黄山松种群结构与动态研究

以“空间代替时间”的方法,以种群径级结构代替年龄结构,采用静态生命表和生存分析的方法,探讨了天柱山国家森林公园黄山松种群结构和动态规律。结果表明,随海拔升高,黄山松种群密度增大,径级分布范围减小,种群存活曲线由Deevey-Ⅱ型之间过渡到Deevey—Ⅰ型,种群由稳定型过渡为增长型。表明由低海拔向高海拔,黄山松种群处于不同的演替和发展阶段。     

Population structure and dynamics of Pinus massoniana Lamb. on mount Jinyun,Sichuan, China

Masson Pine (Pinus massoniana Lamb.) is a pioneer in forest succession in the subtropics of East Asia. However, the species persits, though with decreasing abundance, throughout the various successional phases. Agestructure, spatial pattern, density, population biomass, and their dynamics are described for a population in Sichuan, China, on the basis of a census of all individuals in the population while substituting space with time. In the course of succession, the population density increases and its rate of growth decreases until self-thinning starts; during the phase of self-thinning density decrease and continues to decrease even afterwards, but the rate of growth increase markedly after self-thinning has stopped. The development of population biomass (Bp) during the early succession from shrub-grassland to the early stages of mixed pine and broad-leaved forest can be described by a logistic equation. Later, Bp decrease rapidly. These changes are governed partly by inherent biological features of P. massoniana and partly by the invasion, establishment and development of shade-tolerant evergreen broad-leaved trees. Both self- and alien-thinning occur. Soil conditions affect the rates of these processes.     

Population dynamics of Themisto gaudichaudii in Kerguelen Islands waters, Southern Indian Ocean

Fieldwork was carried out at Kerguelen Islands. Two groups of stations in a coastal area, the Morbihan gulf, were surveyed. At both stations, macroplankton biomass ranged from 2.3 mg dry weight m⁻³ to 89 mg dry weight m⁻³ and consisted mostly of Themisto gaudichaudii with values ranging from 1.9 mg dry weight m⁻³ to 50.6 mg dry weight m⁻³. Biomass was high for sub-Antarctic waters with marked seasonal and inter-zone differences. Biomass minima were observed at the end of the winter, from September to November, while maxima were recorded in summer and in early fall at the beginning of the year between January and April. T. gaudichaudii showed a recruitment of new size classes, mainly from November to January, followed by a rapid growth phase in summer, which slowed down during the southern winter period. Individuals breed after 1 year. Large individuals, older than 1 year, were not a significant presence in the gulf of Morbihan. The main pattern of the population dynamics were characterised by an univoltine life cycle with a very high biomass marked by a strong seasonal signal linked with the hydrological and trophic parameters of the Gulf.     

Population genetic structure of striped mullet, Mugil cephalus, along the coast of China, inferred by AFLP fingerprinting

The striped mullet, Mugil cephalus, is an economically important species for both aquaculture and commercial fisheries in China. In this study, the amplified fragment length polymorphism (AFLP) technique was employed to analyze population genetic diversity and genetic distance between different populations with the aim of elucidating the population structure and gene flow of M. cephalus along the coast of China. A total of 230 fragments with 150–500 bp were identified from 118 individuals by five AFLP primer combinations. The polymorphic loci within populations varied from 46.52% to 64.78%, with an average of 53.91%, and the average heterozygosity from 0.1829 to 0.2282, with an average of 0.2074. The UPGMA phenograms of 118 individuals were constructed based on Dice similarity coefficients and four clusters were recognized. AMOVA analysis revealed that 60.7% of genetic variations were within populations and 39.3% between populations. The estimated genetic distance (φ_ST) value over all polymorphic loci across the six populations was 0.393 (p < 0.0010), indicating a strong population structuring. The pairwise φ_ST value ranged from 0.1112 to 0.5358, with an average of 0.3693. The population pairwise gene flows (average N_m = 0.73) are low. In addition, the result of the Mantel test showed that there was a significant correlation between geographic and genetic distances (r = 0.5434, p = 0.0050). It was speculated that there exist at least four distinct geographic populational subdivisions of M. cephalus along the Chinese coast. This research has provided new molecular data which will aid our understanding of the genetic structure of this species.     

