A procedure for the cultivation of industrial timber plantations of black locust (robinia pseudoacacia l.)

Abstract

A procedure for the cultivation of industrial timber plantations of black locust (Robinia pseudoacacia L.) and their repeated natural regeneration from roots, characterised in that the plantation would be planted from seeds, saplings or cuttings, then, up to 2-3 years of age of the plantation, the rows of the plantation would be weeded 2-3 times annually by mechanical means in a 60-80 cm wide strip, using hand or machine tools. Until the plantation reaches two years of age, dead specimen would be replaced by the plantation's own species, admixed species or by the introduction of further clones. Upon establishment of the plantation and / or subsequent replacement of trees, shade-tolerant or moderately shade-tolerant admixed species would also be planted. At 3-4 years of age of the plantation, the trees would be pruned one month before the start of the spring sap flow, in the course of which shoots and branches would be removed from the lower half to two-thirds of the tree height, and where bifurcation of the trunk occurs, the weaker branches of the tree forks would be cut off at the base. Upon reaching average breast height diameters of 5-10 cm, clearing and schematic thinning would be carried out, in the course of which every second or third tree would be removed, and shoots and branches would be removed from the lower half to two-thirds of the total tree height of the remaining trees. Upon reaching the dimensions corresponding to the target selection (pickets, posts, etc.), a second thinning is performed, and the trees are felled upon reaching the desired dimensions. After felling, a new plantation would be created from the suckers appearing naturally on the roots, which then would be treated as per the procedural steps described above.

Description

[0001] A procedure for the cultivation of industrial timber plantations of black locust (Robinia pseudoacacia L.)

[0002] The subject of the invention is a procedure for the cultivation and repeated natural regeneration from roots of industrial timber plantations of black locust (Robinia pseudoacacia L.).

[0003] The emergence and spread of precision farming brought about significant technical and technological development in agriculture and forest management. New technical solutions became available and have come into general use, such as GPS-based power equipment, plant protection drones, battery-operated handheld tools (e.g. pruning machines), or robotised tilling equipment. The incorporation of these technologies into plantation-type tree cultivation technology is inevitable, as economical, sustainable and climate-friendly production requires the application of precision solutions in this field as well.

[0004] Black locust plantations are widely cultivated across the globe for forestry purposes, characteristically planted as non-indigenous species (guest species). Resulting from the nature of black locust’s adaptability, it is capable, under favourable growing site conditions, of intensively regenerating and spreading from root suckers or - e.g. after a forest fire - from seeds. This raises challenges from the environmental perspective, particularly with respect to preservation of indigenous species and biodiversity. At the same time, timber as a renewable raw material plays a significant role in climate protection, thanks to its considerable CO2 sequestration capability. One solution to establish balance between the two objectives - nature conservation and climate protection - may be the plantations of rapidly growing hardwood species, where efforts should be made to close-to-nature management, apiary use and site amelioration.

[0005] The new acacia varieties and candidate varieties bred and introduced into plantation experiments by Napkori Erdogazdak Zrt., Hungaroplant Kft. and the Forest Research Institute of the University of Sopron have shown outstanding performance in the experimental plantations. For the cultivation of these varieties on a plantation scale, the elaboration and regulated application of a modem cultivation technology, incorporating advanced precision technological elements is inevitable.

[0006] A number of cultivation technologies are known in forestry practice and literature for the plantation-scale cultivation and regeneration of black locust, typically applying solutions based on forestry and arable land cultivation, developed in the second half of the 20thcentury. A common feature of these technologies is that they are built on soil preparation by ploughing, sapling or cutting plantation using planting equipment and mechanical inter-row tilling (e.g. by discing or harrowing). These methods had come into general use from the 1960s, and were last modernised in the 1990s.

[0007] Procedures for the cultivation or regeneration of black locust plantations can be found in patent databases, too. The Hungarian patent application under filing number P9801798, for example, describes a procedure for the natural regeneration of black locust forests from seeds, in the course of which chemical weed control is applied in the vegetation period prior to felling, depending on the weeds in question, especially against blackberry and clematis. The trees are felled in the period between November and April. By setting the waste branches and shrubbery arranged into long piles every 2-4 metres on fire, or by lightly scorching the soil with the help of a mobile scorcher, the skins of the black locust seeds present in the soil are cracked, and the soil is treated with a selective herbicide sparing black locust sprouts at the time the weeds beginto germinate; in the cotyledonous stage of the black locust saplings, the entire surface is sprayed with a fungicide, and if necessary, the 20-30 cm tall stump sprouts are sprayed once or twice with a total (non-selective) herbicide in a targeted manner.

