Land Resources of Cryolithozone and Possible Transformations under Globle Change

Transcription

1 September, 211 Journal of Resources and Ecology Vol.2 No.3 J. Resour. Ecol (3) DOI:1.3969/j.issn x NE Asia Land Resources of Cryolithozone and Possible Transformations under Globle Change Issues about land resources of cryolithozone and their possible transformation under global change conditions we will consider on example of the large region of the Russian Federation - the Republic of Sakha (Yakutia), which is considered as the center of the underground continental glaciation of earth in present conditions. The Republic of Sakha (Yakutia) extends between 77 and 55 4 of northern latitude and 15 3 and of eastern longitude. It stretches from north to south 2 km and from west to east 23 km. The area of largest subject in Russia is km 2, which is equal to 2/3 of the Western Europe and exceeds the area of France 6 times, England, almost 13 times, and covers three time zones and three latitudinal climatic zones: arctic, tundra and taiga. The sum of active temperatures (> 1 ) in the tundra zone is less than 5, in the subzone of northern taiga, 8-12 and the warmest places in Central and Southern Yakutia reach The whole territory of the republic is situated in the wide distribution of permafrost. On the plains which occupy the area about 1/3 of republic the ice complex is developed (Fig. 1) which contains the underground ice up to 5% 9% of ground volume (Fig. 2). In permafrost area all soils belong to the permafrost class, and characterized by a certain depth of thawing during the warm season (.1 3. m and more). Under these conditions soil-forming process in a short time functioning in the uppermost layers of seasonal thawing depth. The weakness of microbiological and biochemical processes associated with lack of heat in some places and a large deficit of moisture which determines the formation of extremely poor by nutrients coarse humus soil types. Due to the nearly bedding of waterproof permafrost, these soils have low water capacity and low buffer capacity, easily dries or over saturates with moisture, rapidly changing rates of physical and chemical properties and polluting. Therefore, soils of permafrost region are easily vulnerable, not resistant to human impacts, and have low natural fertility compared with soils without permafrost. Although many soils of Yakutia due to severe climatic conditions do not possess high levels of fertility, their value lies in ensuring the normal functioning of terrestrial Fig. 1 Ice complex in Yakutia. ecosystems and conservation of flora and fauna of the Northern Territory. The structure of republic soils is shown in Table 1. Despite severe climatic conditions the soil resources of the republic are used in agricultural production. It has historically formed the most northern breeding center in the world and more than three centuries developing centers of agriculture here. Over 7% of republic land fund is in cold areas (tundra, forest tundra and northern taiga) and occupies mountains. That is why these lands by the natural characteristics not available for agricultural production. The area of agricultural lands of republic in 199 amounted million ha (14.7%), at reduced to million ha (8.%, Table 2). As a result of kolkhoz (collective farm) system

2 DESYATKIN R. V.: Land Resources Of Cryolithozone and Possiblbe Transformantions Under Goble Change 273 (A) Fig. 2 (A) Profile of the plain with ice complex; (B) Exposure of upper part of ice wedges in Central Yakutia. (B) Table 1 Soil cover of Yakutia. Soils Mountains Plains (%) (km 2 ) (%) (km 2 ) Permafrost tundra % Permafrost north taiga or cryosols % Permafrost carbonated pale Permafrost taiga Permafrost sod-carbonated Permafrost podsol Permafrost marsh Permafrost meadow-chernozem and chernozem-meadow Permafrost floodland Kurum and stones Permafrost podburs Total Table 2 Land resources structure of Republic of Sakha (Yakutia). Land category at at Area (ha) % Area (ha) % Agricultural land Settlement land Industry, Transport and other land Reserved area Forested land Water Deposits land Total Table 3 Agricultural land structure. Land category at at Difference Area (ha) % Area (ha) % (ha) Arable land Hayfield Pasture Deposit Total breaking it has lost large areas of natural pastures, suitable for horse breeding. At present, by agricultural producers used approximately 54.5% of the lands previously used for agriculture. It was significant dynamics of agricultural land structure. The area of arable lands decreased from 14 4 to 12 9 ha, and on the contrary, the areas of hayfields and pastures increased, from 717 to ha and 676 to ha, respectively. In recent years, due to neglected tillage the category of land appeared, it is deposits (Table 3). All sowing area concentrated in central and south-western regions, which represent the main agricultural and livestock zone of Yakutia. This area takes approximately 27% of all territory, and about 7% of the total population of Yakutia, and 78% of rural population lives here. The main feature of agricultural zone in Yakutia is extreme continental climate. Continentality of climate showed up not only by the high amplitudes of annual temperatures here (1 ), but also by the low precipitation, by amount of which (2 25 mm) Central Yakutia is close to the steppe and semidesert areas. Although up to 75% of annual precipitation falls during

