Important Forestry Species Research Articles

New linkage maps for the Cupressaceae species Chamaecyparis obtusa and Thujopsis dolabrata var. hondae and comparison with the linkage map of Cryptomeria japonica

ABSTRACT Comparative mapping studies, which can determine whether the genome structure differs among genera, have yet to be conducted in Cupressaceae. This study analyzed three important forestry species in Japan: Cryptomeria japonica, Chamaecyparis obtusa, and Thujopsis dolabrata var. hondae. To date, linkage maps have only been constructed for C. japonica. We constructed the first linkage maps for C. obtusa and T. dolabrata var. hondae using double digest restriction-site associated DNA sequencing (ddRAD-Seq) data, expressed sequence tag-derived simple sequence repeat (EST-SSR) markers, and single-nucleotide polymorphism (SNP) markers designed from homologous unigenes obtained from RNA-seq data. The lengths of the linkage maps were 1,835 cM (1,981 markers) for C. obtusa and 1,833 cM (1,295 markers) for T. dolabrata var. hondae. A total of 11 distinct linkage groups were identified in these maps, corresponding to the haploid number of Cupressaceae. Using four published linkage maps for C. japonica, we then constructed a composite linkage map with 7,784 markers. Finally, the three linkage maps were compared using 207 SNP markers designed from homologous unigenes. Although most markers were mapped to the same LG despite representing different species, indicating strong synteny. The high level of interspecific and intergeneric synteny and macro-collinearity detected in Cupressaceae were similar to those of other trees. We also detected three major chromosomal rearrangements between but not within subfamilies, which may have been caused by the taxonomic distance. This is the first example of comparative mapping for Cupressaceae species.

Tetraploid Induction with Leaf Morphology and Sunburn Variation in Sorbus pohuashanensis (Hance) Hedl

Sorbus pohuashanensis (Hance) Hedl. is an important forestry species valued for its ornamental, medicinal, and ecological properties. Polyploidy breeding is an important method of germplasm innovation; however, polyploidy induction and phenotypic variation caused by chromosome doubling in S. pohuashanensis are poorly understood. In this study, S. pohuashanensis seeds were used to explore the effects of different colchicine concentrations, cold stratification times, and seeds from different sources on polyploidy induction. Ploidy levels of the regenerated plants were determined by flow cytometry. The results showed that the tetraploid induction effect of S. pohuashanensis seeds was significantly affected by colchicine concentration, and the highest tetraploid induction rate of 24.75% was achieved by immersion in 0.2% (w/v) colchicine for 48 h. After 2 years of induction, 77 tetraploid plants were obtained. Compared to diploids, tetraploid plants showed significant variations in plant height, leaf morphology (apical leaflet width, middle leaflet width), and diameter of the middle petiole. The stomatal size and chloroplast number increased with chromosome doubling whereas the stomatal number and density decreased. In addition, significant differences in the percentage of sunburn associated with ploidy changes were observed. This study provides a technique for tetraploid induction of S. pohuashanensis seeds, showing the variation in traits caused by polyploidization and the effect of chromosome doubling on sunburn resistance. Tetraploidy induction provides a new direction for S. pohuashanensis germplasm innovation.

Localization of TWISTED NEEDLES Locus on Linkage Map of Japanese Cedar (Cryptomeria japonica D. Don)

Sugi (Cryptomeria japonica D. Don) is an important forestry species in Japan. C. japonica ‘Spiralis’ is a mutant with twisted needles. The mutant is called Yore-sugi in Japan and is known as ‘Rasen’ in other countries. The twisted trait is regulated by a dominant gene called TWISTED NEEDLES, and it can be identified by observing the needles within 1 to 2 months after germination. The TWISTED NEEDLES gene may be useful for improving the efficiency of genome editing technology in C. japonica. In this study, we attempted to identify the linkage group of the TWISTED NEEDLES locus and investigate markers that sandwich this locus using the mapping family. First, we identified the linkage group containing the TWISTED NEEDLES locus based on the distortion from the expected segregation ratio using 32 mutant individuals of the mapping family. The segregation distortion showed that the TWISTED NEEDLES locus was located on the 11th linkage group (LG11). Next, a linkage map of LG11 was constructed based on genotype data from the single-nucleotide polymorphism (SNP) markers and double digested restriction site-associated DNA sequencing (ddRAD-seq) using 123 individuals of the MMY-1 family. On this map, six markers were located at the same position as the TWISTED NEEDLES locus. To investigate markers sandwiching the TWISTED NEEDLES locus, a partial linkage map around the TWISTED NEEDLES locus was constructed using 643 individuals of the MMY-1 family. The TWISTED NEEDLES locus was located in the 0.6 cM region between gSNP01822 and the other five markers (Contig_4705-179, Contig_4518-93, Contig_4398-118, gSNP04056, and Contig_4970-113).

