by Oleg SIROTENKO, Dr. Sc. (Phys. & Math.), All-Russia Research Institute of Agricultural Meteorology;

Vladimir ROMANENKOV, Cand. Sc. (Biol.), P. Pryanishnikov All-Russia Institute of Agrochemistry

All the way back in the 1970s our experts became gravely concerned about the consequences of possible climatic changes for Russia's economy. It was important to understand when planning the future of the country's farm industry: shall global warming cause a significant increase in aridity? How will natural and agroecosystems respond? And shall the soil fertility level keep up? Today we can give a fairly plausible answer to these questions.

Articles in this rubric reflect the opinion of the authors. - Ed.

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Mean rate of change of mean monthly air temperatures (°C/10 yr) on the territory of the former USSR during 1975 - 2004. The warmest and the coldest month described: A - July, B - January.

Now, it is common knowledge that farm production depends greatly on climatic conditions. In particular, periodic droughts (the last one occurred here in Russia in 1998) impede the advancement of the agroindustrial sector, and so a system of measure is needed to minimize their effect. But as far back as the early 20th century two eminent Russian scientists, Acads. Nikolai Vavilov (1887 - 1943) and Dmitry Pryanishnikov (1865 - 1948), suggested programs for further stability of agricultural production by shifting part of the central farming areas northwards, to less arid regions. Today this idea is topical as never before.

PROGNOSTICATION

In 1978 Russia registered the highest harvest of grain crops over 40 years, 136 million tons. We failed to repeat this achievement in the 1980s, in spite of the chemization (chemicalization) and technical retooling programs, and land improvement schemes (irrigation and drainage): grain output did not go up above 100 mln tons. So towards the end of the decade farm experts had to attack in good earnest the problem of probable aridization of the climate and got down to mapping out a new program. They were assisted in this work by the USSR State Committee for Hydrometeorology, the Academy of Agricultural Sciences.

Experts offered a package of steps towards adaptation of farming to changing natural conditions, and this depending on the available water resources. Thus, they recommended to use late, warm-weather and postharvest crops; to develop the stock-breeding branch and recultivate pastoral and feed-growing lands, that is, make the best of additional advantages of warming. Soil protection technologies and drought-enduring crops were suggested for districts short of moisture. It was also recommended to expand the acreage under winter crops and the zones of irrigated farming.

A strategy for increasing soil fertility was needed so as to cushion the effect of uncontrollable hazards. It was necessary to expand the output of mineral fertilizer, lime and plant protection chemicals and meet fully the farm-

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Mean rate of change of temperature indices on the territory of the former USSR during 1975 - 2004: A - sum total of mean daily temperatures above 10°C (°C/10 yr), B - amplitudes of the annual t course (°C/10 yr).

ers needs in these materials. Their broader use was envisaged for the Non-Black Earth Zone of European Russia. However, there were no reliable prognostication methods to enable an effective planning scheme for redistribution of material and technical resources. We have improved the accuracy of our forecasts proceeding from veritable data on climatic changes and economic modeling based on statistical and empirical data.

In 2005 Russia's State Committee for Hydrometeorology promulgated its first forecast titled Strategic Prognosis of RF Climate Changes in a Period Up Until 2010 - 2015 and Their Impact on the Branches of Russia's Economy. The authors of the present article took part in preparing this document, too. Since then we have obtained new results on related problems. Observations made at 455 hydrometeorological stations across the former Soviet Union over thirty years between 1975 and 2004 supply information on how the key agroclimatic indicators changed then. These are above all air temperatures (averaged for the periods when they were not above 10°C as well as the mean January and July temperatures characterizing the coldest and the warmest month of the year (January and July); yearly temperature amplitudes, i.e. the difference of maximum and minimum mean monthly; the Budyko dryness index*). Now what concerns the Budyko index we would like to note: at its values from 0.8 to 1.0 the amount of heat is sufficient for the evaporation of the larger part of precipitation; it contributes to moderate water run-off, satisfactory moistening and good aeration of soil; besides, the soil is aired intensively thereby, and thus optimal conditions are obtained for the organic kingdom, woodlands in particular. But should the dryness index decline below 0.8, excessive moistening of the soil will take place; the same is true of values above 1.0. In either case the biotope is suppressed and transformed accordingly.

Summing up the available data, we mapped contours of territories displaying identical deviations of the indica-

* Dryness (aridity) index according to Budyko - an indicator suggested by Acad. Mikhail Budyko, which is a relation of the annual radiation balance of the littering surface to the aggregate amount of heat necessary for the evaporation of annual precipitation over the selfsame area. - Auth.

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Potential climatogenic changes of yearly produce of vegetation (percent) between 1975 and 2004.

Potential climatogenic changes in the content of organic carbon in soil (percent) between 1975 and 2004.

tor from its average over 10 years. Analyzing our results, we saw that global warming, which affected Russia's territory in the past few years is not even geographically: there are sectors where the mean values are much above the standard - the western (20° - 50° E.) and the eastern (90° - 130° E.) regions, and sectors, where the mean values are equal to, and even below the standard, namely in the Urals and in the Far East. Both the winter and summer rises in air temperature are on the whole favorable for the growth and hibernation of agricultural crops.

