Contemporary pollen flow and mating patterns of a subtropical canopy tree Eurycorymbus cavaleriei in a fragmented agricultural landscape

China's subtropical forests have experienced severe deforestation and most native forests have been fragmented into an archipelago-like landscape. The genetic effect of habitat fragmentation depends largely on the level of gene flow within and among population fragments. In the present study, Eurycorymbus cavaleriei, a canopy tree found throughout subtropical China, was selected as a representative insect-pollinated plant species to assess genetic consequence of forest fragmentation. Contemporary pollen dispersal and mating patterns were estimated in two physically isolated stands of E. cavaleriei within fragmented forests using six highly polymorphic microsatellite loci. We found high genetic diversity (H_E = 0.670–0.754) in both adults and offspring in the fragmented agricultural landscape, suggesting that habitat fragmentation did not necessarily erode genetic diversity of E. cavaleriei. Although substantial pollen travelled less than 100 m, paternity analysis revealed that a large amount of long-distance pollination events occurred, with the average pollen dispersal distance being 1107 m and 325 m for the two stands, respectively. Extensive pollen immigration (39.3–42.6%) indicated that there was effective genetic connectivity among E. cavaleriei stands in the fragmented forests. twogener analysis revealed that the exponential power model was the best-fitting dispersal curve with a fat-tailed (b < 1) dispersal feature. The results from a multilocus mating system analysis suggested that a small amount of biparental inbreeding and some correlated mating events occurred in the fragmented forests, which were similar to our parallel findings in the continuous forests of E. cavaleriei. Estimates of pollen pool structure (Φ_FT = 0.128–0.174) indicated large genetic differences between pollen clouds accepted by maternal trees. The number of effective pollen donors (N_ep) in E. cavaleriei, estimated using both mltr (N_ep = 4.2–5.3) and twogener (N_ep = 2.9–3.9) models, was equivalent to the number of effective pollen donors detected in continuous forests of E. cavaleriei. The pollen dispersal and mating patterns detected here indicated that habitat fragmentation did not have a negative impact on pollen movement in E. cavaleriei, possibly due to its generalist pollination system and the resilient foraging behavior of its pollinators in response to changes in landscape structure. The long distances of pollen-mediated gene flow between patches highlight the conservation value of remnant forest fragments in maintaining genetic connectivity at the landscape scale in subtropical China.     

Pollen dispersal,mating patterns and pollen contamination in an insect-pollinated seed orchard of <Emphasis Type="Italic">Schima superba</Emphasis> Gardn. et Champ.

Pollen flow and mating patterns are the most important factors influencing the genetic structure of insect-pollinated forest trees and are essential parts of genetic management in seed orchards. We investigated pollen flow, the mating system and the level of pollen contamination in a clonal seed orchard of Schima superba Gardn. et Champ. In total, 328 open-pollination progenies coming from 11 mother trees were identified using 13 polymorphic microsatellite loci. A total of 203 full-sib families were identified and were nested among the 11 studied seed donors. The male reproductive success rate from 0.49 to 7.77% for most male parents, with an average of 2.44%. More than 80% of the crosses were found within a distance of 60 m, and the most frequent pollination distance between female parent and male parents was approximately 20 m. Mating system analysis showed that the outcrossing level was very high (t _m  = 1.000, outcrossing rate = 98.5%) in the seed orchard and that there was an average of 2.3 effective pollen donors (N _ep ) per female parent. In addition, the mating success of individual males within neighborhoods was moderately influenced by their fecundity and the direction of their location relative to mother trees. The pollen contamination from outside the seed orchard was high (7.01%). Our findings are valuable for the assessment of seed orchards, and it may be worthwhile to use pollen management strategies to decrease pollen contamination and increase the genetic quality of the seeds produced.     

