Forest management is one of the core and most significant activities of the enterprise. It encompasses the regeneration of existing forests and the establishment of new forests, forest cultures, and plantations, as well as the tending, protection, and improvement of forest conditions, along with the production of forest seed and planting material. The implementation of fieldwork activities engages both the enterprise’s permanently employed forest workers and local residents through contracted services.
In the period 2002–2021, forests were regenerated on a total area of 31,145.91 ha, of which 7,331.60 ha were through natural regeneration and 23,814.31 ha through artificial regeneration. During the same period, a total of 4,444.46 ha of new forests were established.
Afforestation of non-forested forest land directly contributes to the increase of forest cover in the Autonomous Province of Vojvodina. However, this process is accompanied by numerous challenges, the most prominent being the very limited area of available non-forested forest land suitable for afforestation within PE “Vojvodinašume.” For this reason, in cooperation with the Provincial Secretariat for Agriculture, Water Management and Forestry, the enterprise takes part in activities aimed at encouraging local self-governments, private landowners, and holders of agricultural land of lower fertility classes to establish new forests.
In this context, a large number of free seedling distribution campaigns have been carried out for interested local self-governments, communities, institutions, and individuals. During the 2009/2010 afforestation season, through the campaign “Plant Your Own Forest for a Greener Vojvodina”, approximately 150 hectares of new forests were established. At the same time, the largest share of seedlings was distributed free of charge to individuals (86,450 in 2009 and 37,650 in 2010), while the total value of the campaign amounted to 5.3 million dinars. Over the period 2002–2021, the enterprise donated around 200,000 seedlings with a total value of 8.6 million dinars. Supporting the fundamental idea that responsible behavior towards forests and the environment should be fostered from an early age, PE “Vojvodinašume” participates every year in various activities involving educational institutions. The longest-standing tradition among these is the program “For Cleaner and Greener Schools in Vojvodina”, during which the enterprise donates seedlings for schoolyard landscaping and provides vouchers for visits to the protected areas under its management. Each year, around 1,000 seedlings of forest and ornamental tree species are secured for this purpose.
Overview of Forest Regeneration and Afforestation from 2002 to 2021
| Business year | Area (ha) | ||||
|---|---|---|---|---|---|
| Forest regeneration | Afforestation of non-forested land | TOTAL Regeneration + Afforestation | |||
| Natural | Artificial | TOTAL (natural + artificial) | |||
| 2002 | 529,00 | 1.331,00 | 1.860,00 | 238,00 | 2.098,00 |
| 2003 | 644,00 | 1.557,00 | 2.201,00 | 353,00 | 2.554,00 |
| 2004 | 616,00 | 1.097,00 | 1.713,00 | 158,00 | 1.871,00 |
| 2005 | 505,00 | 1.058,00 | 1.563,00 | 253,00 | 1.816,00 |
| 2006 | 379,00 | 1.172,00 | 1.551,00 | 314,00 | 1.865,00 |
| 2007 | 321,00 | 1.077,00 | 1.398,00 | 170,00 | 1.568,00 |
| 2008 | 265,00 | 1.571,00 | 1.836,00 | 177,00 | 2.013,00 |
| 2009 | 267,00 | 913,00 | 1.180,00 | 100,00 | 1.280,00 |
| 2010 | 295,00 | 1.265,00 | 1.560,00 | 23,00 | 1.583,00 |
| 2011 | 355,00 | 1.297,00 | 1.652,00 | 497,00 | 2.149,00 |
| 2012 | 308,68 | 994,77 | 1.303,45 | 356,50 | 1.659,95 |
| 2013 | 452,43 | 1.494,16 | 1.946,59 | 389,13 | 2.335,72 |
| 2014 | 304,97 | 885,07 | 1.190,04 | 392,06 | 1.582,10 |
| 2015 | 404,66 | 1.255,23 | 1.659,89 | 281,97 | 1.941,86 |
| 2016 | 295,72 | 1.226,08 | 1.521,80 | 42,16 | 1.563,96 |
| 2017 | 313,26 | 1.072,68 | 1.385,94 | 325,53 | 1.711,47 |
| 2018 | 238,77 | 712,41 | 951,18 | 50,68 | 1.001,86 |
| 2019 | 192,42 | 1.631,92 | 1.824,34 | 210,30 | 2.034,64 |
| 2020 | 364,68 | 1.178,54 | 1.543,22 | 84,07 | 1.627,29 |
| 2021 | 280,01 | 1.025,45 | 1.305,46 | 29,06 | 1.334,52 |
| TOTAL | 7.331,60 | 23.814,31 | 31.145,91 | 4.444,46 | 35.590,37 |
| AVERAGE | 366,58 | 1.190,72 | 1.557,30 | 222,22 | 1.779,52 |
Based on the Conclusion of the Assembly of the Autonomous Province of Vojvodina, PE “Vojvodinašume” defined the Afforestation Program of Non-forested Areas for the period from 2014 to 2017. As the said Program was not implemented in its entirety, a re-examination was carried out of the areas remaining for afforestation. For that purpose, all non-forested areas recorded in the forest management plans were verified, after which the dynamics of afforestation of non-forested areas assessed as suitable for afforestation were defined. In addition, a re-examination was conducted of the areas allocated by the Conclusion of the Government of the Republic of Serbia. These areas had been verified in the previous period as well, but exclusively from the standpoint of natural characteristics of the land and the suitability of the land for forest establishment. This time, other aspects were also taken into consideration, such as administrative limitations and their position in relation to existing forest complexes. The potential for forest establishment on the subject areas was assessed, and in accordance with the analyses carried out, only those parcels were included where rational management could be organised and which are suitable for afforestation.
