CASMOFOR - Erdősítések szénkörforgalmának modellezése

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Az erdők szénkörforgalmáról

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CASMOFOR

verzió: 4.1

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ACCOUNTING FUNCTION, VARIABLES AND PARAMETERS APPLIED IN CASMOFOR

I. THE CARBON CYCLE OF FORESTS AND FORESTRY

PRELIMINARY NOTES

Equations of CASMOFOR describing the carbon cycle are listed below by pool, and classified in various categories. Balance equations (BE) are ones that are used to calculate new values of the carbon pools at time t. FLUX IN refers to a process, i.e. a sink, by the yield of which the carbon content of the whole forestry system increases. Similarly, FLUX OUT refers to emissions by the amount of which the carbon content of the whole forestry system decreases. The emissions can come from carbon that was fixed by the FLUX IN processes, or from carbon that was already stored in the soil before the start of the simulation. Some carbon that flows through various pools eventually goes to the long-term SINK (in the soil), and remains part of the forestry system for the entire period of the simulation. Equations that are not classified into any of the above categories are used to calculate variables in the above equations, and are noted by other. By the forestry system all the pools and processes within the system boundary of the systems diagram are meant. Variables related to carbon pools and rates of fluxes are expressed as amount of carbon (tonnes of carbon tC), and is calculated once for each calendar year of the simulation for each species and yield class.

Each equation is shown twice in each cell: once with the long names of the variables (in the first row(s) of each cell), and once using their symbols, respectively. Index t refers to any year in the simulation, index (t-1) refers to the previous year. Index (t-x) refers to year x year before the current year. Index (i) means that the variable is a vector of values from year 1 to year x (the factor used in the formula varies with age), where x depends on the process. The respective values of some variables are found in the database of the model, or should be specified by the user. The values of other variables are calculated by the model itself.

CHECKING FOR THE SECOND LAW OF THERMODYNAMICS

To check that all carbon is accounted for, i.e. all incoming fluxes equal to all outgoing fluxes + the changes of the carbon content of the system (including permanent sinks), the below equation is tested after each simulation step to ensure that mass is conserved:

Total Flux IN_t = Total (POOLS_t POOLS_t-1) + Total Flux to SINK_t Total Flux OUT_t

where Total Flux IN_t is the amount of carbon that enters the system in year t; Total Flux to SINK_t is the amount of carbon that moves to long-term carbon sink pools of soil in year t; POOLS_t POOLS_t-1 are the amount of carbon in all pools in time t and t-1, respectively; and Total Flux OUT_t is the amount of carbon that leaves the system in year t.

(Flux IN: amount entering the system; Flux OUT: amount leaving the system to air; Flus to SINK: amount leaving the system to soil and other long-term sink.)

EQUATIONS APPLIED TO MODEL CARBON DYNAMICS IN CASMOFOR:

