Dry matter biomass of a specific part of the tree given in kilograms was derived from the miscellaneous data material and is calculated using the allometric equation:

Biomass = A . v_HSK^B . I_red

where v_HSK is the volume of the timber to the top of 7 cm outside bark in m³, A and B are coefficients from Table 1 and I_red is the reduction factor applicable to dead trees from Table 2  (mainly related to leaves, needles, eventually branches, by default equal to 1). 

Table 1 Coefficients of biomass allometric equation  

Table 2 Reduction factor used in the biomass allometric equation

The biomass of the particular part of the tree is obtained as the sum of all essential components specified below by the numbers in the first column of Table 1: 

• Biomass of stem timber: 1+2+3+5+6+7+9

• Biomass of stem bark: 4+8+10

• Biomass of timber and bark of all branches: 11+12+13

• Biomass of foliage (assimilatory organs): 14

• Biomass of roots and a stump: 15

• Total aboveground biomass: 1+2+3+4+5+6+7+8+9+10+11+12+13+14

• Total tree biomass: 1+2+3+4+5+6+7+8+9+10+11+12+13+14+15

In the growth simulator SIBYLA, the content of the following chemical elements and compounds is calculated: 

• macronutrients: carbon (C), nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sulphur (S)

• micronutrients: iron (Fe), manganese (Mn), copper (Cu), zinc (Zn), molybdenum (Mo), boron (B)

• toxic elements: chlorine (Cl), lead (Pb), arsenic (As), chromium (Cr), cadmium (Cd), nikel (Ni)

• other elements: silicon (Si), aluminium (Al), sodium (Na), titanium (Ti), cobalt (Co)

• ash

• amount of consumed CO₂ 

• amount of produced O₂ 

The content of chemical elements and of ash in trees is calculated following the research of Bublinec (1994) using the unit content of elements (JOP) in 10 mg.kg^-1 of dry matter. The unit amount of elements is related to the tree species and the tree part (i): roots and stump (1), stem timber (2), stem bark (3), branches (4), and foliage (5). The content is given in kilograms, and is calculated using the following formula:

To calculate the content of CO₂ and O₂ , the following relative numbers derived from the molecular weight of oxygen and carbon are used:  

Carbon content is multiplied by the relative numbers specified above to obtain the amount of the consumed carbon dioxide and of the produced oxygen. 

Total biomass production is the sum of biomass production of the main crop at the age t and of all secondary crops by the age t (inclusive): 

Total carbon sequestration is obtained as the sum of carbon amount in the trees of the main crop at the age t and in all secondary crops by the age t (inclusive):

Current biomass increment is calculated from two sequential growth periods as the difference between the biomass of the main crop in two time points separated from each other by the length of the period (delta t = by default 5 years) as follows:  

Current carbon increment is calculated from two sequential growth periods as the difference between the carbon amount of the main stand in two time points separated from each other by the length of the period (delta t = by default 5 years) as follows:  

 Total current biomass increment is calculated from two sequential growth periods as the difference between the total biomass production in two time points separated from each other by the length of the period (delta t = by default 5 years) as follows:  

Total current carbon increment is calculated from two sequential growth periods as the difference between the total carbon sequestration in two time points separated from each other by the length of the period (delta t = by default 5 years) as follows:  

Total mean biomass increment is obtained when total biomass production of the stand is divided by its age:

Total mean carbon increment is obtained when total carbon sequestration of the stand is divided by its age:

Potential tree water transpiration expressed in litres per year, is calculated from the tree crown lateral area cS, mean daily temperature in the vegetation period s₆ and the length of vegetation period s₄ using the formula: 

• k_D is the correction factor of the length of the vegetation period. It is linearly related to the elevation of the forest stand: b₀+b₁.v_nm 

• I_R is the index of rainy days (those with daily precipitation of more than 1 mm). It is related to forest ecoregion and elevation, and is interpolated from the table of climatic amplitude. 

• k_tr is the correction factor of days with transpiration, which converts rainy days into days with transpiration. It is a constant equal to 0.4. 

• a_i and b_i are equation coefficients