Mineral soils. Natural forest regeneration Natural forest regeneration
22.02.2012
In cleared areas, in a relatively short period, a thick grass or moss cover can develop, which prevents seed germination and self-seeding growth. Similar unfavorable conditions are also observed under the canopy of tree stands, in the presence of thick, weakly decomposed litter or highly developed grass cover. In these cases, in order to create favorable conditions for seed germination, soil mineralization is carried out. It is carried out in a harvest year in the second half of summer and autumn before the seeds fall.
When cutting down forests, they are left separately as planting agents. standing trees and groups of 3...6 trees. 15...25 pieces are left per 1 hectare. seed trees or 8...10 groups of trees with a distance between groups of about 50 m, as well as clumps of forest with an area of 0.1...0.5 hectares or seed strips 20...30 m wide. Seed trees and groups should be spaced evenly throughout the area. Seeds are left from wind-resistant species (pine, larch) growing in deep, well-drained soils. They are selected from among the best trees in terms of growth and trunk quality. Seed clumps 20...30 m wide are placed parallel to the long side of the cutting area and perpendicular to the direction of the prevailing winds in the winter-autumn period.
When cultivating the soil to promote natural regeneration of the forest, one should not strive to completely remove the ground cover and litter, since in this case the conditions for seed germination and further growth of seedlings may worsen. Both under the canopy and in clearings, the total treated surface should be about 30%.
Cleaning and fencing of clearings has a positive effect on the course of natural regeneration. By cleaning felling areas, their fire safety and sanitary conditions are improved.
To promote natural regeneration of the forest, a properly organized fire method of clearing cutting areas is of great importance. To do this, on sandy loam and well-drained loamy soils, logging residues are collected in small heaps, evenly distributed over the area, and burned at a time that is not dangerous for fire. This event ensures soil mineralization, decreases acidity and enhances the vital activity of beneficial microorganisms. The fire pits create favorable conditions for seed germination and self-seeding growth.
Fencing of clearings, as a measure to promote the natural regeneration of forests, is effective in places where forest areas are intensively visited by the population or to prevent damage to self-seeding during grazing.
To restore economically valuable and rare breeds, areas can also be fenced off in places with a high density of wild ungulates. The height and design of the fence in these cases are determined taking into account the physical characteristics of the predominant animal species.
A general requirement for forest areas where measures have been taken to promote natural forest regeneration is the prohibition of grazing and haymaking.
It is known that even a large number of seeds that have fallen to the surface of the litter often cannot ensure regeneration under the canopy and in clearings. At the same time, it has long been noted that mixing the litter with underlying soil horizons or simply exposing the mineral layer leads to good germination of seeds, establishment of seedlings and their transformation into undergrowth. This phenomenon is the basis for a very common method of planned promotion of forest regeneration called soil mineralization. Mineralization, both under the forest canopy and in clearings where there are sources of contamination, is carried out in productive years.
With dry sandy soils in clearings, removing litter in small areas or strips 20-25 cm wide is sufficient. Here the living cover grows slowly and cannot quickly colonize the mineralized strip. On fresh loamy and sandy loam soils, it is necessary to make a strip up to 1 m wide or areas of 1 m2. On wet soils it is useful to create micro-rises. If the soil is wet or very fertile, then mineralization, as a rule, does not give positive results.
If the above activities are carried out under the forest canopy (if the canopy density is below 0.6, this is useful to do), then in spruce forests this should be done 7-10 years before felling, and in pine forests 3-5 years. The treated area in clearings should be 30%, and under the canopy 15-20%. Preparing the soil under the tree canopy provides an additional opportunity to obtain natural preliminary regeneration of the forest.
In connection with the allocation of cutting areas 2-3 years before felling in technological map forest exploitation provide for measures to promote natural regeneration under the canopy of spruce, fir, beech, oak and other tree stands: in oak, pine, larch and other mixed plantings, soil loosening 1-3 years before felling, in spruce-fir forest types 5-b years, in beech for 4-5 years.
Tillage is carried out from the second half of summer, and in a mixed forest with the participation of deciduous trees in the fall, after the leaves have completely fallen. Under the canopy of a pine forest, tillage is allowed in early spring, before the end of the mass emergence of seeds from the cones. The main task What is envisaged during tillage is the mineralization of the soil surface, especially where it is covered with herbaceous and mossy vegetation or a thick layer of dead cover. In conditions of damp, excessively moist soils, microelevations are created. If there is an admixture of aspen in highly productive pine and spruce stands, soil preparation is carried out after preliminary ringing of the aspen or its poisoning with chemicals. Ringing is practiced 5-6 years before logging.
