Methodical approaches to evaluation of assortment and quality structure of forest stands in conduсting of severance fellings



N.V. Lyubchich, I.F. Buksha, V.P. Pasternak, M.I. Buksha

Анотація


Introduction. Study of issue of rational use of forest harvesting fund
management is always characterized by a great relevance because the correct
application of scientifically based methods for evaluation of assortment and
quality structure (AQS) of forest stands makes it possible to increase economic
efficiency and profitability of forestry. Most effective use of harvesting fund of
forestry enterprises, including the rational harvesting of cutting areas and
operational control of the output of various assortments, both in bulk and in
money terms, allows to improve profitability by optimizing of economic regulation,
use and reproduction of forest resources. In Ukraine a significant contribution to
the study of this issue was made by O.V. Polyakov and M.A. Polyakov [8, 9, 10].
An analysis of the issue showed, that an important aspect of the economic
efficiency of forestry enterprises improving is introduction of assortment timber
accounting at enterprises. It means that at the stage of forest cutting area allocation it is necessary to determine in addition to the total timber volume,
divided into groups of thickness (large, medium and small) and by category
(merchantable wood, fuelwood), also the presence of today liquid marketed
assortments, with their distribution by grades of merchantable timber and names
of firewood by purpose, as well as the most profitable diameter groups. After
such assortment evaluation of standing wood it is necessary to carry out book
keeping and set prices in the enterprise just for those timber groups by types and
diameter sizes of that have been defined during taxation of cutting areas and
stated in the appropriate form.
We should note, that the existing standards for the evaluation of
assortment and quality structure it is difficult to use for stems distribution by size
and quality categories due to discrepancy with standards. Also in these
standards there is no data on thickness groups, names and characteristics of
assortments that are in demand in today's economy [4].
For the economic analysis of enterprises activity and adaptive planning on
the base of features of harvesting fund of a particular enterprise, it is necessary
to improve methods of evaluation of AQS of forest stands.
Materials and methods. Our study carried out in forestry enterprises of
Kharkiv region aimed in improving of methods of evaluation of assortment and
quality structure of growing forest stands by using of modern technologies.
For assortment of forest stands various methods can be used:
determination of assortment structure of individual trees, model trees, sample
plots, assortment and yield tables. In production activities it is advisable to use
two ways of assortment evaluation of standing wood – assortment by using data
from the available assortment structure and assortment based on bucking of
model trees [4].
Assortment evaluation by using of the available assortment structure on
the base of accounting records of the results of rational bucking actually obtained
during the previous period on specific cutting area that is a kind of sample plot.
Data may be obtained from completed cutting areas both clear cuts and
selective logging on forest plot, for thinning and other cuttings in similar forest
stands by the main taxation peculiarities (species, age, average height and diameter, type of site conditions). When applying this method the appropriate
form is filled – a document for planning of assortments output for individual plot. It
allows taking into account the effect on the assortment output characteristics of
the stands: structure, prevailing site conditions and defects, and other specific
features of single forestry unit.
Assortment evaluation by method of model trees is carried out by taking
into account the distribution of trees by diameter classes and categories of
technical quality. Selected models may bee felled and rationally bucked in
accordance with specified assortment structure for timber harvested in current
year for specific forestry enterprise, or measured by using of programme and
instrumental complex Field-Map, that gives the possibility to measure model
trees remotely and apply virtual bucking of models [12].
Classic method of model trees felling gives accurate results, which is very
important in evaluation of the marketability of valuable species, especially in case
of high-quality assortments, in forest stands with significant or hidden
defectiveness. It also can be used for control of marketability evaluated by other
methods. In accordance to the proposal of V.K. Zakharov [3] the method of
average model, which is widely used to determine standing wood volume can
also be used for evaluation of it assortment structure. Meanwhile, the average
model should be selected by the steps or classes of thickness. Selected model
trees by diameter and uniform quality categories should represent not only the
average forest taxation attributes, but also the average quality characteristics of
uniform quality groups of trees, selected at enumeration: merchantable, semi-
merchantable and fuelwood, i.e. represent the average content of each of these
categories. The author also notes in case of 12-15 models the difference in the
output of basic assortments doesn’t exceed ± 10%. Specified amount of models
should be distributed by stages of thickness, proportionally to stem quantity in
them.
Results. For determination of assortment and quality structure of main tree
species in pine forest stands in allocation of cutting area for severance felling the
following steps were proposed. During sampling of models it is necessary to
consider trees distribution by stages of thickness and technical quality. The order of evaluation and sampling in nature of trees of a particular category of technical
quality does not affect the results of evaluation of assortment and quality
structure of standing wood. Within each category of technical quality
determination of the number of model trees by diameter classes should be
carried out according to their share in the estimated number of models of the
relevant category. Within each category of technical quality the order of models
selection in nature and assigning them numbers does not affect the results of
AQS of standing wood. It should be noted that the leading assortment, according
to [13] on the cutting area should be roundwood with the length 4.0 m, as well as
technological raw materials for processing length 4 m. Based on the content of
the standards [2] and [3] merchantable trees with diameter (at breast height) 8
and 12 cm are not taken into account when evaluating the assortment structure,
because roundwood of them are poles (100% of volume of merchantable small
wood from cutting area), which has only II grade. Names and groups of
thickness of timber are defined in Order of State Committee of Forest
Management of Ukraine [7].


