Calculation of ecological and economic damage in forest management from insect pests

. The work is devoted to the development of the methodology for assessing ecological and economic damage from insect pests in dark coniferous forests of Siberia. On the basis of field data and generalised methodology, the results of calculation of income losses from direct and indirect damage caused by the impact of Ussuri Polygraphus on the fir forests of Krasnoyarsk Krai are presented. The complex monetary assessment is made on the basis of losses of marketable qualities of wood, oleoresin, fir boughs and loss of ecological functions - carbon-depositing, oxygen-producing and water-protecting. The proposed variant of calculation is possible to adapt the assessment of damage caused by various secondary pests and as a result of mass impact of the Siberian silkworm .


Introduction
The loss of ecosystem and economic values by forest communities as a result of large-scale impacts of insect pests has been a topical issue for many years.This factor is second only to forest fires in terms of impact, which also kill significant areas of forests every year.In Siberia, the most significant damage was caused by mass reproduction of the Siberian silkworm (Dendrolimus superans sibiricus Tscetv.) and spread of the invasive species -Polygraphus proximus Blandf (Polygraphus proximus Ussuri).As early as 2009, foci of the Ussuri bark beetle were detected in Krasnoyarsk Krai [1,2].At present, the area of the Ussuri Polygraphus distribution in the regions of Krasnoyarsk Krai is expanding and the negative dynamics of the condition of fir forests infested with this bark beetle persists.
In this case, a comprehensive integrated approach to this problem is necessary to estimate in value terms how much forestry loses as a result of the loss of economically valuable forests.Most of the existing methodologies for calculating ecological and economic damage are devoted to cases related to environmental pollution.These methodologies, when determining the ecological and economic damage, outline the procedure for accounting losses arising from environmental pollution, methods of their calculation, some methods of identifying the relationship between the degree of environmental pollution and the amount of damage, etc. are given.[3].At the same time, no unified approach and approved methodology for assessing damage from mass impact of insect pests has been developed at present.This paper presents one of the possible variants of the approach to the calculation of ecological and economic damage in damaged forest stands.
Based on the categories of forest resources and forest functions, two main types of damage -direct and indirect -should be considered in the comprehensive assessment of total losses of forest use from negative factors [4,5].Direct damage consists of the total loss of economically important forest resources.For example, fir plantations are a source of timber, oleoresin, and non-timber forest resources such as fir boughs and Christmas trees.Indirect damage is the loss of ecological, primarily protective and environment-forming functions of forests.

Materials and Methods
To calculate the ecological and economic damage, the methodology combined by a team of scientists was taken as a basis, which includes the main elements of theoretical and methodological developments in the field of forest management economics and takes into account the peculiarities of economic activity in Siberian fir forests and the specifics of the development of P. proximus mass reproduction foci in the infestation zone [6].
The actual data for testing the methodology were obtained in 2020 as a result of field studies to assess the condition of Siberian fir stands damaged by the Ussuri Polygraphus.The stand characteristics were obtained from the survey of three sites: in Irbeyskoye (sample area 1) and Mininskoye forestry of Krasnoyarsk Krai (sample areas 2 and 3).The initial data for phytocenosis assessment were collected according to the methodology developed by researchers of the V.N.Sukachev Institute of Forestry of the Siberian Branch of the Russian Academy of Sciences together with the Max Planck Institute of Biogeochemistry (Järve, Germany).The methodology was developed by researchers of the V.N.Sukachev Institute of Forestry of the Siberian Branch of the Russian Academy of Sciences in cooperation with the Max Planck Institute of Biogeochemistry (Jena, Germany), which is consistent with international experience [7].
Characteristics of damaged fir stands are given in Table 1.here: t0 -age of the plantation at the time of survey, years; M0 -stock of dried wood per 1 ha at age t0, m 3 ; r0 -minimum rates of payment for standing timber at the age of t0, rub.; kindexation coefficient to the payment rates per unit volume of timber (2.72).
Direct damage from loss of income from fir oleoresin harvesting Dr is calculated by the formula: here N -number of trees with diameter over 20 cm, pcs./ha; sr = 0.0005 t -amount of oleoresin that can be obtained from one fir tree per year, t/year ; rr -minimum rate of payment per unit volume of fir oleoresin, rub/t; kr = 2.35 -indexation coefficient to fee rates.
Direct damage from the loss of fir bark was calculated as the product of the average timber stock in the plantation, the average fir bark mass per 1 m 3 of stem wood, the minimum rate of payment per unit volume of fir bark, and a coefficient to the rates of payment per unit volume of forest resources (excluding timber).
Indirect damage was calculated for the three most significant ecological functions for Siberian fir forests: carbon-depleting, oxygen-producing and water-protecting.
Damage from the loss of the forest's carbon-depleting function DCO2 (rub/ha per year) was calculated by the formula: Here% l -amount of CO2 accumulated by 1 ha of coniferous forest per day, m 3 /day [8]; kCO2 -correction factor determining the absorption capacity of the plantation (for fir up to 20 years -0.3; 21-60 years -1; 61-120 years -0.3) -0.7; yproportion of plantation die-off per year, y = 0.07; p -fir share in the plantation; CCO2 -cost of a quota for emission of 1 tonne of CO2, rub/t [9].
Damage from loss of oxygen-producing function of forests DO2, expressed in rub/ha per year was determined by the formula Here: q -the amount of oxygen released by 1 ha of coniferous forest, m 3 /day; kcorrection factor determining the oxygen-producing capacity of the plantation, depending on the predominant species and age of the plantation; db -the proportion of plantation dieback per year, db = 0.07; p -fir share in the plantation; C -cost of industrial production of oxygen, rub/t [10].
Damage from loss of water protection function is calculated according to the formula: where PR -average annual precipitation, m; S -area 10000 m 2 , r -cost of 1 m 3 water, rub/ m 3 ; dbproportion of plantation dieback per year [9].

