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1.
《Scandinavian Journal of Forest Research》2012,27(4):393-398
The allozyme diversity of ten Korean populations of Corylopsis coreana Nakai, a shrub endemic to Korea, were examined. Although Korean populations are isolated, they maintain moderate levels of allozyme variation (average percent of loci polymorphic=22.4%, mean number of alleles per polymorphic locus=3.97, mean expected heterozygosity=0.109) compared to the means of 26 woody endemic species. A high level of heterozygote deficiency was observed in populations of C. coreana (mean F IS=0.232). Significant heterogeneity in allele frequencies were detected between populations at all polymorphic loci (p<0.001), among-population genetic differentiation accounted for 12.3% of the total variation. Indirect estimates of the number of migrants per generation (Nm) (1.77, calculated from G ST) indicate that gene flow is moderate among populations of C. coreana. The allozyme diversity and population structure in C. coreana may be attributed to relatively long-distance flight of pollinators in early spring, gravity seed dispersal, restricted distribution, and high density in the standing populations of the species. 相似文献
2.
Cyclobalanopsis glauca is a dominant species of evergreen broad-leaved forests in mainland China. This study compares the genetic variation of an artificially regenerated population with its donor population and two other wild populations, by using RAPD markers. A total of 74 clear, reproducible bands were scored for 12 RAPD primers; 72 were polymorphic (P = 97.3%). AMOVA revealed that most genetic variation was within populations and only 10.35% was among populations. Various measures indicated that there is no difference in genetic diversity between the planted and the original populations. ΦST between the planted offspring population and the donor population was larger than those between the planted and other two natural populations, indicating that artificial regeneration might lead to biased genetic composition, given that temporal differentiation is usually lower than spatial differentiation. This divergence may be due to unequal seed production among the maternal individuals and viability differences among seeds. 相似文献
3.
《Scandinavian Journal of Forest Research》2012,27(2):103-116
Native Danish oak stands are fragmented and decreasing because of the extensive use of foreign seed sources. Therefore, the population structure of natural Danish oak stands was analysed by means of six polymorphic enzyme loci. A total of 17 stands of Quercus robur L. (including an ''outgroup'' sample from The Netherlands), seven Quercus petraea [Matt.] Liebl. and two putative hybrid stands were included in the study. The average genetic diversity was similar for the two species as well as for the putative hybrid stands: 0.25 for Q. robur, 0.27 for Q. petraea and 0.26 for the hybrid stands. The genotypic proportions at two (Pgm and Mnr) of the six loci showed many significant deviations from Hardy-Weinberg expectations, always with an excess of homozygotes, whereas the remaining four loci accorded to Hardy-Weinberg proportions, suggesting a low level of inbreeding. The differentiation of the Q. petraea and Q. robur populations was quantified with Wright's F-statistics. The within-species component was low, 0.022, reflecting the wind-pollinated reproductive mode of the two species. The betweenspecies component was 10-fold higher, 0.235, indicating two separate groups. A phylogenetic tree estimated from allele frequencies also supported the presence of these two groups. Despite the two well-separated groups in the tree, it was not possible to assign all individuals to the species to which they supposedly belonged. In total, 10% of the Q. robur individuals and 14% of the Q. petraea individuals were assigned to the other species, suggesting a limited amount of introgression between the two species. 相似文献
4.
ZhangJin-feng LiHui DongJian-sheng WangJun-hui 《中国林学(英文版)》2005,7(1):29-35
In order to obtain information on the genetic structure ofAbies concolor and the genetic variation among 11 populations introduced from America to China, allozyme analysis based on starch gel electrophoresis technology was used. 24 loci of 10 allozyme systems were mensurated, and the genetic structure and genetic diversity of the 11 populations of A. concolor evaluated. The results show that the genetic variation among is significant, and the genetic variation within A. concolor populations is more important. In contrast with other conifers, the variation of A. concolor is above the average level of conifers, and higher than the same level of Abies. The percentage of polymorphic loci (P) was 62.5%, the number of alleles per locus (A) 2.08, the number of effective alleles per locus (Ae) was 1.37, the expected heterozygosity (H) 0.204, and the Shannon information index (/) 0.351 7. There is a short genetic distance (D=0.061) and a low gene flow (Nm=0.839 4) among the 11 introduced populations ofA. concolor with high genetic variation. The genetic differentiation coefficient (Gst) was 0.229 5, which is higher than that of the mean in Abies or Pinus. 相似文献
5.