Later the new changed form of "Statements on enumeration of trees ..."
was introduces in accordance with the Order of State Agency of Forest
Resources of Ukraine [6]. Assuming that in future the form of statements can be
changed to avoid future necessity of adaptation of this statements to calculate
the number of sample trees, N.V. Lyubchich has developed the "universal" form
of "Statements on calculation of model trees for evaluation of assortment and
quality structure..."..
Based on the above, given the experience of evaluation of AQS of
standing wood on the previous sample plots (cutting areas) and taking into
account the necessity of determination of the standing stocks of all assortments
in the context of the above-mentioned groups of thickness and grades [4] the
following order of models selection (at the example of pine stand in Rubezhansky
forestry unit allocated for severance felling) is proposed (Table. 1): 1. Statement of the calculation of model trees to evaluation of AQS of
cutting area
d 1,3 ,
cm
Мodels on categories of technical validity and thickness
stages
Totall
y
trees
Models
merchantable
semimerchantabl
e
Fuelwood
By thickness
stages
trees % N, pcs. trees % N, pcs. trees % N, pcs. %
minimum
amount
8 – – – – – – – – 14 – – – 14 – – –
12 – – – – – – – – 11 – – – 11 – – –
16 51 27 1,6 2 6 11 0,2 – 71 43 2,2 2 128 29 3,8 4
20 84 44 2,6 3 25 45 0,9 1 46 28 1,4 1 155 36 4,7 5
24 40 21 1,3 1 20 36 0,7 1 28 17 0,9 1 88 20 2,6 3
28 15 8 0,5 1 5 9 0,2 – 20 12 0,6 1 40 9 1,2 1
32 1 – – – – – – – 12 7 0,4 – 13 3 0,4 –
36 1 – – – – – – – 3 – – – 4 1 – –
40 – – – – – – – – 6 – – – 6 1 – –
44 – – – – – – – – – – – – – – – –
48 – – – – – – – – 2 – – – 2 – – –
52 – – – – – – – – – – – – – – –
56 – – – – – – – – 1 – – – 1 – – –
Bucked models: 7 * 2 * 5 * *

We first determine (rounding values to integers) proportion of trees in each
stage thickness, excluding trees of 8 - 12 cm, in total of others (462 pcs.)
allocated trees. Then we set the amount of models for each degree of thickness,
rounding obtained numbers to integers. Trees with diameters of 32-56 cm are not
considered in evaluation of AQS as their share in the total number of trees with a
diameter of 16-56 cm is small (0.4 models or less). Thus, in subsequent
calculations appropriate trees with thickness of 16-28 cm will be used. Proportion
of number of calculated trees of each thickness stage is calculated by dividing
the number of trees of each stage thickness of each category technical quality on the number of trees of appropriate category, rounded to integers. The share of
the number of models of calculated trees of corresponding thickness degrees of
each category technical quality is calculated by multiplying the proportion of
number of calculated trees of each thickness stage of each category
corresponding to the total number of models in each category with the following
rounding obtained values to tenth. Number of models in terms of degrees of
thickness of all categories of technical quality calculated by rounding. Thus, the
number of models is: from fuelwood – five, semi-merchantable – two,
merchantable - seven (Table. 2).

