This review covers most of the published literature on potassium (K) fertilization in bareroot seedbeds with the intent to concentrate on the southern United States. The timing and rates of K fertilization for bareroot seedlings are often based on logic and myths and, as a result, K recommendations vary considerably. Some recommend bareroot pine seedlings be fertilized with twice as much K as nitrogen (N) while others apply less than 100 kg ha^-1. It was determined that several long-held claims about K fertilization are invalid. Nursery seedbeds do not need to contain four times as much available K as N and the belief that extra K fertilization will increase freeze tolerance or drought resistance of non-deficient seedlings is invalid. There are no data to support the claim that K fertilization increases root growth or assists in the formation of terminal buds. For sandy seedbeds, there is no need to apply K before sowing. Adding extra K during the fall does not increase seedling morphology or seedling performance when loblolly pine seedlings, at lifting, have more than 0.5% K in needles. A reduction of K fertilization can be achieved by reviewing foliar tests prior to K top-dressings.

The location of the Bolivarian Republic of Venezuela in the tropical region of northern South America, in the Northern Hemisphere, with a total area of 91.64 million ha, of which 49.6 million correspond to natural forests (54.12 % of the national territory). Venezuela shows a series of geographic advantages that allow a rapid growth and development of the trees in comparison with the temperate zones where the growth is extremely slow. However, the occurrence of deforestation processes has intensified in a sustained way in the recent history of the country.

In the period from 1920 to 2008, the loss of 26.43% of the forested area has been recorded. Likewise, in the period 1975-1988, deforestation was estimated at 216,000 ha year^-1, equivalent to 2.9 million ha in 13 years (Catalan 1992). Deforestation has now increased to worrying levels and according to FAO estimates (2010), in Venezuela, a forested area of more than 288.000 ha year^-1 is deforested.

In the middle of the 20^th century several public and private institutions began an important effort to reforest areas of sandy soils of scarce depth on a bed of highly impermeable clay. With erosion processes generated as a result of strong winds that causes severe damage to the little existing vegetation. It was expected that with the passage of time this region could become a desert in the oriental plains of Venezuela. This is how the Maderas del Orinoco Companies (CVG - PROFORCA), the Venezuelan Corporation of Guayana (CVG), Smurfit Kappa Cartón of Venezuela, San Carlos Forestry Development, Masisa. Propulso, among others, started in different regions of the country the establishment of plantations for various purposes. For this they have used fast growing forest species such as: Pinus caribaea var hondurensis, Eucalyptus Urophylla, Acacia magnium, Caraipa llanorum, Tectonia grandis, Hebea brasiliens, Gmelina arborea, Erisma uncinatum, among others. At present, a reforested area of 650.000 ha has been reached. This has favored the protection of natural habitats by reducing the pressure for exploitation and use of the forests.

The legal framework established in the new National Constitution, approved in 1998, is based on decrees of 1825-1829 of the Liberator Simón Bolívar and classifies the territory in diverse forest areas establishing a modern environmental conservation policy. A historical summary and the current legislation with the classification that promises a rational management of the national territory is presented.

This study applied a total energy approach to model seedling growth for container-grown loblolly pine (Pinus taeda L.). Seedlings were grown in three container stocktypes representing a range of cavity volume and density patterns. These seedlings were grown under both controlled greenhouse and outside compound environmental conditions under well-defined cultural conditions. Models for temperature and light ranges were created from work on the ecophysiological performance and morphological development of loblolly pine to these atmospheric conditions. A PhotoThermal data set was created by generating hourly averages of these two environmental variables during the growing season. Light and temperature data were integrated, each weighted equally, into PhotoThermal hours (PT_H) to assess the crop growth response. Loblolly pine seedling growth in both the greenhouse and outside compound was directly related to PT_H. Seedling growth was also related to the container type with the largest cavity volume and lowest cavity density having the greatest growth per PT_H. Application of the PhotoThermal model is discussed for growing seedlings in an operational program having multiple production steps, delivery dates and nursery locations.

The present work demonstrates the effects of moist cold stratification on seed dormancy breaking in Hawthorn (Crataegus monogyna Jacq.). We also examined the fruit and seed morphology. Mature and ripe fruits were collected, the pulp removed and the seeds (stones) left in the sun to dry for three days. Four temperature regimes viz. 4°C, 6.5°C (natural conditions where the fruits were harvested), 10°C and 20°C were used for stimulating seed germination under total darkness. For each treatment, there were four replicates with 50 seeds incubated in a plastic container between two layers of moist sand at 15%. At the end of the experiment, non-germinating seeds were tested for viability using Tetrazolium chloride (TZ).  After 4 months, the final germination (FGP) was expressed as a percentage of the total number of seeds in each treatment. The fruits of Hawthorn were 14.9 ± 0.73 mm long and 15.1 ± 0.84 mm in diameter and weigh 2.05 ± 0.28 g. The seeds were 8.29 ± 0.43 mm long and 6.75 ± 0.39 mm in diameter and weigh (0.25 ± 0.04) g. The thousand-fruit weight was 2,000 g and of the thousand-seeds weight was 280 g. The statistical analysis indicated significant effect (p < 0.0001) of treatment on seed germination. Dormancy in this species was broken most effectively by cold stratification at 4°C and under natural conditions with 76% and 67.5% of FGP, respectively. Most of the nongerminated seeds of C. monogyna were viable (dormant) as judged by TZ.