Climate Change Projections for Bioclimatic Distribution of Castanea sativa in Portugal

The chestnut tree is an important forestry species worldwide, as well as a valuable food resource. Over recent years, Portugal has shown an increasing trend in chestnut tree area, as well as increases in production, hinting at the socioeconomic relevance of this agro-forestry species. In this study, bioclimatic indices are applied to analyse the spatial distribution of chestnut trees in mainland Portugal, namely growing degree days (GDD; 1900–2400 °C), annual mean temperature (AMT; 8–15 °C), summer days with maximum temperature below 32 °C (NTX), and annual precipitation (PRE; 600–1600 mm). These indices are assessed for the baseline (IBERIA01, 1989–2005) and future climates (EURO-CORDEX: 2021–2040, 2041–2060, and 2061–2080) under two forcing pathways (RCP4.5 and RCP8.5), also taking into account the chestnut tree land cover. For the baseline, the GDD showed only 10% suitability for chestnut tree cultivation in southern Portugal, whereas much higher values are found in the north of the country, and at higher altitudes (50–90%). For the AMT, higher elevation areas in northern Portugal show almost 100% suitability. Concerning NTX, the suitability reduces from the west (100–90%) to the east (40%). Regarding PRE, the suitability is heterogeneous throughout the territory, with areas under 50%. A new Chestnut Suitability Index (CSI) was then computed, which incorporates information from the four previous indices. The CSI reveals a suitability ranging from 100 to 75% in the north, while central and southern Portugal show values from 25 to 50%. For future climates, a progressive reduction in CSI was found, particularly for RCP8.5 and in the long-term period. Changes in bioclimatic conditions may restrict the 100% suitability to a narrow area in the north of the country. These reductions in chestnut bioclimatic suitability may have socio-economic and ecological implications for the management of the important agro-forestry species.

Interannual adjustments in stomatal and leaf morphological traits of European beech (Fagus sylvatica L.) demonstrate its climate change acclimation potential.

The current projections of climate change might exceed the ability of European forest trees to adapt to upcoming environmental conditions. However, stomatal and leaf morphological traits could greatly influence the acclimation potential of forest tree species subjected to global warming, including the single most important forestry species in Europe, European beech. We analysed stomatal (guard cell length, stomatal density and potential conductance index) and leaf (leaf area, leaf dry weight and leaf mass per area) morphological traits of ten provenances from two provenance trials with contrasting climates between 2016 and 2020. The impact of meteorological conditions of the current and preceding year on stomatal and leaf traits was tested by linear and quadratic regressions. Ecodistance was used to capture the impact of adaptation after the transfer of provenances to new environments. Interactions of trial-provenance and trial-year factors were significant for all measured traits. Guard cell length was lowest and stomatal density was highest across beech provenances in the driest year, 2018. Adaptation was also reflected in a significant relationship between aridity ecodistance and measured traits. Moreover, the meteorological conditions of the preceding year affected the interannual variability of stomatal and leaf traits more than the meteorological conditions of the spring of the current year, suggesting the existence of plant stress memory. High intraspecific variability of stomatal and leaf traits controlled by the interaction of adaptation, acclimation and plant memory suggests a high acclimation potential of European beech provenances under future conditions of global climate change.