The present warming process is accompanied by a decrease in the annual amplitude of air temperature and consequently, by lower continentality of the climate, a process affecting mostly a significant part of European Russia (barring its north-east) as well as the southern districts of Siberia and the Far East. The multifarious ecological sequels to this trend have yet to be explored in a special study. According to statistical data, such warming contributes to the productivity of farming.

Changes in the dryness index and in the sum total of precipitation show that the aridity of the majority of farming areas of this country has been going down in these last 30 years or staying level. This conclusion holds above all for the North Caucasus, and the Volga and Ural economic regions. At the same time aridity has been going up appreciably in some parts of Siberia (Altai, tracts east of Lake Baikal, for example) and in some districts of the Non-Black Earth Zone in the heart of European Russia.

CHANGES IN THE PRODUCTIVITY OF ECOSYSTEMS

Climatic factors responsible for the most significant losses of farm produce are known all too well to experts. These hazards are heat deficit, frost-kills of winter crops, short growth periods and unfavorable weather during field work. Let us see how these negative factors have been manifest over 30 years between 1975 and 2004. We

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Qualitative estimates of observable changes of agroclimatic conditions for grain-growing in Russia's regions: A - existing trends, B - assessment of changes.

shall proceed from such indicators as moistness, heat supply, thermal conditions of the cold period and continentality of the climate.

Today climatic changes affect agriculture both actually and potentially. For instance, higher moistness and better conditions of field work impact crop productivity immediately. The effect of other factors may be multiple and, besides the direct action, may come into play only upon appropriate adaptation on the land cultivation system. For example, a temperature rise usually speeds up crops maturation and causes lower productivity. However, crop yields go up with more heat-loving and productive crops, i.e. we get an extra resource for boosting productivity. By our data collected since the mid-1970s, changes of climatic conditions have been favorable according to most indices for many land-farming regions of Russia, though their potential positive effects have not been used.

As to negative consequences, we should point to the growth of aridity in the Altai Territory, in the Chita and Amur Regions, and in the Black-Earth Zone of European Russia (their total input into the grain balance credit is not above 10 to 15 percent), and a lower heat supply for farm crops within the Ural Economic Region.

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Effect of air temperature and precipitation changes on the annual productivity of ecosystems (A) and concentration of organic carbon in soil (B), percent.

On the other hand, milder winters and better heat supply for crops cultivated in the Central Black-Earth Zone in European Russia may redress a large part of the losses in productivity due to aridity. But there is no such kind of compensation in East Siberia. At the same time the declining level of precipitation in the Northwestern, Central and part of the Far Eastern region should not result in noticeable negative effects given the high and even excessive level of moistness (reserves of productive moisture in the arable and subsurface layers of the plowland).

Thus, we come to the following conclusion: climate changes registered over 30 years contribute to farm productivity growth in most of this country's regions that provide about 85 percent of marketable grain. The positive trends in crop yields between 1975 and 2004 for 70 percent of the members of the Russian Federation - despite the shortfalls connected with its economic restructuring - confirm this conclusion or do not contradict it at least.

We were also interested in the reaction of natural ecosystems, of course. For a reference point we selected an annual increment of the biomass of natural vegetation in Russia and adjacent countries in the 1975 to 2004 period. We were making estimates on the basis of data supplied by 411 hydrometeorological stations on air temperature and aggregate precipitation. We found that warming contributed to the growth of the productivity of natural ecosystems over a larger part of the former USSR. Maximum values were registered in the western regions of this country's European part, in the North Caucasus, the southern Urals and west of Lake Baikal. Here is some statistics. In the Pskov Region (Russia's northwest) the increment in the biomass of natural vegetation amounted to 24 percent; in the Chelyabinsk Region it was 22 percent; in the Kurgan Region - 15 percent; in the Irkutsk Region - 21 percent; and in the Krasnodar and Stavropol Territories - 28 percent and 22 percent, respectively. Spots of lower productivity (down by 5 - 10 percent in 30 years) were registered in European Russia's northeast, in subpolar regions of Western Siberia as well as in the Chita and Amur Regions, in the Khabarovsk Territory and on Kamchatka.

What it means is this. Changes of the climate go along with changes in the productivity of vegetation, which contributes to the positive part of the carbon balance of ecosystems and which impacts the rate of decomposition of organic matter in soil (i.e. the negative part of the balance). Processes responsible for the mineralization of organic matter are speeded up at higher temperatures according to informed expert opinion; thus the emission of carbon dioxide (CO₂) into the atmosphere intensifies, and this process stimulates further warming through the greenhouse (hothouse) effect.* However, the latest literary data indicate that if the level of moistness declines thereby, such kind of decomposition of organic matter in top-soil does not occur. Our data also show that the observable climatic changes across Russia lead to an increase in the absorption of carbon dioxide by ecosystems.

It should be noted that over the larger part of what was once the Soviet Union there is an uptrend in the concentration of organic matter in soil (with the exception of the tundra plains in Siberia's north and deserts of the Aral Sea region), and this is yet another consequence of warming. But the most favorable conditions for humus buildup are obtained in southern Siberia, above all in the Amur and Chita Regions, and in the Krasnoyarsk Territory.

