Ph. D. in Geography, associate professor, Sukhomlinova V.V.

Amur State University (Birobidzhan Branch), Russia

The influence of fires on the vegetation of The Middle Amur River region of Russia

Fires in nature is one of the most common and destructive phenomenon of all time from the Paleolithic period to the present time. Frequent fires promote the transformation of the ecological environment, soil erosion, disappearance of species and entire communities. From distant times of the mammoth hunters, many years have passed. Civilizations, cultures, natural resources and forms of their use have been changing, but people still accidentally or intentionally burn the ecosystems by creating local problems whichregrow into one global-pyrogenic transformation of ecosystems of the planet. Its essence consists in reducing the level of biodiversity, environmental comfort of environment of human life and, eventually, economic stability.

The causes of fire in nature can be divided into two parts: natural and anthropogenic. There are few reasons for fires of natural biomass ecosystems: thunderbolts, volcanic eruption, and the fall of a meteorite. Anthropogenic causes are more varied. They are such coincidences as matches, cigarette butts, and spark spontaneous combustion of coal seams, etc.; deliberate arson to revenge; preventive ones, agricultural and other fires. At the present moment in most regions of the world people mostly cause fires.

Pyrotechnic effects on ecosystems with different, more often economic, goals have been being produced by people in different parts of the world. Fires traditionally are used in Africa, Asia, Australia, and the Americas [1].

In the RussianFar East region, the use of fire as a weapon of labour became commonplace long ago. According to surveys carried out by Sukhomlinov N.R. and Sukhomlinova V.V. [7] in the Middle Amur River region of Russia, the lighting of herbs is committed for various purposes. They can be divided into two parts rational and irrational.

To rational reasons of prescribed forest fires are all fires committed in agriculture, animal husbandry, and gathering and in the production of so-called preventive annealing. In agriculture, fire is used for burning of stubble fields, forests, bushes, wild herbs, grass, and for the cultivation of virgin lands. In animal husbandryfire is applied for annual burning of pastures and hayfields. These measures prevent their overgrowing by trees and bushes. In addition, it is believed that the burnt young grass grows faster, allowing earlier driving out the cattle at the young greenery.The legend of the early growth of grass on the burned lots isnot true; however, this fact does not prevent to use the argument as an excuse for arson. Hay is mowed once a season at the end of June or at the beginning of July. However, at the end of July, August and even September in monsoonal climate grass on haymaking manages to rise and even throw seeds. This herb is burnt out in autumn and often in spring during drought which is typical for monsoon climate because it is thought that dry grass prevents new grass from “growing” and subsequently hampers haying. Fire is used during collecting the fern; it grows earlieron burnt-out places and is better visible. However, the disappearance of woody vegetation causes the disappearance of the fern. The fire promotes the disappearance of the linden (Tilia sp.). It is the best honey plant in the Far East. However, bee-keepers use fire to eliminate coniferous trees, which displace producing honey trees and to stimulate the growth ofhoney plants.

Application of uncontrolled fires in the Far East has made people to develop methods of protection against fire. In order to buildings will not be damaged by fire formed by people, population arrange competitions on burning: who will light the herb before, he does not burn. As a result these preventive measures caused fires along with agricultural fires.

The irrational reasons of fire using are all cases of arson attacks that cannot be explained and justified even by myths and legends. Fishermen burn riverside vegetation to create comfortable conditions. Hunters use fires to increase primary productivity of farmland and for hunting. Fires are used while illegal felling to create the conditions for the allocation of forest for cutting at lower prices, as well as to hide traces of illegal cuts. Some groups of population use fire to exterminatemidgets and mites. Equally uncertain groups of population use fire as a weapon of revenge as among organizations and between groups of people and individuals. Finally, dry grass and fallen leaves are burntwithout any aims.

