Summary On forest carbon cycle Download and
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version 5.0

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In order to assess carbon sequestration, one needs either field measurements, or models, or both. CASMOFOR can be used if no field measurements are available, or if they cannot be taken, e.g. when predictions are to be made. Such predictions are, e.g., necessary when planning afforestations. The aims of afforestation programs may be numerous, and one aim can be sequestering carbon. CASMOFOR was designed to help users estimate the carbon sequestration potentials of various afforestation programs. By making it possible to quickly compare different variants or options, CASMOFOR is an ideal decision supporting tool.

One needs a complete modeling of the carbon cycle if carbon sequestration is to be estimated correctly and accurately. In the system of forests and forestry, there are many pools (like biomass, dead wood biomass, wood products, soil etc.), and their carbon content is increased and reduced by many processes (e.g., growth, mortality, timber harvest etc.). The overall resultant of these processes change the overall carbon content of the system, since this system is open: it can absorb and emit carbon. Depending on the processes involved, the overall carbon content of the whole system can either increase (in which case the system removes carbon from the air) or decrease (when the system emits carbon to the air).

The ultimate objective of using the model is to estimate how much carbon is removed from, or emitted to, the air by the system. Thus, the focus of the model is not any traditional characteristics of the forests, such as the tree volume, but the amount of carbon in all pools and processes, i.e. the carbon cycle of forests and forestry. Therefore, the amount of all substances that contain carbon in various pools (e.g., biomass, soil) and that pass through these pools by many processes is converted to, and is handled as, amounts of carbon.

However, there are many types of pools and very complicated processes in a forestry system. These together with the spatial dimensions and spatial diversity of pools, and the time scale of the processes render it very difficult to asses the amounts of carbon in the various parts of the system over time. This difficulty is recognized by CASMOFOR, which was designed to predict the amount of carbon fixed by the forest. The model is based on inevitable simplification, which, however, does not pretend to be able to replace measurements when it is possible at all. On the other hand, CASMOFOR was designed to follow a stand after its establishment, and to provide estimates, after several years or decades of growing, for the amount of carbon actually fixed.

CASMOFOR does not pretend and attempt to be as scientific as theoretically possible. Rather, it focuses on practical approaches, by which practical and feasible estimates can be made and which concentrate on the most important pools and processes, i.e. those where the most carbon can be found., and upon which we may have any effect of considerable scale. The ultimate aim of forestations in terms of carbon is to fix air carbon and to keep it within the forestry system in the medium term (i.e. over several decades). Therefore, those pools and processes are of greatest importance where most carbon can be found at this time scale.

Because of the above, not all processes and pools are modeled with the same level of accuracy (or uncertainty). "Well" modeled processes and pools are the ones whose modeling is developed best and where most data (constants, functions, empirical values) are available. Attempts were made to incorporate all bits of information in the biological part of the model that are available in the literature so that modeling of the biological processes, which play the most important role in the system, is as accurate as possible. In addition, an attempt was made throught developing this help to document all important information on the whole model, and to indicate the accuracy/uncertainty of various modeling methods for the user to be able to judge the level of understanding that could be used in the model.

As it was noted above, CASMOFOR was designed so that it can be used for modeling the carbon cycle of forestation programs in Hungary. This means that all information stored in the model are for Hungarian species and site conditions (see specifications at the description of the respective pools and processes below). Although there are many models worldwide that are currently used for similar purposes (e.g. CO2FIX), their parametrization may be difficult because of their structure that is not appropriate to use with data available for the Hungarian conditions. CASMOFOR can be regarded as the model that is ideal for the Hungarian conditions because of its structure and parameters that was tailored for Hungarian conditions.

However, if the forestry system (e.g. thinning regimes, growth data etc.) is similar in another country, and only data are different, the structure of CASMOFOR can be used in this country so that data in the model are replaced with those that are used in that country.

The information content of the model (i.e. the "knowledge base", including growing characteristics of various species, thinning regimes, biomass expansion factors etc.) is stored in one file. This single file (kb.xls) contains growth data, expressed as tC/ha, and derived from growth data expressed as m3/ha*yr, biomass expansion factors (BEF, see details in the description of the model) and carbon content. The file also contains thinning regime data (timing and intensity of thinnings). Together with user.xls, which is used to provide the model with structural data (e.g. area or carbon content by species) of any forest that is present at the start of running the model, all files were designed so that the user itself can modify the data to fit them to actual afforestation situations.

Please note that, under the Hungarian conditions, the intent is that the user changes some data in kb.xls only if better data are available. For other countries, it is possible and easy to modify existing data or include new ones. Since CASMOFOR is already parametrized for the Hungarian conditions, modeling the carbon cycle of Hungarian forests can be better done by CASMOFOR than by any other model.

Scenario specific data, like area and/or biomass data, must be set in user.xls for some specific scenarios. Should the user want to replace/modify any data in the knowledge base, originally specific to the general Hungarian forestry conditions, please contact the developer of CASMOFOR, Zoltan Somogyi, how to do it.)

