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.

Meeting forest restoration challenges relies on successful establishment of plant materials (e.g., seeds, cuttings, rooted cuttings, or seedlings, etc.; hereafter simply “seedlings”). The Target Plant Concept (TPC) provides a flexible framework that nursery managers and their clients can use to improve the survival and growth of these seedlings. The key tenets of the TPC are that (1) more emphasis is placed on how seedlings perform on the outplanting site rather than on nursery performance, (2) a partnership exists between the nursery manager and the client to determine the target plant based on site characteristics, and (3) that information gleaned from post-planting monitoring is used to improve subsequent plant materials. Through the nursery manager–client partnership, answers to a matrix of interrelated questions define a target plant to meet the reforestation or forest restoration objectives. These questions focus on project objectives; site characteristics, limiting factors, and possible mitigation efforts; species and genetic criteria; stocktype; outplanting tools and techniques; and outplanting window. We provide examples from the southeastern United States, Hawai‛i, and Lebanon on how the TPC process has improved performance of seedlings deployed for reforestation and forest restoration.

Involvement in forest restoration programs across North America for the past 40 years, dealing with nursery cultural practices, operational seedling quality programs and defining seedling performance on restoration sites has given me a unique perspective, which I have used to examine programs from both a research and operational perspective. Certain biological patterns and themes continually appeared across these programs and this paper discusses five of the most common themes.Learning To Think Like a Tree – It is important for practitioners to develop an understanding of the ecophysiological performance of tree species in a nursery or forest restoration program in order to understand how seedlings grow. This understanding leads to sound biologically based cultural decisions to improve seedling performance.Stress and the Cyclical Nature of Stress Resistance – Seedlings are exposed to stress when environmental conditions limit their performance. Plants develop physiological resistance attributes to mitigate stress and these attributes change throughout the seasonal cycle. Practitioners have developed hardening cultural practices that enhance seedling stress resistance, thereby improving seedling quality and site restoration success.Seedling Quality: Product versus Process – Seedling quality is an important component of successful restoration. Typically seedling quality is examined from a product perspective, thus defining functional integrity, operational grading or sometimes performance potential. An alternative approach monitors the process, with product quality the final output.Planting Stress and Seedling Establishment – Planting stress is prevalent in forest restoration. The act of planting can result in a seedling that does not have proper connections for water movement through the soil-plant-atmosphere continuum (SPAC). Seedling water stress, reduced growth performance and potentially death can occur if this SPAC connection is not restored.Seedling Death: Sometimes Simple and Sometimes Complicated – Seedling death can occur in restoration programs as a result of environmental extremes or incorrect management practices. Some problems can be easy to diagnose and correct practices can be implemented to rectify the problem. Other times, issues are complicated and it can be a challenge to define the potential factors causing seedling death.

Surface mining causes major destruction of natural landscapes and ecosystems. The most fertile, surface soil layer is lost permanently, together with vegetation, wildlife, and micro flora. Post-mining areas are characterized with diverse edaphic, topographic, hydrographic conditions, which complicate land restoration. Successful establishment of forest ecosystems on such land depends mostly on selection of tree species. The chosen plants must be capable of tolerating a wide range of acidity, fertility, moisture, and have potential to ameliorate such substrates for more demanding species. But, reforestation of heavily damaged ecosystems, such as post-mining areas, demands a new approach in seedlings production. This new approach takes into account specific requirements of habitat and integrates them into “targeted production of planting material”. A good strategy for successful reforestation of post-mining areas is the input of organic matter (compost, mulch). Also, current knowledge and experiences emphasize the potential of beneficial microorganisms such as, mycorrhizal fungi (MF) and plant growth promoting rhizobacteria (PGPR). The majority of studies that deal with beneficial interactions between trees and microorganisms are focused on the mycorrhiza, while plant growth promoting rhizobacteria are less present in silviculture. In this study, the focus is on the reforestation challenges of two mining basins, Majdanpek and Kolubara and suggests beneficial microorganisms as potential solution. The study presents results of several years’ researches on plant response to the presence of mycorrhizal fungi and PGPR. The substrates used for plant growth were Majdanpek and Kolubara mine deposals. Mycorrhizal seedlings were grown in Majdanpek mine deposal, and at the end of the experiment they had 30% higher biomass in comparison to control (seedlings without mycorrhiza). Seedlings linked with fungi had a higher survival rate. Deposals from Kolubara Mining Basin were used as a substrate for seedlings inoculated with PGPR. In the first experiment, Scots pine and Norway spruce were inoculated with Azotobacter chroococcum, Bacillus megaterium, B. circulans, B. licheniformis, B. pumilus, B. amyloliquefaciens. Inoculation resulted with higher biomass production (Scots pine 43%, Norway spruce 34%). Similar results were obtained in the second experiment where Scots pine and black locust were inoculated with Bacillus licheniformis, Aeromonas hydrophila, Pseudomonas putida and Burkholderia cepacia. Both species had higher biomass (around 20%) in comparison to un-inoculated control. The results confirmed the fact that early establishment and successful growth of vegetation on devastated areas depends on the presence and activity of soil microbes. Microorganisms as a “nature’s solution” pose the potential to alleviate reforestation challenges of anthropogenic devastated landscapes. Their presence and activity is crucial for ecosystem stability. In areas with compromised balance, their introduction is justified action for achieving the goal of long term ecosystem sustainability.