3 274 Journal of Resources and Ecology Vol.2 No.3, 211 Temperature ( ) Precipitation (mm) Fig. 3 Annual air temperature dynamics during period. Fig. 4 Annual precipitation dynamics during period. the period with temperatures above, especially the first half of summer, is dry. Therefore, the main factor limiting the development of agriculture in this region is the lack of moisture. In connection with this, application of fertilizer is ineffective, and in dry years even gives negative results. Plenty of sun, the long daylight hours, and the daily average high temperature of summer months and huge resources of fresh water created in Yakutia opportunities for the development of irrigated agriculture. Meanwhile, so far not been adequately studied irrigated agriculture, especially in the permafrost soils. It is not developed scientifically-based timing and rate of irrigation depending on the crop, the varietal agrotechnic, soil conditions; there is no practical experience in the cultivation of crops under irrigation. By agrochemical and agrophysical conditions the arable lands of republic are potentially fertile. They are located mainly in permafrost pale, permafrost sod-carbonated, permafrost meadow-chernozem, and partly in the permafrost taiga and permafrost taiga podsol soils. The first scientifically-based guidelines for the development of the taiga regions in Yakutia under arable land have been proposed by Zolnikov (1954) and Shashko (1961). By conclusion of these researchers arable land should be located on flat areas with ripe forest on the watershed. Optimal size of arable land should be 2 25 m and a width of 2 25 m, and between tillages recommended to left lane of the taiga with the same width. Forest belts are not only windproof, but additionally humidify arable land due to surface and intra-soil runoff which is not used by forest. For stub out forest to making arable land the areas with ice complex, which is widely distributed in Central Yakutia, is particularly dangerous. Reclamation of sites with close location of underground ices to the surface leads to the soil subsidence and formation of ditches and polygons network. So, it is recommend reclamation of sites where underground ice is located at the depth of 2. m and deeper reclamation of these areas before global climate change did not require additional activities against cryogenic processes (planning, water drainage, filling subsidence, etc.). Specificity of soil formation (permafrost presence, lack of drainage, exudative water regime, the weak rate of organic matter decomposition and humus formation, etc.) leads to deterioration of soil properties during their reclamation. According to the republic agrochemical service 35% of agricultural lands, i.e thousand ha have high salinity, 7.8% of arable land, i.e. 85 thousand ha have saline soil, 45.% of arable land, i.e thousand ha have salinity, including 21 2 ha of highly salinized soils. Dynamics of humus in the arable land is negative and amounts up to 3% 4% of the original. According to botanists 4% of pastures, i.e. 226 thousand ha is severely damaged. Analysis of meteorological data shows that global climate changes have affected Central Yakutia too. According to Yakutsk station at the beginning of systematic observations in the the average annual temperature was equal to -11.2, which at the beginning of 21 th century has increased to -7.5 to -9.3 (Fig. 3). Increasing of annual air temperatures is mainly due to increasing of winter temperatures. The same time lengthening of the warm period of the year observed. Spring begins for 1 15 days earlier and ends later in the autumn for 15 2 days than it was in the middle of last century. During the observation period there was a significant increase of precipitation (Fig. 4). If at the beginning of observations the annual precipitation was mm in average, at the beginning of 21 th century it reached 23 24mm. The increase of annual precipitation was mainly due to summer time precipitation (Fig. 4). According to our observations, recent decades has a tendency to increase of snow cover and moisture reserves in the snow. So, if in five years , the average maximum snow

