The rapid decline of whitebark pine (Pinus albicaulis Engelm.), a keystone species of upper subalpine and treeline elevational zones across many of the higher mountains of the western United States and Canada, has prompted the development of restoration strategies and practical restoration applications. Whitebark pine has been federally listed as ‘threatened’ in the United States, which elevates the restoration imperative. Seeding potentially provides a low-cost means of establishing the species in remote areas with limited access and/or land use constraints, but this restoration tool still lacks sufficient advancement to ensure operational success. We present an overview of whitebark pine ecology, outline the factors leading to its decline, summarize ongoing conservation efforts and restoration strategies, and review the available literature on seeding whitebark pine to identify barriers that challenge successful operationalization. Informing and advancing land management for conservation of whitebark pine will require refining seeding protocols by monitoring and reporting on trials to mitigate the main barriers to this application. Additional research is required to reduce seed pilferage by rodents, improve sowing techniques, identify favorable sowing microsites for improved seeding outcomes, and develop a reliable supply chain for seed resistant to introduced disease.

Brazil contains 15–20% of the world’s biodiversity, with forests originally covering 88% of its territory, now reduced to about 58%. The country has committed to restoring at least 12 million ha of forests by 2030. Seeding is a cost-effective method for tropical forest restoration, widely used in Brazil, but its effectiveness for species-rich forests is still uncertain due to low establishment rates for many species. Most seeding research has involved relatively few species, and many are short-lived, raising concerns about long-term ecosystem development. Invasive grasses and loss of native species are major barriers to restoration. There is a significant gap between seed demand for restoration and current production capacity. Seed dormancy can be a barrier to rapid establishment; treatments to break dormancy must be tailored to species and site conditions. Large-seeded species and those with certain functional traits (e.g., deep roots, storage cotyledons) perform best. The main sowing methods are broadcast, line, and seeding holes, each suited to different site conditions. Muvuca is a notable technique involving a diverse seed mix for large-scale restoration. High sowing rates are often necessary due to low emergence and establishment rates. Fencing and ant control (especially leaf-cutter ants (Atta spp. and Acromyrmex spp.)) are critical to protect seeds and seedlings from herbivory and physical damage. Ongoing weed control is essential for successful establishment. Seed availability, low establishment rates, and competition with invasive species are the major limiting factors.

Sweden is known for its coniferous forests, but two oak species occur in the south, Quercus robur and Q. petraea, in pure stands or mixed with other species. Oak forests have declined due to land use changes, industrial forestry favoring conifers, and browsing by wild ungulates. Oak grows best on deep, fertile soils but can survive on a range of sites, supporting high biodiversity, and have cultural, aesthetic, and recreational value. The temperate climate is expected to change, and the increased temperature and rainfall potentially will favor oak over other species. Historically, high sowing rates and low-cost labor contributed to successful oak establishment; planting has since become the main method. Interest in seeding is returning, but predation and germination risks make it less certain than planting. Site preparation and high seeding density can help mitigate losses where heavy acorn predation by rodents is expected. Competition from other vegetation requires intensive mechanical site preparation and periodic cleaning operations. Seeding is more successful on abandoned farmland with less rodent habitat and where agricultural practices can be used for site preparation and maintenance. Expensive fencing is required for protection from browsing, especially in the first 10 years. Restoration success requires regular assessment and management, with lower oak seedling densities acceptable if other species are present. Lack of experience among managers is a barrier; more information and communication about successful practices are needed.

Container characteristics can influence seedling morphology and quality by affecting root development and seedling growth during nursery production. This study evaluated the effects of two container types, Plantagrah and Hiko, on the morphology and quality of one-year-old seedlings of Quercus frainetto, Q. petraea, and Q. pubescens. Twenty seedlings per species and container type were randomly selected. Morphological traits, dry mass traits, rooting intensity (ROIN), and Dickson Quality Index (DQI) were assessed. The effects of species, container type, and their interaction were analyzed using two-way ANOVA, while multivariate variation was explored using principal component analysis (PCA). Significant differences among species were observed for most measured traits. Quercus petraea generally exhibited the greatest diameter, height, and seedling dry mass, whereas Q. frainetto showed the lowest values for most growth-related traits. Container type significantly affected diameter, fine root dry mass, total root dry mass, H/D index, and DQI. Seedlings grown in Hiko containers exhibited larger diameters, greater root biomass, lower H/D values, and higher DQI values than seedlings grown in Plantagrah containers. Significant interactions between species and container type were detected only for shoot:root ratio, indicating that container effects were generally consistent across species. PCA showed clearer separation among species than among container types. The results indicate that container type influences several important indicators of seedling quality and that Hiko containers provide favorable conditions for the production of high-quality seedlings of the studied oak species during the first nursery year.

Mexico is the country with the highest number of species of the genus Quercus, but there has been little research on their propagation in nurseries. Quercus crassifolia is distributed across more than 50% of the national territory; however, no studies have been conducted to document its morphological growth and plant quality in nurseries for reforestation and forest restoration. Some of the key factors in plant production, principally in a technified system, are the selection of containers, substrates, and fertilizer doses. This study therefore evaluated two container sizes, two mixtures of organic substrates, and two doses of controlled-release fertilizer. After nine months of growth in the nursery, morphometric parameters of the plants were recorded, and quality indices were determined based on these values. The results showed that container size, substrate choice, and fertilization dose all influenced the quality of the plant produced. With both fertilizer doses, the 25:25:50 substrate mixture of fresh pine sawdust, composted pine bark, and moss peat produced plants with the highest values of height, diameter, and shoot, root, and total dry biomass. Considering the factors evaluated, the use of 200 mL containers with the aforementioned substrate mixture and the addition of 7 g L^-1 of controlled-release fertilizer will produce plants of Quercus crassifolia suitable quality for use in reforestation.