[目的]研究毛红椿天然群体遗传多样性取样策略,为其种质资源收集、保存和遗传多样性保护等提供参考依据。[方法]利用8对微卫星分子标记进行毛红椿天然群体遗传多样性和空间自相关分析,综合制定其天然群体合理取样策略。[结果]毛红椿天然群体等位基因数平均为7.5个,期望杂合度(H_e)和多态性信息指数(PIC)均值分别为0.643 7和0.636 0,基因分化系数(G_(ST))均值为0.290 7。在遗传多样性取样策略方面,提出了根据毛红椿群体基因分化系数来确定取样群体遗传变异所占总变异比例的运算公式为1-(G_(ST))~(n-1),其中,n为取样群体的数量。当取样群体达到4个时,基本上能包括该树种97.5%的遗传变异;同时确定了目标群体的选择方法,应选择与其它群体间基因分化系数均值较大的4个群体,即贵州册亨(CH)、浙江遂昌(SC)、浙江仙居(XJ)和云南师宗(SZ)。通过构建云南宾川(BC)、云南师宗(SZ)和江西宜丰(YF)群体内取样单株数量与基因多样性和等位基因之间的捕获曲线,确定了群体内取样单株数量应达到15个以上;毛红椿天然群体内300～520 m范围内的单株间存在相似关系,超出此范围个体间差别较大,说明在进行群体内单株取样时,单株间距应大于520 m。[结论]取样群体数量、群体间遗传分化系数、群体内单株数量以及单株间距离等影响了毛红椿取样群体的遗传多样性。毛红椿天然群体遗传多样性取样策略为取样群体4个、每个群体最少取样15个单株,单株间距大于520 m。 相似文献
6.
Jennifer De Woody Tom H. Rickman Bobette E. Jones Valerie D. Hipkins 《Forest Ecology and Management》2009
The most widely distributed tree in North America, quaking aspen (Populus tremuloides, Michx.), reproduces sexually via seed and clonally via suckers. The size of aspen clones varies geographically, generally smaller in the east and large in the arid Intermountain West. In order to describe clone size and genetic structure of aspen in the southern Cascade Mountains, 864 stems from six sites were assayed at 15 isozyme and 6 microsatellite loci. Although isozymes reveal significantly lower levels of allelic richness (P < 0.001) and expected heterozygosity (P < 0.01), differences in genet diversity (isozyme G/N = 0.45, microsatellite G/N = 0.47) and allele frequency variation (isozyme FST = 0.02, microsatellite FST = 0.03) were nonsignificant. While a majority of stands were monoclonal, such stands were small, and the number of clones per stand was positively correlated with stand size (P < 0.0001). High genetic diversity, low genetic differentiation, and a rapid decay of spatial genetic structure consistent with long distance gene flow during seedling recruitment indicate that sexual reproduction is a significant factor contributing to the genetic structure of these populations. These findings further resolve the geographic variation in clonal structure observed in aspen across North America, providing novel information for land management and conservation efforts. 相似文献
7.
Starch-gel electrophoresis was used to resolve nine polymorphic enzyme loci from leaf tissue collected from 20 Korean populations
ofEurya japonica in order to determine differences in allele frequencies between male and female trees. In addition, 84 adults were sampled
and mapped in a population located on Naenaro Island in Korea to examine spatial genetic structure using spatial autocorrelation
analysis. Allele frequencies between males and females gave few contribution to the genetic structuring within populations.
Only nine (5%) of 180 cases were significantly different from both sexes in allele frequencies. On the other hand, Moran'sI was significantly different from the expected value in 31 (23.5%) of 132 cases. In the shortest distance (0<5m),I was significantly positive in 10 (22.7%) of 44 cases. The results indicate that a significant small scale genetic structure
was detected in the population and patch widths were inferred to be approximately 5–7 m. A nonrandom distribution of genotypes
may be indicative of restricted gene flowvia seed and pollen dispersal, and patchy establishments of genetically distinct individuals. These factors are responsible for
shaping population genetic structure ofE. japonica. 相似文献
8.