To follow the trends in the annual productivity of ecosystems and in the presence of organic carbon in soil, we took the data collected over many years and published by Drs. Natalia Bazilevich of the RAS Institute of Geography (1910 - 1997) and Leonid Rodin (1907 - 1990) of the V. L. Komarov Botanical Institute (RAS). We generalized this information in the form of nonlinear regression equations connecting the above indicators with the mean annual air temperature and the annual budget of precipitation. We saw that if the mean air temperature is up by 2°C and the annual budget of precipitation - by

* See: Yu. Israel, "Threat of Climatic Catastrophe?", Science in Russia, No. 4, 2004. - Ed.

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150 mm (humid warming), it should cause a maximum increase in the productivity of ecosystems by 25 percent above the norm, and a 12 percent increase in the reserve of organic carbon in soil. If the aggregate amount of precipitation is down by 150 mm at the same growth of temperature (arid warming), the productivity of ecosystem will fall off by 11 percent, though the accumulation of carbon in soil will continue at slower rates. This means that the upward trend in carbon buildup applies to all of Russia's forest and steppe zones.

These are but tentative results based on data implying a quasiequilibrium state of the soil-vegetation-climate system. Which means that our scenario of changes in the concentration of organic carbon in topsoils would come off only given the stability of the present climatic conditions.

ECOLOGICAL STABILITY OF AGRICULTURE

The impact of global climatic changes on the world's farm industry is assessed today by the productivity indicators for key food crops by and large. However, the question of ecological stability of land farming is yet to be clarified. To begin with, we should be in the clear about how soil fertility and the carbon budget of agroecosystems respond to new conditions.

The global warming problem and the role of soils and a pool of atmospheric carbon (C) have revived the interest in the balance of this element and in adequate agrotechnical techniques towards a stable reserve of C in soils. Otherwise any possible climatic and technological changes may pose a risk of losing one of the most vital factors for the stability of the biosphere: this is how experts evaluate a complex of carbon compounds; earlier carbon was thought to be vital only to high productivity of agroecosystems. This matter has been considered in good earnest by Professor Pete Smith of Aberdeen University (Scotland, Great Britain), 2004, and by Professor Roger Swift, Dean of the Department of Natural Resources, Agriculture and Veterinary Medicine of Queensland University (Australia), 2001, who have published their studies on the subject.

Unlike raw material industries, agriculture makes it possible to lower atmospheric pollution through higher fertility of soil. On the other hand, climate changes may be helpful towards the biosphere's sustainable development given a deficit-free carbon budget at lower expenditures of resources. Higher yields of cultivated crops allow to compensate the present losses of carbon in European Russia if plant residues in the topsoil layer are up by 30 - 40 percent. However, in practical terms such kind of scenario calls for a package of socioeconomic programs aimed at proper land management and specialization of farm production.

The Non-Black Earth Zone of European Russia offers most favorable conditions in this respect. Climatic warming increases the positive component of the C balance of its soils, and decreases the negative one. Higher biological productivity contributes to the C budget, while lower C expenses result from a decrease of soil moisture-a process that slows down mineralization of organic matter. According to our estimates, the obligatory share of grasses in crop rotation will drop by 18 percent in the Non-Black Earth Zone by the year 2050 compared with 1990, while the amount of organic fertilizer (introduced in doses required for sustaining the deficit-free C budget at the level 1.5 percent) - by more than 50 percent. The effect of climatic changes will be the highest in Russia's northwest, where conditions favorable for atmospheric carbon accumulation in plowland could keep improving up until the year 2050.

Cultivated heavy and moderate loamy soils offer the best potential for sustainable accumulation of organic carbon if its content is above 2 percent. Implementation of a complex of adaptive agrotechnical measures - such as changes in the crop rotation structure and in sowing schedules, and optimization of fertilizer dosages - will allow to spur up these processes and create conditions for a 1.4 - 2-fold increase in the level of carbon deposition. Unfortunately the potential of light humuspoor soils is much lower.

Now this point: although further climatic warming could stimulate accumulation of organic matter in soil, the decisive factor will rest with local conditions of farm production and fertility control expenditures. Say, an increase in the proportion of grasses in crop rotation is a handy technique for replenishing the humus reserve; however, their cultivation is often limited by the size of a stock-breeding sector in a particular locality, for fodder transportation costs are rather high. A good deal also depends on the area of meadow - and pasturelands capable of effecting significant changes in the carbon budget - C input and accumulation.

The climate changes over the recent decades tend to widen the imbalance of processes implicated in the synthesis of live biomass and decomposition of dead organic residues, a trend that, in keeping with the ideas of Acad. Vladimir Vernadsky (1863 - 1945), is a motive force of the evolution of soils, natural ecosystems and of the biosphere at large. Variation in the productivity and components of the carbon balance of the bio(agro)sphere in Russia may have different economic and ecological implications, and hence it is necessary to control processes responsible for these phenomena. Therefore, in the opinion of many experts, a monitoring system should be established for keeping tabs on global warming and its consequences for Russia.