Environmental Engineering Reference
In-Depth Information
Following conventional theory on optimization (see, for example,
Nicholson, 1992), the optimal level of agricultural land area (
A
s
) and thus
also forested land area, to give the maximum total value of the region
(P
total
) can be found by taking the partial derivative of the total proi t
function with respect to land area and setting the value to zero.
4
This is
shown algebraically and mathematically in Equations 11.11 and 11.12
respectively.
0
P
t
0
A
5
P
f
(
2* 2 0.2 *
(
A
t
2
A
s
20.8
)
1 0.5
P
l
L
l
0.5
A
s
20.5
5 0 (11.11)
0
P
t
0
A
5 5
(
20.4
(
50 2
A
s
20.8
)
1 0.5
(
10 * 200
0.5
A
s
20.5
)
5 0
A
s
5 1.0
(11.12)
Thus, for a total study area of 50 hectares, the optimal area of agricul-
tural land is one hectare and hence the optimal area of forested land is 49
hectares.
It is obvious that for reasons of clarity and simplicity, this worked
example has been chosen with only a few variables. However, in carry-
ing out the complete research, two critical points must be noted. (1) To
identify the total value of the land, all of the products from it must be
identii ed and assessed. Summing the total proi t from all of these prod-
ucts would then give the total value of the region. For the sake of brevity,
in this worked example only one product from each type of land-use is
given, however the method is equally applicable with numerous products
from each type of land-use. (2) Acquiring the data outlined here requires
a detailed socioeconomic knowledge of the population living within the
region. It must be noted that although the questions outlined here for
obtaining information on the production of goods give a guideline as to
the type of information required, they do not precisely illustrate the meth-
odology for obtaining that information. Much of this information may
not be directly obvious but may have to be imputed through other means.
For example, to obtain an estimation of the price of wild foods that are
not marketed will require more than a simple question. The value may be
able to be imputed, for example, by comparison with the value of other
goods that are marketed. The reader is referred to the other valuation
studies referenced in this report for more detailed descriptions of survey
techniques (for example, Scoones, 1992; Campbell et al., 1997; IIED and
HNWCP, 1997).
