Hybrid poplar cultivation method

Abstract

The invention is a hybrid poplar cultivation method for establishing a new hybrid poplar plantation in place of a harvested hybrid poplar plantation in a floodplain area, comprising the steps of: - in a post-harvest clearing step (S1), removing from the area at least a part of logging residues left in the area, thereafter - in a stump grinding step (S2), destroying stumps left in the harvested area utilising a stump grinder, thereafter - in a heavy disking step (S3), performing soil levelling by crushing at least a part of wood residue left in the area in the soil and on the surface, thereafter - in a deep ploughing step (S4), performing deep ploughing in the area with a depth of at least 60 cm and at most 90 cm, thereafter - in a post-ploughing tillage step (S5), tilling the ploughed area utilising a light disk harrow or a disk harrow, thereafter - in a planting step (S6), establishing a new hybrid poplar stand with a distance between the rows of at least 3.5 metres and at most 5.0 metres, and with a distance within the rows of at least 2.5 metres and at most 4.0 metres, and thereafter, in the new hybrid poplar stand - in a reforestation tending step (S7), performing weed control at least once a year for at least 3 years after planting, by removing at least a part of weeds from between the rows and from the rows, - in a pruning step (S8), performing pruning up to at most two-thirds of tree heights, once each year for a number of years starting at least from the 2nd year after planting, and - performing tending operations in a tending step (S9).

Description

[0001] HYBRID POPLAR CULTIVATION METHOD

[0002] TECHNICAL FIELD

[0003] The invention relates to a hybrid poplar cultivation method for establishing a new hybrid poplar plantation in place of a harvested hybrid poplar plantation in a floodplain area. The invention particularly relates to a method that enables improved utilisation of the production area, providing a modem solution for hybrid poplar cultivation encompassing the entire production cycle, including stump removal by stump grinding, pruning operations, and other technological steps.

[0004] In a general sense, the term “hybrid poplar” refers to poplar clones and varieties (cultivars) produced by less complex breeding techniques, such as simple selection, or by more complex techniques, for example crossing or breeding based on polyploidy. All genotypes selected with a purpose and maintained preserving their genetic material are classified in this group. The term “hybrid poplar” specifically includes clones and intra- or interspecific hybrids of eastern cottonwood (Populus deltoides), and more specifically in particular the hybrids of (American) eastern cottonwood and (European) black poplar (Populus nigra), i.e. , the so-called “Euramerican” clones.

[0005] BACKGROUND ART

[0006] Hybrid poplar forest stands located in riverine floodplain areas, especially mediumheight floodplain areas, i.e. areas lying 2.5 - 5 metres above the expected mean water level of the river cannot be renewed applying conventional technical solutions based on complete soil / site preparation that are applied in areas with no-flood conditions. Because such areas are flooded frequently, there is not always sufficient time in the springtime to perform site preparation, and compacted soil conditions also often make it difficult to apply a strip-type site preparation technology (stump bulldozing). Compared to poplar cultivation in drier areas, due to the more moist conditions, the competitiveness of weeds is much higher, which makes partial site preparation techniques, such as circular soil preparation around the trees and narrow strip-type site preparation, inappropriate for these areas, and for successfully raising the newly planted trees. This is because intensive weed competition may result in a high plant mortality rate, which may lengthen renewal times of poplar stands even by several years. In contrast to groundwater-independent areas, floodplain areas require different methods and scheduling of stand cultivation operations. These considerations have been motivations to conceive a technical solution that can be successfully applied especially in areas characterised by excess water effect, providing much higher timber yields within the framework of the cultivation cycle applied for cultivating hybrid poplar cultivars.

[0007] Methods relating to the cultivation technology of various poplar species, including also hybrid poplars, are disclosed for example in EP 3,257,365 A1 and in US 8,042,300 B2, which, however, do not provide an effective cultivation and renewal solution suited to the special conditions of floodplain areas. Furthermore, a tractor-attached stump grinder apparatus is disclosed in US 2013 / 0056113 A1 .