Effects of selective logging on the mating system and pollen dispersal of Hymenaea courbaril L. (Leguminosae) in the Eastern Brazilian Amazon as revealed by microsatellite analysis

Using nine microsatellite loci, we studied the effects of selective logging on genetic diversity, mating system and pollen dispersal in a population of the tree species Hymenaea courbaril, located in a 546 ha plot in the Tapajós National Forest, Pará State, Brazil. We analyzed 250 offspring (nursery reared seedlings) collected after a logging episode from 14 open-pollinated seed trees. These were compared to 367 seedlings from 20 open-pollinated seed trees previously collected from the pre-logging primary forest. The genetic diversity was significantly lower in the post-logging seed cohort. In contrast to the pre-logging population, significant levels of selfing were detected in the post-logging population (t_m = 0.962, P < 0.05). However, correlated matings were reduced and the effective number of pollen donors almost doubled after harvesting (3.8 against 7.2). Logging also reduced pollen immigration into the plot (from 55% to 38%) and we found no significant correlation between the size of the pollen donors and the number of seeds fathered. Inside the plot, pollen dispersal distance was shorter before logging than after (827 and 952 m, respectively) and the reproductive pollination neighbor area (A_ep) was larger (average of 178 ha). The individual and average variance effective population size within families (ranged from 1.80 to 3.21, average of 2.47) was lower than expected in panmictic populations (N_e = 4). The results indicate that while logging greatly reduced the levels of genetic diversity after logging, it also increased genetic recombination within the population and constrained crossing among related individuals. The results show that low-density tropical tree species such as H. courbaril, when harvested in moderate levels may be resilient to a reduction in the reproductive population and may maintain similar levels of outcrossing and pollen dispersal after logging.     

Genetic consequences of low local tree densities - Implications for the management of naturally rare, insect pollinated species in temperate forests

Early on, researchers of evolutionary biology recognised that heterogeneity in the mating environment is an important source of variation in mating patterns. Focusing on the mating environment, we assessed the effect of conspecific tree density on mating patterns in the naturally scattered forest tree Sorbus domestica L. In an area of more than 100 km², we mapped and genotyped all 189 adult trees and performed a paternity analysis on seeds produced by single mothers. Despite a self-incompatibility system, average selfing rate was 31.9%, but with high variation among mother trees. Over 70% of this variation was explained by local density of conspecifics (i.e. within a radius of 300 m), with isolated trees being more prone to selfing. While we detected high selfing rates in progeny, adult trees showed no signs of inbreeding. As almost all inbreeding in the offspring could be attributed to self-fertilisation, we hypothesise that there is strong selection against selfed individuals. The effective reproductive output of isolated trees, which mainly self, is therefore greatly reduced. These findings have important consequences for the management of naturally scattered, insect-pollinated temperate tree species, often belonging to the family of Rosaceae. For these species, local density of conspecifics should be maintained above a certain threshold (i.e. 0.05 trees/ha in S. domestica), to avoid negative fitness consequences from selfing.     

Gene flow pattern and mating system in a small population of Quercus semiserrata Roxb. (Fagaceae)

Pollen flow from external sources is important for the conservation of tree species in fragmented forests or small populations, because it can be sufficient to prevent differentiation among them, and appears to be able to prevent the loss of their genetic diversity through genetic drift. In this study, we examined the genetic heterogeneity of pollen pools accepted by each Quercus semiserrata seed parent at the Khun Wang Royal Agriculture Research Center, Thailand, both within and among two mast fruiting years (2005 and 2007), using paternity analysis and analysis of molecular variance (AMOVA). The mating systems of the trees were also examined using the multilocus mating system model (MLTR), after determining the genotypes at eight microsatellite loci of 26 seed-trees and 435 seeds from 8 seed-trees in the 2 mast fruiting years. The average distance of effective pollen flow within the plot was estimated to be 52.4 m, and 95% of effective pollen was dispersed within 200 m, indicating that effective pollen flow is highly localized and that most effective pollen is contributed by near-neighbor trees. The proportion of effective pollen that immigrated from external sources was estimated to be 26.2%. The AMOVA analysis based on the pollen haplotypes showed that the pollen pools, both total and for each reproductive year, significantly genetically differed among the seed parents. Using a mixed mating model, the estimate of biparental inbreeding for the total population (t_m − t_s) was 0.013, indicating that a low proportion of mating occurred among close relatives. The effective number of pollen donors (N_ep) was estimated to be 9.987 using the TwoGener model, or 10.989 using the mixed mating model. The effective number of pollen donors of seeds was higher in the mast fruiting year 2005 than in the other examined year, 2007. Consequently the allelic richness and genetic diversity of seeds produced in 2005 were higher than those produced in 2007. Overall, the results show that high outcrossing rates, high levels of gene flow from other populations and heterogeneity in the pollen received by an individual may enhance the ability of populations to maintain effective population sizes. Therefore, these processes may be sufficient to prevent loss of genetic diversity through genetic drift of Q. semiserrata at this study site.     