Soil mineralization can be done by mechanical, fire and chemical methods. Thus, in fresh meadow and reed clearings, ground cover and litter are removed using cover strippers. Apiary and main trails, as well as places where logging residues are burned, are subject to loosening. High germination of seeds on fire pits was observed in cases where the layer of unburnt litter reached 0.5-2 cm, and with thicker litter or when it was completely burned, seed germination decreased.
In conditions of green moss clearings, soil mineralization by fire brings favorable results, especially where the moss layer is dense. Mineralized strips are created by cover peelers, disc cultivators, bulldozers, rippers and other mechanisms. The total area of treated soil should be 20-30%, taking into account damage to the soil cover during logging.
In clearings with heavily podzolic, loamy, moist and damp soils, micro-highs are created in the form of ridges and shafts using double-mouldboard forest and swamp-shrub plows. To promote natural regeneration in coniferous clearings, it is advisable to prepare the soil in late summer, autumn or early spring.
Long moss and sphagnum fellings are treated with chemicals before the seeds begin to spread. In the second half of summer, microelevations are fertilized with chemicals in 500-600 places per 1 hectare in areas of 1 m2 with a consumption of magnesium chlorate at 15-20 kg/ha and 2.4-D at 0.7-0.8 g per 1 m2.
Reed grass and meadow grass, as well as other cereal plants, are cultivated in the spring, and in the northern subzone of the taiga in the second half of summer in areas of 2-3 m2 in size, 500-600 places per 1 hectare at a consumption of ammonium sulfate of 100 kg/ha.
Clearings overgrown with less valuable deciduous trees are sprayed with 2,4-D butyl ether emulsions at a dosage of 0.3-0.4 kg per 1000 m2 for aspen and 0.1-0.2 kg for birch, alder and hazel. Sodium salt 2,4-D is also used in a dosage of 0.3-0.4 kg per 1000 m2. Treatment is carried out in nests measuring 4-5 m2 (1000-1500 nests per 1 ha) or in strips of varying widths. Spraying of the root shoots of aspen or birch and other species is carried out in the first half of summer, when the apical bud is still forming in the plants.
The greatest difficulties in reforestation occur in clearings covered with meadowsweet, reed grass and meadow grass. Then, due to the difficulty of renewal, there are long-moss and sphagnum fellings. Timely preparation of the soil in cleared areas, before the growth of herbaceous vegetation, facilitates the process of reforestation. In cases where measures to promote natural regeneration do not produce positive results, sowing and planting of forests is carried out.
In oak stands on fresh and moist soils with a completeness of the upper canopy of 0.4-0.6, the soil is cultivated after the acorns have fallen, simultaneously embedding them into the soil. If the soil is heavily turfed, the grass cover is removed in strips 0.8-1 m wide, or in areas of 1×2 or 2×2 m.
In the forest-steppe zone in dry oak groves, the soil is loosened to a depth of 15 cm. In elevated areas, microdepressions are created by removing turf or cultivating mineralized areas. Very often, 1-3 years before felling, acorns are “stuffed” in oak forests. Dense undergrowth is thinned by 40-60%.
In beech stands, before the seeds fall, the litter and surface layer of soil are loosened to a depth of 1-2 cm. On gentle slopes, the soil is cultivated only horizontally, and on steep slopes - in areas of 400-600 pcs/ha.
Fencing cleared areas from being eaten by livestock is possible in small areas. There is a particular need to fence off clearings in floodplains and near pastures during regrowth, as they are more sensitive to damage by livestock. In all areas where assistance measures have been taken, grazing, haymaking and litter collection are prohibited.
In the future, one should keep in mind the promotion of forest regeneration by fertilizing it. Other activities that contribute to the resumption of logging include temporary agricultural use.
Plantings that arose as a result of assistance (including from preserved undergrowth) are taken into account in a special book and transferred to a forested area as natural young growth.
The mineralization process is a complex of physicochemical and biochemical redox microprocesses leading to the complete decomposition of organic residues and humic substances themselves to the final oxidation products - oxides and salts. This process is obligatory and necessary in the carbon biocycle cycle, since it determines the release and transition into an accessible form of the main elements of plant mineral nutrition.
It is necessary to distinguish between: 1) direct and relatively rapid mineralization of plant residues without noticeable humification; 2) mineralization of already formed humic substances.
In reality, both processes occur simultaneously in any soil, but their ratio varies depending on specific conditions. Thus, in peat and peaty soils, the mineralization of plant residues is weakly expressed, and the mineralization of humic substances is practically absent. In the steppes, litter arriving on the soil surface is mineralized quickly, while humus substances, being fixed in the soil profile, are mineralized extremely slowly. Automorphic soils of the tropics are characterized high speeds mineralization of not only incoming litter, but also newly formed humus.