[0008] DISCLOSURE OF THE INVENTION

[0009] The object of the invention is to provide a method that enables a more favourable utilisation of the production area allowing for higher yields compared to the prior art technical solutions, providing a modem solution for hybrid poplar cultivation encompassing the entire production cycle.

[0010] In particular, the object of the invention is to provide a method that enables the renewal of hybrid poplar forest stands also in such floodplain areas where strip-type site preparation (stump bulldozing) cannot be applied due to the frequently occurring moist soil conditions in the spring.

[0011] The objects according to the invention have been achieved by providing the method according to claim 1. Preferred embodiments of the invention are defined in the dependent claims. According to the invention, it has been recognised that the entirety of the steps constituting the method is necessary for fulfilling the objectives. The prior art technical solutions have not applied the entirety of these steps in the combination and with the parameters specified according to the present invention, considering especially that the technical solutions applied in forestry tend to become simpler over time, i.e. , they tend to perform the tasks to be completed in as few steps as possible. In contrast to that, the hybrid poplar cultivation method defined in the present application provides such a complex solution that covers the prior removal of residual wood material, the subsequent multiple-step treatment of the soil, planting, and the subsequent treatment of the new hybrid poplar stand which, due to its complexity, runs contrary to the commonly applied and prior art technical solutions, while at the same time it enables forest management suited to the special conditions of floodplain areas and also provides unexpectedly outstanding results in relation to timber yield.

[0012] BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Preferred embodiments of the invention will be explained referring to the accompanying drawings, where

[0014] Fig. 1 is a flow diagram showing a step sequence of the method according to the invention, and

[0015] Fig. 2 is a flow diagram showing an alternative step sequence.

[0016] MODES FOR CARRYING OUT THE INVENTION

[0017] The cultivation technology according to the invention consists of specific cultivation operations, their specific order, and their preferred scheduling / timing. The cultivation technology according to the invention is suited for areas to be renewed, i.e., it is expediently supposed that the area to be planted was previously occupied by an earlier hybrid poplar plantation, and that the growth site conditions of the area are still suited for afforestation with a hybrid poplar plantation. With regard to that it should be considered that the renewal of hybrid poplar plantations is usually allowed in areas that were previously occupied by hybrid poplar plantations. The order and the succession of the steps of the cultivation technology are illustrated in Figs. 1 and 2. The steps of the method according to the invention, i.e., the hybrid poplar cultivation method for establishing a new hybrid poplar plantation in place of a harvested hybrid poplar plantation in a floodplain area are essentially successive, and together provide that the growth of the stand is optimal.

[0018] Step S1 of Fig. 1 is a post-harvest clearing step with the main purpose of removing at least a part (or even the entirety) of logging residues, i.e., branches and pieces of the trunks remaining in the area after the final harvest of the previous forest stand in order to provide the necessary terrain conditions for soil preparation. It is expedient to perform this step as shortly after completing final harvest as possible, by the last week of January at the latest, such that other operations that must be performed before planting in the spring are not delayed. Preferably, either of the following two methods can be applied for removing residual wood material, depending on the distance from populated areas of the forest area designated for renewal. If local population expresses a demand for the wood material for firewood purposes, then the waste wood material can be collected and removed from the harvested area by human labour. In such cases, the expediently applicable condition of public firewood collection is that the wood material not usable for firewood (twigs, bark) must be stacked in pyramids evenly distributed across the harvested area and burned under controlled conditions overseen by the local forester.

[0019] In case there is no demand for the wood material remaining in the harvested area by the local population, the material is collected and removed from the area preferably by applying machines. In such cases it is expedient to shred the remaining branch material utilising a high-power PTO-driven (power take-off) shredder machine. The shredded material produced in such a fashion can thereafter be transported to a local biomass- fired power plant, or can be sold for other purposes, i.e., for example for mulching.

