by Vasily SUKHIKH, Vasily ZHIRIN, Drs. Sc. (Agr.), RAS Center for Forest Ecology and Productivity (Moscow)

About 25 percent of all forests on the Earth are located in Russia.

Their biosphere functions in many ways determine quality of life on our planet. National timber resources are also that huge.

Under efficient utilization, this wealth could become a reliable basis for economic might of our country.

But if we want to achieve a desired forestry management level, first of all, it is necessary to collect objective data on its state, negative and positive processes related to it and to make accurate forecasts.

Overland studies and aerial photography carried out since the 1920s do not give adequate information. Modern space technologies are nowadays replacing traditional methods.

QUALITY INFORMATION IS A CONDITION OF SUCCESS

Broad-scale research works to study natural resources from outer space commenced in 1972 in the USSR*. In the 1970s-1980s specialists of the research division of the All-Union Amalgamation "Lesproekt" (Moscow), the Leningrad Scientific-Research Institute of Forestry and Institute of Forest and Timber named after V. Sukachev of the RAS Siberian Branch carried out comprehensive theoretical and practical studies of the forest as an object of remote sensing. They developed methods of decoding data of space surveys, inclusive of automatized ones, in the geographic information system medium, and substantiated the requirements to conditions and methods of surveys depending on assigned tasks. At the same time scientists estimated the role of these surveys for the actual and prospective monitoring system. They (including the authors of this article) improved outdated and offered more

* See: V. Senkevich, "Russian Space Research at the Turn of Centuries", Science in Russia, No. 1, 2001. - Ed.

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effective technologies of forest inventory and estimation of their state on the basis of data obtained by earth satellites of the first generation ("Meteor-Priroda", "Cosmos", "Landsat", etc.).

These technologies were first introduced in 1978. For the past 28 years scientists studied and mapped out over 400 mln hectares of forest resources in the northeastern regions of Russia, Central Asia, Kazakhstan. They made up a series of small-scale maps, including "Forests of the People's Republic of Mongolia" map of 1:1,000,000 scale (1980).

New technologies based on decoding space surveys allow to perform prompt and objective recording of current natural and anthropogenic changes in the forest resources and forecast their possible aftereffects. Studies of burned-out forests, their utilization, damage by insects, hurricanes, and other impacts carried out in the 1980s, which covered over 600 mln hectares of land in the taiga zone of our country, confirmed efficiency of new research methods. At present scientists apply modern methods to estimate forest recovery rate.

Satellite data have become of high importance to protect "green lungs" of the Earth: it is easier to deal with fires if you know their coordinates, meteorological parameters, online direction data, and spreading rate.

Based on the results of satellite surveys, Russian scientists performed a detailed inventory of raw materials resources for logging enterprises of the Northern Economic Region of European Russia. It simplified the process of forest exploitation control.

But after 1991 these successful research activities supported by a number of national institutions were

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Large-scale color spectrozonal aerial photograph (of about 10 cm resolution) of seeding growth of different height:

1 - birches up to 1.5 m,

2 - birches over 1.5 m,

3 - firsupto 1.5 m,

4 - firsover 1.5 m.

Felled trees are well seen.

Fragment of a space photograph (resolution-8 m) obtained from the Russian earth satellite of the Kosmos series.

Felling sites of different reforestation:

I - unreforested woodlands,

II - young growth of conifer trees,

III - young growth of leaf trees,

IV - areas of mature conifer forests,

V - areas of mature leaf forests.

practically suspended. Only at our Center, the International Institute of Forest and Institute of Forest named after V. Sukachev, this subject has not lost its significance and even received a new impetus.

For the last 10 - 15 years surveying techniques and information processing methods have considerably improved. Geographic information technologies and geopositioning means are widely used in science and practical life of many countries. Multispectral pictures with a spatial resolution of up to lm, comparable with a large scale aerophotography, are now used for civil purposes.