Mineralization processes do not form signs in the solid phase of the soil, so the speed of their occurrence can be judged by soil respiration, which is the total result of mineralization of both plant residues and humus. The highest intensity of CO2 emission from the soil surface is characteristic of tropical rainforests, which is due to the large mass of litter and its rapid mineralization. The lowest rates of soil respiration (less than 0.1 g CO2/m2 per hour) are characteristic of swamp and desert ecosystems. In plant communities of mid-latitudes, significant fluctuations in soil respiration rates were noted - from 0.1 to 9.5 g CO2/m2 per hour, associated with different soil activities in different ecosystems.
Another method for studying mineralization is to observe the kinetics of processes using labeled atoms. It allows you to directly study not only the intensity of the processes of mineralization of plant residues and humus, but also individual groups of compounds. Based on radiocarbon dating data, we calculated the mineralization coefficients of humus and humic acids in chernozem.
As can be seen from the data in table. 3, humic acids are the most resistant to mineralization. Moreover, the rate of their mineralization is different in different parts of the profile and naturally decreases with depth, as the activity of microorganisms weakens. The values of mineralization coefficients are minimal in chernozem soils; in forest soils of the boreal zone they can reach 2.2%/year, and in tropical forest soils they can be even higher.
The set of processes of transformation of organic substances in soils constitutes the process of humus formation, which determines the formation and evolution of the humus profile of soils. The processes of transformation of organic substances include: the entry of plant residues into the soil, their decomposition, mineralization and humification, mineralization of humic substances, the interaction of organic substances with the mineral part of the soil, migration and accumulation of organic and organomineral compounds.
Any organic residues that fall into the soil or are located on its surface decompose under the influence of microorganisms and soil fauna, for which they serve as building and energy materials. The process of decomposition of organic residues consists of two parts - mineralization and humification.
Mineralization– decomposition of organic residues to final products – water, carbon dioxide and simple salts. As a result of mineralization, a relatively rapid transition of various elements (nitrogen, phosphorus, sulfur, calcium, magnesium, potassium, iron, etc.) fixed in organic residues into mineral forms and their consumption by living organisms of subsequent generations occurs.
Humification– a set of biochemical and physicochemical processes of transformation of decomposition products of organic residues into soil humic acids. The result of humification is the fixation of organic matter in the soil in the form of new products that are resistant to microbiological decomposition and serve as batteries for huge reserves of energy and nutrients.
Factors of mineralization
The most intensive decomposition of organic residues to final products occurs at optimal soil moisture (60...80% of total moisture capacity) and temperature (20-250C). As humidity and temperature increase or decrease, the rate of decomposition of residues decreases. With a constant and sharp lack of moisture and high temperatures, little plant residues enter the soil, their decomposition is slowed down and occurs in the form of “smoldering” processes. The rate of decomposition of plant residues largely depends on the type of biogeocenosis and soil type.
The chemical composition of plant residues also has a great influence on the intensity of litter decomposition. With a high content of plant residues in compounds that are resistant to microbiological influence, they accumulate on the soil surface in quantities significantly exceeding the scale of annual litter (soils of the tundra and taiga-forest zone). For this reason, wood, pine needles and other components of plant litter, containing a lot of lignin, resins, tannins, but few nitrogenous protein compounds, decompose slowly. The above-ground mass of grasses, especially legumes, decomposes faster, and root residues mineralize at a lower rate due to an increase in the proportion of the lignin-cellulose component in them. When plant residues are enriched with protein compounds, their decomposition proceeds very intensively (forest-steppe soils).
It is important to take into account the peculiarities of climatic conditions that determine the nature of the functioning of soil fauna and microorganisms.
The mineralogical and granulometric composition of the soil has a significant influence on the rate of mineralization. Under optimal decomposition conditions in soils of heavy granulometric composition, rich in highly dispersed clay minerals, mineralization processes are inhibited. This is due to the high values of the free surface of minerals, due to which intermediate decomposition products and newly formed humic substances are sorbed on them, which prevents their further mineralization. In soils with a predominance of primary minerals, sorption is practically not expressed, so the mineralization process is very active. This is typical for soils of light granulometric composition, and therefore they always contain little humus. In soils with an acidic reaction environment, the decomposition processes of residues are inhibited due to inhibition of bacterial microflora. In the presence of polyvalent metals (iron, manganese, aluminum) in the soil, complex organo-mineral compounds are formed that are resistant to the action of microorganisms. Monovalent cations and the alkaline reaction of the environment promote the formation of mobile water-soluble organic compounds, which favors their subsequent mineralization.