Such large-scale and uncontrolled use of fire to influence on vegetation has brought to all the plant formations are at the stage of pyrogenic transformation in the Amur River region. Moreover, the longer and more active population burns their ecosystems, the stronger they are, the more fires in the nature get a character of large scale natural disaster [4, 5, 6].

The vegetation of the Amur River region is formed under conditions of transitional community that is the interpenetration of different types of zonal vegetation. In formingof plant associationmostly plants of dark coniferous and broad-leaved types of zonal vegetation take part. Communities of the larch (Larixsp.) and tundra ones on mountaintops or in the lowlands on the perpetually frozen soil penetrate in this mosaic of plant associations. Despite this phytocoenotic diversity, the Middle Amur River region is the territory of interpenetration of two types of plant associations: broad-leaved and dark coniferous. Coexistence of so various plant associations is possible in several ways.

In one case, it is a biocoenoticdistribution on the slopes of varying exposure. Under ideal conditions the northern slopes are covered with dark coniferous forests, the southern ones with broadleaved. Species diversity of trees of dark coniferous forests is limited with the Khingam fir(Abies nephrolepis (Trautv.) Maxim.), the Siberian spruce (PiceaobovataLedeb.), which rarely forms a compact grouping, and the Ajanspruce (Piceaajanenses (Lindl. etGord.) Fisch.Ex Carr.), dominating almost throughout the whole territory. The lower tier is typically formed by the mosslayer, or low bush species: Rhodococcumvitis-idaea (L.) Avror.,Chamaepericlymenumcanadense (L.)Aschers. Et Graebn., Vaianthenumbifolium (L.) F. W. Schmidt,PirollaasarifoliaMichx., Oxalis acetosellaL. Shrubs and lianas are missing completely.

Broad-leaved plant associates are usually on the southern slopes. They have a variety of woody and herbaceous species, as well as a large number of vertical and horizontal structures. As a rule there is one more wood layer, formed by the bird cherry trees - PadusaviusMill.,Padusmaackii (Rupr.) Kom.,the Amur maakia(MaackiaamurensisRupr. Et Maxim.), theJapanese angelica tree (Aralia elata (Mig.) Seem.), and maples-Acer ukurunduenseTrautv. Et Mey., Acer tegmentosumMaxim., Acer mono Maxim., Acer ginnala Maxim. The characteristic feature of broad-leaved species is the presence of deciduous tree and herbaceous vines.

In natural conditions dark coniferous species in the absence of destructive factors penetrate into southern slopes and broadleavedinnorthern. As a result truly mixed plant associates, where the spruce is close tothe vine, the Manchurian walnut, the Amur corktree, the Korean Cedar, the Mongolian oak. In the early stages of the formation of mixed plant associatesdark coniferous species are displacing deciduous ones, infiltrating the southern slopes. At the stages of aging, when crown of most dark coniferous trees dries out and shrinks in size, the possibility to penetrate the northern slopes of the deciduous species.

Studiesofpyrogenic degradation of vegetation were hold in the mountainous part of the Middle Amur River region, specifically in Little Khingan, Bureja,Sutar and Shuhy-Poktoj mountains, at altitudes up to 1400 m above sea level, in the administrative territory of the Jewish autonomous region and the southern part of Khabarovsk Territory, adjacent to the northern boundary of the JAR. In the district of workmodeling lots were allocated, which covered the territory of approximately 2000 hectares, which included various elements of topography and plant associates in different pyrogenic conditions. The model station was a few plots of 400 m², wherethe basic indicator species of plants and their formed horizontal and vertical structures were recorded. Pyrogenic conditions were determined with the help of fixation of observed fires or different pyrogenic marks such as traces of old fires in the form of burnt parts of trunks, crowns; coals in soil, etc.

Regular fires, occurring from the use of prescribed forest fires, change the species content of plant associations, environmental conditions and resource potential of the territory. The broad-leaved, cedar broadleaved and dark coniferous forests possess the most resource value of the integrated nature of the area.The resources of data of these ecosystems are presented lots of species that can be used as a source of timber, food and pharmaceutical products. Their ecological value is to fill ecological niches and accumulate living organics. Each ecosystem is valuable for it accumulates a certain number of living and dead organic matters in accordance with the conditions of the environment, thus contributing to the formation and maintenance of the biosphere.