Dhiraj Naik Durgeshwer Singh Varsha Vartak Sharayu Paranjpe Sujata Bhargava 《New Forests》2009,38(1):99-115
Gmelina arborea is an important timber-yielding tree that grows naturally in the tropical and subtropical regions of Southeast Asia and has
also been introduced as a plantation species outside these regions. Genetic diversity in this tree species was observed in
stone/seed-related traits and in vitro responses of cultured nodal segments from plants of eight different populations representing
natural forests, fragmented forests and plantations. Variance analysis showed significant differences between populations
for these traits. However, it was not possible to separate the different populations using these traits by multivariate analysis,
even after environmental variation was reduced over six subcultures. Genetic diversity was therefore analysed using molecular
markers. Inter-simple sequence repeat (ISSR) primers yielded 95% polymorphic loci among the eight populations and UPGMA analysis
enabled separation of these populations on the basis of their genetic distances. Diversity was also analyzed using population
genetics parameters like Nei’s genetic diversity and gene differentiation. Nei’s genetic diversity was 0.29 between populations
and 0.11 within populations. AMOVA analysis indicated 41 and 59% within- and between-population genetic diversity, respectively.
Mantel test suggested that genetic differentiation between six Indian populations was positively correlated to geographic
distance (r = 0.626, P = 0.029). Assessment of the genetic variation in G. arborea populations is an important step in selection of conservation strategies for this species since diversity forms the basis
for species adaptation. 相似文献
9.
Patricia E. Maloney Detlev R. VoglerAndrew J. Eckert Camille E. JensenDavid B. Neale 《Forest Ecology and Management》2011,262(5):770-779
Historical logging, fire suppression, and an invasive pathogen, Cronartium ribicola, the cause of white pine blister rust (WPBR), are assumed to have dramatically affected sugar pine (Pinus lambertiana) populations in the Lake Tahoe Basin. We examined population- and genetic-level consequences of these disturbances within 10 sugar pine populations by assessing current population structure and trends for 1129 individuals, genetic diversity for 250 individuals, and frequency of WPBR-resistance for 102 families. Logging had occurred in 9 of 10 sites and fire suppression was evident in all stands. High density of white fir (Abies concolor) is often an indicator of fire suppression and we found a negative relationship between sugar pine survivorship and white fir basal area (r2 = 0.31). C. ribicola was present in 90% of stands (incidence range: 0-48%) and we found a significant relationship between mean host survivorship and disease incidence (r2 = 0.46). We estimated population growth rates (λ) from size-based transition matrices. For six of 10 sugar pine populations λ was ?1.0, indicating that these populations appear to be stable; for four populations, λ was <1.0, indicating populations that may be in decline. A population specific drift parameter, ci, which is a measure of genetic differentiation in allele frequencies relative to an ancestral population, ranged from 0.009 to 0.048. Higher values of ci indicate greater genetic drift, possibly due to a bottleneck caused by historical logging, other agents of mortality or much older events affecting population sizes. Effects of drift are known to be greater in small populations and we found a negative relationship between sugar pine density and ci (r2 = 0.36). Allele frequency of the Cr1 gene, responsible for WPBR-resistance in sugar pine, averaged 0.068 for all populations sampled; no WPBR infection was found in one population in which the Cr1 frequency was 0.112. Historical disturbances and their interactions have likely influenced the population biology of sugar pine in the Tahoe Basin; for some populations this has meant reduced population size, higher genetic drift, and poor survival of small- and intermediate-sized individuals. Possible management strategies include restoring population numbers, deploying WPBR-resistance, treating stands to promote natural sugar pine regeneration, and enhancing genetic diversity. 相似文献
10.
11.