[0020] After completing the post-harvest clearing step, the harvested area becomes suitable for continuing the site preparation operations, more particularly for performing stump grinding in step S2. Hybrid poplar plantations exclusively contain uniform-aged trees of essentially uniform size planted in a regular grid, which implies that it is certain that the stem diameter at the base at the time of final harvest exceeds 30 cm, which makes them suitable for stump grinding.

[0021] Destroying the stumps that remain in the harvested area is an extremely important part of the method according to the invention, as thorough soil preparation cannot be performed without previously completing this step. The operation is expediently performed applying a stump grinder attached to a high-power tractor, which, in addition to destroying the above-surface part of the stumps, also crushes root collars and thicker roots. It is recommended to utilise such a stump grinder for the operation that is connected to the tractor via a support frame, allowing it to exert large forces, for example in a manner described in above referenced prior art document. Such a solution allows for effectively carrying out the operation even under the conditions prevailing in floodplain areas. The stump grinder can be expediently raised and descended during the operation by means of a hydraulic adapter. The proposed cutting mechanism is a stump grinder with drill or cylinder, because this allows for destroying stronger roots originating from the root collar. The stump grinder apparatus mounted on a rear attachment point of a tractor preferably enables crushing / shredding of plant parts remaining in the ground down to a depth of at least 0.5 metre, more preferably to a depth of approximately one metre. Depending on the terrain conditions and on the technical parameters of the tractor, the operation can even be performed at rate of 1 .5- 2.0 hectares / day.

[0022] To facilitate subsequent tillage operations, after stump grinding it is preferable to collect the larger-sized debris and root pieces that have come up to the surface and remove them from the area to be renewed. Considering the dimensions of this type of wood material, collection and removal can be organised easily as public firewood collection. Otherwise, if necessary, a machine solution can also be chosen, e.g. by performing one-three passes in the area utilising a tree spear dozer, the roots and stump residues can be moved to the edges of the area. After completing stump grinding, soil preparation for planting can begin. The first operation of planting - partly also applied for site preparation - is a heavy disking step S3. A disking apparatus can be considered heavy disking equipment if it has a mass per disk plate between 60 and 90 kg.

[0023] After removing / destroying the stumps, wood parts (i.e., roots, remains of stumps, occasionally branches) with dimensions that could hamper ploughing may still remain in the upper layers of the soil and on the surface. Therefore, heavy disking is performed with the objective of crushing at least part of these wood parts, and to smooth out the smaller unevennesses of the terrain. It is worthwhile to carry out heavy disking in two passes, in two mutually perpendicular directions in order to provide better-quality crushing and soil levelling. It is recommended to perform this operation as shortly after stump grinding as possible, preferably by the second week of February at the latest. For this operation it is preferable to apply heavy disking equipment with high draw bar power demand (i.e. above 250 hp or approx. 186.4 kW) specially developed for forestry applications that is able to operate in uneven terrain covered with wood debris or wood parts.

[0024] In order to incorporate more air in the soil and to improve soil structure, and thereby to ensure the success of forest renewal and planting, a next step S4 is a deep ploughing, deep tillage of the area performed with a predetermined depth of soil inversion of at least 60 and at most 90 cm. This makes alluvial soils - which are often very compacted - more porous, which facilitates organic matter release in the soil. In addition to that, the roots of hybrid poplars have especially high air demand, so the initial intensive growth of the plants is also aided by deep tilling of the soil. However, tillage should be performed considering the conditions of the location. If soil defects, for example calcareous accumulations or a soil layer with a high gravel fraction content can be found above the predetermined tillage depth, it is necessary to reduce the ploughing depth, restricting the ploughing operation to the soil horizons located above the soil layer with unfavourable properties. In view of the fact that the most appropriate time of the year for planting hybrid poplars is in the spring, it is expedient to perform ploughing as soon as possible after site preparation, until the last week of February at the latest. Ploughing in itself does not make the soil suitable for planting a hybrid poplar plantation, so it is also necessary to till the ploughed area utilising a light disk harrow or a disk harrow in step S5. In the case of a light disk harrow, the mass per disk plate is maximum 60 kg. Depending on the soil conditions, the disking operation is expediently performed in two or three passes, if possible in two mutually perpendicular working directions. After disking, the soil is free from weeds and does not contain any wood parts that would hinder the planting machines. The quick completion of ploughing is also important for conserving moisture in the soil. Because of that, and also to facilitate the scheduling of spring works it is worthwhile to perform disking immediately after ploughing, possibly within a week.