Effects of Thinning on the Growth and Relative Change in the Diameter of a Mahogany Plantation

Honduras mahogany (Swietenia macrophylla King) is an important forestry tree species in low altitude areas in central and southern Taiwan and has good potential for sustainable forestry in tropical regions. The aim of this study was to understand changes in the diameter at breast height (DBH) and stand structure of large-leafed mahogany. A lower layer thinning experiment was conducted in 2011 in a 14-year-old mahogany plantation in Guanmiao, Tainan City, Taiwan. Four zones of heavy, moderate, and light thinning, as well as a control were established and DBH surveys were conducted in 2011, 2012, 2013, 2015, and 2017 at tree ages of 14, 15, 16, 18, and 20 years, respectively. The DBH trend was observed using simple linear regression with continuous slope values and the Weibull density function was used to match the distribution of diameter classes and compare the average DBH growth under different thinning treatments. The results showed that the growth of small diameter trees remained slow after felling, whereas medium-intensity thinning could result in a similar increase in DBH for larger diameter trees within a certain period. The stand structure remained skewed (c < 3.6) six years after harvesting and spatial allocation needed to be re-adjusted to alleviate competition pressure. The mean periodic growth of a single tree DBH after thinning was significantly different from that of the un-thinned trees at tree ages of 16, 18, and 20 years (p value < 0.05). However, the difference between thinning treatments was not significant and the effect of moderate thinning and intensive thinning was a similar in terms of promoting the mean periodic growth of single wood.

A century old regeneration problem of Shorea robusta Gaertn. F. in south Asia: SWOT analysis (Review)

Shorea robusta (Sal) Gaertn. F. a commercially and ecologically important forestry species of south Asia, is facing serious regeneration problem since last century. The continuously diminishing natural regeneration is associated with numerous abiotic and biotic factors, like edaphic, micro-climatic, physiological, genetic, anthropogenic, pathogens, insect-pests, etc. Following a good seed year and timely commencement of monsoon, Sal seeds germinate readily, and thousands of seedlings cover the forest floor. Subsequently, these get afflicted with die-back syndrome impeding shoot growth. Regular fire incidences during hot and dry season further aggravates the problem. Among biotic factors, Hoplocerambyx spinicornis , Cylindrocladium floridanum and Inonotus shoreae causes severe heartwood decay, blight and dieback leading to mortality. Moreover, over-exploitation, illegal felling, grazing, etc., have severely depleted the Sal forest. This review systematically explores the factors contributing to regeneration problem in S. robusta and opines appropriate silvicultural operations and management strategies for the conservation of Sal forests through SWOT (Strengths, Weaknesses, Opportunities and Threats) analysis. We emphasized on the ecological aspects, soil characteristics, micro-climatic factors and importance of associated species to develop sustainable management regimes. Highlighting all facets of Sal regeneration problem and SWOT assessment, we suggest comprehensive weaknesses and threat perceptions to formulate strategies to seal the gaps.

Structural Root-Plate Characteristics of Wind-Thrown Norway Spruce in Hemiboreal Forests of Latvia

An increase in extreme weather events is predicted with increasing climate changes. Changes indicate major problems in the future, as Norway spruce (Picea abies L. Karst.) is one of the most important forestry species in Northern Europe and one of the most susceptible to damage from extreme weather events, like windstorms. Root architecture is essential for tree anchorage. However, information of structural root-plate volume and characteristics in relation to tree wind resistance in drained deep peat soils is lacking. Individual tree susceptibility to wind damage is dependent on tree species, soil properties, tree health and root-plate volume. We assessed the structural root-plate dimensions of wind-thrown Norway spruce on freely drained mineral and drained deep peat soils at four trial sites in Latvia, and root-plate measurements were made on 65 recently tipped-up trees and 36 trees from tree-pulling tests on similar soils. Tree height, diameter at breast height, root-plate width and depth were measured. Measurements of structural root-plate width were done in five directions covering 180° of the root-plate; rooting depth was measured on the horizontal and vertical axes of root-plate. Root-plate volume was higher in drained peat soils in comparison to mineral soils, and root-plate width was the main driver of root-plate volume. A decreasing trend was observed in structural root depth distribution with increasing distance from the stem (i.e., from the center to the edge of the root plate) with a greater decrease in mineral soils.

