The experiments were led to study the effect of pretreatments and their duration on germination behavior of three Acacia species A. cyanophylla Lindl., A. farnesiana L. and A. decurrens Willd. by analyzing three parameters (GP: germination percentage; MGT: germination mean time (days) and GRI: germination rate index) for various times of incubation (5, 10 and 15 days) in Petri dishes. Pre-sowing treatment included immersion in concentrated sulphuric acid for 60, 90 and 120 minutes. The sowing in distilled water (Control) had no positive effect on the germination induction. Generally, the seed pretreatments were very useful to improve germination. Time of immersion significantly (P < 0.0001) affected GP, MGT and GRI in all species. Increasing the duration of sulphuric acid immersion (from 60 to 120 min) improved the germination percentages for A. cyanophylla and A. farnesiana seeds to (98% and 99%), respectively. However, increasing this duration had a negative effect on A. decurrens seed germination, reducing the final germination percentage from 97% at 60 minutes of immersion to 43% at 120 minutes.

In the past, the entire region of Poland was overgrown by forests. Due to economic changes, the forest cover was reduced to 40% in the 18th century and 21% after the Second World War. After the war, Polish foresters undertook considerable efforts to increase the forest cover to 30.8% by 2015. Polish forests are characterized by the dominance of oligo- and mesotrophic coniferous species (68.7%). This include the pioneer species, Scots pine. It covers approximately 60% of the area. The species composition of Polish forests determined the dominance of artificial regenerations. However, the currently prevailing direction of forest culture is natural regeneration. This tendency is related to “greening” of the forest management, the priority of PERSONAL durability over productivity and culture of multifunctional forests. A natural or seminatural direction of forest culture is being promoted. Renewal of the species such as fir, beech, oak, or spruce from the last stages of succession have always taken place in a natural manner, whereas the statistics are generated by the dominant species preferring open areas during renewal. Currently, the scale of natural regenerations of the pine is increasing. It is increasingly common to value the favorable economic aspect of natural renewal of the species, and the experience of practitioners supported by scientific research increase the likelihood for success. In Poland, the majority of methods of regeneration proceedings (forest cutting) and the law are directed at obtaining and promoting natural renewal. Independent of the concept of natural renewal promotion, the location of Poland in the intermediate climate zone, between the influence of oceanic and continental climates, resulted in the formation of valuable tree stands with high flexibility and tolerance to growth conditions. They are divided into seed stands, excluded stands, and timberlands. Thus, Poland is in possession of a great base for seed collection. At the beginning of 1990s, a rapid need for container seedlings occurred due to numerous disasters (wind-broken trees, gradations). Currently, in Poland, 17 field nurseries are in operation producing 1–10 million seedlings. In 1992, Poland received a loan from the World Bank to conduct afforestations and the “National Program for Increasing the Forest Cover” was started. The main objective of the plan is to increase the forest cover to 30% in 2020 and 33% in 2050. Within the program, it is planned to include vegetation of the natural succession in the area of approximately 80,000 ha. 

Two pH experiments were conducted at a sandy, bareroot loblolly pine (Pinus taeda L.) nursery in Texas. A sulfur trial (0, 813, 1626, 2439 kg ha^-1 of elemental sulfur) was installed to determine if lowering soil pH would result in nutrient toxicity symptoms and affect seedling morphology. Although soil acidity in the sulfur study ranged from pH 3.9 to pH 5.0, none of the treatments resulted in micronutrient toxicity and none affected height growth, root-collar diameter, root mass, shoot mass or the root-mass ratio (root dry mass/total dry mass). Acidifying soil with sulfur increased leaching of calcium, potassium, magnesium, manganese and zinc but there was no effect on seedling morphology. The objective of the liming trial (0, 813, 1626, 3252 kg ha^-1 of dolomitic lime) was to determine if increasing alkalinity would result in an iron deficiency and reduce seedling growth. As expected, applying lime increased the calcium and magnesium levels but had no effect on soil levels of iron, phosphorus, potassium, sulfur, zinc and sodium. However, the root-mass ratio was reduced by applications of dolomitic lime (pH ranged from 5.3 to 6.0). Differences in soil properties (i.e. plot location) had a greater effect on seedling morphology than lime applications. Foliage levels of manganese and boron were reduced by the highest rate of lime and sulfur, respectively.

