Burlando Paolo

Modeling terrestrial carbon and water dynamics: a critical appraisal and ways forward

Project Number: CH-5841

Project Type:	Dissertation
Project Duration:	07/31/2010 - 07/31/2014 project completed
Funding Source:	other ,
Leading Institution:	ETH Zürich
Project Leader:	Prof. Paolo Burlando Chair of Hydrology and Water Resources Management Institut für Umweltingenieurwissenschaften (IfU) ETH Zürich HIL D22.3 ETH Hoenggerberg 8093 Zurich Phone: +41 (0) 44 633 38 12 ; +41 (0) 44 633 38 13 FAX: +41 (0) 44 633 15 39 e-Mail: burlando(at)ifu.baug.ethz.ch http://www.ifu.ethz.ch/hydrologie/index_EN

related to this project.

for which the project has a relevance.

Research Areas:

Landscape

Disciplines:

environmental sciences

Abstract:
Terrestrial carbon and water balances and their variability under changing cli- matic conditions and anthropogenic disturbances are topics of great societal and scientific importance. The role of vegetation in shaping carbon and water dynamics is of paramount significance. Many numerical models, reflecting dif- ferent degrees of complexity and abstraction, have therefore been developed to mimic plant function. The aim of this thesis is to (i) shed light on how vegeta- tion functioning is simulated in state-of-the-art terrestrial ecosystem models, (ii) provide a critical appraisal of model strengths and weaknesses, and (iii) present ways forward to remove some of the identified model limitations. The first part of the thesis provides a thorough evaluation of a state-of-the-art, process-based, dynamic vegetation model, LPJ-GUESS, by means of a global sensitivity analysis. The rationale is that since process-based models embed physical causalities, the sensitivity of the simulated processes should also re- flect measurable and observed sensitivities. Having scrutinized the structural and parameterization issues underlying LPJ-GUESS, reflecting also that of other, structurally similar dynamic vegetation models, the subsequent parts of the the- sis are devoted to two major model limitations, namely (1) the lack of spatial representation and simplified soil water hydrology, and (2) the lack of ecological realism due to simplified representation of plant trait variability.
The former limitation is analyzed with a novel ecohydrological scheme, D-LPJ, which is based on an iterative coupling between a spatially explicit, process- based hydrological model (TOPKAPI-ETH) and a well-established dynamic veg- etation model (LPJ). The advantages of D-LPJ over the original, aspatial ap- proaches of LPJ and LPJ-GUESS are illustrated for a topographically-complex area located in the central Switzerland. The aggregation-induced biases due to smoothing of spatial heterogeneities through coarse-grained aspatial represen- tations are also explicitly quantified.
The second limitation is investigated with an innovative Monte Carlo approach that is applied to simulate the diversity of plant traits. This approach revises the broad vegetation categories, based on a discrete and static parameteriza- tion (named Plant Functional Types), often incorporated in terrestrial ecosystem models. Proxy plant species are generated using observed multivariate distribu- tions of coordinated plant traits. Their performance is assessed with a mecha- nistic ecohydrological model (T&C) across continuous, naturally occurring, me- teorological gradients in the European Alps. The significant importance of trait- induced variability in simulating water and carbon dynamics is quantified and an alternative, probabilistic approach is presented, enhancing the ecological re- alism within models.
The last part of the thesis provides a synthesis of the aforementioned findings to- gether with a critique of commonly applied approaches for modeling terrestrial carbon and water dynamics. Directions for future model improvements are high- lighted, combining deterministic with probabilistic concepts, aiming towards a predictive framework of terrestrial ecosystem functioning.

Publications:
Pappas, C. (2014): Modeling terrestrial carbon and water dynamics: a critical appraisal and ways forward. Dissertation. ETH Zürich.
pdf Dissertation


Last update: 10/26/17
Source of data: ProClim- Research InfoSystem (1993-2024)
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