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The Socio Economic Analysis (SEA) allows analysing a wood stock due to the aspects of costs, revenues and subsidies in a given time frame.
SEA uses the 4C information about the harvested wood, standing stock and silvicultural operations of a simulated area, sorts the input analog to WPM into different timber grades and computes the costs, assets and subsidies per year. Unlike the WPM it analyses also the standing stock in respect to its financial value. As further input SEA needs a "sea_prices.wpm" input file with the current prices. This file contains timber prices, silvicultural costs and possible subsidies.
To get started following is required:
- Set the flag_wpm to the desired value
- Make sure forest management took action
- A "sea_prices.wpm" file must exist in the input directory (can not be a dummy file).
| flag name |
value |
description |
flag_wpm |
0 |
no calculation of sea and wpm |
|
1 |
calculation of wpm with the German parameter set |
|
2 |
SEA calculation |
|
3 |
WPM and SEA calculation |
|
21, 31 |
WPM with other parameter sets |
Four output files are generated. The output includes the different sorted timber grades of standing stock and harvested wood, estimated costs, assets and resumed values as liquidation value, net present value (NPV) and NPV+.
| extension |
description |
"_sea" |
costs and revenues for standing stock, harvested timber, silvicultural costs, fixed costs and subsidies |
"_sea_ms" |
timber grading of harvested wood |
"_sea_st" |
timber grading of standing stock |
"_sea_npv" |
liquidation value, NPV, NPV+ (NPV with four different interest rates a-d, the first rate a is 0) |
The liquidation value indicates the value of the standing stock over the years. NPV contains the revenues of harvested timber in regard to the given interest rates.
The Implementation of SEA contains following components
- data module
- SEA functions
- implemented interfaces in the 4C simulation
- initial, allocate and deallocate functions
This table lists variables stored in the data_wpm module used for SEA.
data_wpm Description
| stored in |
description |
mansort, standsort, manrec |
data from the 4C simulation
mansort: harvested timber
standsort: standing stock
manrec: management information
|
nr_years |
simulation years number |
mansort_tg, standsort_tg |
sorted timber grades of harvested wood and standing stock |
chainsaw_prices, harvester_prices, planting_price, planting_subs, fence, fix, brushing, tending_prices, ext_for |
prices from the SEA prices file |
int_rate |
interest rates for NPV |
sum_costs |
cumulative costs: entire sum of all costs and partial sums (subsidies, silvicultural costs, harvested timber costs, standing stock costs) per year |
subsidy |
stores subsidies calculation values |
npv |
the estimated NPV values |
net_prices |
timber prices per species |
hsystem |
percentage of chainsaw to harvester methods of harvesting (usually set to 0.2 to 0.8) |
plant_year |
year of planting |
flag_plant |
planting flag for estimation of the planting |
ms_costs, ms_assets |
the costs and revenues for harvested timber |
st_costs, st_assets |
the costs and assets for the standing stock |
The SEA consists of following steps:
- sorting of standing stock and harvested timber into timber grades
- calculation of costs, silvicultural costs, subsidies and revenues for sorted timber grades per year
- calculation of summation values: liquidation value, NPV, NPV+
The Sorting of Timber Grades
The assortments from mansort and standsort inputs are sorted in the way similar to the first step in WPM. The single timber grades results from sorting the wood according to the type, specification and the diameter of the trunk. The mansort input (harvested timber) must be summed up due to the years of management listed in manrec input (s. WPM). The standing stock grading is done for each year.
Timber Grading of Harvested Wood and Standing Stock
| type |
spec |
diam in cm2
| timber grade index |
number of timber grades
|
fue |
1, 2, 3, 4 |
|
1 |
4x |
in1 + in2 |
1, 2, 3, 4 |
|
2 |
4x |
sg1 + sg2 |
1, 2, 3, 4 |
<15 |
3 |
20x |
15-20 |
4 |
20-25 |
5 |
25-30 |
6 |
> 30 |
7 |
ste1 + ste 2 |
1, 2, 3, 4 |
25-30 |
8 |
12x |
25-30 |
9 |
> 35 |
10 |
The volume per year v specified in the timber grades is calculated by the following equation:
v = volume * number,
where volume and number are estimated in the timsort.f subroutines.
A fix part (0.4) of timber grades values are shifted to the timber grades of the lower quality.
(sg1, sg2, ste1, ste2) => (in1, in2)
(in1, in2) => (fue)
The results of timber grading are stored in "sea_ms" and "sea_st" output files.
The Economical Analysis
The sorted timber amounts can now be evaluated due to the timber prices, silvicultural costs and subsidies.
The harvest costs, also the virtual harvest of the standing stock, are calculated. For the amount of harvested timber the actual harvests are taken into account. For the standing stock potential harvest costs are calculated yearly. Analog the revenues due to the given prices are computed.
The silvicultural costs and corresponding subsidies are estimated due to the management in certain years. Management operations are:
- tending
- brushing
- felling
- shelterwood system 1 and 2
- felling after shelterwood system
- thinning,
- planting
Planting costs are down to the amount of the planted trees per ha and the tree species. The planting method is estimated by the stored flag_plant. Some management activities combine several costs and subsidies categories.
Costs and revenues can now be aggregated over the years to the NPV and NPV+ due to the interest rates.
The costs and revenues for every tree species are aggregated per year in the output file "_sea". NPV and NPV+ values can be found in the "_sea_npv" output file.
The overview of the SEA subroutines are shown in the following table.
Subroutines and their Description
| subroutine |
description |
read_sea_prices |
read the SEA prices file |
sort_standsort, sort_standsort |
timber grading of harvested timber and standing stock |
sort_industrial |
fix part (0.4) of timber grades is shifted to the grades of lower quality |
calculate_harvest_costs |
calculate harvest cost |
calculate_assets |
calculate revenues for the standing stock and actually harvested wood due to the net prices |
calculate_costs |
calculate costs and corresponding subsidies due to the management method:
tending, brushing, felling, shelterwood system 1 and 2, felling after shelterwood system, thinning, planting
|
calculate_npv |
calculate NPV, NPV+ due to the interest rates |
The coupling of the SEA and the 4C implementation can be distinguished into two parts:
- the input interface and
- the output interface
As mentioned above, SEA uses mansort, standsort and the manrec data modules. Also the information about planting, such as planting year, amount of planted trees and the stock mixture is a matter of concern. Some general information such as number of simulation years are needed, too.
For the output the changes were made to match the 4C output interface in three files: amod_out.f, old_out.f, output.f.
The deallocation of wpm is called after the one simulation run is over in finisim.f
Input Interface
| data |
where |
mansort |
sorting of timber in timsort.f, harvested timber |
standsort |
sorting of timber in timsort.f, standing stock |
manrec |
management subroutines in management.f |
year etc. |
import of the data_simul module |
plant_year |
planting subroutines in planting.f |
num_plant |
planting subroutines in planting.f |
flag_plant |
planting subroutines in planting.f |
SEA Subroutine Calls in 4C
| content |
Fotran files |
SEA subroutine calls |
simul.f
finisim.f
|
SEA data, subroutines etc. |
wpm.f
wpm_wood_proc.f
amod_wpm.f
|
output interface |
amod_out.f
old_out.f
output.f
|
input interface |
timsort.f
management.f
planting.f
simul.f
amod_simul.f
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 Download the user manual of SEA
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