Thus, soil properties directly or indirectly affect the rate of decomposition of organic residues. The direct influence is expressed in the degree of development of the processes of interaction of decay products with soil components, the indirect influence is expressed in the regulation of the intensity of the vital activity of microorganisms and their composition.
Humus formation concepts
While the mineralization of organic residues has been studied in some detail, the mechanism of humification remains unclear. To date, a number of concepts for the formation of humic substances have been proposed, but all of them are hypothetical.
Condensation (polymerization) hypothesis.
It was first put forward by A.G. Trusov (1913). M.M. Kononova made a great contribution to the development of this hypothesis. The essence of the humification process, from her point of view, can be characterized by the following provisions:
The process of humification of plant residues is accompanied by the mineralization of their constituent components to carbon dioxide, water, ammonia and other components;
All components of plant tissues can be primary sources of structural units of humic acids in the form of decomposition products, products of microbial metabolism, decomposition and resynthesis;
The responsible link in the process of formation of humic substances is the condensation of structural units, which occurs through the oxidation of phenols by enzymes such as phenoloxidases and their interaction with amino acids and peptides;
The final link in the formation of a system of humic substances - polycondensation (polymerization) is a chemical process.
Biochemical oxidation hypothesis
I.V. Tyurin considered the process of humus formation from a fundamentally different perspective. He believed that the main feature of humification is the reaction of slow biochemical oxidation of various high-molecular substances with a cyclic structure. This position was further developed in the works of L.N. Alexandrova.
According to L.N. Alexandrova, humification is a complex biophysical and chemical process of transformation of intermediate high-molecular-weight decomposition products of organic residues into a special class of organic compounds - humic acids.
Humification is a very long process and consists of 3 stages:
New formation of humic acids (biochemical oxidative acid formation), i.e. The formation of the humic acid system is carried out with the direct participation of microbial oxidases. At the same stage, the fractionation of the system of formed humic substances into humic and fulvic acids begins. Interacting with the mineral components of the soil and ash elements released from plant residues, the resulting system of humic substances breaks up into groups. The less mobile part is formed as a group of humic acids, and more dispersed fractions that form soluble salts make up the group of fulvic acids.
At the second stage, further transformation of the newly formed acids occurs. In humic acids, the degree of aromatization gradually increases due to the partial destruction of aliphatic components and intramolecular groups. An important feature of this stage is its hydrolytic and oxidative orientation.
At the third stage, gradual mineralization of humic substances occurs, which is carried out with the participation of a diverse system of microorganism exoenzymes. The main reactions of this stage are hydrolysis and oxidation, which results in the hydrolytic breakdown of molecules of humic compounds, the destruction of heterocyclic and aromatic groups, and ultimately the complete oxidation of decomposition products to ammonia, water, and carbon dioxide. Fragments of molecules of humic substances of aromatic nature do not undergo complete mineralization, but, interacting with newly formed compounds, are re-involved in the process of humification.
Matrix completion or fragmentary renewal of humic substances
The theory of fragmentary renewal by A.D. Fokin is based on the fact that the products of decomposition of organic substances may not form an entirely new humus molecule, but are included by condensation, first in the peripheral fragments of already formed molecules, and then in cyclic structures. Thus, the atomic and fragmentary composition of soil humus is constantly updated due to new inputs of organic material. In this case, peripheral fragments are updated several times faster than nuclear ones. The decomposition products of organic matter are almost simultaneously included in all fractions of soil humus, and in quantities approximately proportional to the content of this fraction.
^ 9.2 Soil surface mineralization
Mineralization of the soil surface is carried out in the presence of fertilizers in order to create favorable conditions for seed germination and survival of seedlings under the canopy of plantings entering the felling with a density of no more than 0.6, in clearings and clearings by treating the soil with mechanical, chemical or fire means, depending on the mechanical composition and soil moisture, density and height of ground cover, thickness of litter, degree of mineralization of the soil surface during logging operations, number of seeders and other site conditions. The proportion of the mineralized surface should be at least 30% of the area of the entire site. Plowing and milling strips should be located no closer than 5 m from seed crops or 2-3 m from groups of surviving undergrowth and undergrowth.
Optimal timing for mineralization of the soil surface
In the year of fruiting in late summer or autumn, and in some cases - in early spring next year with the simultaneous planting of seeds that fell in the autumn winter period.
Soil mineralization must be carried out in the seed year with a seed harvest of at least the third point.
Tree stands, under the canopy of which, after mineralization of the soil surface, self-seeding of the main species has appeared, are subject to felling during the period when its greatest preservation is ensured.
^ 9.3 Fencing of clearings
If there is a risk of damage to young trees by domestic and
wild animals, areas with natural reforestation should be
fence on all sides or in places where livestock is driven.
