Project D: Thermodynamics and soil-vegetation-atmosphere transfer processes

Objectives and Hypotheses

Biospheric Theory and Modelling,Max Planck Institute for Biogeochemistry, Jena

Literature/RefsKleidon, A. and Schymanski, S. (2008): Thermodynamics and optimality of the water budget on land: A review. Geophysical Research Letters 35(20), p.L20404. doi: 10.1029/2008GL035393.Schymanski, S.J., Sivapalan, M., Roderick, M.L., Hutley, L.B. and Beringer, J. (2009): An Optimality-Based Model of the Dynamic Feedbacks between Natural Vegetaton and the Water Balance. Water Resources Research 45, p.W01412. doi: 10.1029/2008WR006841.Schymanski, S.J., Kleidon, A., Stieglitz, M. and Narula, J. (2010): Maximum Entropy Production allows a simple representation of heterogeneity in semiarid ecosystems. Phil. Trans. R. Soc. London, Ser. B

365, p.1449–1455.

Approach and Workplan

Contribution to overall WP

Stan Schymanski Axel Kleidon

Task 1. Thermodynamics-based formulation of soil-vegetation-atmosphere transfer (SVAT) processesStarting point: Vegetation Optimality Model (VOM) (Schymanski et al. 2009). To do: (a) Represent driving forces for water fluxes by generalised thermodynamicForces, (b) Thermodynamic formulation of the carbon balance in terms of free

WP 2.1 “Surface and vegetation domain”:• Closure relations for the SVAT pathway (Tasks 1, 3)• Dynamic adaptation of natural vegetation to its environment (Tasks 2, 5)• Differential root water uptake in the soil profile (Tasks 2, 5)

WP 2.2 “Subsurface flow domain”:• Effect of roots on preferential flow paths (Task 4)

WP 3.2 “Synthesis of organising principles and rules for forming dynamic functional units”:• Vegetation sensitivity to external boundary conditions (Task 3)

WP 3.3 “Multi-objective validation and assessment of minimum data needs”:• Effect of input data on accuracy of results (Task 5)

Free energy

Entropy

Radiation

Rainfall

Degrees of Freedom• Vegetation properties• Macropores• Spatial organisation

Organising principles• Max. Net Carbon Profit• Max. Gross Primary Productivity• Max. Entropy Production• Min. Energy Expenditure …

Observations• Remote sensing (TP B)• Monitoring and tracers (TP G, H)

Forcing data• Atmospheric (TP C)• Soil properties (TP B, G)• Drainage strength (TP G)• Land use (TP B, Lippmann)

Thermodynamic constraints• Conservation of Mass• Conservation of Energy• Production of Entropy

Dynamic model output• Water fluxes• Vegetation dynamics

Task 3. Adaptation of the VOM to the Attert catchment(a) Deciduous trees, (b) land use types, (c) rainfall interception, (d) parameterisation for each elementary functional unit (EFU), (e) integration of VOM in CAOS model (TP S)

Task 2. Implementation and comparison of different optimality assumptionsBiologically motivated vs. thermodynamically motivated organising principles

Task 5. Evaluation with observational data(a) Temporal dynamics (TP B, G, H), (b) spatial organisation of vegetation (TP B, S), (c) spatial organisation of roots (TP G, H, S), (d) effect of the amount of input data (TP B, C, S)

Task 4. Investigation of causes and effects of spatial heterogeneity and organization(a) Lateral fluxes and spatial organisation in the catchment (TP S), (b) preferential flow and organisation in the soil domain (TP I, J, S)

Fig. 1: The Vegetation Optimality Model (VOM). Left: representation of perennial and seasonal plants, right: simulated and observed fluxes (Schymanski et al. 2009)

Fig. 2: Interplay of thermodynamics, organising principles, forcing data and observations for the testing of hypotheses.

Fig. 3: Effect of rain (P) and patterns on simulated biomass (Bv). After Schymanski et al. (2010)

Fig. 4: Free energy transfer to the soil matrix and associated entropy production.

Haste nicht noch ein schönes bild vom VOM?Struktur und/oder Ergebnisse? Sollte rein, lieber den Rest etwas kürzen

MA,p

y r,p

MA,s

y r,s

VOM

energy transduction and dissipation, (c) Imple-ment a detailed energy balance in the VOM, (d) Verify the internal consistency of the formulations and consistency with previous results of the VOM.

Fig. 1: Soil, vegetation and atmosphere as thermodynamic systems, with boundaries shown as dotted lines. Arrows: mass fluxes across system boundaries; boxes: dissipative processes. subscripts: P = precipitation, S = soil, V = vegetation, A = atmosphere, O = ocean. From Kleidon and Schymanski (2008).