[0025] The next stage is planting in step S6. New hybrid poplar plantations can be established applying various planting grids or patterns. According to the invention, the distance between the rows may vary between 3.5 m and 5.0 m, while the distance within the rows may vary between 2.5 m and 4.0 m, depending on the planting material that is available for restocking / establishment, and on the quality of the growth site in relation to planting poplar trees. In case rooted cuttings are planted applying sapling planters or hole driller equipment, and provided that the growth site conditions are near-optimal (for example in the case of good or medium to good growth sites) a denser grid (corresponding to ~1000 trees / hectare) can be recommended, while in the case of planting poles by deep drilling, which is more expensive than the previous option, or if the growth site is of lower quality (for example in medium, poor to medium, or poor- quality growth sites) it is expedient to choose a planting grid width lower plant density (~600 pcs / ha).

[0026] Other considerations may also be taken into account for selecting the planting grid of the plantation. Applying a wider planting grid (for example with a row spacing of 5 metres) facilitates the movement of floodwater in the area, allowing for quicker draining. Selecting a larger row spacing is also motivated by the ever more frequent application of machines for wood harvesting in the plantations. Wider rows also facilitate the movement of crawlers equipped with felling and bucking adapters in the area. However, in areas that are flooded less frequently, the application of planting grids with greater plant density can be recommended. In the case of shorter planting distances, the topsoil becomes interwoven by the root system of the trees in a shorter time and root interconnections are formed more quickly, which results in a more stable tree stand that has improved resistance against high winds that occur more and more frequently. According to the invention, it has been recognised that by applying the above-described between-row distance and within-row distance ranges, protection of the trees against falling and the production of valuable, high-quality timber can be provided simultaneously.

[0027] For selecting the propagation material, it is worthwhile to consider the site conditions of the area. In the case of compacted soil (clay), where the proportion of the clay fraction of the soil exceeds 55%, it is expedient to plant poles applying a deep drilling technology. On humous alluvial soil (alluvial soil with a humous layer having a thickness of 20 - 40 cm or even greater than that, with the organic material content of the layer being between 1 - 2% or greater) it is recommended to plant rooted cuttings applying a hole drilling technology.

[0028] Irrespective of the chosen planting technology, special attention should be paid to properly filling up the planting hole and to soil compaction. Pockets of air remaining around the roots of the plants may cause the destruction of the roots and thus may kill the plants. If it is possible, “mudding in” the trees during planting has a beneficial effect on tree survival. This provides temporary capillary saturation of the soil encompassing the roots of the plant, while it also helps in removing cavities from the soil near the roots. Also, special attention should be paid to the treatment of the planting material before planting; it is of utmost importance that drying out of the planting material is prevented, because it would significantly reduce the viability of the plants. For this reason, the propagation material should be transported to the area to be planted at most one hour before planting, and it is also recommended to soak the propagation material for 1 -2 days prior to planting.