^ 9.4 Leaving seeders
Leaving seed trees (trees and clumps) is a mandatory silvicultural measure during the allocation and development of cutting areas as the most important condition for ensuring regeneration, but is not included in the plan for promoting natural regeneration of the forest as an independent type of measure. The placement and quantity of pollutants left are determined by regional guidelines (manuals), rules of logging in the forests of Kazakhstan (2005).
The number of seeds (indicated in the logging ticket) left at the cutting site, their location and configuration depend on the biological characteristics of tree species, growing conditions, skidding methods, width of cutting areas, presence of undergrowth, etc. Seed plants must be wind-resistant, abundantly fruiting, with a good trunk shape , without hereditary defects.
In large clearings, where the spread of seeds from adjacent forests is excluded and when it is economically beneficial, it is advisable to leave seeds: seed seeds of free-standing wind-resistant trees of pine, larch, cedar, 15-30 pcs/ha; seed groups of 5-10 pieces/ha (in a group there are 3-6 pines, larches, cedars and sometimes spruces); seed clumps - forest areas with an area of 0.1-0.5 hectares of square, rectangular or other shape (in cutting areas wider than 200 m); seed strips - forest areas in the form of elongated strips 20-25 m wide. It is recommended to set aside spruce clumps measuring 40 X 50 m in the absence of excessive moisture and 60 X 60 m on damp soils (at a distance of 100-150 m from one another).
^ 9.5 Addition of fellings
In clearings where the amount of self-seeding, retained undergrowth and undergrowth is insufficient for successful natural regeneration of the forest, additional planting of seedlings and saplings is possible. At the same time, the quantity seats should not exceed 25% of the accepted norm
for continuous forest crops under these conditions.
The results of measures taken to promote natural forest regeneration are assessed in accordance with the current technical documentation, approved by the authorized body. A tally sheet of the measures taken to promote natural regeneration of the forest is compiled, which is an appendix to the “Act of technical acceptance of areas with measures taken to promote natural regeneration of the forest.” The document is introduced after the work and takes into account the measures taken to promote the natural regeneration of the forest. The act of technical acceptance of measures taken to promote ES is introduced when accepting areas with measures taken to promote natural regeneration of forests. It reflects the implementation of planned activities in general and according to individual criteria.
10 Protective afforestation
^ 10.1 Adverse natural phenomena, their brief description
The climate on the territory of Kazakhstan is characterized by two the most important features: a small amount of precipitation and an abundance of heat and light during the growing season of agricultural plants. The discrepancy between the amount of heat and moisture increases from north to south of the republic.
The location of the southern regions of lowland Kazakhstan at fairly low latitudes gives the climate an arid character, as a result of which desert landscapes are developed here. To the north, aridity softens and desert landscapes give way to semi-desert, then steppe, and in the very north – forest-steppe.
Along with the continental climate on the territory of the republic, the frequency and strength of such unfavorable climatic phenomena for agriculture as drought, hot winds, dust storms, cold and blizzard winds is increasing.
^ Under the Drought one should understand an unfavorable combination of hydrometeorological conditions, leading to dry air and soil, in which the water balance in the plant body is disrupted, causing a sharp decrease or complete loss of the crop. Drought can be soil, atmospheric or general.
^ Soil drought is the depletion of water reserves in the soil. The causes of soil drought are the lack of autumn precipitation, snow blowing from fields, large surface runoff of melt and storm water, lack of precipitation in the spring. summer period, violation of agricultural practices for growing crops, excess salts in the soil, causing physical dryness of the soil.
^ Atmospheric drought lies in the lack of moisture in the atmosphere. Most often it is observed when high temperature and low relative humidity. Atmospheric drought includes periods with temperatures above 25°C and relative humidity less than 20%. At the same time, plants' moisture consumption for transpiration sharply increases, the productivity of moisture use decreases, and the root system does not have time to provide water supply from the soil. Atmospheric drought is an inevitable consequence of continental climate.
The combination of soil and atmospheric drought is called total drought. The most destructive is drought accompanied by hot winds.
Sukhovei is a complex of meteorological conditions that cause high evaporation. There are weak and strong dry winds. Weak dry winds occur when the wind speed is 5 m/s, the relative air humidity is below 20% and the air temperature is more than 25°C. Strong dry winds are observed when wind speeds are above 8 m/s, relative humidity is below 20% and air temperature is more than 30°C. Dry winds can last for several days in a row.
The occurrence of dry winds was previously explained by the arrival of dry air masses from deserts and semi-deserts. Currently, their occurrence is explained by intense air movement along the periphery of a stable anticyclone, in the center of which hot weather is usually observed.
