Forest simulation models in Germany: main developments and challenges

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COST ACTION FP0603 Forest models for research
and decision support in sustainable forest
management

• Forest simulation models in Germany main
  developments and challenges
• WG1

Thomas Rötzer Chair of Forest Yield Science TU
Muenchen
1st Workshop and Management Committee
Meeting.Institute of Silviculture, BOKU.8-9 of
May 2008Vienna, Austria
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Main features of German forests

• Forest cover (total/share) 11 106 ha (32 )
• Growing stock, annual growth and cuts
• growing stock 3,4 109 m³ 309 m³/ha (data
  BWI2)
• annual growth 134 106 m³ timber
• annual cuts 89 106 m³ timber harvested
• Main species spruce (Picea abies) 35 (forest
  area)
• pine (Pinus silvestris) 31 (forest area)
• beech (Fagus silvatica) 25 (forest area)
• oak (Quercus petraea) 9 (forest area)
• Main non-wood products and services recreation,
  water reserve, other environmental servcices
  (e.g. ersoion preotection), hunting
• Main risks wind damages, insects (e.g. bark
  beetle), droughts and fires (particularly in NE
  Germany)
• Management and silvicultural characteristics
  commercial forests (liability to manage),
  multiple use, sustainable management

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Forest modelling approaches and trends

• Empirical models
• Model name contact institution remarks
• SILVA Pretzsch TU München more or less a
  hybrid model
• BWIN-PRO Nagel NW-FVA
• WEHAM Bösch FVA BW extrapolating
  forest inventory data

Hybrid models are a between pure empirical
models (e.g. WEHAM or BWIN-PRO) and pure
mechanistic (better physiological) models. A
type of such a hybrid model is SILVA, in which
also mechanistic approaches are included (type
efficiency).
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Forest modelling approaches and trends

• Empirical models
• Trends in modelling
• Upscaling from tree to stand to enterprise
  (Landscape) level
• Flexible technical frameworks (interfaces to
  modern forest inventories)
• Advanced statistical methods
• Introduce lessons learnt from advances in
  biology/ecology
• Recent research is concentrating in
• - linking management oriented models with
  physiologically based models
• - climate change and climate adaptation studies
• - carbon sequestration
• - management scenarios under multi-criterial
  objectives
• - climate change and sustainability

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Forest modelling approaches and trends

• Mechanistic models
• Model name contact institution remarks
• BALANCE Rötzer TU München
• 4C Lasch, Suckow PIK Potsdam
• FORMIND/FORMIX Huth UFZ Leipzig rain forest
• TREEDYN3 Bossel Uni Kassel
• TRAGIC Hauhs BITÖK Bayreuth

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Forest modelling approaches and trends

• Mechanistic models BALANCE
• Main features
• single tree based model
• simulation of physiological processes on
  compartment (roots, stems, brach, leaves), tree
  and stand level
• for pure and mixed stands
• simulation of water-, carbon- and nitrogen cycle
• calculation of the micro-climate (temperatue,
  radiation) for every single tree
• management tool for thinning
• influence of competiton, stand structure and
  species mixture is regarded
• phenology module to simualte annual development
• species beech (Fagus sylvatica L.), Norway
  spruce (Picea abies L. Karst.), Scots pine (Pinus
  sylvestris L.), oaks (Quercus robur L., and
  Quercus petraea Liebl.)

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Forest modelling approaches and trends

• Mechanistic models 4C (FORESEE Forest
  Ecosystems in a Changing Environment)
• Main features
• has been developed to describe long-term forest
  behaviour under changing environmental conditions
  (Lasch et al., 2005)
• describes processes on tree and stand level
  basing on findings from eco-physiological
  experiments, long term observations and
  physiological modelling.
• includes descriptions of tree species
  composition, forest structure, total ecosystem
  carbon content as well as leaf area index
• establishment, growth and mortality of tree
  cohorts are explicitly modelled on a patch on
  which horizontal homogeneity is assumed
• management of mono- and mixed species forests and
  short rotation coppice can be simulated
• calculates the water, carbon and nitrogen budget
  of the soil
• coupled with a wood product model and
  socio-economic analysis tool
• species beech (Fagus sylvatica L.), Norway
  spruce (Picea abies L. Karst.), Scots pine (Pinus
  sylvestris L.), oaks (Quercus robur L., and
  Quercus petraea Liebl.), birch (Betula pendula
  Roth), aspen (Populus tremula (L.), P.
  tremuloides (Michx.)), Aleppo pine (Pinus
  halepensis Mill.), Ponderosa pine (Pinus
  ponderosa Dougl.).