Now we can well imagine the possibilities of decoding different space surveys-photographs with resolution from 1 to 20 m (KFA-1000, MK-4, etc.) and scanners of 1 to 1,000 m resolution (QuickBird, IKONOS, IRS, Monitor-E, SPOT, Landsat, MSU-SK, MODIS, etc.). Methods of information processing have also been developed to be used for needs of forest management. Thus, the forest state and dynamics monitoring has become one of the most important and promising methods: it allows to improve significantly the quality of remote sensing data. In this article we will tell you about latest scientific achievements which are highly

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effective to guarantee accurate exploitation and regeneration of forests.

NEW "KEY" TO OLD PROBLEMS

Since ancient times clean felling in Russia has been the main factor of transforming forest cover: for the last 150 years over 150 mln hectares were felled. In the 1970s-1980s about 2 mln hectares of mature forests were cut down every year (about 1 mln at the present time).

Under the RF Forest Code in force it is allowed to fell trees for industrial purposes only in the regions where such activities can be substantiated from the environmental and economical points of view-total area of forests in these regions is about 330 mln hectares. Other territories (403 mln hectares) are not subject to such impact as they are specially protected or are hard-to-reach or reserved with low productivity.

Forest felling is far from being an elemental phenomenon, its scope and arrangement are planned. As a rule, every year there appear stripped areas of different size in taiga (from 0.1 - 0.5 hectares to 50 - 100 hectares), configuration and localized inside production economic structures. Under the current standards they should be dispersed evenly in order to minimize the negative impact on environmental and resource functions of forests. But in practice owing to the absence of road infrastructure and striving of entrepreneurs to reduce costs, basic volumes of massive cuttings are concentrated along access roads.

Intensive logging is carried out in the European-Ural part of the country, in southern regions of Siberia and Far East, near the Trans-Siberian line. Thus, for the last 60 years felling was performed on about 60 percent of lands covered with forests in Chuvashia, 58 percent such lands in Udmurtia, 57 percent - in Tatarstan, 54 percent - in the Kirov and Perm Regions, 50 percent - in Mordovia and the Kostroma Region, 48 percent - in the Sverdlovsk Region, 46 percent - in the Vologda Region and 41 percent - in the Vladimir Region.

Lumbering operations are often performed with a significant violation of existing norms. For example, works are commenced when felled area flora of adjoining coupe has not regenerated yet. Or people do not take into account direction of felling sites, which must correspond to the direction of prevailing winds (it helps to spread seeds). Sometimes species of wood that are believed less valuable stay untouched and there appear so called undercuts-forest plots heavily suffering from hurricanes because of bareness around. A great number of rooted up trees is a favorable living space for destructive insects.

It is worth speaking about situations when logging operations are performed out of the set limits on the neighboring plots.

Eventually, secondary forests are formed in place of mature ones, which in all respects are less valuable. Besides, reforestation is a long process, and by the beginning of 2003 about 3,427.8 thous. hectares of felled areas have been stripped.

It becomes clear that the opportunity to control all phases of forest exploitation, identify new logged areas, estimate conformity of their location and sizes to permits and set parameters is essential for our forest management. Scientists should offer a corresponding monitoring system based on satellite data and geo-information technologies. Such approach is the only way to perform observations on huge and often hard-to-reach territories.

FOREST USE IN THE SATELLITE "OBJECTIVE"

Specialists of our Center performed a series of observations on test plots located in different regions of Russia. We checked and adjusted boundaries and areas of felled sites, operation periods, determined species of cut down trees, defined levels of regeneration of cuttings, availability of undercuts or illegal cutting drifts, as well as measured exposition and slope ratios, other parameters.

Unlike other forest objects, satellite images are brighter. If the resolution is less than 3 m, skidding corridors* with machinery advance traces, clumps of mature trees (seed plants) and young growth, undercuts, illegal felling sites, log decks and other characteristic features are usually well distinguished.

