. Xu, et al. Identification of key biological controls in forest dynamics based on a sensitivity analysis to the Community Land Model with Ecosystem Demography, CLM4.5(ED), JGR-Biosciences, Submitted. 4. Ter-Mikaelian, M. T. and M. D. Korzukhin. Biomass equations for sixty-five North American tree species. Forest Ecology and Management 97(1): 1-24., 1997. 0 1 2 3 4 5 6 1 30 59 88 117 146 176 Basal Area (m2/ha) Years Default CA_FATES Needleleaf, evergreen Broadleaf, deciduous Testing default FATES in Sierra Forest, CA, USA. (Single point) Very low basal area, biomass, and stem density. Competitive exclusion of needleleaf evergreen trees AGB = 18 MgC/ha; Density = 87 stems/ha