Density-dependent selfing and its effects on seed performance in a tropical canopy tree species, Shorea acuminata (Dipterocarpaceae)

In the conservation and management practices of natural forests, sound reproduction and regeneration form the basis of the maintenance and viability of the tree populations. To obtain and serve biological information for sustainable forest management, we investigated reproductive biology and inbreeding depression in seeds of an important dipterocarp tree species, Shorea acuminata (Dipterocarpaceae), by both field and laboratory experiments. Results of parental analysis of immature and mature seeds showed that selfing rates varied greatly, from 7.6 to 88.4% among eight mother trees, and the mean overall selfing rate was 38.3%. Observed outcrossing events within a 40-ha study plot were predominantly (76.5%) short-distance events with a mating distance (md) ≤ 100 m. Since the selfing rate sharply decreased with increase in the number of flowering conspecifics (i.e., individuals of the same species) within a 100-m radius from the mother trees, the local density of flowering conspecifics appears to be the key factor determining the outcrossing rate in S. acuminata. However, the extremely high selfing rate (88.4%) observed for one tree could not be simply explained by the low local density of flowering conspecifics. Instead, differences in its flowering phenology (its flowering peaked ca. a week earlier than most of the other examined individuals) may have severely limited its receipt of pollen from other conspecifics, and thus promoted selfing. Since there were no significant differences in the proportion of selfed progeny between immature and mature seed stages, there was no evidence of selective abortion of selfed seeds during seed development. However, the seed mass of outcrossed progeny was heavier than that of selfed progeny, and heavier seeds showed higher success rates at germination and seedling establishment. These results suggest that inbreeding depression resulted in reductions in seed mass and may reduce the fitness of selfed seeds in S. acuminata. In addition, the outcrossing rate of S. acuminata was more sensitive to low local conspecific flowering-tree densities than that of a sympatric bee-pollinated dipterocarp species with greater pollination distances. These results suggest that the management of local adult-tree densities is important for avoiding selfing and inbreeding depression in future generations, especially in a species like S. acuminata with predominantly short-distance pollination.     

Effect of local stand density on reproductive processes of the sub-boreal conifer Picea jezoensis Carr. (Pinaceae)

The effect of local pollen donor density (conspecific) and local total tree density (all species) on pollen pool diversity, outcrossing rate, and filled seed ratio were examined in a natural stand of the sub-boreal conifer Picea jezoensis Carr. Seed cones were collected from 17 mother trees, and the percentage of filled seed were calculated for five cones per tree. In addition, local stand density of pollen donors and total trees were investigated within r<30 m from the focal mother trees. Using four polymorphic microsatellite markers, the average pairwise kinship coefficient F_S and multilocus outcrossing rate t_m were estimated on germinated seedlings sampled from 14 mother trees. F_S showed significant positive correlation to local total tree density (r=0.541, p=0.046). Since F_S is inversely proportional to the effective number of pollen donors N_ep, genetic diversity of pollen pool was decreased in mother trees with higher local total tree density. Applying a generalized linear mixed model to filled seed ratio and local stand density of pollen donors and total trees, a negative impact of local pollen donors on filled seed ratio was found. We conclude that both local stand density as well as global stand density are important in the management of a natural stand of P. jezoensis.     

Mating System and Pollen Contamination in a Pinus brutia Seed Orchard

Mating system parameters and pollen contamination were estimated in an 11-year-old Pinus brutia Ten. clonal seed orchard, located in Antalya, Turkey, with the aid of isozymes. Isozyme analysis was performed on both maternal (megagametophyte) and embryo tissues of seeds collected from the seed orchard and the surrounding natural stand. Fourteen loci encoding nine enzyme systems were assayed. Based on a multilocus estimator, the proportion of viable seeds originating from outcrossing (tˆ_m) in the seed orchard was found to be 0.947; the remainder (0.053) was due to selfing. We estimated that 85.7% of the orchard seed resulted from pollen contamination by trees in surrounding stands. This may be related to the young age and subsequent low pollen production of the orchard. Only 9% [i.e., 1.0−0.857 (contamination)−0.053 (selfing) = 0.090] of the orchard offspring was due to cross-pollination among clones within the orchard. Due to the high level of pollen contamination, it is estimated that genetic gain in this seed crop is less than 57% of that expected if all offspring resulted from random mating among orchard clones (i.e., no contamination).     