Images of lower resolution are less recognizable owing to generalization of data. The main decoding parameter here is shape of felling sites, as their boundaries are rather clear and outlines are geometrical-all these factors enable scientists to identify the above-mentioned objects. Color multizonal images show violent contrast between "stripped" areas and neighboring forest edges, that is why characteristic features of their internal structure are represented better.

As a result we found out: effective assessment of forest exploitation requires satellite data and aerial photos of different spatial, spectral, and time resolution. If satellite images of a certain technological quality are

* Skidding corridors-temporary roads, formed inside cuttings for passing machinery in order to limit loads on the soil and seedling growth, - Ed.

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not available, scientists can use aerial photographs of small and middle scale.

In 2005 specialists of our Center developed guidelines to a remote monitoring of forest exploitation activities, envisaging integrated use of satellite data, computer forest assessment and cartographic databases, schemes of felling sites, and some other information.

In particular, on the basis of satellite images of 20 - 50 (100 - 250) m resolution, we offer to identify taiga zones suffering from clear felling, determine total area of such zones in set time limits (taking into account intervals of performing satellite surveys), and give general estimation of resource exploitation. These images are supposed to help scientists to valuate uniformity of forest fund use, show if boundaries of operational sites correspond to set limits. We pay special attention to forest categories: on some of them all-out felling operations are prohibited.

Monitoring on the basis of decoding satellite images with a special resolution of no less than 3 - 10 m or small and middle scale aerial photographs of 3 - 5 m resolution help solve two groups of problems. First, we recommend to identify felling sites (inclusive coupes of 0.1 hectares and more carried out without permits via at all felling method) and determine their location, areas, and volume of stored wood. Besides, it is necessity to check if current standards and norms are violated.

In cases requiring additional detailed information, which could not be obtained via satellite surveys or small and middle scale aerial photography, we recommend to apply extreme large-scale (resolution not less than 10 cm) and large-scale (resolution not less than 0.5 m) aerial images. Using such pictures we can assess condition of felling sites after performed works, check if boundaries of "stripped" areas coincide with planned parameters, valuate if actual scheme of forest management meets requirements of technological maps and plans. Besides, we can determine area, composition and reserves of wood. There is a great number of other details interesting for specialists: if seed plants and after-growth of valuable species of trees have been preserved, if there is any stored wood left on the site, its condition and location. Finally, we can valuate quality of slash removal and disturbed lands (the latter is connected with the risk of erosion process development).

Methodology of research works under consideration includes measuring, analytical, interactive or automated decoding of satellite images under office conditions using geographic information technologies and consequent random check-up of achieved results in field conditions or via comparison with data of large scale aerial photography and forest organization.

Let me say a few words about accuracy of characterization of objects on the photos. Area of one separate felling site or undercut could be determined with a maximum error of ±15 percent. Large scale aerial photos allow to estimate volumes of timber left on the felling site with an error index of not more than ±15 percent; error index for areas of coupes, compact undercuts and illegal felling sites, zones of eliminated second growth and zones poorly cleaned from logging waste is about ±5 percent (reliability - 0.68).

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In 2005 bodies of the Federal Forestry Agency took our recommendations into consideration and carried out a remote monitoring of forest exploitation procedures at the territory of 53 mln ha; they were satisfied with the accuracy of achieved results. Amount of penalties imposed on lumbermen made up 0.9 bin rubles. In 2006 the Agency inspected over 100 mln ha, and in 2007 it is planning to carry out check-ups on the territory of 200 mln ha, which is equal to the total area of major national logging regions.

TREES ARE GROWING UNDER SUPERVISION

It is not necessary to say that reduction of vegetation of former felling sites, burnt-out areas, and other lands, including those not of forest fund, should be well-timed and of high quality. But how to trace it in hard-to-reach taiga regions? In this situation we can refer to monitoring. Its methodology consists in decoding multizonal diversification satellite photos of different spacial resolution (including winter ones) and large scale aerosurvey data.