Dust or black storms is the process of destruction and transfer of the upper horizons of soil by strong winds. They occur at different wind speeds: on light sandy loam soils at a wind speed of 10-12 m/s, and on cohesive soils at 12-15 m/s. Soils containing more than 50% of aggregates less than 1 mm in size are considered erosion-hazardous.
Black storms are observed more often in May-June, when the soil in the fields is still poorly covered with vegetation. They occur during the daytime and last from one to three hours. The number of days with dust storms, especially in Northern Kazakhstan, can reach 60 or more per year. The most destructive black storms, sometimes covering large areas of the steppe zone, recur every 5-10 years.
Blizzard and cold winds are also negative natural phenomena.
Blizzard winds blow snow from elevated places, wind-impacted slopes, and sometimes from flat fields into ravines and ravines. Often, soil particles are blown from the fields along with the snow.
When snow is blown from fields, the likelihood of winter crops and grasses freezing increases, the flow of moisture into the soil decreases, and preconditions are created for the occurrence of soil drought.
Cold winds in winter sometimes cause freezing of agricultural crops, as well as freezing of trees and shrubs in gardens and forests. In spring, cold winds cause damage to plants, delay their growing season, and contribute to the formation of local frosts.
To reduce the negative impact of the above unfavorable natural phenomena Of all the means that agriculture currently has, the most effective and economically accessible is the use various types protective forest plantations.
^ 10.2 Types of protective forest plantations
Forest reclamation plantings, especially in combination with other measures, protect the soil well from erosion, increase the humidity of fields, and weaken the harmful effects of droughts, hot winds and dust storms. The yield of agricultural crops and the gross harvest of grain and other products in fields protected by forest belts is higher than in open ones, not only in years of drought, but also in favorable years. In addition, forest reclamation plantings reliably protect agricultural areas from destruction by washout and erosion.
Very important has the cultivation of forest plantations along the banks of rivers, lakes, reservoirs, around gullies and ravines, along railways and highways to protect them from drifts of snow and sand, as well as the creation of forest plantations for the consolidation and economic development of sandy massifs.
Forest reclamation measures to protect soil from wind and water erosion and improve the microclimate provide for the creation of highly effective systems of contour-reclamation plantings of drainage areas, expediently located throughout the land use area, taking into account the terrain and the condition of the soil cover. This system includes the following types of protective forest plantations:
A) forest shelterbelts 9-12 m wide; they are placed on arable land in plain conditions and on watersheds to protect fields from the harmful effects of hot winds, blizzards and wind erosion;
B) water-regulating forest strips up to 15 m wide; they are placed on arable slopes to regulate surface runoff, reduce water erosion of soil, and improve the microclimate of fields;
C) ravine and ravine forest strips 15-21 m wide along gullies and ravines and gully-gulley forest plantations inside gullies and ravines to regulate surface water flow, stop water erosion, economic use of unproductive lands, and improve the microclimate in adjacent fields.
In addition to these main types of reclamation plantings for agricultural fields, there are others that take into account the specifics of the protected territory:
A) forest strips on irrigated lands along irrigation and drainage canals to reduce water evaporation, lower groundwater levels, protect fields from dry winds and dust storms;
B) forest strips and plantings on pasture lands to increase the productivity of pastures and protect animals from wind and heat;
C) canopy and massive forest plantations on unused areas agriculture broken sandy soils to consolidate the sands, turning them into productive lands;
D) forest strips along roads to protect against snow and sand;
D) protective and decorative plantings in rural areas populated areas and around them to improve the environment;
E) forest plantations on mine dumps for their reclamation.
A properly created system of contour-reclamation plantings in an adult state is a unique device that, under constantly changing weather conditions, automatically regulates them, preserving the soil from wind and water erosion, improving the microclimate of the fields and the entire agricultural landscape in general. All this makes forest reclamation important in solving the problem of nature conservation and improving the natural conditions of agricultural production.
^ 10.3 Structures of forest strips
Protective forest plantings in most cases are a system of forest strips, the influence of which on the microclimate, soil, hydrological processes and agricultural yields depends on their design.
The design of forest strips refers to the degree and nature of their wind permeability. The design is determined by the ratio in the profile of the strip of gaps and dense (not blown) areas.
For successful implementation For their main purpose in different soil and climatic conditions, forest strips are given an appropriate design - dense (windproof), moderately openwork, openwork, openwork and blown (Table 10.1)
Forest strips of dense construction consist of trees of all tiers and shrubs, with a high density of their placement and without gaps along the entire vertical profile. The wind flow usually does not pass through such a strip, but flows around it from above.