On January 15, 2025, American Forests and Planscape convened the 2025 Reforestation Summit at the Google.org offices in San Francisco, California, U.S. This collaborative event combined American Forests’ decades-long experience in post-fire reforestation planning and implementation with Planscape’s innovative, community-driven forest restoration planning platform. The objective of the summit was to initiate the development of an integrated reforestation tool(s) to support an end-to-end pipeline approach to post-fire reforestation. The summit brought together more than ninety leading scientists—both in-person and virtually—from across the United States to advance the state of reforestation science and practice (Figure 1). We first provide a brief summary of the 2025 Reforestation Summit, then describe the decision support tools (DSTs) that were discussed at the summit, and lastly discuss the next steps and challenges for building out an integrated reforestation tool(s).

We present a novel way of estimating embryo lethals using doubled haploid (dihaploid or DH) female gametophytes grown in tissue culture. This DH-based lethals estimate is hypothesized to be lower than the more common method where lethals are estimated from one generation of selfing. The chief reasoning is the early mortality spike observed for selfed embryos of larch and other genera in the Pinaceae. This early mortality spike occurs at the stage when diploid embryos embed into haploid female gametophyte tissue. However, this stage is missing for DH embryos which grow in a petri dish thus the DH lethals estimate is hypothesized to be lower compared to seed counts. This DH estimate is based on 20,000 haploid female gametophytes cultures from which two surviving diploidized embryos were recovered. Lethals based on diploidized haploids (DH) have not been reported for a conifer previously because, aside from larch, only a few conifer species continue female gametophyte development in absence of pollen. Our chief finding is that, contrary to our hypothesis, the DH-based lethals estimate was similar to lethals estimated obtained from selfed seeds in published studies. Thus doubling haploid female gametophytes can be used to estimate embryo lethals when diploidization is conducted on a massive scale.

An adult tree of Larix decidua Mill., European larch, was produced from doubling one haploid female gametophyte. Whether this tree can produce normal male meiocytes is the crucial question. This adult’s pollen mother cells (PMCs), or male meiocytes, were squashed and stained. Male meiosis was normal and no abortive pollen grains were observed. This female gametophytic apomict of a conifer, a dihaploid adult, is 100% homozygous yet also reproductively competent with normal male meiosis and functional male pollen. Here we show that doubled female gametophytes can produce embryos and reproductively competent adult trees. This shows a way to gain rapid homozygosity and produce completely inbred lines for larch. This is a novel breeding shortcut reported for the first time for a conifer species.

The production of high-quality planting material for the most commonly used woody species in urban greening is a complex challenge influenced by several factors. One of the key factors in seedling production, especially in pots, is the selection of an appropriate substrate. Testing various substrates for different species is an ongoing process. In Bosnia and Herzegovina, four of the most frequently used taxa for urban planting in the region were tested: two varieties of northern white-cedar (Thuja occidentalis L.), namely 'Smaragd' and 'Columna', as well as European boxwood (Buxus sempervirens L.) and Forsythia (Forsythia × intermedia). One-year-old rooted cuttings were transplanted into two-liter pots using five different substrates: plain soil, compost, lumbrico humus, peat, and a combination of all these substrates. At the end of the growing period, morphometric parameters of the seedlings were measured, and based on these measurements, quality indices were determined. The results showed that each species and variety responded differently to the various substrates. Generally, the best results for most of the taxa were obtained using locally produced lumbrico humus and compost. However, some seedlings, such as Thuja occidentalis 'Smaragd', exhibited similar growth characteristics across all substrates tested. Considering the varying costs of the substrates, it is possible to plan the production of these seedlings with significantly better quality while also reducing production costs.

Sonderegger pine (Pinus x sondereggeri H.H. Chapm.), the natural hybrid of longleaf (Pinus palustris Mill.) and loblolly pine (Pinus taeda L.), commonly occurs in longleaf pine seedlots grown in forest tree seedling nurseries in the southeastern United States. Because longleaf pine seedlings have a grass stage with minimal epicotyl development (< 1 cm), the initiation of stem growth (12 to 15 cm) in longleaf pine seedlots has been used to indicate that hybridization with loblolly pine (Pinus taeda L.) has occurred. Sonderegger pine seedlings are typically culled at the nursery due to observations of poor form and wood quality after outplanting. However, research documenting Sonderegger pine seedling morphology has not been published for more than 60 years, and to our knowledge, no seedling quality assessments have been made. To better understand how morphological traits of longleaf and loblolly pine are expressed in hybrid seedlings, stem length, hypocotyl length, and root collar diameter (RCD) were compared among one-year-old container-grown longleaf, loblolly, and seedlings visually classified as Sonderegger pine. Sonderegger pine seedlings had a range of stem development, with most (62%) seedlings measuring < 12 cm tall. Some pure longleaf pine seedlings had up to 10 cm of stem elongation, but the cause of early height growth in these seedlings is unknown. More than 90% of Sonderegger pine seedlings met or exceeded RCD recommendations for planting loblolly (≥ 3.2 mm) and longleaf pine (≥ 4.75 mm).