[0008] The subj ect of the Hungarian patent under filing number 803 / 84 is a procedure for the vegetative propagation of deciduous species, especially black locust in free growth medium, advantageously prepared topsoil, using collected and appropriately prepared root cuttings. The main idea is cutting a 4-5 cm deep groove in the soil appropriately prepared by weed control, disinfection and soil loosening, into which 20-25 pcs per running metre of 4-5 cm long roots 5-16 mm in diameter are planted at equal distances, so that the roots lie essentially horizontally in the soil. After placing the roots, the groove is covered and the soil is compacted by rolling. The planted roots are then irrigated with an amount of water equivalent to 5 mm of precipitation, and the desired humidity of the soil is subsequently ensured by regular irrigation until root growth commences. Then, irrigation is gradually decreased or completely abandoned in accordance with the water requirement of the wood varieties.

[0009] The procedure described in the Hungarian patent under filing number Pl 100320 applies to intensive plantations formed from deciduous woody plant varieties for energy and / or timber industry use, and for the formation of protective plant belts and / or bee pastures and / or for the establishment of mushroom farms suitable for human consumption and / or animal feed. In the course of the procedure, soil preparation and weed control are performed as necessary, followed by planting, and specimens of fast growing, sprouting, woody plant varieties are planted in the growing site, the hydrological properties of which correspond to the plant varieties’ requirements, by seeding and / or planting seedbed saplings and / or stem cuttings, forming average growth spaces of 0.207 m2, such that the growing plants form a continuous canopy latest by the end of the vegetation period. Specimens of woody, deciduous, fast growing and sprouting plant varieties are planted in the growing area of the intensive plantation according to the invention; the growing area being a growing site with hydrological properties corresponding to the plant variety, and the specimens of the plant variety are arranged in small growth spaces measuring a maximum of 0.207 m2on average.

[0010] As a summary, it can be established that neither of the above solutions considers a complex procedure that would be suitable for creating and sustaining industrial timber plantations capable of multiple regenerations. In addition, they also lack modem experimental results and the integration of precision technologies, and therefore cannot meet contemporary technical and ecological requirements.

[0011] Considering the technical deficiencies, the introduction of a modern cultivation technological procedure to set up and sustain black locust industrial timber plantations grown from natural root sprouts and regenerated multiple times seems necessary, taking into account the latest opportunities precision forest management has to offer, as well as the aspects of nature conservation and climate protection. The use of the technical solutions applied earlier may be continued, however, the agricultural and forestry sectors are also severely impacted by labour shortage. This calls for techniques that require the employment of a reduced headcount of higher qualified professionals. Such technical solutions include drones, robots, GPS-controlled tractors and battery-operated handheld tools. The need to employ as few persons in the agricultural sector as possible clearly supports the adoption of these techniques. Another criterion of precision plantation management is climate-friendly operation: less fuel, less chemicals applied, and high degrees of precision and economy upon execution of the technical tasks (less diesel consumed). These new methods must be incorporated into the plantation-based tree cultivation technology, as this is the only way the operation of these plantations planned for 20+ years can be successful.

[0012] The solution of the target task is presented by the procedure specified in claim 1. The advantageous variants of the invention are presented in claims 2 - 13

[0013] Hereinafter, the invention is introduced in greater detail with the help of the steps of the implementation process.

[0014] In the first step of the procedure to be patented, the plantation is planted from seeds, saplings or cuttings. The planting grid typically uses an inter-row spacing of 300 cm that allows both mechanised maintenance and subsequent harvesting and forwarding. Establishment generally takes one year, with the plantation foreseen to be sustained for 20+ years, but it may potentially last centuries. This requires precise planning and accurate implementation. There are few sectors of the national economy where planned management can last a period spanning from 20 years to several centuries. In case of hardwood industrial timber plantations - since black locust can be successfully regenerated 10-20 times from roots - even an operational period spanning several hundred years is realistic. Such plantation-type forests do exist, currently in their 10- 15thfelling cycles (in agriculture, this is known as monoculture, but the no-till technology used in forestry creates a stable local ecosystem, in contrast to the annual cycles of disturbance in agriculture).