2. Distribution of model trees by diameter classes
№ Model Diameter
class
Category
1 20 merchantable
2 20 merchantable
3 24 merchantable
4 16 merchantable
5 28 merchantable
6 16 merchantable
7 16 Fuelwood
8 16 Fuelwood
9 20 merchantable
10 20 Fuelwood
11 20 Semi-
merchantable
12 24 Semi-
merchantable
13 24 Fuelwood
14 28 Fuelwood

Results of bucking of defined above models are input in statement (Table.
3). 3. Statement (Field) to evaluation of assortment and quality structure



model

d,
cm
Category of
technical
quality
Roundwood: length – 4.0 m, diameter in cm.
Sawlog poles
14-18 cm 20-24 cm 6-13 cm
ІІ ІІІ ІІ ІІІ ІІ
1 20 merchantable – 18 – – 13;11;9
2 20 merchantable 16 18; 16 – – 13
3 24 merchantable 18; 16 14 – – 12: 8
4 16 merchantable – – – – 13;11;9;8
5 28 merchantable 18 16; 14 20 22
6 16 merchantable – – – – 13;11;10; 7
7 16 merchantable – – – –
8 16 fuelwood – – – – –
9 20 merchantable – 18; 14 – – 13;11;8
10 20 fuelwood – – – – –
11 20
Semi-
merchantable
– 14 – – 12; 10
12 24
Semi-
merchantable

18; 16;
14
– – 12
13 24 fuelwood – – – – –
14 28 fuelwood – – – – –

Continuation of table 3.


model

d,
cm

Category of
technical
quality

Rowmaterials for
processing, length.
- 4.0 m, diameter –
in cm Fuelwood length 1m,
diameter in cm 4 cm and
>
on wood
chips
14-18
cm 1 20 merchantable – – 24(2m); 4(2m)
2 20 merchantable 9 – 12(2m); 11(2m);8
3 24 merchantable – – 4(2m)
4 16 merchantable – – 3(2m); 6(2m)
5 28 merchantable – – 13(2m); 11; 7(2m)
6 16 merchantable – – 5(2m); 4
7 16 merchantable – –
16(2m); 14(2m); 12(2m);
10(2m); 8(2m); 7(2m);
6(2m);3
8 16 fuelwood – –
16(2m); 14(2m); 13(2m);
11(2m); 8(2m); 7(2m);
5(2m);3
9 20 merchantable – – 7(2m); 5
10 20 fuelwood – –
20(2m); 18(2m); 14(2m);
12(2m); 10(2m); 10(2m);
8(2m);6(2m)
11 20
Semi-
merchantable
– 16 10;8;6;4
12 24
Semi-
merchantable
10 – 10; 7(2m)
13 24 fuelwood 10; 12 18; 16 24(2m); 22(2m); 6(2m)
14 28 fuelwood – – 14(2m); 12(2m); 10(2m)

Volumes of assortments estimated at the cutting area by categories and
grades are given in the statement (Table. 4).
4. Statement (cameral) for evaluation of assortment and quality structure


model

d,
cm

Category of
technical
quality

Roundwood (m
3
) : length 4 m
Total
sawlog poles
14-18 cm 20-24cm 6-13 cm
ІІ ІІІ ІІ ІІІ ІІ
1 20 merchanta 0,24 0,09 – – 0,14 ble 5
2 20
merchanta
ble
0,38 0,095 0,22 – – 0,062
3 24
merchanta
ble
0,40 0,220
0,07
3
– – 0,11
4 16
merchanta
ble
0,17 – – – – 0,17
5 28
merchanta
ble
0,62 0,120
0,17
0
0,1
5
0,18 –
6 16
merchanta
ble
0,17 – – 0,17 –
7 16 fuelwood - – – – – –
8 16 fuelwood - – – – – –
9 20
merchanta
ble
0,36
0,19
0
0,170 –
10 20 fuelwood - – – – – –
11 20
semimerch
antable
0,16
3