Genetic variation, mating patterns and gene flow in a Pinus pinaster Aiton clonal seed orchard

? Relatedness among parents, variation in clonal fertility and background pollination deviate the realized genetic gain and the gene diversity of open pollinated seed orchard from expectation, in particular in wind pollinated species such as Pinus pinaster Aiton.

? This work investigates the genetic variation, the mating system and the pollen contamination in a P. pinaster clonal seed orchard (CSO), by screening the 60 clones from the CSO and the seeds collected from 21 mother-trees with three nuclear microsatellites.

? The expected diversity was similar, but the observed heterozygosity decreased 20% in the progenies compared with the parental trees. The outcrossing rate was 90.1%, the biparental inbreeding 21.7% computed through a multilocus approach, and the observed selfing 3.9%. The observed gene flow from outside the CSO was 52.4%.

? From the results we concluded that the observed gene flow and the biparental inbreeding were high, and care should be taken in the implementation and management of future CSO, in particular clones should be checked for relatedness and the ramet number could be directly proportional to their breeding value.

     

Reduction of pollen contamination in Scots pine seed orchard crop by tent isolation

This study examined the differences in mating system between indoor versus outdoor Scots pine (Pinus sylvestris L.) seed orchard using DNA markers. By analyzing the paternities in seed crops from isolation tents, we found a significant reduction in contamination rate, from 23% in the outdoor open blocks to 0% inside the tents. Increase in selfing rate and a decrease in genetic diversity in the crops were also observed inside the tents. These undesirable effects can be mitigated to some extent by the supplementation of extra pollen genotypes, e.g. selfing rate decreased from 14.4% to 6.6% and the effective number of fathers increased from 6 to 11.4 in the tents without and with supplemental mass pollination, respectively. Our study showed that tent isolation may become an effective rescuer for seed orchards where pollen contamination is severe.     

Genetic diversity of Pinus densiflora pollen flowing over fragmented populations during a mating season

We attempted to evaluate the genetic diversity of long-distance transported pollen flowing over fragmented Pinus densiflora populations during a mating season. A P.?densiflora clonal seed orchard, which was located in a rural area where many fragmented populations exist, was selected for pollen capture. Immigrant pollen captured by three clones having different flowering times was regarded as the pollen flowing over fragmented populations during a mating season. The genetic diversity (H _e) values of the immigrant pollen captured by the three clones were high (H _e?>?0.894). The correlation of paternity (r _p) values of the seeds having immigrant parent generated from the three clones were calculated to be negative. From these parameters, the pollen cloud is considered to have maintained high genetic diversity during the mating season. The genetic composition of the pollen cloud showed slight variation. The pollen captured by different trees (i.e., clonal ramets of the three clones) was significantly different based on analysis of molecular variance. Especially, the pollen pools captured by trees planted in the western side of the orchard were significantly different from the gene pool of the surrounding populations. Factors affecting this differentiation could be that the donors of the pollen transported to the orchard vary with time, as well as nonuniform dispersal of the pollen. From these results, the pollen flowing over fragmented P.?densiflora populations is considered to have high genetic diversity, compensating to some extent for fragmentation.     

北京城区银杏行道树生长现状与健康状况研究

The planting site, size, and health condition of street tree Ginkgo biloba in Beijing urban area were investigated and the influence factors were analyzed based on filed survey. The results showed that G. biloba were mainly planted in tree pit within strip planting median. The average height, diameter at breast height and canopy diameter were 8.11 m, 13.22 cm and 4.07 m, respectively, 82.9% trees were less than 10 m in height, and most G. biloba trees were still in the initial stage of height and diameter increment. The tree health status was described with three classes: class I (healthy), class II (fair) and class III (unhealthy). The percentage of class I, II and III for G. biloba trees in Beijing urban area accounted for 16.0%, 37.2% and 42.9% respectively. The results of analysis showed that the health status of G. biloba was associated with the site condition, tree size and management practices. The trees planted in urban forest patch grew better than the trees planted in green belts and tree pits; meanwhile, the bigger trees were healthier than the smaller ones. In addition, the effects of urban heterogeneous environment and human activities on the health of Ginkgo biloba were analyzed and the suggestions on management were launched.     