An improved pollen number counting method using a cell counter and mesh columns

BackgroundThe determination of pollen number is important in evolutionary, agricultural, and medical studies. Tree species of the Cupressaceae family cause serious pollinosis worldwide. Although Japanese cedar (Cryptomeria japonica) is the most important forestry species in Japan, it is also the biggest cause of pollinosis in the country. Japanese cedar trees have been selected for growth speed and superior morphological traits and then cloned. These clones may vary in their pollen production, but there has been little research on how many pollen grains are produced by a single male strobilus (flower). A recently reported method for counting pollen number with a cell counter was applicable to Arabidopsis species and wheat, but was not suitable for Japanese cedar because the strobilus does not open with heating (e.g. 60 °C, overnight).ResultsHere, we report an improved pollen counting method for Japanese cedar using a precise and rapid cell counter in combination with home-made mesh columns. The male strobilus was gently crushed using a pestle. Large and small debris were then removed using 100- and 20-μm mesh columns, respectively. We successfully detected pollen sizes and numbers that differed between two clones using this method.ConclusionsThis improved method is not only suitable for counting pollen from Japanese cedar, but could also be applied to other species of the Cupressaceae family with hard scale tissue covering the pollen. Moreover, this method could be applied to a broader range of plant species, such as wheat, because there is no need to wait for anthesis and debris can be removed efficiently.

First report of Sydowia polyspora causing disease on Pinus pinea shoots

AbstractThe fungus Sydowia polyspora is frequently isolated from conifers worldwide and is considered a pathogen on several hosts. Stone pine (Pinus pinea) is one of the most important forestry species throughout the Mediterranean basin due to the value of the edible pine nut. Stone pines showing tip dieback, needles with tan‐ to yellow‐coloured lesions and shoot death, observed in stands in Portugal, were sampled for analysis. Fungal colonies covered with cream‐coloured spore masses, were consistently obtained. Morphological and phylogenetic analyses of the ITS rDNA region enabled identification of these isolates as S. polyspora. Inoculation tests showed that the fungus caused lesions on excised P. pinea shoots. The symptoms observed might have a negative effect on pine nut production, and thus, evaluation of the impact of this disease is of relevance to future research. This paper is the first to report S. polyspora causing disease on P. pinea.

Assessment of morphological variation and association studies in Litsea glutinosa (Lour.) C.B. Rob. from Central India

ABSTRACTLitsea glutinosa (Lour.) C.B. Rob., one of the important non-timber forestry species in Central India, is represented by highly fragmented populations and has been drastically reduced for the last 40 years, promulgating government ban on its extraction. In the present investigation, we investigated variation for important morpho-metric traits, i.e. tree height (m), clear bole height (m), girth at breast height (cm), crown radius (m), crown diameter (m), crown height (m), number of primary branches, leaf area (cm2), leaf weight (gm), specific leaf area (cm2/g), bark wt/unit area (g), and their relationship. Investigation revealed existence of high level of variation for clear bole height, crown diameter, girth at breast height, and crown radius. A critical perusal of character correlation and path analysis revealed that tree height followed by crown radius, girth at breast height, and number of branches had the highest positive direct effect on bark weight/unit area. These traits should be included in the selection criteria for L. glutinosa. The observed high estimates of genetic variation for morpho-metric traits are, however, in contrast to the established relationship between genetic variation and population size. Populations of Balaghat and Chhindwara localities should be given due considerations for in situ conservation as they are in viable numbers and grouped in major clusters.

Exogenous succinic acid mediates responses of Larix olgensis A. Henry to cadmium stress