Fires impact on vegetation of the Middle Amur River region is that the species possessing a weak resistance to fire disappear from the content of species that make up the mosaic of plant associations. Change of species content, decrease of accumulation of organic material (living and dead) contributes to changing of environmental conditions. Altered environmental conditions prevent the resumption of those species whichsuffer from fires. As a result this area loses a set of specieswhich provided the resource value of ecosystems and environmental conditions of people in accordance with the climatic norm.

All theplant associations of the analyzed territory are incurred pyrogenicimpact with varying regularity and force. This forms the mosaic of plant associations at different stages of pyrogenic transformation. In assessing the prospects of the presence and abundance of species, as well as the development of the mosaic of plant associations we used a scale of pyrogenicdegradation developed by us for dark coniferous and broad-leaved transitional community of the Middle Amur River region [2, 3]. For typical mixed-broadleaf and dark coniferous forests of the Jewish autonomous region, we have identified four stages ofplant associations’transformation with sets of indicator species which as a result of pyrogenic impact disappear entirely, weaken or strengthen its presence.

1. Lack of transformation. It is formed by a one-foldlow fire or repeated, but weak and rare (the interval of 15-20 years), grassroots fires. None of the typical species of trees does disappear at this stage. The spruce, fir tree and the Korean pine(PinuskoraensisSieboldetZucc.). weaken their presence due to the death of regrowth and germs. The yellow birch and broad-leaved species especially manchusmaples, lindens, the Manchurian ash (FraxinusmandshuricaRupr.), the Manchurian elm (Ulmuslaciniata(Trautv) Mayr.) and (Ulmus japonica (Rehd.) Sarg.)increase their influence. The Japanese angelica tree and the Amur maackia are activated. On the border of bottomland andhelophium the conditions for activation of the larch and the black birch (BetuladavuricaPall.) are created. Thus, weak transformation of transitional community plant associates does not eliminate species, but changes their relationship.

2. Moderate rejuvenation. It occurs because of prolonged impact of low mainly stable fires with a large time interval – 10-20 years. In this case, elimination of the spruce and maybe the fir tree is possible. Cedar remains, but loses its capacity in the form of regrowth. The yellow birch (BetulacostataTrautv.), the Mongolian oak (GuercusmongolicaFisch. Ex Ledeb.), the Manchurian ash and all the species of the elm, the manchus mapleand the small-leafed maple, the Amur corktree (PhellodendronamurenseRupr.), and the Amur maackiaare activated and become dominants. There is an active penetration of the larch, the black and flat-leaved birches (BetulaplatyphyllaSukacz.), the Populustremula(Populustremula l.),and thegoat willow (Salix capria l.).

3. Strong rejuvenation. It is possible with prolonged exposure ofstable and running fires with a time period of 7-10 years. In this mode pyrogenic damage develops, which cause rapid loss of trees from hitting vital organs, first of all because hollows of trees at the bottom. The essence of this graduation is that loss of mature trees of dark coniferous broad-leaved plant association is not compensated by itsregrowth, because in a short time fire interval only species with rapid growth and a marked ability to resume from the root manage to grow. These species arethe Mongolian oak,the yellow and black birch, andthe Populustremula. At this stageall coniferous treescompletely disappear exceptthe larch, which also has a high tolerance.

The Manchurian walnut (JuglansmandshuricaMaxim.), elm trees, the Manchurian ash, the linden, fragrant poplar(PopulussuaveolinsFisch.),themanchus maple, the Padusmaackiiseverely weaken their presence. The phytocoenotic role of the Amur corktree, the maple, and the Amur maackia initially increases and then begins to subside. On the border with boggy meadows, especially in with permafrost, the larch, the black birchbordering lowland floodplains,goat willow onmid-mountainwatersheds, the birch and the Populustremulabegin to dominate the larch. At this stage, the communities can be formed with a prevalence of one species. These species include: the Mongolian oak, the black birch, and the daurica birch.