A. Dounavi N. Koutsias M. Ziehe H. H. Hattemer 《European Journal of Forest Research》2010,129(6):1191-1202
Analyses of distribution patterns and genetic structures of forest stands can address distinct family structures and provide
insights into the association of genetic and phenotypic variation patterns. In this study, point pattern analysis and spatial
autocorrelation were used to examine the spatial and genetic structures in two naturally generated beech stands, which differ
in age, trunk morphology, and stand management. Significant tree clumping was observed at distances up to 20 m in the young
forest stand, whereas dispersion at distances under 10 m was observed in the old stand. The spatial analysis based on Ripley’s k function of the two different groups of trees showed that the non-forked trees match in both stands the spatial pattern of
all trees while the forked were randomly distributed. Additionally, according to the bivariate analysis, forked trees in both
stands were randomly distributed as related to non-forked tree positions. Finally, Moran’s I values were not very high, though significant genetic autocorrelation was identified at distances up to 20 m in the young
stand, suggesting the existence of distinct family structures. However, no significant genetic structuring was observed in
the old stand. Our findings suggest that spatial genetic patterns are impacted by stand age, environmental factors and human
activities. The spatial distribution of forked trees was not clearly associated to family structures. Random effects and also
micro-environmental variation could be additional factors explaining forking of beech individuals. 相似文献
12.
To investigate the effect of tree species on soil N dynamics in temperate forest ecosystems, total N (Nt), microbial N (Nmic), net N mineralization, net nitrification, and other soil chemical properties were comparatively examined in beech (64–68 years old) and Norway spruce (53–55 years old) on sites 1 and 2, and beech and Scots pine (45 years old) on site 3. The initial soil conditions of the two corresponding stands at each site were similar; soil types were dystric Planosol (site 1), stagnic Gleysols (site 2), and Podzols (site 3). In organic layers (LOf1, Of2, Oh), Nmic and Nmic/Nt, averaged over three sampling times (Aug., Nov., Apr.), were higher under the beech stands than under the corresponding coniferous ones. However, the Nmic in the organic layers under beech had a greater temporal variation. Incubation (10 weeks, 22 °C, samples from November) results showed that the net N mineralization rates in organic layers were relatively high with values of 8.1 to 24.8 mg N kg–1 d–1. Between the two corresponding stands, the differences in net N mineralization rates in most of the organic layers were very small. In contrast, initial net nitrification rates (0.2–17.1 mg N kg–1 day–1) were considerably lower in most of the organic layers under the conifer than under the beech. In the mineral soil (0–10 cm), Nmic values ranged from 4.1–72.7 mg kg–1, following a clear sequence: August>November>April. Nmic values under the beech stands were significantly higher than those under the corresponding coniferous stands for samples from August and April, but not from November. The net N mineralization rates were very low in all the mineral soils studied (0.05–0.33 mg N kg–1 day–1), and no significant difference appeared between the two contrasting tree species. 相似文献
13.
Alnus trabeculosa Hand.-Mazz. is classed as “near threatened,” and efforts should be made to conserve the species, but effective action would
require understanding of its genetic variation and structure. Therefore, the genetic variation at 12 isozyme loci was examined
in seven populations of the species in Japan. The expected heterozygosity within species (H
es=0.222) and the expected heterozygosity within populations (H
ep=0.199) were found to be slightly higher than in most other woody species. The coefficient of genetic differentiation (G
ST=0.146) was also high. The northernmost population had the lowest values for almost all measures of genetic variation, and
populations in southern Japan tended to show greater within-population variation than those in northern Japan. The level and
distribution of genetic variation in this species might be related to its life history and ecological traits, and distribution
history. 相似文献
14.
《林业研究》2021,32(5)
Mexican beech [Fagus grandifolia subsp.mexicana(Martinez) A.E.Murray] is a subspecies endemic to the Sierra Madre Oriental Mountains and considered endangered due to the low density of its populations and high degree of habitat fragmentation and environmental specificity.Because its morphological and genetic variation is associated with its ability to adapt to changes in environmental conditions,the objective of this study was to determine whether phenotypic and genotypic variation exist,and it relationships with population reduction events.In four beech populations in the states of Hidalgo and Veracruz,we analyzed 11 morphological variables for leaves and 6 micros atellite markers.The morphological variables that to discriminate between populations were related to the size of the leaf,but a robust differentiation pattern was not found,given that independent groups of leaves were identified.The populations located closest to each other,had greater genetic variation and less genetic distance;populations in the extreme north and south had the lowest genetic variation.Genetic differentiation among populations was associated with reduction in population size.In the 3 localities in Hidalgo,recent bottlenecks were identified,and in Veracruz,an old bottleneck was found.Variation in leaf morphology and genetic structure of Mexican beech populations could be the result of a combination of various geographical,climate and ecological factors. 相似文献
15.