Trace metal contamination of soil is an increasing problem. Organic acid application can restore trace metal elements such as cadmium (Cd) in contaminated soil. Changbai larch (Larix olgensis A. Henry) is an economically important forestry species in northeast China; however, growth is inhibited by severe Cd contamination. We investigated the effects of different concentrations of exogenous succinic acid (SA) on Cd tolerance and physiological and morphological toxicity in L. olgensis seedlings. Seedlings were planted in pots containing Cd-contaminated or uncontaminated Haplic Cambisol. Seedlings in Cd-contaminated soil were treated daily with SA solution at 0, 0.04, 0.2, 1.0, and 2.0 mmol kg−1 of soil for 10, 20 or 30 days. Cd treatment induced seedling damage and significantly increased the relative conductivity and malondialdehyde content of the leaves, inhibiting soluble protein and proline contents, superoxide dismutase and peroxidase activity, chlorophyl fluorescence and pigment content. Decreases in the length, surface area, volume of roots and leaves, and specific root length were also observed. Effects increased in control plants with time. SA treatment also reduced the Cd content of the fine roots and leaves and Mg, K, and Ca contents. Moreover, plant growth was significantly promoted and damage was reversed, especially at 5.0 and 10.0 mmol L−1 SA for 30 days. SA therefore alleviated Cd-induced injury, improving tolerance to Cd stress. SA application combined with afforestation could therefore help restore Cd-contaminated soil in northeast China. Further studies aimed at determining the detoxification mechanism of L. olgensis seedlings are now required.

Optimal Locations of Biomass Logistics Centers for Energy Uses in the Province of Badajoz (Spain)

The forest biomass of the province of Badajoz (southwestern Spain) is around 274,335 tons, which is equivalent to 112,000 toe of energy. Consequently, the quantification, analysis, and mapping of the energy potential from the residual biomass, considering the most important forestry species of the studied province, were performed. Moreover, the optimum locations of biomass logistics centers were established. Results of this study are within the value chain of biomass, regarding to the production, transformation, commercialization, and use of the existing biomass to generate energy, heat, and electricity.

Light-growth responses of Sitka spruce, Douglas fir and western hemlock regeneration under continuous cover forestry

Natural regeneration is crucial for silvicultural approaches based on the continuous presence of a forest cover, or Continuous Cover Forestry (CCF). Light is considered one of the most important factors affecting regeneration growth under canopy cover. Sitka spruce, western hemlock and Douglas fir are important forestry species both in Europe and in North America with potential to be used together under CCF management. Our aim was to develop predictive early-growth models for these species growing beneath forest canopies, and to investigate species differences in terms of shade tolerance.We sampled regenerating trees growing under canopy cover at multiple sites in the UK. We compared alternative asymptotic non-linear models as a function of light availability to simulate the height growth for all species and the diameter growth for Sitka spruce and western hemlock only. We included tree size and intra-regeneration competition as predictors, which affected the asymptotic growth at full light and/or the growth rate at which such asymptote was reached. We also calibrated models of apical dominance ratio (ADR, for all species) and live crown ratio (LCR, for Douglas fir and Sitka spruce only) as a function of light availability, tree size and intra-regeneration competition.Species-specific non-linear models best simulated the light-growth responses (3-points Logistic for Sitka spruce, Michaelis-Menten for western hemlock, asymptotic with offset for Douglas fir). Tree size in all cases increased the asymptotic growth and in two cases also the growth rate. Competition significantly reduced the growth for Sitka spruce and western hemlock, with the diameter growth reduced more than height growth. Both the ADR and the LCR increased with light availability, with species-specific differences for LCR but not for ADR. For Sitka spruce an apical dominance ratio of 1.5 can be used in the field to identify adequate growing conditions. An increasing shade tolerance ranking was found as Douglas fir ≤ Sitka spruce < western hemlock.We conclude that modelling light-growth requires species-specific non-linear functions and that predictions are improved by including size and competition. The developed predictive models for height and diameter growth will allow accurate modelling of the study species in CCF management.

TodoFirGene: Developing Transcriptome Resources for Genetic Analysis of Abies sachalinensis.