It must also be noted that some processes (e.g. soil preparation before planting, or erosion before planting or after clearcut etc.) that are not part of the normal afforestation system from planting to final cut are not modeled in CASMOFOR. Although these processes may be important sources of emissions (e.g. much carbon can be emitted from the soil during ploughing), they are outside the scope of CASMOFOR, are very roughly modeled, and are only modelled to get a rough idead of how important these processes could be with regard to the total sequestration of an afforestation system.

The flowchart of the carbon fluxes (processes) and pools of a typical Hungarian forestry system can be seen below. Help on any process or pool can be obtained either by looking for them in this help system, or by clicking on the approppriate part of the flowchart when running CASMOFOR, where the flowchart is also shown.





CASMOFOR is an accounting-type of model. It models many processes and pools based on the physical or biological processes in the forests, then sums them up. It accounts for every molecule of carbon dioxide that enters or leaves the system.

The various parameters, the structure of the model (pools, processes, external forces etc.), and information on accuracy and sources of error can be found in the detailed description of the model.

Some general characteristics of the model are the following:

  • CASMOFOR models changes after the onset of the modelled events, but it does not model the baseline scenario. In other words, it is asumed that no carbon stock changes would have changed on the land afforested if no afforestations had been made. Afforestation could be regarded as a type of mitigation scenario.

  • It is supposed in the CASMOR model that normal, professional forest management is carried out on the forested land.

  • The model works with so called batches of scenarios. In one batch, on can handle lands of varying structure by maximum three species, and maximum six yield classes. More complex forestation programs can be constructed by repeatedly running CASMOFOR by setting the number of batches with different scenarios.

  • Land size is not limited. The model was designed to make predictions for:

    • forest compartments of several ha to several tens of ha

    • afforestation programs of maximum 1 million ha comprising forest compartments.

  • Land area unit: hectare

  • Land use type: at the beginning of the modelled period, land is supposed to be unforested (while it is also possible to have a forest of specified structure, by species, yield class and age, at the beginning of the running of the model, see modelling of growth). Then, the area of forest is increased by forestations in the mitigation scenario.

  • Species are treated separately. The silvicultural system of all species is so that they are growing in unmixed even-aged stands.

  • Step of defining changes over time: one year.

  • The maximum age of species is 120 years. This is due to the limitation of the software and the program design. However, the length of the simulation period can be as long as 240 years in case data for the age of 121-240 years is available. In this case, two consecutive runs are necessary for each species: one up to the age of 120 years, and another one for the period of 121-240 years of age. The second run must be started with a stand that is a modelled result of running the afforestation from 1 year to 120 years in the firt run. However, estimates beyond one rotation period makes predictions less reliable even if data is deemed to be available  (which, normally, is not the case for Hungary).

  • Units of carbon: metric t carbon.

  • The model can calculate with current costs of, and revenues from, all forestry operations. This way, the user can get an idea of the timing and extent of the economic costs and benefits of the mitigation option of afforestations.

Note that CASMOFOR was programmed as a system of MS Excel based spreadsheets by using MS Visual Basic (for Excel). The intent with all this was that (i) the use of the system is user-friendly, (ii) the parametrization of the model is easy for the user, (iii) both the structure of the system and parameters are transparent, and (iv) the whole system can easily be checked, fixed and developed further.

Finally, note also that great effort was made to document the model (its structure and knowledge base, all pools and processes etc.) so that the model is transparent, and that any modifications or development can later be made by either the author or users.

New in Version 4 compared to Version 3:

  • New and enhanced Monte Carlo analysis module.
  • Enhanced silvicultural module.
  • Lot of new outputs.
  • Enhanced help and user-friendliness.
  • New and enhanced web representation.
  • Fixing bugs in program.
  • Data have been checked/corredtec/added.


New in Version 3 compared to Version 2:

  • Version 3 is much more user friendly as Version 2 was. This is in reaction to requests for a model that could be used by anyone. Species scenarios have been combined as batches, and the program can now be run up to 10 batches. This makes it much easier to run afforestation programs that are made of many species: after running one batch, it is not necessary now to quit from the program and running a new batch etc., rather, many scenarios can be simulated in just one run.
  • There is an extended help, including lots of new text on how to run the software.
  • Lots of data have been added. This includes yield data, as well as silvicultural model data for all of the most important tree species in Hungary. Factors and assumptions applied in the model have also been corrected and added.
  • A new model has been added that is able to calculate costs and revenues of the afforestations. This economic model includes both establishment costs, as well as net costs of all other silvicultural operations.
  • A new module is added to perform sensitivity analysis (Monte Carlo analysis). This module can be used to study the possible effects of errors in the parameters of the model, some of which is still based on inadequate measurements, data from the literature or expert judgement.
  • Finally, a whole new set of outputs (both tables and graphs) are added for much extended analysis of the results of running the model. The results of the simulations, whether for one batch only or for many batches, are stored in the same file. Scenarios can be both added up or compared, and the results file includes both comparative, as well as summatory statistics on demand. The output analyses amounts of carbon, economics of the afforestation programs, as well as carbon economics: unit costs of carbon sequestered or emitted.

This webpage was last modified by Zoltan Somogyi 29 June 2014.

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