[0029] Subsequently, a reforestation tending step S7 is performed in the new hybrid poplar stand. This involves the necessity of keeping the areas between the rows of the plantation, and also the rows thereof, free from weeds for at least 3 years after planting to prevent the growth of water and nutrient competition-weeds. It is expedient to perform the removal of at least a part of weeds, and more particularly, removal of the weeds from the rows applying a clearing saw one-three times per year, while weed control in the areas between the rows is expediently performed applying a tractor- attached light disk harrow also one-three times per year. It is sufficient to remove weeds from the vicinity of the plants during the scything operation, i.e. , from circular areas with a diameter of 1 metre around the trees. Due to the presence of false indigo (Amorpha fruticosa L) that occurs frequently and in large numbers in floodplain areas, it is recommended to equip the clearing saws with brush cutter blades. It is recommended to prolong the disking operation to the time period after the acceptance of the reforestation by the forest authority, i.e., after the 3rd year, because, as it was also mentioned above, the roots of hybrid poplars require continuous soil aeration, which can be provided by low-depth disking. In the case of a wide planting grid (with a distance of 4.5-5 m between the rows and a distance of 3.5-4 m within the rows) and regular planting distances (afforestation applying deep drilling), the plantation can be disked perpendicular to the row direction, or diagonally with respect to it, at an angle of approximately 45°. Applying such a planting regime, weed control and soil aeration can be performed in the plantation much more effectively compared to a conventional planting regime.

[0030] The production of high-quality veneer logs requires that pruning is continuously performed in hybrid poplar plantations, preferably up to a height of 6 m, in a pruning step S8. On the lower trunk portions, pruning can be started as early as in the second year of the plantation. At the start of the second year, the height of the trees in the plantation is usually between 3 and 5 metres, i.e. , at this age the size of the trees usually does not allow pruning to a height of 6 metres, because an important rule is that a canopy portion with a height of at least one-third of the tree height must remain after the pruning operation. For this reason, a free trunk height of at least 6 metres can only be achieved over multiple years. It is expedient to carry out the pruning operation once per year, between January and May; it can even be performed up until final harvest in order to remove shoots that may reappear in the lower trunk sections.

[0031] The smaller the diameter of the branches removed during pruning, the shorter the time the plant needs to close the wounds. During the pruning operation it is necessary to cut the branches as close to the trunk surface as possible to prevent the formation of rotting knots. With pruning operations started early enough it can be provided that the knots (branch stubs) remain inside the peeling envelope (cylinder), thereby forming valuable veneer material. Preferably, these operations can be performed utilising secateurs up to a height of about 2 metres, and utilising a pole pruner or branch scissors up to the height of 2-5 metres. Above a height of 5 metres it is recommended to apply a boom lift vehicle; from the elevated work platform the branches can be accessed and removed utilising secateurs or a pole saw.

[0032] Depending on the growth vigour of the stand and on the planting grid, the final harvest grid can be created by three-four tending treatments in step S9, which tending treatments comprise selective thinning and stimulating thinning operations. Canopy closure and the state immediately preceding it are important to consider for scheduling, because in the case of hybrid poplars the reduction of available growth space often results in non-recoverable growth loss. It is therefore expedient to complete tending operations before canopy closure. If the characteristics of the plantation allow it, it is worth waiting for the trees to generate as much tree mass as possible, because tending is a costly operation which should “pay for itself” as much as possible, i.e., the income from the harvested timber should cover the costs of the operation if possible.

[0033] During the planning of fending operations, i.e., during selecting the trees to be thinned out it is necessary to assess the trees individually, because due to the growth site imbalances, the slightly different growth space, and the various biotic and abiotic harmful effects the individual trees are subjected to, tree growth is not completely uniform. Regular thinning, i.e., thinning affecting every second tree in each row can only be carried out in plantations with a completely regular planting grid and extremely balanced growth. During preliminary harvesting operations, and partially also before them, it is necessary to build skid trails in the plantation to facilitate the extraction of large-sized and heavy timber.

[0034] In the embodiment according to Fig. 1 , the steps S1 - S9 are performed sequentially, but as can be seen in Fig. 2, such an embodiment is also feasible in which the steps following S6 may overlap in time, being carried out in parallel with each other, i.e. , they may be performed in a temporarily independent manner.