Pool	Balance equation (BE), fluxes, or other equations	Equations, variables and parameters (pools and processes (in one-year steps) are in terms of tC ha^-1)
Above- ground woody biomass	BE	Above-ground woody biomass = above-ground woody biomass_t-1 + woody increment mortality thinnings - final cuttings AGWB_t = AGWB_t-1 + CAIC M TH FC
	Flux IN	current annual increment of above-ground woody biomass = current annual increment (of tree volume) * wood density * carbon content of wood *CAIC = CAI d * cf** d = weight of oven-dry biomass / volume of fresh wood (at the stand level), tdm m^-3 cf = carbon fraction of (oven dry) wood
		mortality = above-ground woody biomass_t-1 * (density dependent mortality ratio + density independent mortality ratio) *M = AGWB_t-1 (ddm + dim)** ddm: sepcies dependent dim: randomly generated ddm + dim <= 0,4
		thinnings = above-ground woody biomass_t-1 * thinning ratio *TH = AGWB_t-1 thr** Thr = species specific, depends on age and yield class
		final cuttings = above-ground woody biomass_t-1 of stands of rotation age FC = AGWB_t-1 of stands of rotation age (final cutting is supposed to take place at the beginning of the year, and is immediately followed by regeneration) Rotation age: species specific, depends on yield class
Dead wood	BE	dead wood = dead wood_t-1 + deadwood increment - decomposition of (i.e., emission from) decomposable dead wood DW_t = DW_t-1 + DWI EW
		increase of deadwood = (mortality + thinnings * (1 wood product part of thinning fuelwood part of thinning) + final cuttings* (1 - wood product part of final cutting fuelwood part of final cutting) )* (1 - non-decomposable fraction) *DWI = [M + TH (1 wpTH fpTH) + FC * (1 wpFC fpFC)] * (1-ndf)**
	Flux OUT	emission due to decomposition of deadwood = Sum_i(dead wood_t-i / time needed for deadwood to decompose_i) for i = 1 to x EW = Sum_i(DW_t-i/DTw_i)
	Flux to SINK	Non decomposable dead wood fraction = (M + TH non-productTH * FC non-productFC) * ndf **UWI = (M + TH non-productTH FC non-productFC) * ndf***
Leaves	BE	amount of (living) leaves at the end of year = amount of leaves at the end of previous year + increment due to tree growth decomposable leaf loss due to harvest and mortality undecomposable leaf loss due to harvest and mortality *LL_t = LL_t-1 + LI DLI DLI ndf / (1 - ndf)**
	Flux IN	increment of leaves = aboveground woody biomass increment * (leaf increment/AG woody biomass increment) *LI = CAIC increment ratio**
		amount of decomposable leaves that die in year (due to harvest and within year and end-of-year leaf mortality) = [(leaves_t-1 + increment of leaves) * non-living/living + (leaves_t-1 + increment of leaves) * non-living/living * (1-non-living/living) * fraction of leaves dying and falling at the end of year)] * (1 - non-decomposable fraction) *DLI = [(LL_t-1 + LI) nll + (LL_t-1 +LI) * (1 - nll) * fdlleaves] * (1-ndf)** fdlleaves: species specific (broadleaves: 1; conifers: <1)
		non-living/living biomass ratio = increase of deadwood / aboveground woody biomass of the previous year nll = DWI/AGWB_t-1
	Flux to SINK	Non decomposable fraction = amount of leaves that become decomposable dead * ndf/(1-ndf) ULI = DLI ndf / (1-ndf)*
Dead leaves	BE	dead decomposable leaves = dead decomposable leaves_t-1 + amount of decomposable leaves that die in year decomposition of dead leaves DL_t = DL_t-1 + DLI EL
Dead leaves	Flux OUT	Total emission due to decomposition of leaves = Sum_i(dead leaves_t-i / time needed to decompose_i EL = Sum_i(DL_t-i/DTL_t) for i=1 to x
Roots (below ground biomass)	BE	Roots at the end of year = Roots_t-1 + increase of root biomass amount of decomposable roots that die in year amount of undecomposable dead root that die in year *R_t = R_t-1 + RI DRI DRI ndf / (1-ndf)**
	Flux IN	increase of root biomass = current annual woody increment * (root-to-shoot ratio) *RI = CAIC rts**
		Decomposable dead roots increment = = [(Root biomass_t-1 + increase of root biomass ) * (non-living/living) + (increase of root biomasss ) * (1 - non-living/living) * Fraction of roots of trees (relative to root increment) that dies at the end of year ] * (1 non decomposable fraction) *DRI = [(R_t-1 + RI) nll + (LI_t-1 + LRI) * (1-nll) * fdlroots] * (1-ndf)**
	Flux to SINK	Non decomposable dead root biomass increment = decomposable dead roots increment * ndf/(1-ndf) *URI = DRI ndf/(1-ndf)**
Dead Roots	BE	Dead decomposable roots at the end of year = carbon in dead decomposable roots_t-1 + total decomposable dead roots increment decomposition of (i.e., emission from) decomposable dead roots DR_t = DR_t-1 + DRI ER
Dead Roots	Flux OUT	Total emission (tC) due to decomposition of roots = dead roots_t-i / time needed to decompose_i for i=1 to x ER = DR_t-i / DTR_i
Wood products	BE	Wood products = Wood products_t-1 + wood product increment wood products becoming unused WP = WP_t-1 + WPI WPU
		wood products increment = (timber from clearcut + timber from thinnings) * (1 lost part) *WPI = [FC used part * (1-fuelwood part) + TH * used part(t) * (1-fuelwood part(t)] * (1 - lost part)**
		wood products becoming unused = wood products increment X years before WPU = WPI_t-i X: mean life time of wood product (species specific)
	Flux OUT	Emission from (decomposition of) unused and unburnt wood product = wood products becoming unused_t-1 * (1-unburnt fraction) * time needed to decompose(t) *EUUWP = WPU_t-1 (1-unburnt)**
Fuelwood	BE	Fuelwood = fuelwood_t-1 + fuelwood increment from harvest + loss in wood processing + unused wood products becoming fuelwood emission from firewood FW = FW_t-1 + FWI + LWP + UWPF EFW
		Fuelwood increment from harvests = fuelwood from clearcut + fuelwood from thinning *FWI = FC used part * fuelwood part + TH * used part_t* fuelwood part_t**
		Loss in wood processing = wood product increment * lost part / (1 lost part) *LWP = WPI lost part / (1 lost part)**
		Wood product becoming fuelwood = wood products becoming unused_t-1 * unburnt fraction *UWPF = WPU_t-1 unburnt**
	Flux OUT	emission from burning firewood = avoiding fossil fuel burning = fuelwood carbon_t-1 * (1-unburnable fraction) *EFW = FW_t-1 (1-unburn)**
	Flux to Sink	Unburnable fuelwood = fuelwood_t-1 * unburnable fraction *UFWI = FW_t-1 unburn**
Soil	BE	soil = soil_t-1 + net flux to sink loss due to afforestation and regeneration operations loss due to afforesting grasslands S = S_t-1 + FS CLO GAL (Net flux to sink, which includes soil respiration, and loss due to afforesting grasslands are only calculated for 75 years after afforestations. After that time, net flux to sink is supposed to be zero, i.e. transfer of carbon from other compartments to soil is equal to soil respiration, and no more losses are supposed to take place due to converting grassland to forest.)
		carbon loss due to afforestation operations = afforestation area * area specific loss *CLO = A asl** asl: to be specified by the user
		carbon loss due to afforesting grasslands = afforestation area * percent of area of grassland * time-dependent difference of carbon stock between cropland and grassland *GAL = A glp * diff_CL_GL** glp: to be specified by the user diff_CL_GL: values are taken from a country-specific equation
	Flux to SINK	Flux to permanent sink = total amount of dead organic matter becoming undecomposable and unburnt = undecomposable dead leaves pool + undecomposable dead roots + undecomposable dead wood + unburnable fraction of firewood FS = ULI + URI + UWI + UFWI