Allozyme Diversity and Population Genetic Structure of Pinus densata Master in Northwestern Yunnan, China

We investigated the levels and patterns of genetic diversity of Pinus densata Master in Yunnan. Horizontal starch-gel electrophoresis was performed on macrogametophytes collected from nine populations in northwestern Yunnan, China. Compared with other gymnosperm species, P. densata has higher mean values for all measures of genetic diversity. Allozyme polymorphism (0.99 criterion) was 97.0% and 71.4% at the species and population levels, respectively. The average number of alleles per locus was 3.1 and 2.0 at the species and population levels. Mean expected heterozygosity was substantially higher in P. densata than average values investigated for other gymnosperms both at the population (H _ep = 0.174±0.031) and at the species (H _es = 0.190) levels. Of the total genetic variation, less than 12% was partitioned among populations (G _ST = 0.112). Our allozyme survey supports the suggestion that the observed higher diversity in P. densata may be attributed partly to its hybrid origin between two genetically distinct species, P. yunnanensis and P. tabulaeformis. In addition, we suggest that introgression would give rise to the increase in genetic diversity occurring in P. densata.     

Population dynamics of annual Salicornia species in the tidal salt marshes of the Oosterschelde,The Netherlands

1. The population dynamics of two Salicornia species from the Bergen op Zoom salt marsh (south-west Netherlands) was examined. Based on the results of several field studies three preliminary life tables were constructed, two for S. procumbens agg. populations growing respectively on the mud flats and in the salt marsh, and one for S. europaea agg. living in the upper marsh.
2. The life cycles are described and quantified in terms of eight phases and the transition probabilities between them, starting from a notional individual representative of each population.
3. The models depicting the life cycle of S. procumbens show a mean offspring number of 4.26 individuals per parent for the mud-flat population and 0.18 for the salt-marsh population. The S. europaea model gives an output of 0.44 individuals per parent. These results reflect the fluctuations in population size observed in sample plots over the years 1976–78.
4. Comparison of the transition probabilities reveals that on the mud flats most S. procumbens individuals die during pollination and seed germination, while the population in the salt marsh proper is thinned especially during the seed phase in winter time and during the growth from established seedlings to maturation. S. europaea behaves in a similar but less pronounced way to S. procumbens in the salt marsh.
5. Probabilities for one flower or one seed to produce a mature flowering plant were calculated, and were compared with those found in the literature. They are roughly of the same order of magnitude as the probabilities for other annual species, but much higher than those reported for biennial species.

     

灵空山油松种群年龄结构与动态分析

对山西灵空山自然保护区的油松（Pinus tabulaeformis）种群进行了调查,利用生存分析理论及谱分析理论,分析了油松种群径级结构和静态生命表,绘制了存活曲线,同时分析了种群数量的周期性。主要结果如下：（1）油松种群幼苗幼树个体数较多,中径级的个体数较稳定,而高径级由于种间竞争及环境因子的影响,个体数明显下降。（2）油松种群的存活曲线呈现Deevey-Ⅱ型。动态表现为前期增长,中期稳定,后期衰退。（3）油松种群波动存在小周期,但变化不大,说明油松种群发展较为稳定。     

Multilocus structure in Pinus contorta Dougl.

We studied isozyme variation at 21 loci in 66 populations from three subspecies of Pinus contorta Dougl.; 35 in spp. latifolia, 20 in spp contorta and 11 in spp. murrayana. The objectives were to assess gametic disequilibria and multilocus structure. There was considerable differentiation of allele frequencies at 19 polymorphic loci across the 66 populations and within the subspecies. Allele frequencies at many loci correlated with geographic variables. Genetic variability varied considerably among populations within subspecies but the subspecies means were similar. The mean number of polymorphic loci and the mean heterozygosity over 19 polymorphic loci were, respectively, 13 and 0.194 in latifolia, 12 and 0.196 in murrayana, and 12 and 0.180 in contorta. The mean heterozygosity correlated with longitude and altitude across the 66 populations and with latitude in latifolia. Gametic disequilibria were evident in 40 populations; 29 in latifolia, eight in murrayana and three in contorta. Gametic disequilibria correlated with latitude across the 66 populations and with longitude in latifolia. The single-locus F _ST averaged 0.0339 in latifolia, 0.0567 in murrayana, and 0.0764 in contorta. The multilocus F _STM was 0.1227 in latifolia, 0.2926 in murrayana, and 0.3328 in contorta. Multilocus Wahlund and founder effects, migration patterns, and natural selection, probably played significant roles in generating and maintaining the multilocus genetic structure in P. contorta in general and the subspecies latifolia in particular.     

Population growth and stabilizing age structure of the tughlaqabad rhesus

The rhesus population at Tughlaqabad is characterized by (1) moderately high natality, (2) a changing and perhaps stabilizing age structure, and (3) a declining growth rate. Although natality at this site has been high and relatively invariant over a 7-year period, the proportion of nonreproducing juveniles has increased, necessitating a lower rate of growth. The trapping of rhesus for export, which was practiced in India as recently as 1978, may be largely responsible for the changing nature of the Tughlaqabad age structure but this conclusion remains only conjectural.     