Todo-matsu (Abies sachalinensis) is one of the most important forestry species in Hokkaido, Japan and is distributed from near sea level to the alpine zone. Due to its wide spatial distribution, the species adapts to its environment, displaying phenotypes of ecological relevance. In order to identify candidate genes under natural selection, we collected the transcriptome from the female and male flower, leaf and inner bark. De novo assembly with 34.7 Gb of sequencing reads produced 158,542 transcripts from 69,618 loci, whose estimated coverage reached 95.6% of conserved eukaryotic genes. Homology searches against publicly available databases identified 134,190 (84.6%) transcripts with at least one hit. In total, 28,944 simple sequence repeats (SSRs) and 80,758 single nucleotide variants (SNVs) were detected from 23,570 (14.9%) and 25,366 (16.0%) transcripts, which were valuable for use in genetic analysis of the species. All the annotations were included in a relational database, TodoFirGene, which provides an interface for various queries and homology search, and can be accessed at http://plantomics.mind.meiji.ac.jp/todomatsu/. This database hosts not only the A. sachalinensis transcriptome but also links to the proteomes of 13 other species, allowing a comparative genomic study of plant species.

Efficacy of extracts from eight economically important forestry species against grapevine downy mildew (Plasmopara viticola) and identification of active constituents

Downy mildew caused by the oomycete Plasmopara viticola is the most devastating pathogen of grapevine. In this study, extracts of the bark of eight important northern forestry species were screened to find extracts showing activity against this pathogen and to identify the active compounds. Extracts from all eight species showed activity against P. viticola, the most promising, dichloromethane extracts of three Larix species, almost completely protecting grapevine from downy mildew under semi-controlled conditions. Five promising lead compounds were isolated: larixol, larixyl acetate, lariciresinol and lariciresinol acetate from Larix species and 7α,15-dihydroxydehydroabietic acid from Pinus sylvestris. These compounds showed 90%–100% efficacy. Larixol and larixyl acetate or 7α,15-dihydroxydehydroabietic acid are present in significant amounts in Larix or P. sylvestris bark extracts, respectively.The identified active compounds are gained from a renewable resource potentially available in large quantities at relatively low prices, making them interesting candidates for the development of a plant-derived fungicide active against a key pathogen in agriculture, providing an opportunity to the forest industry to transform low value by-products into high value-added, bioactive extracts.

In Vitro Tetraploid Induction from Leaf and Petiole Explants of Hybrid Sweetgum (Liquidambar styraciflua × Liquidambar formosana)

Liquidambar is an important forestry species used to generate many commercial wood products, such as plywood. Inducing artificial polyploidy is an effective method to encourage genetic enhancements in forestry breeding. This report presents the first in vitro protocol for the induction of genus Liquidambar tetraploids based on the established in vitro regeneration system of hybrid sweetgum (Liquidambar styraciflua × Liquidambar formosana). The leaves and petioles from three genotypes were pre-cultured in woody plant medium (WPM) supplemented with 0.1 mg/L thidiazuron (TDZ), 0.8 mg/L benzyladenine (BA), and 0.1 mg/L α-naphthalene acetic acid (NAA) for a variable number of days (4, 6 or 8 days), and exposed to varying concentrations of colchicine (120, 160, 200 mg/L) for 3, 4 or 5 days; the four factors were investigated using an orthogonal experimental design. Adventitious shoots were rooted in 1/2 WPM medium supplemented with 2.0 mg/L indole butyric acid (IBA) and 0.1 mg/L NAA. The ploidy level was assessed using flow cytometry and chromosome counting. Four tetraploids and nine mixoploids were obtained from the leaves. Pre-treatment of the leaves for 8 days and exposure to 200 mg/L colchicine for 3 days led to the most efficient tetraploid induction. Producing 11 tetraploids and five mixoploids from petioles, the best tetraploid induction treatment for petioles was almost the same as that with the leaves, except that pre-culturing was required for only 6 days. In total, 15 tetraploids were obtained with these treatments. This study described a technique for the induction of tetraploid sweetgum from the leaves or petioles of parental material. Based on the success of polyploid breeding in other tree species, the production of hybrid sweetgum allotetraploids constitutes a promising strategy for the promotion of future forestry breeding.