II. CARBON ECONOMICS

1. NET ANNUAL FORESTRY COSTS_t (EUR or HUF) = TOTAL of ALL ANNUAL COSTS_t - TOTAL OF ALL ANNUAL REVENUES_t

where TOTAL of ALL ANNUAL COSTS_t (EUR or HUF) is the sum of all costs, at current prices, of all forestry operation on all area of the afforestation project that are due in year t; and TOTAL of ALL ANNUAL REVENUES_t (EUR or HUF) is the sum of all revenues, at current prices, of all forestry operation on all area of the afforestation project that are due in year t.

2. TOTAL NET FORESTRY COSTS_t (EUR or HUF) = SUM_i(NET ANNUAL FORESTRY COSTS_i)

where TOTAL NET FORESTRY COSTS_t is the total costs from the beginning of the afforestation project, i.e. year 1, summed up to year t; and i = 1 to t.

3. TOTAL CARBON IN FORESTRY SYSTEM_t = AGWB_t + R_t + LL_t + DW_t + DL_t + DR_t + WP_t + FW_t + S_t

where TOTAL CARBON IN FORESTRY SYSTEM_t is to total amount of carbon accumulated in all pools of the afforestation project area up to year t in all carbon pools since year 1; all other symbols as in the table above.

4. TOTAL NET SPECIFIC COSTS_t (in EUR/tCO₂ or HUF/CO₂) = TOTAL NET FORESTRY COSTS_t / TOTAL CARBON IN FORESTRY SYSTEM_t

where TOTAL NET SPECIFIC COSTS_t is the total net forestry costs per a tonne of CO₂ sequestered by the afforestation system by year t.

TOTAL NET SPECIFIC COSTS_t are also calculated with only the sum of AGWB_t + R_t in the denominator to estimate total net specific costs of sequestering carbon in the tree biomass.

A weblapot utoljára Somogyi Zoltán módosította 2011. április 22-én.

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