Population structure and reproductive status of two Banksia shrubs at various times after fire

Populations of the obligate-seeder, Banksia ericifolia, were even-aged. Seedling recruitment occurred only after fire. Mean genet size (height + canopy diameter; H+D) increased progressively with elapsed time since fire in stands last burnt 2–23 years before 1981. Populations of a co-occurring resprouter, B. oblongifolia, were mixed-aged. Genet size varied significantly between stands, but this variation was not explained by regressions of H+D on years since fire. In addition B. oblongifolia seedlings were recruited both after fire and in patches of heath unburnt for 16 years.Most flower and seed production in B. oblongifolia occurred in the stands last burnt less than 10 years previously. More than 30% of genets had not produced cones since the last fire, irrespective of how many years had elapsed. In contrast, few B. ericifolia genets had produced cones five years after fire, but by 16 years after fire nearly 100% had. Overall, about 51% of B. ericifolia inflorescences and about 28% of B. oblongifolia inflorescences set seed. The number of seeds in seed-bearing cones was not significantly different between species.Resprouting B. oblongifolia genets began flowering sooner after fire, but B. ericifolia subsequently overtook them in accumulating a bank of serotinous seeds. In the stand unburnt for 23 years the largest B. ericifolia genets had more than twice as many cones as the largest co-occurring B. oblongifolia. However, when accumulated cone production was compared for genets of equal H+D over all stands, there was no difference between species.We thank the New South Wales National Parks & Wildlife Service for permission to do this work in Ku-ring-gai Chase National Park. We are grateful to Don Adamson, Lynn Day, David Haig and James Sim for constructive comments on earlier drafts.     

西天目山黄山松阔叶林的冠层干扰与动态推测

根据年龄结构和直径生长图分析研究了浙江省西天目山黄山松阔叶混交林的冠层干扰年表和发展动态。结果表明黄山松在该林地的定居发生在１８６１－１８８０年之间,黄山松定居３０－４０年后,其他阔叶树开妈在林下萌发生长,形成目前的黄山阔叶混交林,该林浆被阔叶叶树取代。     

Population dynamics of Panonychus osmanthi (Acari: Tetranychidae) on two Osmanthus species

Panonychus osmanthi is a non-diapausing species of spider mite that superficially resembles P. citri. It infests Osmanthus species, which are evergreen roadside and garden trees. The population dynamics of P. osmanthi were studied on Osmanthus aurantiacus and O.×fortunei during a three-year period. Seasonal changes in P. osmanthi populations were fundamentally the same in each year, although their density differed greatly from year to year. TheP. osmanthi population was bimodal, with one peak in spring (May–June) and another in winter (November–January). Populations abruptly declined after the spring peak. Predators showed a delayed density-dependent response to changes in spider mites from spring to summer, whereas in autumn and winter, predators were few because they had entered diapause. To determine the effect of predators on the rapid decline of spider mites just after the spring peak, the predators were removed by treating the trees with a synthetic pyrethroid. As a result, spider mite density did not decline after the spring peak and remained at a high level during the June-August period when spider mite density is usually very low. This suggests that predators play an important role in the drastic decline of P. osmanthi density just after the spring peak. This revised version was published online in July 2006 with corrections to the Cover Date.     

Population structure and responses to disturbance of the basidiomycete Resinicium bicolor

Summary Resinicium bicolor (Alb. & Schw. ex Fr.) Parm. [=Odontia bicolor (Alb. & Schw. ex Fr.) Bres.] is an outcrossing resupinate basidiomycete associated with root and butt rots of trees, but is itself only very weakly pathogenic. The distribution of genets among every spruce stump in a 70-year-old 1250 m² spruce stand was analysed using somatic incompatibility testing. R. bicolor was present on 40% of 8-to 10-year-old stumps. Nineteen genets were found occupying 32 stumps; yielding probabilities of colonisation following establishment by basidiospores of 0.20–0.24 and by mycelial extension or dispersal of 0.16–0.20. The probability of colonisation decreased with increasing distance from a point of establishment. R. bicolor responded to both enrichment and destructive disturbances by the formation of an extensive cord system which enabled it to colonise discontinuously distributed resources and to overgrow fungi adjacent to it in a single resource unit, including Heterobasidion annosum.     

