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Duration: 2008 -

MEPHYSTO: Combining population dynamics and drought related ecophysiology in the regional forest model TreeMig

A landscape scale forest population dynamics model is extended with ecophysiology, and particularly the mechanisms of drought effects on trees.

Frame

The project is part of the COST action FP0603 “Forest models for research and decision support in sustainable forest management” (http://www.cost.esf.org/index.php?id=143&action_number=FP0603) which aims at extending the scope of forest models from growth only to population dynamics and ecophysiology.    

Project members and partners

• Marc Scherstjanoi
  

• Heike Lischke
  

• Roman Zweifel
  

• Esther Thürig
  

• Niklaus Zimmermann
  

Collaboration with

• Matthias Dobbertin
  

• Andreas Rigling
  

Rationale

For sustainable forest management over large areas and for simulating different forest functions especially under changing conditions, different aspects of the system “forest” must be modelled jointly: ecophysiological/biogeochemical processes, population dynamics, spatial interactions, and horizontal/vertical species stand structure. We develop a forest model with a stand-size grain suitable to be applied on large areas for assessment of, e.g., climate change or management effects on forest functions. This is achieved by merging and if necessary up- and down-scaling model functions of ecophysiological and population dynamical processes contained in existing models (single tree physiology, local scale ecophysiological, empirical forest growth, spatio-temporal forest landscape, and dynamic global vegetation models).
Drought is predicted to occur more frequently with climate change, thus the main focus is on drought and the mechanisms how it affects the trees.

Research questions

1. What are the mechanisms by which drought affects trees?
2. Which is the best (sufficiently accurate and efficient) way to model and simulate these mechanisms?
3. How can population dynamics and ecophysiology be combined in a landscape scale model concerning...

...allocation of water and carbohydrates to trees and organs? ...spatial heterogeneity of soil water and trees?

Methods

The project builds on the climate-driven forest landscape model TreeMig (Lischke et al., 2006).  Process descriptions from various existing models are compiled, evaluated and included into TreeMig. This involves a thorough scaling of process formulations.  Drought effects, involving soil water balance, stomata regulation, photosynthesis, CO₂ fertilization effects, allocation of carbohydrates, dynamics of reserve pools and the relationship between these and regeneration, growth and mortality are studied in literature and other models and included into MEPHYSTO.

Keywords:

population dynamics, ecophysiology, TreeMig