Russian Forests & Forestry

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FOREST DYNAMICS

Dynamics of Russian forests for 1961-2003 at the country level is presented based on data of State Forest Account (SFA). The SFA is the only source that presents aggregated forest inventory information for all Russian forests by a definite date. The SFA set forth a specific procedure for collecting and updating data on the status and distribution of forests at the national level. Between 1961 and 1998, the SFA was provided, as a rule, every five years. Because the FSA aggregation comes from a hierarchical summarization of data from initial inventories, the accuracy of SFA data at the national scale is closely linked to the accuracy of forest inventory methods. Three basic methods have been used in Russian forest inventory during the last 50 years: forest inventory and planning, so called aerotaxation, and remote sensing. A short description of methods of forest inventory is given below.

The accuracy of the SFA data for the time period 1961–1998 is affected by several factors. First, it depends on the share of areas inventoried by different methods and on the accuracy of these methods. The impact of the standard errors of primary inventory units on aggregated data is negligible because the number of primary inventory units in Russia is around 50 x106, although the systematic errors require specific considerations. Second, inventories of different regions were carried out at wide and irregular intervals, and the methods used to update the data for specific dates were not consistent during the considered time period, and in some cases were very oversimplified and imperfect. Third, modifications to the inventory manuals (the most serious was done in 1964) made some changes to classifications and definitions, although the basic definitions, such as FA, UFA, etc., were not changed. Fourth, changes in data used for growing stock evaluations (e.g., yield tables) also affect the overall accuracy of the growing stock estimation. Numerous control surveys reported that the major part of indicators estimated by the FIP for each stand was of satisfactory accuracy, excluding the growing stock for immature, mature, and overmature forests, which was underestimated for all regions of the country

Methods of forest inventory used in State Forest Account

On-ground forest inventory and planning (FIP, the Russian term lesoustroistvo) has been and still is the dominating forest inventory method used in Russia. It was developed and initially implemented in forests of regions with the most intensive forest management and harvest. The basic concept of the FIP has not changed over time in spite of the fact that 13 different FIP manuals have been issued. Since the FIP manual was issued in 1952 (MFM of the USSR, 1952), the methodological design of the FIP has been the same, in spite of numerous technological improvements, which have been implemented in succeeding manuals (Gosleshoz SSSR, 1964; Goscomles SSSR, 1991; FSFMRF, 1995a). Thus, the SFA provides a rather sufficient basis for consistent analysis of aggregated forest inventory data for the entire period 1961–1998.

The FIP is carried out within the boundaries of separate forest management enterprises (leshoz) in managed forests every 10 to 15(20) years. There are three levels of detail and accuracy provided by the FIP, depending on the economic development of the region inventoried and the value of forests. As a whole, the FIP presents a rather detailed description of each primary inventory unit (including forest land categories, species composition, age, average diameter at breast height and average height by species, basal area, growing stock, quality of wood, site descriptions, information on forest products other than wood, undergrowth, a number of different ecosystem indicators, etc.). The size of primary inventory units varies widely, from 3–5 ha in densely populated areas of European Russia to 30–50 ha and more in remote forests of the European North, Siberia, and the Russian Far East. The principal inventory method is the ground ocular estimation, which is combined with measurements of the most important indicators of the forest stands under investigation (basal area, average height, etc.). Aerial photographs are obligatory and are used for delineating the primary inventory units and for mapping the forests at different scales. The FIP manuals require a very accurate estimate of stand indicators. For instance, the growing stock in each inventory unit for stands intended to be harvested during the next 10 years should be estimated with a standard error of ±10% (confidential probability 0.95). For stands of other categories of productive forests, the accepted standard error (probability 0.95) is 15–20%, and for unused and unmanaged unproductive forests up to 30%. The systematic error of a forest enterprise as a whole is also strongly limited (at 2–3% of the total growing stock).

In spite of the fact that the first forest inventory in Russia dates back to 1790 (Garkin and Sagreev, 1967), only 248 x106 ha (about one-fifth of the total forest fund area) had been inventoried by FIP at the beginning of 1948. At that time an area of about the same size had been inventoried by rough and approximate surveys using different applications of aerial inventories. In order to provide a simplified but relatively reliable survey of all previous uninventoried territories of the forest fund of the former Soviet Union, the so-called aerotaxation (an aerial inventory method) was implemented at the end of the 1940s as a special inventory procedure (mainly for the European North, and major territories of Siberia and the Russian Far East). The total area covered by aerotaxation between 1948–1956 was 896.2 x106 ha. Principal features of aerotaxation included (1) air photography of surveyed territories (usually at the scale of 1:100,000, in southern regions 1:25,000–30,000) and preliminary delineation of primary inventory units on air photographs, (2) a system of aircraft routes, designed at regional level depending on the landscape specifics and the percentage of forest cover (the average distance between neighboring routes was 2–4 km in zones of middle and southern taiga, and up to 4–8 (12) km in northern and sparse taiga); and (3) a quantitative, visual estimation of forests made by inventory experts, from aircraft for each polygon delineated on air photographs. Areas of primary inventory units were large (from several hundred to several thousand hectares), and the survey accuracy of each inventoried stand was low. Nevertheless, aerotaxation enabled the collection of the first aggregated data for all the forests of the country.
Beginning in the mid-1970s, unexploited northern and remote forests, estimated earlier by aerotaxation, were inventoried based on remote sensing methods using aerial and satellite photographs (photo-statistical method). Usually, a four-stage sampling procedure was used (or a simplified two- or three-stage procedure for regions with a low degree of forest cover). In its full scale, as a first step, a contour and analytical interpretation of satellite imagery was provided for all of the inventoried territory. For each delineated primary inventory unit, a land category was defined, and a dominant species or a group of species, an age group (usually three groups), and relative stocking were assessed for forested areas. Primary units were combined in strata, which were formed by dominant species, age groups, and landscape types. On the basis of variability inside of the strata, sampling was planned to provide the accuracy of the total growing stock for the region inventoried at ±2% (probability 0.95), the systematic error was meant to not exceed ±3% (which meant that the “summarized” error was about 3.5–4%). As a second step, air photography on multi-spectral films was provided for about 5% of the area in a systematic manner at scale 1:7,000 to 1:10,000. The contour and analytical interpretation of the primary inventory units were given for all working areas of air photographs in this second step. The measuring interpretation of selected inventory units (photo-samples) was provided as a third step. Finally, as a fourth step, on-ground measurements for selected photo-samples (5 to 10% of the total number of photo-samples) were given, in order to establish empirical models of the dependence between biometric indicators of stands and such features as interpreted signs, estimation of accuracy, and elimination of systematic errors. This method gives a high degree of accuracy for the objects inventoried, about ±2% for the total growing stock.

By 1990, a total of 665.8 x106 ha were inventoried by the FIP (by this time, part of the territories had been inventoried three to five times). During the last decade, the extent of new inventoried areas declined dramatically, and by 1998 the total area inventoried by the FIP method had increased only to 670 x106 ha, and 262.8 x106 ha were inventoried by remote sensing methods. Areas that were initially inventoried solely by aerotaxation and had not been inventoried using any other method later accounted for about 172 x106 ha (mainly in the extreme northern forest tundra and tundra areas). The current state of forests in these territories is more or less unknown, but the impact of these areas on the aggregated data for the country is supposedly not significant because they account for only 1.5–2% of the total growing stock of the country.

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