Extensive disturbance to the ecologically, socially, and economically important pine (Pinus spp. L.) forests of the Mediterranean region has created a strong need for forest restoration throughout the region. Seeding could potentially be a viable option for regenerating some of the 10 pine species that occur in the region, especially the fire-adapted serotinous species, but previous seeding efforts have been marked with inconsistent success. From our synthesis of available literature and practical experience, we briefly summarize the history of applied trials and pine seeding research, examine the factors that determine pine seeding success, and discuss what we have learned that can make seeding an ecologically and economically viable approach to pine forest establishment in the Mediterranean region. Future refinement of autonomous drones for seed delivery, selection of favorable sowing microsites, and improvement of seed coating technologies that minimize seed predation and support seedling establishment will support “precision restoration” practices that promise to advance pine seeding to an operational scale in the Mediterranean region.

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.

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.

The present study was carried out in 16rd year afforestation sampled from southern Turkey of Taurus cedar (Cedrus libani A. Rich) and Crimean juniper (Juniperus excelsa Bieb.). Variation, competition and correlation were examined based on seedling height and stem diameter at base data collected from two samples areas 500 m² each. Growth performances were different at the areas for the species, while averages of Taurus cedar (223.6 for height and 65.3 mm for stem diameter at base) had higher than Crimean juniper (106 cm and 58.5 mm) in total areas. The results emphasized importance of species selection in afforestation. Significant (p<0.05) differences between areas and species were found according to results of analysis of variance. Positive and significant phenotypic correlation (p<0.05, r>0.52) was estimated between the characteristics in both species and areas. It could be used for tending in afforestation areas.

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).