Investigating optimal site conditions for flower bud production in Eucalyptus smithii orchards in South Africa

ABSTRACTEucalyptus smithii is an important commercial forestry species in South Africa. The species’ shy and erratic flowering tendencies hinder its genetic improvement and seed production. Breeders and seed producers are highly dependent on paclobutrazol (PBZ) applications for encouraging flower and seed production in E. smithii orchards. During the summer of 2003/04, an E. smithii flowering field trial series was established across a range of high elevation (1568–1828 m asl), cool temperate (13.8–15.5°C mean annual temperature (MAT)) commercial forestry sites in South Africa. The main objective was to investigate the interaction between PBZ and a range of climatic and landscape factors on E. smithii floral bud (umbel) production. The main aim was to define optimum environmental conditions for E. smithii umbel production and potential orchard establishment. In the fifth and sixth years after planting, 64% and 83% of the control (nil PBZ) grafted trees and 94% and 94% of PBZ-treated trees produced umbels. In the fifth year, PBZ application increased mean (across-site) umbel production per tree by 132%. Regardless of whether PBZ was applied or not, mean umbel production varied markedly across sites. In the absence of PBZ application, E. smithii test orchards located on south-west facing slopes in high elevation (>1550 m asl) areas at the lower end of the applied MAT range were generally the most productive on the basis of umbel crop. The study demonstrated that, through careful site selection, dependency on PBZ to achieve satisfactory umbel production in reproductively mature E. smithii trees may be substantially reduced. Within the elevation and MAT ranges applied in the trial series, E. smithii orchards situated in low positions in the landscape were at high risk of being severely damaged by frosts.

Construction of a core collection and evaluation of genetic resources for Cryptomeria japonica (Japanese cedar)

In order to improve the accessibility of genetic resources, a core collection needs to be constructed and appropriately evaluated. For Cryptomeria japonica, the most important forestry species in Japan, we constructed a core collection derived from 3,203 plus trees. First, genetic redundancy was removed based on SSR genotypes from the plus tree population. One diploid accession from each of the 539 groups that were identified using information on the original growing location was then selected considering the conservation conditions. We defined this population composed of 539 individuals as a core collection for C. japonica, and then evaluated the collection status of this core collection from multiple viewpoints. This core collection proved to contain on average one entry selected per 10 km radius (314 km2) from 10 × 10 km grid squares with an area of more than 40 % covered with C. japonica, and covered more than 85 % retention of all 12 environmental factors affecting plus trees, while maintaining almost the same genetic diversity as the complete set of plus trees. These methods of evaluation from multiple viewpoints, using a geographic information system and genetic markers, were efficient in determining whether the collection of resources was complete, and, if not, where additional efforts for balancing a deficit should be devoted.

Genetic comparison between natural and planted populations of Pinus brutia and Cupressus sempervirens in Syria

There is wide consensus that ongoing deforestation contributes to global warming and poses a threat to species diversity. Less understood is whether the practice of creating plantations might also erode genetic diversity and undermine the genetic structure of tree populations. We tested these hypotheses in natural and planted populations of Pinus brutia Ten. subsp. brutia and Cupressus sempervirens L. var. horizontalis (Mill.), 2 important forestry species in the Mediterranean region. We used plant material from 3 different bioclimatic regions in Syria. Using RAPD markers, we evaluated the genetic diversity and structure of 12 populations of P. brutia (6 natural, 6 planted) and 9 populations of C. sempervirens (3 natural, 6 planted). Expected heterozygosity (He) and percentage of polymorphic loci (PPL) were high in both species (P. brutia: He = 0.241, PPL = 81.2%; C. sempervirens: He = 0.241, PPL = 78.8%). In accordance with our assumptions, plantations of P. brutia manifested significant reduction in mean genetic diversity; this result, however, was not revealed in C. sempervirens. Analysis of molecular variance (AMOVA) demonstrated that the genetic structure of plantations differed from that of natural populations. Interestingly, plantations of both species harbored more genetic differentiation among them than natural populations. The partitions created by AMOVA also showed a significant differentiation between 2 groups, natural populations versus plantations in the 2 species, and among bioclimatic regions only in C. sempervirens. This result was corroborated by cluster analyses, which indicated a closer relationship among populations from the same geographic region. Genetic distance was positively related to geographic distance only in natural populations of P. brutia. Plantations in our research showed a significant reduction in genetic diversity, particularly in P. brutia, and stronger among-population genetic differentiation compared to natural populations. We recommend that forest management incorporates genetic diversity and differentiation as an important criterion for selecting appropriate tree stock material.