Indonesia’s more than 120 million ha of forest are considered a global biodiversity hotspot. Over-exploitation, land conversion, fires, and natural disasters have degraded almost 13 million ha. In response, the government has launched various restoration programs, aiming to reduce greenhouse gas emissions and decrease vulnerability to disasters like floods, landslides, and droughts. Indonesia aims to restore 12 million ha of forests and 2 million ha of peatlands by 2030. Seeding is a cost-effective alternative to planting seedlings, suitable for large-scale restoration, especially in remote or labor-limited areas. Success depends on species selection, seed quality, land preparation, timing, and maintenance. Seed encapsulation in briquettes or balls can be adapted for aerial seeding using drones or helicopters. Biofertilizers and hydrogels can improve germination and survival. Medium- to large-seeded species generally perform better in seeding applications. Land preparation (clearing and soil loosening at the sowing point or plot) and optimal sowing time (early-mid rainy season) are critical for success. Weeds are controlled around seedlings typically for up to three years until plants are established. Seeding costs about half as much as planting polybag seedlings for the same number of surviving plants. Further research is needed to optimize seeding practices for various species and site conditions.

Temperate broadleaf forests occupying river floodplains of the southern United States are rich in tree species diversity, with various species of bottomland oaks (Quercus spp. L.) often comprising a primary overstory component in these forests across the region. Comprehensive research to support development of seeding as a method for artificially regenerating bottomland oaks began in the early 1980s and quickly advanced to produce reliable practices for establishing oak-dominated stands. Large-scale forest restoration was initiated across the region during the late 1980s at which time bottomland oak seeding practices were adapted for broad scale use due to their relatively low costs. This manuscript presents a synthesis of basic bottomland oak ecology, factors leading to degradation of bottomland oak sites and stands, favored techniques and practices for restoring bottomland oak forests through seeding, factors that limit success and impose risks upon seeding projects, and silvicultural principles for seeding bottomland oaks in the southern United States.

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.

This article is aimed as a basic introduction to conifer somatic embryogenesis for someone with a general interest in applications of this technique and/or who is interested in starting some practical work in the field. We also present data from an example study on individual trees’ ability to initiate somatic embryogenesis in Norway spruce (Picea abies). A total of 158 trees were each tested for ability and relative competence to initiate somatic embryogenesis from the zygotic embryos by observing the initiation frequency for ten zygotic embryos from each individual tree. Furthermore, we conducted a case study by following the process for SE plant formation for a selection of 48 cell lines that were monitored through the SE developmental pathway, with data collected on the success rates at different steps. We then evaluated the relative importance of different steps for the outcome of plant formation and yield.

In the context of variable climate conditions, selecting high-quality Sessile oak (Quercus petraea (Matt.) Liebl.) reproductive material is crucial for sustainable forestry. This research aimed to assess the genetic potential of 86 selected plus trees by analyzing seedling morphological characteristics and quality indices. The ultimate goal was to identify the most promising genotypes for establishing seed orchards. Root collar diameter (D), seedling height (H), stem dry mass (SDM), and root dry mass (RDM) were measured under uniform nursery conditions. The following derived indices were calculated: seedling height to root collar diameter ratio (H/D), stem dry mass to root dry mass ratio (SDM/RDM), and Dickson’s quality index (DQI). Descriptive statistics, one-factorial analysis of variance (ANOVA) and Pearson correlation analysis were performed as well. The results showed significant variability in all observed morphological characteristics and quality indices among half-sib families, confirming a strong genetic influence. Correlation analysis indicated strong positive relationships between DQI and all primary morphological characteristics (r≤0.94), confirming DQI as the most effective integrative indicator of seedling quality. The combined ranking of the half-sib families, based on DQI, H/D, and SDM/RDM, identified those with optimal morphological characteristics, including an optimal H/D ratio, balanced SDM/RDM, and a high DQI value. The identified superior half-sib families represent valuable genetic material for the establishment of future seed orchards, thereby contributing to the production of better-quality seedling material and to improved forest ecosystem resilience under climate change.

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.

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).