[0015] The first technical task after establishment is the care for the plants. The plantation requires maintenance up to 2-3 years of age. The inter-rows are typically cultivated by disc harrowing and / or harrowing, but black locust is a so-called hoed plant, and is particularly thankful for manual hoeing in the first year after planting. The modem solution to this in precision management is the rotary hoe. With the help of a GPS-controlled tractor or robot, a rotary hoe may pass at a distance of 5-10 cm from the rows, tilling the soil until black or simply “kneeling” (damaging but not killing) weeds, depending on its adjustment. After the so-called “kneeling”, the weeds remain alive, but their water uptake is restricted, preventing their further growth. Thus soil cover is preserved, preventing direct drying. The rotary hoe tilling also has a flail mode, in which the stems of the weeds are torn by the equipment. This is likewise a good solution, but the evaporation of the soil surface is more intensive in this case than when the weeds are simply “kneeled”. Evaporation is highest when the soil is hoed to black, i.e. no weeds remain in the area. Rotary hoe row tilling performs weed control in a strip approximately 60-80 cm wide along the rows. This leaves a grass-covered strip about 100-150 cm wide in the 300 cm inter-row, protecting the soil from dehydration; the weeds in this strip do not jeopardise the growth of the trees.

[0016] In the next step, replacement of the dead specimens are carried out until 1-2 years of age of the plantation. Replacement takes place using the own varieties of the plantation, but the replacement operation provides opportunities for the introduction of admixed species and further clones. Replacement is carried out by GPS-controlled robotic hole drilling or with the help of planting bars, in the places of the dead trees.

[0017] The next step after replacement - or as part of it - is the introduction of admixed species. This is recommended right upon establishment, but is also possible during replacement, individually or in groups or rows. Typical admixed species are shade-tolerant / moderately shade-tolerant species (Ulmus, Acer, Fraxinus), which are also hardwoods. The introduction of admixed species drastically increases biodiversity, and also improves the condition and persistence of the plantation spectacularly.The following step is the first pruning of the plantation at 3-4 years of age. Formerly, pruning was very rarely applied in industrial wood forests and plantations, as it is highly labour intensive and difficult work. However, manual and petrol engine equipment have been replaced by battery-operated handheld tools: shears, pruning machines, optionally available with lengthened handles. These are typically used in viticulture and horticulture, but are perfectly adaptable to woody plantations, too. With a 1.5-2 metre handle extension, branch bases 40-50 mm in diameter can be precisely cut through using these lightweight and ergonomic tools. The batteries weigh 1-2 kilograms and can work through 12-hour shifts, even under cold conditions. In the course of pruning, care must be taken to preserve the self-healing capability of the live branch cut off, meaning that the branch is not to be cut off directly along the trunk’s surface, but outside the collar around the base of the branch. The collar is an organ that helps the tree’s natural self-healing process. Many of the branches dry and break off on their own during selfpruning, and the pruning activity further accelerates this process. A black locust plantation should be pruned at least 2 times, first at 3-4 years of age, when the lower half to two-thirds of the tree’s height is cleaned up, i.e. all branches should be cut off to obtain excellent, knot-free trunks without forks. The black locust is prone to forking. It is advisable to tend to tree forks right in the year of appearance: the stronger or healthier shoot should be preserved with the other fork branch being cut off; this will result in a monopodial straightening of the trunk, almost without any trace. Pruning should be carried out one month prior to bud bursting (start of the spring sap flow), in order to minimise the period the wounds are left without protection. The branches cut off should be arranged in rows, where they will serve as natural duff, not obstructing subsequent inter-row tilling, replacement, clearing and thinning.

[0018] The next step is the first thinning and clearing, performed when the diameter at breast height of the plantation’s trees has reached 5-10 cm. A schematic thinning is performed, e.g. by removing every second or third tree. Due to the black locust’s exceptionally quick growth, the plantation already yields useful material at this stage. Typically schematic thinning is applied, in which case every second or third tree is removed, or some other unique scheme is used. The important point here is that thinning must be planned ahead, i.e. we must also plan what we will be cutting off at the next thinning. Black locust sprouts from roots outstandingly well. After clearing / thinning, new shoots will emerge from the remaining stumps very intensively. The stump sprouts must be broken off and the growth of one strong root sprout must be supported. This is also the process of natural forest regeneration, and can also be put to perfect use in the plantation. Simultaneously to this operation, the second pruning is also performed, in the course of which branches are again cut off the lower trunk section. Side branches are pruned off the lower half to two-thirds of the tree’s height, obtaining a clean trunk, specifically for the target selection of industrial timber. The proportion depends on the condition of the trees and how densely they are planted. Intensive growth will be ensured by the foliage on the remaining branch system. Foliage measurements have confirmed (for willow species), that the difference of total foliage between adjacent juvenile trees of the same age may be up to even six fold, meaning that trees develop photosynthesising structures at exceptionally high levels of redundancy (far above their own requirement for building woody structures), therefore there is ample room to prune off branches to obtain improved timber quality without jeopardising the health or trunk-building capability of the trees.