[0035] An exemplary list of floodplain growth site types suitable for planting hybrid poplars, also listing the expected growth vigour and the recommended cultivars, is included in Table 1 at the end of this description. For compiling the list of the cultivars recommended for the different growth site types, data recorded in earlier experimental hybrid poplar plantations have been evaluated. Based on the resulting dataset, cultivars with a growth rate greater than the experimental average, or greater than the growth rate of the standard cultivar (‘1-214’) were selected for each growth site type variant. For those growth site type variants for which no experimental data were available, the cultivars suitable for planting were determined utilising information obtained utilising the evaluation of similar growth sites and by extrapolating certain experimental data.

[0036] In a preferred embodiment of the invention, therefore, the given floodplain soil is classified according to the five parameters included in the first five columns of Table 1 , that is, forestry climate category, hydrological category, genetic soil type, topsoil depth and physical soil type of the topsoil as growth site parameters, i.e., the growth site type variant is determined. The parameter included in the sixth column of Table 1 , “growth site quality (growth vigour)” indicates the overall assessment of the given parameter set, i.e., the degree to which the given growth site type variant can be considered appropriate for the purposes according to the invention. Subsequent to that, from the hybrid poplar cultivars that can be preferably planted, the cultivar or cultivars to be planted are selected based on the table, so the hybrid poplar cultivars to be planted are selected based on the growth site parameters, i.e., the quality of the growth site (it is recommended to select a single cultivar per area).

[0037] The method according to the invention can be implemented by any combination of the parameters of the steps set forth above tailored to the given application, so the description included above also includes the examples for the modes of carrying out the invention. In the following, the steps of a possible particular implementation of the method according to the invention will be described. Example

[0038] - A forest renewal area is designated on a site of a previous hybrid poplar plantation harvested from a medium-height floodplain area, i.e. , an area lying 2.5 - 5 metres above the expected mean water level of the river.

[0039] - In a post-harvest clearing step, the logging residues left in the area are collected utilising a tractor, and are shredded utilising a shredder machine driven by the PTO of the tractor, followed by transporting the shredded material to a biomass power plant.

[0040] - In a stump grinding step, the stumps left in the harvested area are destroyed utilising a stump grinder mounted to a rear attachment of a tractor utilising a support frame, crushing residual plant parts remaining in the soil to a depth of one metre with the stump grinder. Passes of the area are then performed utilising a tree spear dozer, thereby moving the roots and stump residues to the edges of the area.

[0041] - In a heavy disking step, at least a part of wood residue left in the area in the soil and on the surface is crushed utilising heavy disking equipment, simultaneously also performing soil levelling in two passes, in mutually perpendicular directions.

[0042] - In a deep ploughing step, deep ploughing is performed to a depth of 80 cm in order to incorporate more air in the soil and improve soil structure, thereby to improve the chance of success of forest renewal / planting.

[0043] - In a post-ploughing tillage step, the ploughed area is tilled utilising a light disk harrow or a disk harrow in two passes, in mutually perpendicular directions.

[0044] - In a planting step a new hybrid poplar stand is established applying a distance of 4.5 metres between the rows and a distance of 3.5 metres within the rows, in a regular planting grid.

[0045] - In a reforestation tending step, weed control is performed twice a year for 3 years after planting, by means of light disking in the area between the rows, and with a clearing saw in the 1 -metre-diameter circular areas around the trees.

[0046] - In a pruning step, pruning is performed up to two-thirds of tree heights, but at most to a height of 6 metres, once each year for five years starting from the 2nd year after planting, between January and May, utilising secateurs up to a height of 2 metres, and utilising a pole pruner or branch scissors up to the height of 2- 5 metres, and above a three height of 5 metres, from the elevated work platform of a boom lift vehicle, utilising secateurs.

