DIGITALNA ARHIVA ŠUMARSKOG LISTA
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ŠUMARSKI LIST 3-4/2013 str. 25     <-- 25 -->        PDF

With the "management of the herds" sub-model, growth of the fallow deer and red deer in terms of organic or conventional farming can be simulated. In organic farming of red deer, the upper limit is 5 adult animals/ha while the upper limit for fallow deer is 10 adult animals/ha. Animals in the first year of their life, which are born in the herd, are considered in this quota. Upper limits are prescribed in the Regulation on Organic Production and Processing of Agricultural Products (Official Gazette RS, No. 71/2010). In terms of conventional farming, the maximum livestock unit for fallow deer and red deer is 1.4/ha (Kästner and Baumgärtel 2010). Performance factors (e.g., hind/yearling pregnancy (70 %), hind pregnancy (90 %), rearing of calves (85 %), annual rejuvenation of the female animals (25 %), and annual rejuvenation of the male animals (25 %)) were used in the sub-model, and they can be changed. Information on the meat growth and weight of fallow deer and red deer carcasses was taken from Kästner and Baumgärtel (2010).
The "feed ration" sub-model allows us to calculate the cost of feed, depending on the type of farming (organic or conventional). Assuming norms and needs of wildlife (Naderer and Huber 2004, Riemelmoser and Riemelmoser 2006, Golze 2007) and the nutrient content of feed (Dlg 2011), with the help of the optimization software tool "What’s Best Industrial for Excel, WB", it is possible to obtain an optimal composition of feed (minimizing the cost of feed). In calculating the most favorable price of feed, data on costs per unit of output for each type of feed are used (cost price).
The "game enclosure" simulation model can simulate the arrangement of the game enclosure. All input data can be varied. The "trees-silvopastoral system" sub-model simulates the structure and density of trees in the game enclosure of the silvopastoral system. In order for the area to be eligible for agricultural policy measures (farm subsidies), the number of trees per hectare should not exceed 250 trees/ha. At this tree density, it is assumed that grass cover is at least 80 % and cover by tree canopy is less than 75 % (described by the Regulation on the Register of Actual Use of Agricultural and Forest Land) (Official Gazette RS, No. 122/2008). The "trees-forest" sub-model is meant for the simulation of the individual plantation "islands" of the trees in the game enclosure. In this way, the biodiversity would increase, as 17 different tree species are included in this sub-model. Surfaces in scenarios where "forest" is included are in Area 1 (4.2 ha), Area 2 (4.7 ha), Area 3 (4.4 ha), and Area 4 (4.2 ha). As can be seen in Table 1, we used the density of 1,080 trees/ha for forest plantation. In scenarios where forest is not included, the above-mentioned surfaces are under the silvopastoral system. Surface under trees, density of trees, species of trees, and prices of tree seedlings can be changed in both sub-models.
A dynamic method for investment projects has been used in assessing the investment, covering the financial part of the comparative analysis of total costs and revenues (CBA). Per-hectare periodic costs and revenues are itemized in Table 5.
The NPV is calculated as follows:
               
where
I – investment in the area regulation
n – number of years
Pi – annual net income or net loss, for the year "I," where Pi is calculated with the model as described earlier – result is cash flow (Pi = R – C, where; R – revenue; C – cost), costs and revenues are provided in Table 7
r – discount rate
The internal rate of return (IRR) is defined as the discount rate that results in NPV = 0 and represents the highest discount rate acceptable for the project.