Douglas-fir has been planted in Bavaria for over 100 years. Its high growth potential and good wood quality combined with its silvicultural characteristics have increased interest in the species which can easily be integrated into existing natural ecosystems. In order to be successful in the establishment of Douglas-fir one must select the best provenance (only the so called “green” or viridis coastal type form is suitable for Bavaria), maintain a broad genetic base and carry out proper silviculture. The goal of the study was to check the origin/provenance (coastal or interior type) of older Bavarian Douglas-fir stands, the respective genetic variation of the stands and also the natural regeneration, the collected seed and the plants raised in the nursery. Possible changes in the genetic composition and diversity due to selective processes in the nursery phase were also investigated. Isoenzyme gene markers were used for the study. The majority of the investigated older stands apparently belong to the coastal type Douglas-fir; however, we also found mixed stands and stands solely of the interior (unsuitable) type. Older stands show large variation in their genetic diversity (v
gam between 19.9 and 90.1). Some of the stands of unsuitable provenance have natural regeneration and others have been selected as seed collecting stands. Through natural regeneration the genetic structure of the older stands is passed on to the following generation. The same is true for reproductive material collected from such stands. In comparison to seed collected from stands in the USA (from stands selected by the EU for seed collection), seed from Bavarian stands is genetically very heterogeneous in respect to the allele variants and the diversity. No significant changes in the genetic population structure were found in the nursery due to sowing or transplanting. The critical stage for obtaining high quality reproductive material of Douglas-fir is the selection of seed collecting stands and the harvesting procedure. The resulting consequences for seed collection and procurement of suitable reproductive material for Douglas-fir are discussed. 相似文献
16.
As a N2-fixing tree species, sea buckthorn (Hippophae rhamnoides) is well adapted to arid regions and is utilized for multiple purposes in China. Current knowledge of genetic variability of H. rhamnoides is limited in terms of rangewide distributions. Eleven natural populations of sea buckthorn in northeastern and northwestern China were analyzed to detect genetic variation among and within populations, by use of ISSR (inter-simple sequence repeats) markers. Using eight primers, 207 polymorphic loci were observed, ranging in size from 250 to 2500 bp. The coefficient of gene differentiation (Gst = 0.0679) showed that the total molecular variance of 11 populations was mainly existed within populations. The genetic variation within and among the 11 populations was 93.21 and 6.79%, respectively. No significant correlation between genetic and geographic distances of the populations was found using ISSR markers. Our study provides a population-level genetic profile for further investigation and conservation of genetic diversity of sea buckthorn. 相似文献
17.
Aristotelis C. Papageorgiou Amaryllis Vidalis Oliver Gailing Ioannis Tsiripidis Seraphim Hatziskakis Stefanos Boutsios Spiros Galatsidas Reiner Finkeldey 《European Journal of Forest Research》2008,127(1):81-88
The recent taxonomic classification of beech in Europe considers existence of one species (Fagus sylvatica L.) with two subspecies: F. sylvatica ssp. sylvatica and F. sylvatica ssp. orientalis. Four beech populations growing on the Greek part of the Rodopi Mountains were studied using morphological traits as well
as DNA molecular markers (AFLPs and chloroplast DNA SSR). The aim of the study was to describe the variation patterns of beech
in the Rodopi Mountains and to test the hypothesis of possible introgression between the beech subspecies’ sylvatica and orientalis in this area. Both morphological traits and gene markers revealed a possible influence of F. orientalis on the east side of Rodopi and at the low elevations, while characters resembling F. sylvatica were observed mainly on the western part of the mountains and in higher altitudes. There was a clinal increase of genetic
diversity from the west to the east, reaching a level firstly reported for beech populations. These results can be explained
either by the existence of a main refugial area for beech during the last glaciation or by the occurrence of a recent hybridization
among the subspecies, which were spatially isolated during the last glaciation and came into reproductive contact during their
postglacial remigration. These two scenarios are not necessarily mutually exclusive. 相似文献
18.