This paper provides first report for European white elm potential for biomass production. High density plantation (71,428 seedlings ha^-1) was established on spring 2012^th near Belgrade from one-year-old seedlings, produced from seed. Weed control and irrigation was practiced only in the first growing season, without fertilization. In a three year rotation, European white elm plants in a high density plantation reach average height of 341.11 cm and average root collar diameter of 31.9 mm, with height increase of about 1 m, diameter increase of about 1 cm per year. At the end of three-years rotation total produced biomass was 90 odt ha^-1, or 30 odt ha^-1 year^-1. Biomass production of European white elm is in range or higher compared to traditionally used species, indicating the need for further research on planting material, plant density and cultural practices.  

The conference on "Reforestation Challenges" took place on 20-22 June 2018 in Belgrade, Serbia, at Faculty of Forestry of the University of Belgrade. This was the fourth meeting on reforestation challenges, after three successful meetings in three previous years (2015 – Belgrade, Serbia; 2016 – Krakow, Poland; 2017 – Session at the IUFRO Congress in Freiburg, Germany). This Conference, like the first one, was organized by Faculty of Forestry of the University of Belgrade, IUFRO (specifically by IUFRO Unit: 3.02.00 - Stand Establishment and Treatment), and Reforesta Scientific and professional Society.

Beech is the most important tree species in forests of Serbia. However, despite its significance, the taxonomic status of beech in Serbia is unclear. Morphology of the cupules can be successfully used to distinguish species and within species taxa. In this paper we report results on cupules morphology, measuring the same attributes reported by Mišić (1955): 1) Length of the longest valve of cupule, 2) Width of that valve (at widest point), 3) Distance between base of the longest valve and peduncle, 4) Length of cupule without peduncle, and 5) Length of peduncle. The length of cupule and peduncle length from 12 populations in Serbia are in the range reported for Fagus sylvatica in Serbia and western Eurasia. Results of cluster analysis shows a grouping of populations in two groups:1) the southeast group, and 2) group consist of populations from northwest, east and southeast of Serbia. Populations from this southeast group also consist the group of populations on altitude over 850 m, indicating presence of ecotypes. The exception is population from Stara Planina (1,520 m a.s.l.) which is grouped with populations from altitudes under 850 m.

This paper adds to the evidence base in the discussion to what extent woodland development can be a means to restoring the land affected by mining. We investigate the formation of vegetation communities in sites on a former Sulphur quarry in the Roztochya district of the Lviv region in Ukraine to answer the research questions: How can the formation of vegetation cover affect the disturbed sites and what knowledge can be used in restoration practices elsewhere? We perform an experiment examining which types of vegetation are suitable for the restoration. We explore the influence of restored vegetation and re-emerged woodlands have on the process of soil rehabilitation and the increasing organic substance in it. We examine the impact of various combinations of vegetation on land rehabilitation. Explaining the degree of colonization of waste land by various types of vegetation helps us to reveal the trends of regenerative processes and identify the most promising for restoration tree species in affiliation with the ground vegetation. The results can assist decision-makers in choosing compatibility alliances of vegetation to sustain regeneration processes. Although this research is location specific, the knowledge developed can to a degree be applied to similar places, in the temperate zone.

Early growth and survival of tree seedlings is often poor on reclaimed coal surface mines in Appalachia. Biochar produced in bioenergy generation has potential for use as an amendment to improve seedling performance. Mine soil was collected from a recently reclaimed coal surface mine in Wise County, Virginia and mixed with loblolly pine (Pinus taeda L.) sawdust biochar, simulating application rates of 2.3, 11.2 and 22.5 Mg ha^-1. Unplanted leaching columns and 4 L tree planting pots were filled with these biochar-soil mixtures, plus controls of pure mine soil and pure biochar. For the tree planting pots, additional pots were created where the biochar was applied as a topdressing at the same application rates as in the mixtures. One-year-old seedlings of both American sycamore (Platanus occidentalis L.) and black locust (Robinia pseudoacacia L.) were planted. Unplanted leaching columns were leached with collected rainwater for six months to simulate weathering. Trees were grown for one growing season. Black locust had higher average above-ground dry woody biomass (24.4 g) than American sycamore (17.0 g), and also higher below-ground biomass (61.0 g compared to 30.2 g). The pure biochar produced greater average below-ground biomass (99.9 g) than the pure mine soil (46.9 g). All of the biochar treatments produced greater average above-ground woody biomass (19.1 g – 33.4 g) than the pure mine soil (10.9 g). After weathering, biochar provided less available soil phosphorus, calcium and iron than the mine soil itself while increasing soil carbon and organic matter. High (22.5 Mg ha^-1) biochar applications increased soil volumetric water holding capacity to 18.6% compared to 13.4% for pure mine soil. Naturally-occurring herbaceous biomass in the pots was negatively correlated with above-ground woody biomass at r = -0.483. Topdressing and full incorporation of biochar were not significantly different in their effects on biomass. Results suggest that pine biochar either broadcast at 2.3 - 22.5 Mg ha^‑1, or mixed in planting holes with backfill soil, will promote faster above-ground growth and larger root systems in seedlings in mine soils. Further studies should test these methods in the field over multiple years and further refine recommendations of the rate of biochar to use and how best to apply it. New systems are being developed in Appalachia to produce biofuels and biochar from local biomass and to recycle biochar into the land base to enhance future biomass productivity. Applying 4 L of biochar mixed with the backfill of newly-planted trees is the top recommended practice for tree performance.