4. Radical rejuvenation. It is characteristic of plant associations exposed to annual or every 2-5 years period of burning. In this case, the forest gradually is replaced by herbal communities as old trees die from chronic pyrogenic damage, and regrowth do not manage to grow in fire periods of time. Trees with a good ability to root rejuvenation exist in these communities in the form of shrubs. Most of all to such species can be includedthe Amur maple, the Mongolian oak, the Amur maackia,the daurica birch, the black birch, and the PopulustremulaPopulus.

At this stage of pyrogenicrejuvenation there are no dark coniferous and broadleaved species forming plant associates of zonal vegetation. The feature of radical rejuvenation is the irreversibility of the process of degradation when plant associates, losing species of zonal vegetation, are unable to restore to its original state. It occurs with the existence of formedgramineous monodominant communities changing the thermal and moisture mode and preventing the emergence of seedlings of trees, as well as with forming of radical rejuvenated forest over large areas.

Thus, with regular pyrogenic impact over large areas the species content of plant associations changes greatly. The most vulnerable are the species of the mountain taiga forest. Species of broad-leaved plant associates some of which for a while can be severely and even radically rejuvenated community have greater resistance to fire different. It means with the activation or maintaining the same level of pyrogenic ecosystem effects of the Middle Amur River region the Ajan spruce,the Siberian spruce,the Khingam fir,the Korean pine, and the yellow birch will soon disappear from the list of species. The final stage of degradation is the extensive forest destruction, which will be accompanied by increasingof climate contrast and reducing its comfort. Thus, preservation of speeds of burning of ecosystems of the Far East leads to forest destruction, water logging, and outbreaks of some plant-eating insects and a sharp decline of biodiversity.

Fire is a factor of all anthropogenic factors which most of all promotes turn of the evolution of ecosystems backwards. This rejuvenating ecological effect grows proportionally to the square of the territories involved in the pyrogenic transformation. With long-term effects of pyrogenic factor zonal vegetation disappears andvegetation with low species diversity and which is not corresponding to climatic norm is formed in its place. This state is fixed by fall of species have been forming zone vegetation, making it impossible to restore.

Literature

1. WalterG. The vegetation of the terrestrial globe.Ecological and physiological characteristic.V.3. М.: 1975. 432 p.

2. SukhomlinovaV.V. Thepyrogenicdegradationofnaturaldarkconiferousandbroad-leavedforestsintheAmur River region // Regionsofnewdevelopment environmental problems, ways of solution: proceedings of the interregional practical conference, Khabarovsk, 10-12 October, 2008, 2 vol. – Khabarovsk: DVO RAN, 2008. V. 2. p. 456-460.

3. SukhomlinovaV.V. Thestagesofdegradationofforest ecosystems with regular grass fires in the coniferous-deciduous forests// Forest ecosystems in the North East Asia and their dynamics: proceedings of the International Conference. Vladivostok: Fareastscience, 2006 p. 138-141.

4. Fire management in biologically valuable forests of Amur-Sihote-Alinskogoecoregion: projectfeasibility, ed. Prof. A.S. Sheingauza. – Khabarovsk, 2004. – 130 p.

5. FuryaevV.V.Periodsofhighpeakburnabilityandtheirroleinforest production process. Siberian ecological journal,No 1 1996, pp. 67-71.

6. FuryaevV.V. The role of fire in forest management. Novosibirsk: Science, Syb. publishing company, 1996. 253 p.

7. Sukhomlinova V.V., Sukhomlinov N.R., Fire in the Far East: A Tool in Natural Resource Management, or Weapon of Destruction? // Russian Conservation News, 1996. - № 7. - P. 28-29