T. Jung 《Forest Pathology》2009,39(2):73-94
During the past decade, and in particular after the wet year 2002 and the dry year 2003, an increasing number of trees and stands of European beech (Fagus sylvatica L.) in Bavaria were showing symptoms typical for Phytophthora diseases: increased transparency and crown dieback, small‐sized and often yellowish foliage, root and collar rot and aerial bleeding cankers up to stem heights of >20 m. Between 2003 and 2007 134 mature beech stands on a broad range of geological substrates were surveyed, and collar rot and aerial bleeding cankers were found in 116 (86.6%) stands. In most stands the majority of beech trees were declining and scattered or clustered mortality occurred. Bark and soil samples were taken from 314 trees in 112 stands, and 11 Phytophthora species were recovered from 253 trees (80.6%) in 104 stands (92.9%). The most frequent species were P. citricola, P. cambivora and P. cactorum. Primary Phytophthora lesions were soon infected by a series of secondary bark pathogens, including Nectria coccinea, and wood decay fungi. In addition, infected trees were often attacked by several bark and wood boring insects leading to rapid mortality. Bark necroses were examined for their probable age in order to determine whether the onset of the current Phytophthora epidemic was correlated to rainfall rates recorded at 22 Bavarian forest ecosystem monitoring stations. A small‐scale survey in nine Bavarian nurseries demonstrated regular infestations of all beech fields with the same range of Phytophthora species. The results indicate that (1) Phytophthora species are regularly associated with beech decline and may also be involved in the complex of ‘Beech Bark Disease’, (2) excessive rainfalls and droughts are triggering the disease, and (3) widespread Phytophthora infestations of nursery stock might endanger current and future silvicultural projects aiming on the replacement of non‐natural conifer stands by beech dominated mixed stands. 相似文献
19.
A majority of beech forests across Maine first experienced beech bark disease (BBD) from 1935 to 1960 when sap feeding by an introduced beech scale insect, Cryptococcus fagisuga, allowed lethal fungal infections primarily by Neonectria ditissima and/or Neonectria faginata. Beech stands along the Maine–Quebec border in northern Maine were excluded from this initial killing phase presumably due to cold winter temperatures that inhibited scale survival. However, a sharp increase in beech mortality after 2002 occurred in previously uninfected border stands and stands long affected by BBD. Beech mortality averaged 50% across northern Maine during 2003–2006. To identify plausible stresses that could explain the mortality, a dendropathological study was conducted from 2005 to 2006 in northern Maine that quantified temporal and spatial relationships between possible stressors with beech mortality and growth decline. Nineteen sets of high‐ and low‐mortality plots were located randomly across four bioregions. Increment cores were taken from both beech trees (n = 565) and associated tree species (n = 450). A growth change index of increments was used to evaluate beech responses to biotic and climatic stresses. A prolonged period of relatively mild winters without temperatures lethal to scale insect (Neonectria was found infecting weakened trees across the region. Drought, beech scale and Neonectria are plausible explanations for the episode of high beech mortality in northern Maine. This is the first report of a major killing phase of beech within the BBD ‘aftermath’ forests. 相似文献
20.
Within the framework of an interdisciplinary project on the effects of climate and forest management on beech-dominated deciduous forests (Swabian Jura, south-western Germany), forest meteorological investigations are carried out to analyse the influences of exposure and canopy density on the microclimate within various beech stands (Fagus sylvatica L.). This second paper of the series Microclimate within beech stands focuses on the thermal conditions that exist mainly in the near-surface layer at different test plots. They were analysed by air temperature, Ta, (at 1.5 m a.g.l) and soil temperature, Ts, at six depths measured continuously in the period 1999–2003. The main results can be summarized as follows. (1) The thermal situation within the beech stands described by Ta depended primarily on the turbulent air-mass exchange conditions which were based on the slope-specific energy balance of the forest floor and advective heat fluxes. (2) The thermal situation within the soil described by Ts at 3 and 20 cm depth was governed by the molecular heat transport. Therefore, the heating and cooling rates of Ts were always lower than for Ta. Higher Ta and Ts values for the test plots on the SW slope showed that the thermal conditions within the beech stands depended primarily on the exposure. (3) Based on slope-specific differences of daily extremes of Ta and Ts at 3 cm depth between the silviculturally treated and control plots, the influence of the more pronounced height growth of the understorey vegetation under the near-surface thermal conditions could be clearly verified for the NE slope.Abbreviations PAR Photosynthetically active radiation - PAI Plant area index - LAI Leaf area index 相似文献