Transnational Accesses

Technical information


Alt-For is a suite of models for simulating forest development at different scales.

Fields of application

The models in AltFor provide the user the opportunity to quantify effects of management and climate on their forest resources and subsequently on some of the services these resources provide. These forest resources can be either at the genetic composition within a stand, the total stand performance or the performance of forests within its landscape. The user will gain insight in forest processes in a specific stand or landscape:

  • Genetics in forest stands
  • Gene flow in forest stands
  • Interaction between (articifial) selection (e.g. climate change or management) and stand genetics
  • Effect of stand structure on storm damage
  • Management effects on carbon fluxes
  • Carbon accounting of forest stands
  • Forest management effects on forest landscape
  • Interaction between herbivory and the forest landscape


ForGEM is an individual, process-based, distance-dependent simulation model. Trees compete for light, and photosynthates are allocated over tree parts. This determines the growth of individual trees. Trees produce seeds, which may germinate depending on the environmental circumstances. ForGEM has modules for gene flow, management, and storm damage.

FORGEM output

(Image: Alterra. Forgem output for a floodplain forest)

Kramer K, Buiteveld J, Forstreuter M, et al. (2008a) Bridging the gap between ecophysiological and genetic knowledge to assess the adaptive potential of European beech. Ecological Modelling, 216, 333-353. doi:10.1016/j.ecolmodel.2008.05.004

Kramer K, Vreugdenhil SJ, van der Werf BDC (2008b) Effects of flooding on recruitment and survival of riparian tree species: a field and modelling study on the floodplains of the river Rhine. Forest Ecology and Management, 255, 3893–3903. doi:10.1016/j.foreco.2008.03.044

Schelhaas MJ, Kramer K, Peltola H, Werf DCvd, Wijdeven SMJ (2007) Introducing tree interactions in wind damage simulation. Ecological Modelling, 207(2-4), 197-209. doi:10.1016/j.ecolmodel.2007.04.025

Schelhaas, MJ (2008). The wind stability of different silvicultural systems for Douglas-fir in The Netherlands: a model-based approach. Forestry, 81(3), 399 - 414. doi:10.1093/forestry/cpn028


CO2FIX is a simple modelling framework that quantifies the C stocks and fluxes in a forest stand. It calculates changes in carbon stocks in all carbon pools over time. A stand is here defined as an area that can be considered as relatively homogeneous in terms of vegetation structure, growth dynamics, and species composition, and contains a number of trees for which a common set of characteristics can be created. The carbon in vegetation –above and below-ground, soils as well as in wood products derived from the stand are included. The model has an accounting as well as a financial module.

(Image: Alterra. Carbon storage in a Scots pine stand in the Netherlands, simulated with CO2FIX)

Nabuurs, G.J., & M.J. Schelhaas. 2002. Carbon profiles of typical forests types across Europe assessed with CO2FIX. Ecological Indicators 1: 213-223. doi:10.1016/S1470-160X(02)00007-9

Masera, O. R., J. F. Garza-Caligaris, et al. (2003). "Modeling carbon sequestration in afforestation, agroforestry and forest management projects: the CO2FIX V.2 approach." Ecological Modelling 164(2-3): 177-199. doi:10.1016/S0304-3800(02)00419-2

Groen, T.A., Nabuurs, G.J., Schelhaas, M.J., 2006. Carbon Accounting and Cost Estimation in Forestry Projects using CO2Fix V.3. Climatic Change 74(1-3), p. 269-288. doi:10.1007/s10584-006-1827-z


FORSPACE is a spatially explicit model that aims to give a realistic description of the processes that determine forest dynamics at the scale of a landscape (up to thousands of hectares). Gap dynamics in relation to herbivores are an important aspects of FORSPACE. FORSPACE tracks cohorts of identical individuals per species. The vertical structure is represented by different height cohorts per species. Currently the model is under development and opportunities for access depend on the questions addressed.


(Image: Alterra. FORSPACE output, dominant tree species in shrub layer for different forest and herbivory management scenarios (eik = oak, fijnspar = spruce, grove den = Scots pine, douglas = douglas fir, beuk = beech, berk = birch (from GrootBruinderink et al. 2004, Alterra report 0.112,

Kramer, K. , T.A. Groen & S.E. van Wieren: The interacting effects of ungulates and fire on forest dynamics: an analysis using the model FORSPACE. Forest Ecol. Manage. 181 (2003), 1/2: 205-222. doi:10.1016/S0378-1127(03)00134-8