Oriental beech established in the Hyrcanian forests, is a valuable tree whose habitats are constantly exposed to destructive factors which change the nutritional status of soil and leaves. Analysis of foliar elements is a commonly used method for studying tree nutrient status that indicates site's quality. Foliar analysis of beech (Fagus orientalis Lipsky) was carried out in Kojour (Mazandaran) in order to assess the nutritional balance of trees in a damaged forest site (a direct result of livestock grazing and anthropogenic perturbations). Sunny leaves of dominant trees were taken in August and foliar concentration of macroelements, N, P, Ca, K and Mg were measured. The diagnosis and recommendation integrated system (DRIS) analysis was applied for evaluating the nutritional state. The results showed deficiency with K and P in disturbed stands. Nutrient Balance Index (NBI) indicated imbalance in nutrient status. These results suggest the usefulness of DRIS for foliar tissue analysis as an indicator of nutritional status and elemental stress in natural forests.

Direct seeding has been considered a forest restoration option for centuries. Over the past half century, the use of this practice has declined in developed countries as forest regeneration programs have advanced with the production of quality seedlings that can successfully establish restoration sites. Direct seeding is being reconsidered as a restoration option as the potential size of the worldwide forest restoration program has grown because of massive deforestation in third-world nations and due to global climate change. This review examines direct seeding from a number of perspectives. First, merits of using this practice in restoration programs are defined. Major merits of this option are that it can be done quickly, over hard to reach and large disturbed areas, and at a relatively low cost. Second, current research findings from restoration programs are discussed. The major finding is that seedling establishment rates are low (i.e. typically around 20% of seeds planted) due to site conditions, seed predation and vegetation competition, and field performance (i.e. survival and growth) is lower than planted seedlings. Third, operational practices for the application in restoration programs are reviewed. To successfully conduct direct seeding programs practitioners need to consider seedbed receptivity, seed distribution and seeding rate. Fourth, potential new practices are presented. Some of these new practices attempt to create a more effective means to disperse seed across the site, minimize seed predation or create a more favorable microsite environment. This review provides a synthesis of what is known about direct seeding, thereby allowing practitioners to make a rational decision of whether to apply this practice towards their forest restoration program.

Plantations offer a high potential to respond to the increasing pressure on forests to deliver social, economic, and environmental services. Exotic tree species have a long history of use in plantation forestry, mostly because of their improved productivity compared with that of native species. Because of their impacts on land management and the environment, questions arise regarding the compatibility of exotic tree plantations with sustainable forest management (SFM), the overarching paradigm driving forest legislations in Canada. Our objectives were thus to i) briefly review the historical and current use of exotic tree species in Canada, ii) identify the social, economic and environmental issues related to the use of exotic tree species in Canadian forestry, based on sustainable forest management criteria, and iii) identify perspectives related to the use of exotic tree species in the sustainable management of Canadian forests. Results show that six out of ten Canadian provinces do not have specific legislations to control the use of exotic tree species for reforestation within their borders. The use of exotic tree species is mainly controlled through third-party certification agencies. Exotic tree species represent a small proportion of the planted seedlings in Canada and Norway spruce is the most common one. The use of exotic tree species is compatible with sustainable forest management criteria used in Canada, but forest managers must take into account several issues related to their use and maintain a social license to be entitled to plant them. Issues are highly dependent upon scale. The zoning of management intensity could provide environmental, economic and social benefits, but costs/benefits analyses should be carried out. The concept of naturalness could also be useful to integrate plantations of exotic species in jurisdiction where SFM strategies are based on ecosystem management principles. Monitoring of hybridization and invasiveness of exotic species must be included in landscape analyses to forestall loss of resilience leading to compromised structural and functional ecosystem states. The use of exotics species is recognized as a tool to sequester carbon and facilitate adaptation of forests to global changes, but it is necessary to carefully identified contexts where assisted migration is justified and disentangle planned novel ecosystems coherent with global changes generated by assisted migration from those emerging from invasive species forming undesired states.