Population dynamics of Plantago maritima along a distributional gradient on a Baltic seashore meadow

Demographical studies of Plantago maritima along a 60 m long gradient, from waterfront to terrestrial meadow, revealed a correspondence in population dynamics. The gradient can be seen as a transition from dominance of density-independent mortality factors, mainly flooding, to a dominance of density-dependent mortality, mainly due to competition for light. In lower parts the variation in density of plants varies greatly between years, the flowering and seeding are good as well as the establishment of seedlings, i.e. there is a high turnover rate. In upper parts the flowering, seeding and establishment are poorer but the life expectancy is longer which results in a low turnover rate. The establishment of seedlings is mainly controlled by the access to light, in lower parts now and then dominated by the effects of flooding. Population characteristics change along the gradient so that reproductive effort, in terms of produced seeds per rosette, and allocation of biomass into reproductive organs is higher in lower parts but the reverse in upper, specimens in lower parts also start to grow and flower earlier.Nomenclature follows J. Lid (1979), Norsk og Svensk Flora. Det Norske Samlaget, Oslo.     

Population dynamics ofAzospirillum brasilense and its bacteriophage in soil

Summary This study examined the ecology and interaction ofAzospirillum brasilense and its bacteriophage in soil. Four Chernozemic soils from Canada, a Latosol and three Podzolic soils from Brazil were assayed for phage. Only the Latosol containedA. brasilense phage. None of the soils contained phage for otherA. brasilense orA. lipoferum strains tested. Recovery of phage from soil depended on the growth of indigenous or added host cells. A phage isolated from the Latosol had a hexagonal head of 100 nm and a tail of 200 nm. This phage was morphologically distinct from previously described Azospirillum phage and its host range was limited toA. brasilense strains 29145 and 29711.Survival and recovery of phage added to phage-free soil was dependent on the phage, the initial phage population, the presence of host cells and nutrients, and the soil. Phage persisted in soils at undetectable levels for at least seven weeks, but were still able to interact with multiplying host cells and exhibit a 1000-fold increase in number. Phage required a host cell population of at least 100–1000 per g of soil in order to multiply. The phage burst detected under these conditions increased as the cell to phage ratio increased. Long term incubation studies showed that the activity of phage in soil closely followed the activity of host cells and thus both were manipulated by appropriate amendments to soil.     

Population dynamics ofDaphnia rosea in a small eutrophic pond

The population dynamics ofDaphnia rosea were studied in a small, eutrophic fish-free pond during November 1986–November 1987.D. rosea showed two density peaks in 1987, a high peak in spring and a slightly lower one in autumn, but they disappeared in mid- and late summer when a smaller cladoceran,Ceriodaphnia reticulata, dominated. The rapid decline in density ofD. rosea in mid-May and the low density in June/July were preceded by or coincided with a period of increased male density, the appearance of ephippial females, smaller body length of adult females, decreased brood size, and increased frequency of empty brood chambers, all of which indicate a worsening food situation. The rapid density decline ofD. rosea in mid-May was considered attributable neither to increasing water temperature, nor predation by the dipteranChaoborus flavicans, but to insufficient food conditions for the maintenance of stable reproduction. Although edible phytoplankton was abundant in June/July, the general food situation was not suitable forD. rosea due to blooms of the large-celled dinoflagellate,Ceratium hirundinella, which probably inhibited the feeding activity ofD. rosea. TheC. hirundinella blooms might also be important for the shift of the dominant herbivore from the largerD. rosea to the smallerCeriodaphnia reticulata in August/September.     

庐山黄山松种群结构及数量动态研究

庐山黄山松(Pinus taiwanensis)广泛分布于海拔800 m以上至山顶地段,在庐山现存植被中占有非常重要的地位。为了更好地了解黄山松在庐山的更新和演替情况,该文通过对庐山黄山松种群的调查,以种群径级结构代替年龄结构,采用\"空间代时间\"的分析方法,编制庐山黄山松种群的静态生命表,结合种群结构动态指数、时间序列平均推移法模型等方法对黄山松的种群结构和数量动态进行了分析。结果表明:(1)庐山黄山松种群结构呈纺锤形,幼龄和老龄个体数量较少,中龄个体多,目前处于比较稳定的阶段。(2)黄山松种群死亡高峰出现在第8龄级,个体平均期望寿命第2龄级最大,种群存活曲线属于Deevey-Ⅰ型。(3)随着时间的推移,老龄个体逐渐增多,小径级出现缺失,种群表现出衰退趋势。建议在保护区经营和管理的过程中,对黄山松林进行适当的人工抚育,补植一些适宜的落叶阔叶树种,以丰富该地区的树种多样性以及群落结构。     

Population dynamics of the annual halophyte Spergularia marina on a Baltic seashore meadow

The population dynamics of the annual Spergularia marina was studied during four years on three different sites on a Baltic seashore meadow. The population density varied significantly both between years and between sites. At one of the sites the average population density was higher than at the two other sites. Both differences in reproductive capacity and in density-independent mortality caused differences in population size. Variation in population seed yield or loss of seed or both, between years, to a large extent determined the variation in the population density between years.