0,07
3
0,090 –
12 24
semimerch
antable
0,34
0,29
0
0,053 –
13 24 fuelwood – – – – – –
14 28 fuelwood – – – – – –
Total:

m
3
2,84 0,435 1,11
0,1
5
0,18 0,965
%* 56,5 8,6 22,1 3,0 3,6 19,2
Total at cutting area, m
3
59 10 26 3 4 16
Continuation of table 4




mod

d,
cm

Category
of
technical
quality
Rowmaterials for processing
(m
3
), length. 4 m
Fuelwoodа (м 3
),
lemgth 1m and 2m
Total (m
3
)
marketable
4 cm
and >
on
14-18
cm
20-
24
cm
Total el wood
chips
1 20
merchant
able
– – – – 0,01 0,25
2 20
merchant
able
0,032 – – 0,032 0,06 0,47
3 24
merchant
able
– – – – 0,004
0,40
4
4 16
merchant
able
– – – – 0,01 0,18
5 28
merchant
able
– – – – 0,05 0,67
6 16
merchant
able
– – – – 0,006
0,17
6
7 16 fuelwood – – – – 0,15 0,15
8 16 fuelwood – – – – 0,171
0,17
1
9 20
merchant
able
– – – – 0,01 0,37
10 20 fuelwood – – – – 0,29 0,29
11 20
Semi-
merchant
able
– 0,095 – 0,095 0,02 0,28
12 24
Semi-
merchant
able
0,037 – – 0,037 0,02 0,40
13 24 fuelwood 0,09 0,22 – 0,31 0,23 0,54
14 28 fuelwood 0,095 – 0,51 0,61 0,08 0,69
Total:

m
3
m
3
0,32 0,51 1,08 1,11 5,03
%* 5,0 6,4 10,1 21,5 22,1 100
Total at cutting area,
m


10 13 21 44 46 149 Note: during bucking of model tree No. 5 with diameter "28 cm" no any large-
sized assortment was obtained that is why 2 m
3
of large-sized wood determined
by monetary value we include to calculation of AQS to average volume.

When using a software-tool set Field-Map with laser inclinometer
rangefinder TruPulse 360B with built-in scale for remote diameter measurement
it is possible to calculate tree stem volumes on the base of remotely measured
stem profiles of model trees without felling (see Fig. 1).


Fig. 1. TruPulse 360B with built-in scale for remote measurement of stem
diameters

Stem profile is built by using of 6-point method developed by IFER, Czech
Republic [12]. Diameter measurement is carried out at stump level, at heights 1.3
and 2 m, also tree height is measured. Places for remote measurement of two
diameters depend on tree crown length:
 If the base of live crown is between 1/3 and 3/5 of tree height, it is
necessary to measure diameters at the crown base and in the middle of
stem (half of the height from the crown base);
 If the base of live crown is lower than 1/3 of tree height, diameters are
measured at crown base and at 3/5 of stem height;
 If the crown base is higher than 3/5 of tree height then diameters are
measured at 1/3 and 3/5 of tree height.
The data on trees measurements are used in software Field-Map
StemAnalyst for parameterization of stem profile equations. On the basis of
obtained model it is possible to calculate the tree volume only by using two
parameters: the diameter at breast height and height of the tree. In the program Field-Map StemAnalyst it is possible to perform virtual
assortment structure of cutting area: for each tree the stem volume and user
predefined assortments that you can get from this tree are calculated, priority and
cost of assortments are also defined by the user. Priority and value of
assortments can also be specified by the user. The software can be used to
simulate various empirical models, in particular – thickness of bark crust models,
models of availability of false core and probability of stem rot.
Conclusions. The most appropriate method of evaluation of assortment
and quality structure is selection of models on the basis of proportional
representation-stage considering their distribution by categories of technical
quality. It allows increasing the accuracy of AQS evaluation of standing wood and
provides efficient use of forest resources. Using of software and instrumental
complex Field-Map makes it possible to calculate the volume of tree stems and
evaluate AQS without felling of model trees. Such non-destructive method for
assessing of AQS of standing wood is promising in terms of monetary valuation
of cutting areas and auction sale of growing wood.


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