Mid-term Program of Afforestation of Non-forested Areas of PE ‘Vojvodinašume’ for the Period 2022–2030
| Year | Conclusion of the Government of the Republic of Serbia (ha) | Extended Reproduction (ha) | TOTAL (ha) |
|---|---|---|---|
| 2021/2022. | 38,24 | 110,61 | 148,85 |
| 2023 | 10,58 | 23,57 | 34,15 |
| 2024 | 9,75 | 30,44 | 40,19 |
| 2025 | 23,77 | 49,81 | 73,58 |
| 2026 | 29,14 | 56,94 | 86,08 |
| 2027 | 36,48 | 67,85 | 104,33 |
| 2028 | 40,37 | 69,73 | 110,10 |
| 2029 | 61,12 | 71,84 | 132,96 |
| 2030 | 50,58 | 91,71 | 142,29 |
| Total | 300,03 | 572,50 | 872,53 |
For the successful regeneration and cultivation of quality young growth of a new stand, as well as for the preservation of the authentic gene pool of the most important autochthonous forest tree species, in natural regeneration, it is necessary that preparatory works are harmonised with the periodicity of abundant seed production of the parent stand.
Natural regeneration of forests from seed is mostly applied in mixed forests of hardwood broadleaves, i.e. in pedunculate oak, ash, and hornbeam forests, which are the most widespread in the area of Ravni Srem, and to a very limited extent in the river valleys of Bačka and Banat. Pedunculate oak forests in Ravni Srem are extremely valuable and represent unique forest communities on both the national and European scale. Although it is the principal forest tree species under the given stand and habitat conditions, pedunculate oak is biologically the weakest, bearing in mind the fact that it is the most difficult to regenerate. The reasons for the impeded natural regeneration of pedunculate oak are numerous, the most important of which are as follows:
Seed yields are less frequent in comparison with other species. Under our conditions it bears fruit at intervals of every second to every fourth year, while hornbeam and field ash, as competing species, bear fruit every year or every second year;
The young growth of pedunculate oak, being a distinctly heliophilous species, requires a lot of light and living space for growth and development, and therefore poorly tolerates shading by competing tree species;
In the first years of life it grows more slowly in comparison with competing species;
It is characterised by heavy seed, so that it is able to seed naturally only a part of the soil surface which lies in the immediate vertical projection of the crown;
The young growth poorly tolerates prolonged retention of flood waters;
Natural regeneration is endangered by venison, small rodents, harmful insects, and phytopathogenic fungi.
All measures implemented in stands during the process of regeneration through shelterwood fellings, tending and protection are directed towards creating optimal conditions for the regeneration and survival of pedunculate oak during the first years of growth and development.
The preparatory cut of the shelterwood fellings is carried out two years prior to the planned beginning of the regeneration of pedunculate oak, as the principal tree species, in the year of the expected seed yield. On this occasion, surplus trees of competing forest tree species which bear abundantly, such as ash, hornbeam, field maple, wych elm and others, are removed. For the purpose of maintaining mixed stands, i.e. successful regeneration of these species in the desired proportion of mixture, it is sufficient in the preparatory cut to leave three to five mature trees per hectare, spatially evenly distributed across the area.