杉木种子发芽率和苗木高生长的近交效应

在杉木种子园中对6个无亲缘关系的无性系进行了双列杂交,包括自交。同时取亲本的自由授扮种子作为对照。在他们的子代林中,取一个全同胞家系和一个自由授粉家系,各选4至6株开花植株连同它们的亲本,分别进行自交、回交、同胞内交配和异交测定。结果表明,杉木近交使得种子发芽率和苗木高生长量大幅度下降。近交衰退随着近交系数(F)的增加而加大。同异交相比,自交、回交和全同胞交配、半同胞交配组合的种子发芽率分别平均降低约88％、42％和20％,苗木平均高度分别下降27％、17％和13％左右。结果也显示,在不同个体之间近交衰退程度存在明显差异。     

Seed cone production enhanced by injecting 38-year-old Larix occidentalis Nutt. with GA4/7

The influence of injecting 38-year-old Larix occidentalis with gibberellin A_4/7 (GA_4/7) on seed and pollen cone production was studied in western Montana, U.S.A. Two natural stands thinned to several spacings in 1961 were chosen. The two widest spacings were used. In 1991, 60 trees selected for study at each site were randomly divided into two groups of similar DBH, half as controls and half injected in June 1991 with a solution of GA_4/7 in ethyl alcohol. The volume injected was adjusted to the DBH of each tree (60 mg per 5 cm diameter). In June 1994, half the trees treated with GA_4/7 in 1991 and half the untreated trees were injected with GA_4/7 in the same manner as before. In 1992 and 1995, seed cone production increased on GA_4/7-treated trees compared to the controls. Pollen cone production was significantly increased by GA_4/7 treatment but only at one site. Delayed effects of GA_4/7 on seed cone production was not evident in subsequent years after treatment. Foliar and shoot damage on treated trees was attributed to GA_4/7 treatment but most trees recovered completely the following year. Finally, GA_4/7 treatment did not affect cone length, potential seed per cone or filled seed per cone.     

Senescence of Manilkara zapota trees and implications for large frugivorous birds in the Southern Yucatan Peninsula,Mexico

It has long been established that mature forests are mosaics of patches in different development phases but it has seldom explicitly been taken into account in ecological studies. We demonstrate here that these development phases, which are related to the population dynamics of trees, play an important role in the distribution of fauna based on observations on frugivorous birds. In an area close to the Calakmul Biosphere Reserve in Mexico, we studied the abundance of large forest bird species in relation to forest development phases, with a methodology that seems promising for ecological diagnosis and prognosis in forest management planning. Fine-scale forest mapping and bird counts were carried out in two block-transects of 40 m × 3000 m. Tree sampling in a sub-transect was used to generate population characteristics of trees. Large bird species preferred mature or senescent forest patches, whereas relatively young, growing forest patches were avoided. Important large tree species such as Manilkara zapota, Thouinia paucidentata, Guaiacum sanctum and Esenbeckia pentaphylla, characteristic of older forest patches, showed skewed size distributions indicating stress or overexploitation. The population of M. zapota, a key fruiting species that accounted for 26.5% of the total woody biomass, was most heavily affected by stress. A future collapse in the population of M. zapota, a decrease of the total area of older forest, and a decline in the abundance of large birds is likely if stress on the system continues at this level.     

Effects of bamboo stands on seed rain and seed limitation in a rainforest

Bamboos often negatively affect tree recruitment, survival, and growth, leading to arrested tree regeneration in forested habitats. Studies so far have focused on the effects of bamboos on the performance of seedlings and saplings, but the influence of bamboos on forest dynamics may start very early in the forest regeneration process by altering seed rain patterns. We tested the prediction that the density and composition of the seed rain are altered and seed limitation is higher in stands of Guadua tagoara (B or bamboo stands), a large-sized woody bamboo native from the Brazilian Atlantic Forest, compared to forest patches without bamboos (NB or non-bamboo stands). Forty 1 m² seed traps were set in B and NB stands, and the seed rain was monitored monthly for 1 year. The seed rain was not greatly altered by the presence of bamboos: rarefied seed species richness was higher for B stands, patterns of dominance and density of seeds were similar between stands, and differences in overall composition were slight. Seed limitation, however, was greater at B stands, likely as a resulted of reduced tree density. Despite such reduced density, the presence of trees growing amidst and over the bamboos seems to play a key role in keeping the seeds falling in B stands because they serve as food sources for frugivores or simply as perches for them. The loss of such trees may lead to enhanced seed limitation, contributing ultimately to the self-perpetuating bamboo disturbance cycle.     