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Modelling non-timber products and services

• Scenic beauty and recreation
• L-Vis (S. Seifert, TUM), Silvisio (ZALF) and
  Lenne 3D (lenne.de) for the visualisation of
  (forest) landscapes
• Water balance
• BALANCE, 4C
• Nitrogen leaching
• 4C
• Biodiversity and Habitat Assessment
• SILVA (Silva provides many indices for stand
  structure and diversity (as well as for monetary
  yield)

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Models for predicting risk of hazards

• CAfSD (TUM)
• Cellular automaton for simulating storm damages
  after disturbation (e.g. construction of highway
  tracks through a forest).
• BALANCE (TUM)
• droughts, mechanistic disturbances (insect
  damages), ozone stress
• 4C (PIK)
• simulates the climatic fire risk according to
  the fire risk index of the German Weather Service
  (DWD)
• (FVA BW)
• Schmidt, M. Bayer, J. Kändler, G. (2005) storm
  "Lothar" Approach for a inventory based risik
  analysis. FVA-Einblick 2/2005

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Research highlight

• National Research Program Sustainable Forestry
• Consequently managed long-term research plot
  network (since mid/end of the 18ties) as data
  source for the model SILVA (TUM)
• Long-term experience in constructing forest
  growth models AND transfer to management practice
  (TUM)
• Overall study (SILVAKLIM) of the German forest
  growth sector under climate change
• Potential and dynamic of carbon sequestration in
  forests and timber (www.cswh.worldforestry.de)
• Todays forests for tomorrows enviroment
  (www.enforchange.de)

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Future challenges

• GENERAL
• Developing concepts for embedding models in the
  decision flow of forest management
• Link management issues with C-sequestration and
  climate change
• Including hazards
• SILVA
• Linking a process based model with a management
  oriented model (SILVA) and a soil model
  (mCentury)
• Including wood quality
• Estimation of carbon storage
• Including nutrient storage and export
• FVA-BW
• Development and implementation of efficient
  approaches for prognosis and imputation in forest
  inventory software applications

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Future challenges

• BALANCE
• Linking a process based model with a management
  oriented model (SILVA) and a soil model
  (mCentury)
• Simulations regarding adaptation strategies as a
  response to climate change
• Influence of extreme events (e.g. droughts) on
  forest growth
• 4C
• A model of root growth dynamics, as a part of the
  forest growth model to improve the simulation of
  the water balance in the soil and stand
• Modelling the competition in the rooting zone

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Innovative references
Nagel, J. Schmidt, M. (2006)The Silvicultural
Decision Support System BWINPro. In Hasenauer, H.
(Ed.) Sustainable Forest Management, Growth
Models For Europe, Springer, Berlin, Heidelberg.
59-63. , ISBN-10 3-540-26098-6 Nothdurft, A.
and Kublin, E. and Lappi, J. (2006) A non-linear
hierarchical mixed model to describe tree height
growth. European Journal of Forest Research
125/3 281289. Pretzsch, H., Grote, R.,
Reineking, B., Rötzer, T., Seifert, S.(2007)
Models for Forest Ecosystem Management A
European Perspective. Annals of Botany 101
1065-1087. Pretzsch, H., Biber, P., Dursky, J.
(2002) The single tree-based stand simulator
SILVA construction, application and evaluation.
For. Ecol. Manage. 162 3-21. Rötzer, T.,
Seifert, T., Pretzsch, H. (2008) Modelling above
and below ground carbon dynamics in a mixed beech
and spruce stand influenced by climate. European
Journal of Forest Research DOI
10.1007/s10342-008-0213-y. Schmidt, M. Nagel,
J. Skovsgaard, J.-P. (2006)Evaluating
Individual Tree Models. In Hasenauer, H. (Ed.)
Sustainable Forest Management, Growth Models For
Europe, Springer, Berlin, Heidelberg. 151-163.
,ISBN-10 3-540-26098-6