4 DESYATKIN R. V.: Land Resources Of Cryolithozone and Possiblbe Transformantions Under Goble Change 275 depth in the forest was 37.5 cm, then in the last five years (23 27) it has increased to 46.2 cm, and water reserves in snow cover was 6.8 and 73.8 mm, respectively. Climate warming and increased precipitation cause negative consequences for agriculture on the areas with the ice complex. This is due to, primarily, with increased degradation of ground ice and the transformation of natural land cover. Transformation of permafrost landscapes in time of climate change is starting to increase the depth of soil seasonally thawing layer. If 4 5 years ago the depth of soil seasonal hawing in Central Yakutia was m, in recent years this value increased up to m. The depth of active layer in northern soils of Kolyma river basin, during this period increased from.6.9 to m and more. Increasing the active layer depth affects the capacity of permafrost soils, increasing of water capacity, and disturbing the traditional balance of heat and moisture not only soil, but the entire landscape. With close occurrence of the ice complex, increase of seasonal thawing depth leads to irreversible consequences. Changing of soil water-physical properties is accompanied by a transformation of their morphological structure, which are expressed: in the first place in the change of thickness and intensity of soil surface horizons. Secondly, the appearance in the soil of bluishgrey, thixotropic BG and Bca,g horizons at the middle and lower part of profile. Further melting of ice wedges causes complete saturation of soil by water and the appearance of small ponds that act as heat accumulators and acce lerating even more rapid melting of permafrost. Waterlogging and gradual degradation of the soil layer completes by formation of young thermokarst lakes dyedya. Further evolution of soil at such sites goes according to the laws of alas soil formation (Fig. 5). Another factor of climate change negative impact is an increase of this territory moisture, which leads to an expansion of the water surface of the lakes and reduction of grassland area. For example in dry years (23 24), the surface area of the typical alas lake in Central Yakutia was just over.3 ha, in wet years increased to ha (Fig. 6). The area of alas grasslands decreased from 63.4 to ha, it caused reduction of grasslands productivity from centner in 2 21 up to centner in The above example clearly shows not only size decreasing, but alas grassland productivity at increasing of territory moisture and mass formation of the primary thermokarst lakes. Reducing of pasture and grasslands, despite an increase of biological productivity will make a substantial negative adjustment in production of cattle in cryolithozone. In recent decades, on the plains of Central Yakutia with ice complex Fig.5 Soil formation scheme inside of thermokarst depressions alases. A, B, C horizons, LD lake deposits, T/LD decomposed lake deposits. It is phase of one organic layer formation. Alas soils have several buried organic layers.

5 276 Journal of Resources and Ecology Vol.2 No.3, Area (ha) Lake Grassland Fig. 6 Proportion of grassland and lake in Ulakhan Sukkhan alas. under present climate warming (.6.9 y -1 ) when goes plantsoil cover disturbance it is marked increase in the temperature of upper permafrost at the bottom of the ice complex layer with annual amplitudes of about 1 2. Permafrost research on arable land in Central Yakutia in the context of global climate change have shown that for a very short period (1992 2) soil surface of permafrost with polygonal-ice wedge can have subsidence from 1.8 m to 3.6 m (Gavriliev et al. 1984; Gavriliev 29). Further increase of temperature and humidity in cryolithozone will be accompanied by intensive formation and development of thermokarst, thermoerosion and other cryogenic processes, which can lead to changes of hydrological processes in macroscale: the increased runoff and cryogenic flooding of cryolithozone rivers, the development of thermokarst lakes and water-logging area. In vast areas of permafrost affected by this degradation processes, soil will be completely destroyed and the soil cover will radically restructured with the temporary loss of their fertility. Thermokarst degradation of large areas on a large scale in the boreal forest zone will reduce the forested area. At the same time, the warming climate in the temperate zone of Yakutia without ice complex will improve the heat supply of soil and deepening of the active layer, a more intensive biochemical and microbiological processes flow, and in general will have a positive influence to improve soil fertility. Such changes of soil fertility in an agricultural area of the republic will have a dominant role in human activity in the near future. References Desyatkin R V, B I Ivanov. 29. Problems and perspectives of agricultural production of cryolithozone in conditions of global changes, Climate global changes and prediction of agriculture risks. Rosselkhozakademia, (in Russian) Desyatkin R V About some ecological problems of agriculture production in Yakutia, Ecology problems of Yakutia. Issue 1. Biogeographic Investigations Yakutsk, (in Russian) Desyatkin R V Water balance disturbance under anthropogenic degradation of taiga-alas landscapes. Siberian Ecology Journal, 3 4: (in Russian) Gavriliev P P, A A Mandarov, I S Ugarov Hydrothermal melioration of agriculture lend in Yakutia. Novosibirsk: Nauka. (in Russian) Gavriliev P P, I S Ugarov, P V Efremov. 29. Ice rich arable land usage in Central Yakutia in condition of climate change. Nauka i obrazovanie, 56(4): (in Russian) Shashko D I Climatic conditions of Central Yakutia agriculture. SB RAS, 264. (in Russian) Zolnikov V G Soils of eastern part of Central Yakutia and their usage, Materials about natural conditions and agriculture of Central Yakutia. SB RAS, (4): (in Russian) R. V. DESYATKIN Institute for Biological Problems of Cryolithozone SD RAS, Yakutsk, Russia rvdes@ibpc.ysn.ru