优良红松坚果型优树的选择方法(英文)

于1988-1998 年对长白山、小兴安岭和完达山地区天然红松林以及黑龙江省鹤岗地区人工红松林结实量进行了实地调查和测定。根据调查和测定数据，对红松结实特征，包括结实量、球果长度、球果数量、出种率，种子千粒重、种子产量、种子大小、种子空实率、球果虫害率、结实指数等，进行分析方差分析、多重比较和逐步回归，得出各项结实因子对结实量的贡献率，将球果长度、千粒重和出种率确定为优树选择的重要指标，然后采用加权系数法确定红松坚果型优树，并制订出天然红松林坚果型优树标准和红松人工林坚果优树标准。本项研究为建立红松坚果园选择优树提供了方法和标准。     

Mating patterns,genetic composition and diversity levels in two seed orchards with few clones—Impact on planting crop

Paternity analyses using microsatellites were conducted in two conifer clonal seed orchards (CSOs). The aim was to study mating patterns and potential dysfunctions such as unbalanced male contribution, and how these factors influence genetic diversity. The effect of unequal male contribution was quantified by the status number (N_S), which reflects build up of coancestry in the seed orchard crop due to low number of clones and unequal male contribution. This approach was also used to quantify the effect of clonal differences in germination percentages on effective population sizes. Furthermore the genetic diversity of the Abies alba and Larix kaempferi CSOs was compared to other alternative seed sources via observed heterozygosity and allelic richness.     

Mating patterns of the gum arabic tree (<Emphasis Type="Italic">Acacia senegal synonym Senegalia senegal</Emphasis>) in two different habitats

Understanding the variation of mating patterns in disturbed habitats provide insight into the evolutionary potential of plant species and how they persist over time. However, this phenomenon is poorly understood in tropical dryland tree species. In the present study, we investigated how Acacia senegal reproduces in two different environmental contexts in Kenya. Open-pollinated progeny arrays of 10 maternal trees from each environmental context were genotyped using 12 nuclear microsatellite markers. Overall, A. senegal displayed a predominantly allogamous mating pattern. However, higher multilocus outcrossing rate (tm) was found in Lake Bogoria (tm = 1.00) than in Kampi ya Moto population (tm = 0.949). Higher biparental inbreeding (t _m  ? t _s  = 0.116) and correlation of outcrossed paternity (rp = 0.329) was found in Kampi ya Moto than in Lake Bogoria population (t _m  ? t _s  = 0.074, rp = 0.055), showing the occurrence of mating among relatives. Coefficient of coancestry (Θ = 0.208) showed that full-sibs constitute about 21% of the offspring in Kampi ya Moto population compared to about 14% (Θ = 0.136) in Lake Bogoria population. The results demonstrate that low adult tree density of A. senegal may be promoting seed production through consanguineous mating and suggest that man-made disturbance can affect mating patterns of the species. Despite these mating differences, trees from both populations can contribute as seed source for conservational plans, and to support effective genetic conservation and artificial regeneration programs of A. senegal. We suggest collection of seeds from at least 42 and 63 trees in Lake Bogoria and Kampi ya Moto populations, respectively, to retain a progeny array with a total effective population size of 150.     

Roles of seed and pollen dispersal in natural regeneration of Castanopsis fargesii (Fagaceae): Implications for forest management

Natural regeneration is an important process to reverse the loss of forests. Understanding the process of natural regeneration is crucial for achieving sustainable forest management. In this study, we examined the effects of seed and pollen dispersal in naturally regenerated populations of Castanopsis fargesii. Genetic variation in six populations along two successional series (three successional stages in each series: early, pre-climax, and climax) was assayed using RAPD (random amplified polymorphic DNA) markers. High genetic variability was observed as measured with Shannon's information index. A majority of genetic variation was distributed within populations (Φ_st = 0.1271) and significant isolation by distance existed among populations. A contrasting pattern of genetic variation along these two series was observed, representing different scenarios of natural regeneration processes. The ratio of the number of migrants between the mature populations to the number of migrants from the mature to immature populations was estimated as 1.146 ± 0.099 to 1.981 ± 0.164, implying that comparable seed and pollen dispersal might exist at a fine spatial scale (∼2 km²). The results suggest the critical role of seed dispersal in shaping genetic composition and diversity in the second-growth forests. Barriers to seed dispersal from a variety of genetic sources could result in low genetic diversity in naturally regenerated populations. Management that facilitates the connectivity of newly regenerated stands with mature forests could be effective for natural regeneration given the predominant role of short-distance dispersal of seeds in this species.