Stripes of moderately openwork, openwork and openwork-blown structures are also created from trees of different tiers and shrubs, but less dense, with small gaps along the vertical profile.
Table 10.1- Structures of forest strips
| Constructions | Wind permeability in summer, % |
|
| between the trunks | in the crown |
|
| Dense | 0-10 | 0-10 |
| Moderately openwork | 15-20 | 15-20 |
| Openwork | 25-35 | 25-35 |
| Openwork-blown | 60-70 | 15-30 |
| Ventilated | 60-70 | 0 |
The strips of a ventilated structure are usually distinguished by one layer of trees and the absence of shrub undergrowth, as a result of which such strips are easily permeable to air flows in the lower ground layer. In the lower part, there are 1.5-2 m gaps between the soil surface and the tree crowns.
^ 10.4 Forest shelterbelts
Placement of shelterbelts. The requirement for the placement of shelterbelt forest belts is to ensure maximum protection of soil and crops from wind erosion, hot winds and strong winds with minimal occupancy of arable land for plantings.
The forest shelterbelt system consists of main and auxiliary strips of blown or openwork structures.
The main (longitudinal) stripes perform the main protective role and are placed perpendicular to the prevailing most harmful winds in the area.
In fields of complex configuration, it is allowed to deviate longitudinal forest strips from this direction, but not more than 30°.
Auxiliary or transverse forest strips are created perpendicular to the longitudinal ones in order to weaken the influence of harmful winds that have the same direction as the main strips.
The distances between the main forest belts are set depending on soil conditions and should not exceed:
On meadow-chernozem and leached chernozem - 500 m;
On ordinary and southern chernozems – 450 m;
On dark chestnut soils - 300 m;
On typical chestnut soils - 250 m;
On light chestnut soils – 200 m;
On gray soils – 300 m;
On steppe sandy loam soils - 300 m.
As for the distance between auxiliary (transverse) stripes, taking into account the productive use of agricultural machinery, it is set within 1500-2000 m.
With this placement of forest strips, the arable area will be divided into rectangular cells bordered by green ribbons.
For the passage of tractors with trailed implements and vehicles, gaps 20-30 m wide are left at the intersections of main and transverse forest shelter belts. In addition, for the same purposes, gaps up to 10 m wide are made in longitudinal forest belts every 500-700 m.
In the steppe regions of Northern and Western Kazakhstan, 2- and 3-row main shelterbelts with a row spacing of 3-4 m have the highest reclamation and protective properties. With the deterioration of forest conditions, tree species need to increase the feeding area. This requirement is met in practice by reducing the number of rows, increasing the row spacing and the distance between plants in the rows (Table 10.2).
Table 10.2 - Placement of plants in shelterbelts (row spacing, row distance, m) according to KazNIILKhA data
Preparing the soil for forest strips. The main goal of soil preparation in any soil-climatic zone is to create a good water and food regime, to ensure best conditions for successful growth and development of the root system of trees and shrubs. With good soil preparation, woody plants take root better and grow faster, reducing the cost of supplementing plantings and agrotechnical care.
The soil for forest strips is prepared using the black or early fallow system. The black fallow system includes the sequential implementation of the following soil cultivation methods: stubble peeling with disk ploughers or flat cutters 10-12 days before the main plowing; autumn plowing with plows with moldboards to a depth of 25-27 cm with simultaneous rolling with ring rollers; in winter, 2-3 times snow retention; during the spring-summer period, 3-4 times continuous tillage of the soil with cultivators or flat cutters; autumn plowing with plows without moldboards or subsoilers to a depth of 35-40 cm.
The early fallow system includes: the main plowing of the soil in May with plows with moldboards to a depth of 25-27 cm with simultaneous rolling with ring rollers; 3-fold summer tillage of the soil with cultivators or flat cutters; autumn plowing of the soil with plows without moldboards or subsoilers to a depth of 35-40 cm.
Kazakh Research Institute forestry and agroforestry recommends preparing the soil for protective forest plantations using the black or early fallow system, but replacing the usual autumn fallow plowing with deep plantation plowing to a depth of 50-60 cm (the so-called “plantation fallow”). Such soil preparation promotes greater accumulation of moisture (15-30%) than conventional fallow, reduces soil salinity and, most importantly, destroys the compacted carbonate horizon, which creates favorable conditions for the active growth of root systems of woody plants.
Planting forest strips. The best time to plant forest strips is spring. If the autumn is wet and warm, good survival rate of plantings is also observed in the autumn: before the onset of frost, the plants manage to restore part of the active root system and can withstand the drying effects of wind and frost. In areas with harsh winters, fall planting should be avoided.
In any case, it is better to plant coniferous trees in the spring.