The three major functions of a potting medium for plant production is to provide support, to retain water and nutrients, and to allow oxygen diffusion to the roots. A potting medium should meet the requirements of practical plant production such as: to be available and ready at all times, easy to handle, lightweight and to produce uniform plant growth. Constituents such as natural soil, peat, sand, perlite and vermiculite are commonly used as substrates for container plant production. Nevertheless, these materials might be fully or partially replaced by various organic or inorganic wastes, thus achieving environmental and economic benefits. This study presents a synthesis of results extracted from many trials on waste materials as potting media substitutes for the seedlings production of the following native plant species: Pinus halepensis, Quercus ilex, Quercus macropleis and Ceratonia siliqua. The studied waste materials were either organic or inorganic components including: spoils of peridotite, raw rice hulls, coconut fiber and kenaf (the ground stem of the plant H. cannabinus L). The experimental potting media tested were: peat:perlite (3:1), a common medium used for seedling production, peat:spoils of peridotite (3:1), peat:rice hulls (3:1), peat:rice hulls (1:1), peat:coconut fiber (1:1), kenaf (100%) and kenaf:peat:rice hulls (3:1:1). The main physical (water retention characteristics, bulk density, particle density, total porosity) and chemical (N, K, Ca, Mg, soluble P, exchangeable cations, pH and loss on ignition) properties of each potting medium were measured. For each plant species the following seedling quality parameters were assessed: morphological characteristics (shoot height, root collar diameter), shoot and root biomass, Dickson's quality index and shoot and root nutrient concentrations. Then seedlings were planted in the field and their survival and growth was monitored. The feasibility of replacing peat or perlite with various waste materials as well as their effect on seedling quality and field performance are discussed.

The afforestation of bare lands, sandstone, and skeletal terrains are one of the biggest challenges forestry scientists face. These terrains are characterized by specific ecological conditions that are generally unfavorable for the growth of woody species. These are usually shallow soils, unstable, and poor in nutrients and moisture. The characteristics of these habitats make said terrains unfavorable for the regeneration of forest vegetation. It is therefore crucial for the success of afforestation to gain detailed knowledge and understanding of environmental conditions. Only after the detailed research and study of field conditions can the selection of species for afforestation, including selection of species characteristics and technology of planting, begin. Mistakes made during previous establishments of green areas are one of the main reasons some species of vascular flora have disappeared. This alone expresses the undeniable importance of knowledge on habitat specifics, work schedule, and selection of species for afforestation. With the aim to implement the future afforestation within the planned scope, it is necessary to organize an effective nursery production of seedlings with characteristics that will suit the environmental conditions of bare lands, sandstones, and skeletal terrains whose afforestation is planned.

This article focuses on the creation of seed sources for forest planting or seeding with a special focus on clonal seed orchards supporting planting Norway spruce and Scots pine in Sweden. Supporting long-term breeding and low input breeding is discussed. The focus is not on clonal forestry, although this is discussed. Natural regeneration is not dealt with and provenance choice only briefly. It is not a manual or literature review and focus on my own evaluations, but more detailed reviews can be found in the literature cited. It is intended to contribute some familiarity with many of the relevant genetic aspects on forest plantations.

In the keynote, major reforestation challenges in Scandinavia will be highlighted. The following countries make up Scandinavia: Iceland, Norway, Sweden, Finland and Denmark. For Iceland, with only a forest cover of 2%, a major reforestation challenge is the deforestation and overgrazing in combination with land degradation and extensive soil erosion. The challenges include the conflicts with livestock farmers. For centuries the commons were used for sheep and horse grazing. However, more and more of farmer grazing land have been fenced up, allowing the regeneration of birch and plantations of other species to increase. With a forest cover of 37% and 69% respectively, for decades a major reforestation challenge in Norway and Sweden has been the risk of seedling damages from the pine weevil. Unprotected seedlings can have a survival rate of less than 25% after being planted. Pine weevils feed on the bark of planted young seedlings at regeneration sites. If the seedling is girdled, it will not survive. In Sweden, and soon in Norway, pesticides have been forbidden. In the keynote, new methods and technology will be presented based on non-chemical protection. In Finland, with a forest cover of 75%, a major reforestation challenge is linked to the forest structure. The structure of Finnish forestry includes many private forests in combination with small regeneration sites. This implies a situation where logistics and methods for lifting and field storage provide a major challenge in order to preserve seedling quality until the planting date. Due to this situation, new logistic systems and technologies are being developed in Finland, including new seedling cultivation programs (including cultivation under Light Emitting Diodes (LEDs)) to match the access of fresh planting stock to different planting dates. In Denmark, with a forest cover of 13%, a major reforestation challenge is the possibility of future plantations based on a wide range of relevant species. For this to become a realistic option, new methods and technology have to be developed in reforestation activities that support this possibility. These methods and technology should make it possible to not be limited to certain species due to problems and restrictions during field establishment. This due to the prospect of establishing stable, healthy, and productive stands of various forest species that can be adapted to future climate change.