In this phase of work it is necessary to select and visibly mark three to five trees of the principal tree species per hectare, which will be preserved for the purpose of protecting biodiversity and landscape appearance.
After the preparatory cut, site preparation for the regeneration process begins. The successful occurrence and development of pedunculate oak seedlings requires the provision of favourable light conditions, which implies the removal of the understorey layer from the stand. The understorey layer is removed in two phases, depending on the dimensions (diameter) of the individuals. Understorey with a diameter of more than 7 cm is cut with chainsaws, and the stumps, for the purpose of suppressing sprouting capacity, are coated with a chemical agent. From the felled wood material, small-sized firewood is produced. Understorey of smaller dimensions, less than 7 cm in diameter, is removed mechanically, by forest mulchers, which, in aggregate with tractors, move between the parent trees of the stand. The understorey is removed on the entire regeneration area in two passes, during which the understorey and the logging residue generated during the preparatory cut are mechanically shredded.
The species that form the understorey are characterised by strong sprouting capacity. From their stumps, strong and dense shoots develop very quickly, which, together with herbaceous weeds, create competitive relations with the cultivated plants. For the purpose of providing conditions for the occurrence and development of future pedunculate oak seedlings, the suppression of developed shoots and weed vegetation is carried out by applying herbicides based on glyphosate.
After the completed site preparation, in the year of abundant seed yield of pedunculate oak and natural seeding of the part of the soil surface located within the vertical projections of the crowns of the parent trees, seed is sown (reseeding) on the remaining part of the soil.
For the purposes of reseeding, under conditions of interrupted canopy of parent trees, quality pedunculate oak seed (selected, qualified and seed of known origin) is collected in registered seed facilities, as well as in clonal and generative plantations established in the area of the Forest Estate “Sremska Mitrovica”.
After the successful completion of natural seeding and artificial reseeding of acorns, the regeneration cut is carried out. In this way, the canopy of the stand is opened, thereby creating favourable conditions for the occurrence and development of oak seedlings. The remaining trees, by their shading, prevent excessive weed occurrence, protect the seedlings from excessive insolation and overheating, and at the same time, if necessary, provide additional seeding of the soil until final successful regeneration. In cases when the year of abundant seed yield of accompanying species coincides with the acorn yield, during the regeneration cut all remaining trees of these species are removed, and otherwise they are removed in the year after abundant seed production.
With the appearance of oak seedlings, the implementation of regular tending measures begins, which in the very first year already includes illumination of the young growth. Illumination of pedunculate oak young growth is carried out manually and chemically. During manual illumination, plants of accompanying species, which occur in large numbers and thus hinder the proper development of the seedlings of the principal tree species, are cut with billhooks. Depending on the representation and developmental stage, competing species can also be suppressed by selective herbicides, which are applied in appropriate solution concentrations with water by means of atomizers. In the second year, mapping is carried out by establishing sample plots, on which the individuals of oak young growth are counted for the purpose of assessing the success of regeneration. Regeneration is considered successful if there is on average one plant per square metre on the regeneration area, i.e. ten thousand plants per hectare.
After determining successful regeneration, the final cut is carried out, when only three to five standing trees of the principal tree species per hectare remain on the regeneration area, in accordance with FSC standards for forest certification.
On sites where pedunculate oak is in its ecological optimum in the area of Srem, the long-term projection of forest management is primarily directed towards the production of quality assortments through the application of thinning as a tending measure. The effects of tending are determined on permanent experimental plots, primarily in young stands, whose development is in accordance with changes in the ecosystem. Thinning is the principal tending measure in forests, the aim of which is to provide, by cutting, sufficient space and conditions for the development of trees which are of the highest quality in both biological and technical terms.
In the floodplains of large rivers, selected planting material of poplars and willows is used for afforestation, characterised by intensive increment and short rotation. Willow plantations are established on former clear-cut areas, in river inundations and on non-forested sites with increased soil moisture. Selected clones have been introduced into production, mostly belonging to the species Salix alba L., distinguished by rapid growth and resistance to diseases. By planting several selected clones in mixture on the same sites, greater biological stability of these plantations is achieved and the risk of major damage caused by various biotic and abiotic factors is reduced.
Autochthonous poplars have not found application in the use of planting material for the establishment of production plantations on larger areas. An exception is black poplar, which was sometimes planted in riparian forests as well as in the Deliblato Sands. Interest in more extensive planting of poplars appeared in parallel with the expansion of the use of softwood broadleaves in wood processing (Rončević et al., 1999).