Spring planting is carried out as early as possible in the period before sowing grain crops for 5-7 days and must be completed before the buds open.
The establishment of forest belts is carried out by planting seedlings or saplings and, in some cases, cuttings (poplars, willows).
Seedlings of tree and shrub species, usually 1-2 years old, with a well-developed fibrous root system at least 25-27 cm long, are dug out from the nursery in autumn and spring, coniferous species - pine and larch - better in spring. Seedlings plowed up with a digging bracket are selected from the soil, sorted, tied into bunches of 100 pieces, temporarily buried or transported to the planting site. When transporting, the roots of the seedlings are layered with wet straw or sawdust, and then covered with straw or a tarpaulin on top.
Forest strips should be created by planting cuttings in exceptional cases - under irrigated conditions, in depressions or in well-moistened soil. To do this, cuttings are cut 25-27 cm long with an upper cut diameter of 0.5-1.0 cm with well-developed buds.
In some cases, protective forest plantations are created by planting seedlings, i.e. large-sized planting material 3-5 years old, 1.5-3.0 m high. Poplar, birch, elm, ash, maple, linden seedlings are usually used.
Maintenance of forest strips. An important condition for successful afforestation in steppe regions is loosening the soil and destroying weeds in young plantings. If careful care is not taken care of, the soil becomes compacted, weeds grow quickly, suck out soil moisture, and young plants can quickly die. It is especially important to combat weeds in the first years of plant life, when the planted seedlings and saplings are separated, are in a unique microclimate and are not able to compete with weeds.
Agrotechnical care of forest belts includes mechanized cultivation of row spacing, weeding in rows and plowing of edges. Cultivators and flat cutters are used to cultivate row spacing. The edges are plowed with plows.
The timing and number of treatments are determined depending on the condition of the soil and the intensity of weed growth. In the first year, row spacing is treated 4-5 times, in the second year – 3-4 times, in the third and fourth years – 2-3 times. In subsequent years, throughout the life of the plantings, the row spacing is treated at least 1-2 times annually. The depth of tillage is 8-10 cm. The edges of the strips are plowed twice a year - in summer and autumn. Plowing depth is 18-22 cm.
With timely and good care, woody plants grow quickly and close their crowns. A forest plantation is formed. Closed forest belts are excluded from the arable land area and transferred to forest land.
In order to maintain shelterbelt forest belts in a ventilated and open-ventilated condition, special care measures are carried out in them - removal of lower branches, thinning of plantings, removal of underdeveloped, shriveled, diseased and damaged trees, as well as overgrowth.
Pruning of the lower branches begins 3-4 years after planting and is repeated after 2-3 years. First, they are pruned to a height of up to 1 meter, and then the crown is raised to 2 meters. The branches are removed with sharp pruners and a hacksaw. It is better to do pruning in the summer in dry weather and remove the removed branches from the field immediately.
Thinning of plantings begins at the age of 5-6 years, and subsequently is carried out as necessary. It is better to carry out this work in the fall. Depending on the density of the plantings, from 25 to 50% of the trees are removed for the first time. In all cases, trees are removed evenly over the entire area. Underdeveloped, withered, diseased and damaged woody plants are removed annually in spring and autumn.
Inventory and addition of forest strips. After forest planting work, usually not all planted plants take root. Some of them die off in the first year after planting. The reasons for the death of planted plants may be poor soil preparation, poor-quality planting material, untimely agrotechnical care, etc.
An inventory or recording of the area of created strips and the survival rate of plantings is carried out annually at the end of the growing season, and of closed plantings - periodically.
Taking into account the survival rate begins with a general inspection of the plantings in nature. In the case of great heterogeneity in the survival rate of plants in the area of forest belts, relatively characteristic areas are identified by eye, the boundaries of which are plotted on a schematic map of forest belts. Within each plot, trial plots are laid out to accurately record the survival rate of plants. In areas of forest belts up to 3 hectares, the size of the trial plot should be 5%, in areas of 4-5 hectares - 4%, from 6 to 10 hectares - 3% and over 10 hectares - 2%. A complete count of surviving and dead plants is carried out on the trial plot. Moreover, a trial plot is laid out across the entire width of the forest belt.
For each forest strip, an inventory list is compiled and the average percentage of plant survival for each homogeneous area is calculated. Depending on this, they plan and carry out additional plantings, i.e. planting plants in waste areas. Survival rate is considered high when 85-90% of plantings contain living plants. In this case, no additional plantings are made. If the mortality is over 50% of the number of plantings, then such forest belts are not supplemented; they are considered dead, plowed up and replanted. Planting is usually supplemented by hand using a shovel with high-quality planting material.