The first phase of works lies in analyzing inventory data when we determine the origin of forest growth (secondary or primary) on former felling sites and burnt-out areas within the conditions of the geographic information system. Then, we separate accumulations of homogeneous zones (so called strata) with a similar character of natural reduction process of tree vegetation. Then we decode multispectral satellite images with a spacial resolution of 1 - 10 m and divide these strata into classes: fresh felling sites and burnt-out areas, zones with leaf, mixed conifer-leaf, leaf-conifer or conifer reforestation. In the same way we analyze and classify overgrowth cut over 10 - 20 years ago.

Then, via analysis of aerospace images we estimate on a selective basis efficiency of artificial and natural reduction of burnt-out and cut-over sites: identify undergrowth with participation of coniferous species of trees under cover of leaf forest stand. Identification of lands not covered with forests and classification of color (multispectral) aerospace images is performed by means of automatic and interactive methods of decoding using spectral and textural features (maximum possible magnification of images on a computer monitor).

To estimate volumes of medium (0.6 - 1.5 m high) and high (more than 1.5 m) conifer young growth on former felling sites (burnt-out places) and under cover of leaf forest stand, in the forest before and after forest cleaning, conifer-leaf or leaf-conifer underwood, scientists apply frequency-of-occurrence coefficient. It's equal to the ratio of number of statistically located zones with even one viable young tree within the limits of the felling (burnt-out) site to the total number of registered zones; this coefficient is measured in percents or in unit fractions.

Frequency of occurrence of a conifer seedling growth under cover of leaf forest stand is estimated on the basis of data of aerial surveys carried out in a leafless period: scientists separate testing areas - one or two large square zones of 20x60 or 30x60 m - on large scale airphoto pairs (1:1,000) or computer monitors and line out a network of elementary zones of 2x2 m (300 - 450 zones in total).

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Photo of the felling site in the Arkhangelsk Region on the aerial photograph: plot 1 - works were permitted and completed; plot 3-works were permitted but not performed; plot 2 - works were performed without permission (illegal felling of trees).

To perform calculation of middle and high conifer young growth on recent felling sites, we recommend to use winter space images (including panchromatic ones) with a spatial resolution of no less than lm or data on large-scale aerial surveys with a resolution of no less than 0.1 m.

The methodology of estimation of forest regeneration described above could be used in logging regions. To evaluate forest regeneration in a vast area of reserve taiga forests in the North-Eastern part of the country, it is expedient to take into account spectral features of space images with a spatial resolution of 1 - 10 m and models of natural forest regeneration. The latter depend on species of trees prevailing before cutting, landscape and site conditions.

Work procedures are performed using plats or forest plans co-located with outlines of burnt-out sites on space images within the limits of a geographic information system. Scientists find data on native or secondary type of forests for each zone and form strata. On the basis of regional features of interrelation of forest types and duration of forest regeneration, processes of change of tree species, specialists evaluate then regeneration level on lands considered woodless. In case of positive results, these territories could be classified as "covered with forest", but such requalification is individual for each land plot.

If there is a decision to change land category, scientists make a survey description which includes average age, height, diameter, density, and forest yield. These parameters are determined for strata in general in accordance with models of regeneration and growth of underwood created on the basis of last inventory data as well as using materials of design and research organizations.

Information obtained in the course of monitoring procedures is applied to amend records of forest funds and plans of regeneration activities. These data are to be corrected every 10 - 20 years while performing regular forest inventory.

At the present time the methodology of remote monitoring of natural forest regeneration on felling sites, burnt-out places, over bare and nonforested areas is transferred to the Federal Forestry Agency for testing and implementation.

The above examples describe areas of application of space data in a forest sector but partially. Space information is effectively used for forest inventories, fire protection, forest pathology monitoring. At the same time we improve technologies-all means of remote sensing and methodology of analysis and processing of aerospace information are continiously developing.