[0019] The next step is the second thinning, in which a schematic approach may likewise be applied. Its timing must be selected depending on the desired target selection, i.e. pickets, posts, sawlogs, etc. The stumps / roots of the removed specimens will naturally sprout, but black locust has a high light requirement, and the shade of the remaining trees will render sprouting less intense.An optimally selected inter-row space will also make forwarding and removal trouble-free. Branches and twigs would remain in the forest.

[0020] The next step is the harvest of the trees. In the course of the end usage, the remaining end usage trees are harvested. The trunks of these trees are already significantly thicker. A 20-year cycle can be planned for the new varieties / clones; the diameter of black locust can reach 40+ cm in a good growing site, which is perfect raw material for sawntimber or veneer. In the course of the end usage, the admixed species should also be harvested. It is advisable to select admixed species that can also regenerate by sprouting, because the admixed species will already be present in the regenerated forest. If the admixed trees used do not sprout, they will have to be reintroduced manually into the regenerated forest.

[0021] The regeneration phase begins after end usage, but in reality, it starts way before that, in the clearing / thinning phase. Black locust can be regenerated perfectly from root sprouts by coppicing. The roots may be torn up, resulting in more intensive sprouting (using a wedging tool pierced into the ground adjacent to the stump using earthworking equipment, or by pulling a cutter in between the rows, depending on the soil conditions). Thinning must also be carried out, although the sprouts do thin up on their own to some degree. The new population will grow even more intensely, as a completely developed root system is already available, feeding the new trunks. Replacements must be performed after logging, as the plantation will be so dense in the first 2-3 years that it will make physical entry and work difficult (due to the density of the plantation and the spines of the trees). Replacement is also possible in the course of clearing, using shade-tolerant admixed species. The subsequent work phases in the sprouted plantation are identical to those in the first generation. Based on experience, regeneration by sprouting can be repeated infinitely, although some researches have indicated that black locust may become “soil-weary”. One reason for this phenomenon of the “soil-weariness” of black locust is the drastic decrease of the macroporosity of soil, due to it being undisturbed for several generations. In its original habitat, black locust is a pioneer species of disturbed soils, requiring a high level of air in the soil, also due to the root nodule bacteria living on its roots. Present plantations can be safely dimensioned for 5+ cycles.

[0022] A further and constant task during maintenance of the plantation may be chemical protection against game damage, but this is only necessary in the first 1-2 years of the plantation, until the trees grow large enough to be safe from game. Of the chemical solutions, those rated “organic” (e.g. wool-based substances) are safe to apply; these typically have highly unpleasant smells and tastes, and effectively repel game from the treated area after the first encounter. Spreading on the trunks is the best solution, and it may also be performed by robots. The growing trees must be retreated or resprayed, in accordance with their growth pace. The game in the area quickly learn that the treated trees are not edible, therefore the frequency of treatments may be reduced. Antler-bearing game use the trees above 4-5 cm of diameter at breast height to clean their antlers, which may significantly damage the cortical tissue. Chemicals offer no protection against this; only electric fences and the reduction of the number of game in the area are effective. Phonic alarms may also be useful in this period.

[0023] Irrigation may be an additional supplementary step, necessary due to climate change. The plantation requires irrigation in its first, second and occasionally, third year of vegetation. Earlier, this task was absolutely unknown in the practice of forestry. However, with the sinking of the groundwater table and the changes in summer precipitation patterns, it is becoming inevitable at an increasing number of locations. Cheap, point irrigation systems must be deployed. Irrigation of the total area would be an unnecessary waste; black locust is sensitiveto the macroporosity of the soil, therefore flooding irrigation is not recommended. Shallow trench surface irrigation is suitable on the other hand, although its application is highly labour-intensive. Using irrigation hoses, plantations of 20-30 hectares may be watered by one person at a frequency of 21-30 days, from early spring to late summer

[0024] The advantage of the procedure according to our invention is that after a single establishment, the plantation can be safely regenerated through 5+ cycles, meaning that repetitive regular end usage and regeneration can sustain the plantation for several decades or even centuries. In case of hardwood plantations, this is particularly significant, as few forms of enterprise exist in which a plantation and its corresponding infrastructure can function efficiently and sustainably for such a long period of time. Furthermore, the procedure integrates the tools and equipment of precision farming into forest management. The application of the integrated precise technologies - e.g. robotised machines, organic protection against game damage and the use of admixed species - is not only labour-efficient but environmentally friendly as well. The plantation thereby created is sustainable on the long run and may be cyclically regenerated for decades, while yielding resistant and versatile timber.