[0047] - In a tending step, thinning treatments are carried out, creating the final harvest grid by three-four tending operations (by i.e. , one clearing, one-two selective thinning and one stimulating thinning operations), selecting the trees to be cut by individual assessment.

[0048] The example set forth above and, more generally, the invention provides a method that allows the renewal of hybrid poplar forest stands providing excellent effectiveness and high yield in floodplain areas where site preparation applying a strip-type technology (stump bulldozing) cannot be performed due to soil moisture.

[0049] Table 1

Claims

CLAIMS1 . A hybrid poplar cultivation method for establishing a new hybrid poplar plantation in place of a harvested hybrid poplar plantation in a floodplain area characterised in that the method comprises the following steps:- in a post-harvest clearing step (S1 ), at least a part of logging residues left in the area is removed therefrom, thereafter- in a stump grinding step (S2), stumps left in the harvested area are destroyed utilising a stump grinder, thereafter- in a heavy disking step (S3), soil levelling is performed by crushing at least a part of wood residue left in the area in the soil and on the surface, thereafter- in a deep ploughing step (S4), deep ploughing is performed in the area with a depth of at least 60 cm and at most 90 cm, thereafter- in a post-ploughing tillage step (S5), the ploughed area is tilled utilising a light disk harrow or a disk harrow, thereafter- in a planting step (S6), a new hybrid poplar stand is established with a distance between the rows of at least 3.5 metres and at most 5.0 metres, and with a distance within the rows of at least 2.5 metres and at most 4.0 metres, and thereafter, in the new hybrid poplar stand- in a reforestation tending step (S7), weed control is performed, at least once a year for at least 3 years after planting, by removing at least a part of weeds from between the rows and from the rows,- in a pruning step (S8), pruning is performed up to at most two-thirds of tree heights, once each year for a number of years starting at least from the 2nd year after planting, and- in a tending step (S9), tending operations are performed.

2. The method according to claim 1 , characterised in that in the stump grinding step (S2) a stump grinder mounted to a rear attachment point of a tractor utilising a support frame is applied, performing stump grinding in the soil to a depth of at least 0.5 m.

3. The method according to any of claims 1 or 2, characterised in that heavy disking in the heavy disking step (S3) and / or light disking in the post-ploughing tillage step (S5) are performed in two passes, in mutually perpendicular directions.

4. The method according to any of claims 1 to 3, characterised in that in the deep ploughing step (S4) tillage is performed such that if a soil layer with unfavourable properties is located above a predetermined depth of soil inversion, ploughing is restricted to the soil portion located above the soil layer with unfavourable properties.

5. The method according to any of claims 1 to 4 characterised in that in the planting step (S6)- if the proportion of the clay fraction of the soil exceeds 55%, poles are planted applying a deep drilling technology, and- if the thickness of the humous layer of the soil is at least 20 cm, and the organic matter content of this layer is at least 1 %, rooted cuttings are planted applying a hole drilling technology.

6. The method according to any of claims 1 to 5, characterised in that in the reforestation tending step (S7), weed control is performed 1 -3 times per year with a clearing saw within the rows and with a tractor-attached light disk harrow between the rows.

7. The method according to claim 6, characterised in that a regular planting grid having a distance between the rows of 4.5-5 m and a distance within the rows of 3.5-4 m is applied, and weed control utilising a light disk harrow is carried out also in a diagonal direction with respect to the rows.

8. The method according to any of claims 1 to 7, characterised in that in the pruning step (S8), pruning is carried out once a year.

9. The method according to any of claims 1 to 8, characterised in that in the tending step (S9) 3-4 tending operations are carried out before canopy closure.

10. The method according to any of claims 1 to 9, characterised in that the growth site quality of the floodplain area is assessed based on forestry climate category, hydrological category, genetic soil type, topsoil depth, and physical soil type of the topsoil, as growth site parameters, and the hybrid poplar cultivars to be planted are selected based on the parameters and / or the resulting assessment.

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