The first intensive plantations of hybrid poplars Populus × euramericana (Dode) Guinier were established with selected Italian cultivars, of which the most well-known and still widely used is clone I-214. Later, a series of domestic clones of eastern cottonwood Populus deltoides, selected at the Poplar Research Institute (now the Institute of Lowland Forestry and Environment), entered into use, the most notable of which are listed with the following parent numbers: Bora; B-81; Pe 19/66; Antonije; 665; 4/68; S 1-3; S 1-5; S 1-8; S 6-36; NS-1; NS-2. In addition to the mentioned clonal cultivars, the Hungarian hybrid cultivar Populus × euramericana Pannonia (M-1) is also present to a significant extent, which, along with clone I-214, is the most widespread cultivar in production. It is characterised by a high ability of cutting rooting and resistance to bark canker disease Dothichiza populea Sacc. et Br.
The establishment of poplar plantations has primary importance in the overall technology of plantation establishment. The determination of the basic elements of the plantation establishment process is conditioned by the prior examination of site conditions, as well as by the choice of the purpose of the plantation, i.e. the desired production objective. Depending on the above parameters of establishment technology, the cultivar (clone), the method and the choice of planting material are determined as the basic elements in the process of plantation establishment (Rončević et al., 2008).
Two basic types of planting are applied – classical or shallow planting of rooted seedlings at a depth of about 60 to 80 cm, and deep planting of unrooted seedlings at a depth of about 2.5 m. Planting density is determined by the production purpose (technical wood or biomass), the selected cultivar and the site. Biomass is produced in “dense plantations” with 3,500 to 14,000 plants per hectare, when a rotation (production cycle) of four to eight years is planned. For the production of technical wood, the most commonly used planting spacings are: 3.0 × 6.0; 4.25 × 4.25; 5.0 × 5.0; 6.0 × 6.0; and 7.0 × 7.0 m. In the case of the last two spacings, thinnings as tending measures are not applied.
Tending of seedlings is an important part of the overall technology in the cultivation of softwood broadleaves. In floodplain areas, tending measures are to some extent conditioned by the occurrence and duration of floods, and are therefore less intensive compared to plantations in protected areas without floods. In plantations with incomplete establishment and tending technology, soil is most often partially tilled at establishment by ploughing between the rows of stumps, which in more extensive application of technology may be omitted. After planting the seedlings, in the following years weeds are partially suppressed by hoeing around seedlings, disc harrowing or by applying herbicides. Tending is applied during the first few years until crown closure, when poplars by creating shade protect themselves from the proliferation of understorey and weed vegetation. In intensive plantations, soil is completely tilled during establishment, which in the first few years enables the implementation of tending and protection measures (disc harrowing, protection against insects, protection against plant diseases, etc.), while after crown closure the understorey and weeds are most often suppressed by mulching, but also by herbicides. In addition to soil tillage and protection, other tending and silvicultural measures are also carried out, such as pruning of branches and thinning.
Pruning of branches is an important silvicultural measure, implemented in order to obtain higher-quality wood assortments. It is carried out several times, depending on the biological characteristics of the cultivated cultivars, and may be corrective or by removing entire whorls of branches. It is not recommended to remove more than one third of the assimilation surface of the seedling.
Thinnings provide adequate living space for the plants in plantations and in this way create conditions for faster growth and development of the remaining trees, thereby achieving the production of higher-quality and more valuable assortments. Thinnings should be carried out in a timely manner, depending on the age and the cultivated cultivar (around the sixth to eighth year), because delayed thinnings do not produce the expected effects.
The high importance of wood production in intensive plantations of softwood broadleaves is indicated by data on the results of this production in PE “Vojvodinašume”. Considering the total forested area, artificially established stands of clonal poplars participate with 22.8% by area, 19.5% by volume, and 41.4% by volume increment. When the contribution of clonal willows is added to that of clonal poplars, these species participate in the growing stock with 22.5% and in the increment with 43.6%.
Previous experience has confirmed that once selected cultivars, i.e. clones, cannot be a permanent solution for the successful establishment and cultivation of poplars and willows. Therefore, the creation of new selections and their testing in field experimental plantations is the subject of constant and long-term work of specialised institutions. The result of many years of successful cooperation are cultivars with great genetic potential in terms of adaptability and productivity, which, with appropriate tending and protection measures, at the end of the rotation provide high yields per unit area.