Claims

Claims:

1. A procedure for the cultivation and repeated natural regeneration of industrial timber plantations of black locust (Robinia pseudoacacia L.) from roots, characterised in that a) the plantation is planted from seeds, saplings or cuttings,b) up to 2-3 years of age, the rows of the plantation are weeded 2-3 times annually by mechanical means in a 60-80 cm wide strip, using hand or machine tools,c) up to 2 years of age of the plantation, dead specimen are replaced by the plantation’s own species, admixed species or by the introduction of further clones,d) upon establishment of the plantation and / or subsequent replacement of trees, shade-tolerant or moderately shade-tolerant admixed species are also planted,e) at 3-4 years of age of the plantation, the trees are pruned one month before the start of the spring sap flow, in the course of which shoots and branches are removed from the lower half to two-thirds of the total tree height, and in case of bifurcating trunks, the weaker branches of the tree forks are cut off at the base,f) upon reaching average breast height diameters of 5-10 cm, clearing and schematic thinning are carried out, in the course of which every second or third tree is removed, and shoots and branches are removed from the lower half to two-thirds of the remaining trees, g) upon reaching the dimensions corresponding to the target selection (pickets, posts, etc.), a second thinning is performed,h) the trees are felled upon reaching the desired dimensions,i) after felling, a new plantation is created from the suckers appearing naturally on the roots, which then are treated as per the procedural steps described in points b) - g).

2. A procedure according to claim 1 for the cultivation and repeated natural regeneration of industrial timber plantations of black locust (Robinia pseudoacacia L.) from roots, characterised in that the mechanical weeding is performed using GPS-controlled rotary hoes.

3. A procedure according to any of the claims 1 - 2 for the cultivation and repeated natural regeneration of industrial timber plantations of black locust (Robinia pseudoacacia L.) from roots, characterised in that in the course of mechanical weeding, the soil is hoed black (weed-free).

4. A procedure according to any of the claims 1 - 2 for the cultivation and repeated natural regeneration of industrial timber plantations of black locust (Robinia pseudoacacia L.) from roots, characterised in that in the course of mechanical weeding, the weeds are “kneeled” (damaged but not killed).

5. A procedure according to any of the claims 1 - 2 for the cultivation and repeated natural regeneration of industrial timber plantations of black locust (Robinia pseudoacacia L.) from roots, characterised in that in the course of mechanical weeding, the weeds are flailed.

6. A procedure according to any of the claims 1 - 5 for the cultivation and repeated natural regeneration of industrial timber plantations of black locust (Robinia pseudoacacia L.) from roots, characterised in that the admixed species are selected from the following group: Ulmus, Acer, Fraxinus or other shade-tolerant species.

7. A procedure according to claim 1 for the cultivation and repeated natural regeneration of industrial timber plantations of black locust (Robinia pseudoacacia L.) from roots, characterised in that the admixed species are introduced individually, in groups or in rows.

8. A procedure according to claim 1 for the cultivation and repeated natural regeneration of industrial timber plantations of black locust (Robinia pseudoacacia L.) from roots, characterised in that pruning is performed with the help of battery-operated handheld tools, shears and pruning machines.

9. A procedure according to claim 1 for the cultivation and repeated natural regeneration of industrial timber plantations of black locust (Robinia pseudoacacia L.) from roots, characterised in that the replacement of trees is performed by GPS-controlled robotic hole drilling or with the help of planting bars.

10. A procedure according to any of the claims 1 - 9 for the cultivation and repeated natural regeneration of industrial timber plantations of black locust (Robinia pseudoacacia L.) from roots, characterised in that the plantation is treated with “organic” rated chemicals spread on the trunks at 1 - 2 years of age.

11. A procedure according to any of the claims 1 - 10 for the cultivation and repeated natural regeneration of industrial timber plantations of black locust (Robinia pseudoacacia L.) from roots, characterised in that point irrigation is performed in the first, second and occasionally, third vegetation year of the plantation.

12. A procedure according to claim 1 for the cultivation and repeated natural regeneration of industrial timber plantations of black locust (Robinia pseudoacacia L.) from roots, characterised in that when the new plantation is regenerated from root sprouts, the roots are torn.

13. A procedure according to claim 12 for the cultivation and repeated natural regeneration of industrial timber plantations of black locust (Robinia pseudoacacia L.) from roots, characterised in that when the new plantation is regenerated from root sprouts, the roots are torn using a wedging tool pierced into the ground adjacent to the stump using an earthmoving machine, or by pulling a cutter in between the rows.