Results and Discussion
The results of calculation of direct damage caused by the impact of Polygraphus ussuriiskii in the studied stands of Siberian fir are presented in Table 2.The main share of direct damage is due to the loss of timber.This is explained by the fact that this resource is in high demand and has a higher price compared to other resources.
The damage from loss of fir oleoresin was not calculated for 1 sample area, as the average diameter of damaged trees is 17.8 cm, and fir stands can be harvested only when the tree reaches a diameter of 20 cm (Order of the Ministry of Natural Resources and Environment of the Russian Federation No. 911 of 9 November 2020 "On Approval of the Rules of Oleoresin Harvesting").The small damage from the loss of fir oleoresin is related to its low cost, about 149 rubles/t in Krasnoyarsk Krai ("Resolution", 2007).
The results of indirect damage calculation are given in Table 3.The predominant losses here are those associated with the weakening of the carbondepleting function of the forest.These high losses are related to the cost of CO2 emission quotas.Then there are losses from the water conservation function, which can be related to the high amount of precipitation that falls per year on average.
In this case, the calculation involves including the value of losses of the most basic forest resources and ecological functions in the damage calculation.Obviously, in order to obtain an objective assessment when considering direct and indirect losses of useful functions, it is necessary to individually consider and define damage assessment criteria depending on the structure of the forest area (species composition, age, forest type, all economically significant forest resources possible to obtain and other criteria).
For example, in this case potential direct damage was not calculated, as the stands that were investigated belong to mature stands.Losses from the harvesting of Christmas trees were also not included in the calculation, as the young generation of the forest, which is usually the object of harvesting in such cases, was viable and showed no signs of damage in the study areas.
The ecological literature shows the complexity of ecosystem functioning and the unpredictability of ecosystem responses to multiple external influences.Among other things, ecosystems can demonstrate significant resistance to stress, but also sometimes suffer rapid, catastrophic changes after violation of certain thresholds [10].
At the same time, in the practice of implementation of the methodological approach to assessing ecological and economic damage, the simplicity of calculation and availability of necessary information for reliable obtaining the value equivalent are important.The values that were obtained in the course of this work reflect the lowest value of damage, because they were obtained on the basis of the minimum rates of payment for wood on the root.In reality, the value of timber and other forest products, given the market value, may exceed the payment rates by dozens or more times.
The list of ecosystem functions of forests is much broader, but quantifying their economic importance is currently very difficult [10,11,12].

Conclusion
As a result of a comprehensive assessment of losses from the negative impact of the Ussuri Polygraphus on stands of Siberian fir growing on the territory of Krasnoyarsk Krai, the following results were obtained.
In the general structure of direct economic damage from Ussuri Polygraphus prevails the damage from timber loss.The content of direct damage in plantations significantly depends on the taxation characteristics of the stand.In addition, the amount of damage is determined by both the share of fir in the stand and the degree of damage.In indirect damage in fir forests of the study area, the first place is occupied by losses from the carbondepositing function, followed by water-protecting and oxygen-producing functions.The size of the total economic damage from the reduction of ecological functions of the forest, calculated using the methodology used, was greater than the direct damage from the loss of timber and secondary wood resources.
The presented damage calculation is one of the possible variants due to the structure of damaged stands.Estimation of losses based on the results of field data provides the most reliable baseline data for determining the size of ecological and economic damage, compared to cases when forest inventory materials or other data sources are used for calculation.
A similar approach and calculation criteria can be recommended in the case of damage of Siberian fir stands by other secondary pests.
Determination of the dried forest value C F (t0) was carried out on the basis of the current rates of payment (for the first category of taxes -hauling distance up to 10 km) and their indexation coefficients (Resolution of the Government of the Russian Federation of 22.05.2007N 310 (ed.15.06.2023) "On rates of payment per unit volume of forest resources and rates of payment per unit area of forest land owned by the federal government"):  ( 0 ) =  0  0  (1) E3S Web of Conferences 462, 03059 (2023) AFE-2023 https://doi.org/10.1051/e3sconf/202346203059

Table 1 .
Characterisation of Siberian fir stands on sample plots

Table 2 .
Indicators of direct damage in stands of Siberian fir damaged by Ussurian polygraphus

Table 3 .
Indirect damage from exposure to the Ussuri Polygraphus (per year)