Increased summer drought and wildfires as a consequence of continuing climate change are expected to lead to disturbance of Mediterranean ecosystems. Seedlings recruitment is sensitive to both stresses and, therefore, any adaptation and restoration strategy devised to protect these forests should take into account a careful study on their effects on seedling development. As a substantial fraction of net primary productivity of forested ecosystems is channelled in the belowground compartments, the knowledge of how roots behave under stressful conditions becomes of primary importance to select the right management strategy to be implemented. This work tries to enlighten the events occurring in the fine root portion of the root system in young seedlings of three co-existing oak species (Quercus ilex, Quercus trojana and Quercus virgiliana) under controlled conditions. We have made a comparative analysis of the effect of these two stresses, alone or in combination, with the aim to evaluate the tolerance level of these seedlings and, therefore, to obtain an indication of their recruitment potential in the field. The parameters investigated were biomass and a number of morphological traits. Data obtained suggest that a decrease in diameter could be part of a tolerance strategy in all three oaks tested together with a reduction of root length. In addition, tolerance to water shortage could require a reduction of carbon allocated belowground, in particular in the very fine roots, which leads to an overall reduction of the root system dimension. Q. trojana seedlings seem to be the fastest in resuming growth after stress interruption but a good recovery was also found for the remaining two oak species. Although our study provides interesting information regarding a possible tolerance strategy taking place in the fine root compartment when seedlings of these three oak species undergo water stress and fire treatment, more information is needed before any suggestion can be made as to which species would be best suited to make these forests more resistant to global changes.

Most of the Iberian Peninsula has a Mediterranean climate, which strongly determines the objectives, strategies and techniques of forest restoration. This communication addresses a main forest restoration challenge for Mediterranean-climate woodlands in Spain: the transformation of old monospecific pine plantations to more diverse, resistant and resilient forest systems. I also present how afforestation methods and some ideas on plant quality have evolved in the last 80 years. Productivity of Mediterranean forests is low, which discourages private owners to invest in woodland management. Therefore, woodland management strongly relies on public funds. Large-scale afforestation in the 20th century has created huge areas of monospecific pine plantations, which have been under thinned and are very simple structurally with almost no understory. The stands are very prone to fires, diseases and drought dieback. However, old pine plantations can facilitate the establishment of late successional trees and shrubs when properly thinned. Therefore, pine plantations are an opportunity for restoring several types of oak-dominated forests at a large scale and resources should invested to preserve and gradually transform these plantations into mixed forests. Funds should be invested in thinning progressively rather than to plant new areas. In many plantations close to oak forests remnants, thinning is the only management required. However, many pine plantations are far from seed sources and enrichment plantations together with thinning are needed. Extensive enrichment plantations are expensive. Therefore, an option is to develop a network of small islets strategically placed inside pine plantations and properly managed as seed foci to foster pine plantation colonization. This option is cheaper than conventional extensive low-density enrichment plantations but research is needed to assess its effectiveness for pine plantation transformation.

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.

Over the past five decades, researchers in the southern United States have been working with nursery managers to develop ways to reduce the cost of producing seedlings. In this regard, the Southern Forest Nursery Management Cooperative (at Auburn University in Alabama) has helped reduce hand-weeding costs and losses due to nematodes and disease. As a result, nursery managers are able to legally use a variety of registered herbicides and fungicides for use in pine and hardwood seedbeds.  Other changes over the last three decades include a reduction in the number of nurseries growing seedlings, a reduction in the number of seedlings outplanted per ha, an increase in the number of container nurseries, an increase in the average production per nursery, an increase in production by the private sector, growing two or more crops after fumigation, the development of synthetic soil stabilizers, applying polyacrylamide gels to roots and the use of seedling bags and boxes for shipping seedlings.

The concern for environmental protection has existed since the time of first human civilization. As society develops, the chain of changes during the natural flow of processes in ecosystems has been supplemented by a new link - pollutants. They have an effect on all other members of the ecosystem (changes may be visible immediately or harder to spot), which leads to an extremely complex relationship with nature. The values of some parameters of pollutants reached an alarmingly high level. The tendency to reduce the risk of air, soil, water, plant, and animal pollution to a tolerable limit, which would salvage the environment and most importantly human health, became a global problem. Heavy metals as pollutants have been an interest of researchers for their conduct, especially in forest ecosystems, which has been expressed in the previous year's more than ever. With its numerous toxic effects, heavy metals are endangering the existence of plant species that live in already contaminated environments. This is all an argument regarding the fight of modern society that the emission of polluted materials gets reduced in order to avoid multiple negative effects, which can endanger the existence of living organisms in general, as an argument for the continuation of numerous researches that are conducted in this area. The monitoring of heavy metals is of significant importance because their toxicity and accumulations are vital for the ecosystem. Polluted soils can be reduced and they can restore their function using physical, chemical, and biological techniques. Physical and chemical methods are very expensive and cause mainly irreversible changes, thus destroying biological variety. The biological recovery of contaminated soil represents an efficient method of reducing health risks for both mankind and the ecosystem.  For this purpose, biological indicators are used. Numerous researches have led to improvements of the initial idea about using plants as a remediation of the environment and the removal of different contaminants from contaminated medias into promising technologies of environmental protection under the title "Phytoremediation". This technology consists of the reduction of concentrations of polluted materials in polluted soils, water, or air. Plants have the ability to store, degrade, or eliminate metals, pesticides, solutions, explosives, and crude oils. Its derivatives and various other contaminants form mediums that contain them. This paper especially considers methods of the possibility of the usage and application of plants in restoring soil contaminated by heavy metals as well as other pollutants.

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.