Comparison of species ordinations resulting from alternative indices of interspecific association and different numbers of included species

Summary Several measures of interspecific association are compared. Dispersion and covariance are limited in value because they respond to the commonness of the species compared. Correlation is not so limited but it responds to discrepancies in commonness among the species. The practical result of these relationships between commonness and association is that only the most common species can occupy periferal positions in a species ordination. Rare species are relegated to positions near the center not on the basis of their phytosociological pattern but simply because of their rarity. Both Cole's index of association and the tetrachoric correlation overcome the problem imposed by the relationship between ordination position and species commonness and they both produce very similar results. The effect of differing numbers of species on the ordination configuration is examined using both Pearson's correlation and Cole's index. The basic pattern of the ordination is set with the first few species when Cole's index is used, however, since rare species are given more weight in the analysis with this index, the addition of several very rare species can change the configuration of the ordination.Nomenclature of species is given in Table 1.Research supported by the Eastern Deciduous Forest Biome Project, US-IBP, funded by the National Science Foundation under Interagency Agreement AG-199, BMS69-01147 A09 with the Energy Research and Development Administration — Oak Ridge National Laboratory. Research also supported by the U.S. Energy Research and Development Administration under contract with the Union Carbide Corporation. Contribution No. 240 from the EDFB, US-IBP. Publication No. 790. Environmental Sciences Division, ORNL.     

Dissolved oxygen concentration and diversity of benthic macroinvertebrates in an artificially destratified lake

Changes in species composition and diversity of benthic macroinvertebrates during summer and fall were compared in an area of a lake artificially destratified and in an arm not destratified. Numbers of species, diversity, and density were significantly correlated with the concentration of dissolved oxygen, while none of the biotic variables were correlated with temperature.Research supported with funds from the Oklahoma Water Resources Research Institute     

温度和水分对无芒隐子草和条叶车前种子萌发的影响

研究了无芒隐子草 (Cleistogenessongorica)和条叶车前 (Plantago lessingii)种子萌发对不同温度和水分渗透势的响应。温度在 10℃恒温至 5 0 /2 0℃变温范围内设 11个处理 ,水分渗透势在 0～ - 1.8MPa区间以 0 .2 MPa为间隔设 10个处理。结果显示 :无芒隐子草鞘内小穗的种子具有很高的生活力 ,其萌发温度幅较宽 ,在 10～ 5 0 /2 0℃温度区间 ,较高温度促进萌发 ;条叶车前种子萌发温度幅较窄 ,在 10～ 30℃温度区间 ,较低温度促进其萌发。无芒隐子草和条叶车前种子的最佳萌发温度分别为35 /2 0℃变温和 2 0℃恒温 ,在此条件下的发芽率分别达 94 %和 6 1% ,后者发芽率低的原因是种子存在生理休眠。两种植物种子萌发的最低水分阈值为 - 1.6 MPa,发芽率皆随渗透势降低而呈直线下降趋势 ,但条叶车前较无芒隐子草下降缓慢。发芽率 (y)与渗透势 (x)的回归方程 ,无芒隐子草为 y1 =- 10 .976 x1 98.4 (r2 =0 .95 4 ) ,条叶车前为 y2 =- 5 .90 9x2 6 0 .2 (r2 =0 .96 4 )。随着水分胁迫的加剧 ,供试种胚芽长呈逐渐下降趋势 ,但胚根长呈先增加 (无芒隐子草在 - 0 .6 MPa,而条叶车前在 - 0 .4 MPa)而后下降的趋势。讨论了两种植物种子萌发对不同温度和水分响应的生态学意义     

Synchronous decline of native bitterling population detected from 9 years of survey in rivers and agricultural ditches around Lake Kasumigaura,Japan

Ichthyological Research - To assess the population dynamics, abundance of bitterling species and two non-bitterling cyprinid species were investigated in Lake Kasumigaura, Japan. Fish capture was...     

Effects of flooding on Eucalyptus camaldulensis and Eucalyptus globulus seedlings

Summary Flooding for up to 40 days induced morphological changes and reduced growth of 6-week-old Eucalyptus camaldulensis and Eucalyptus globulus seedlings. However, the specific responses to flooding varied markedly between these species and with duration of flooding. Both species produced abundant adventitious roots that originated near the tap root and original lateral roots, but only E. camaldulensis produced adventitious roots on submerged portions of the stem. Flooding induced leaf epinasty and reduced total dry weight increment of seedling of both species but growth of E. globulus was reduced more. In both species dry weight increment of shoots was reduced more than dry weight increment of roots, reflecting compensatory growth of adventitious roots. Adaptation to flooding appeared to be greater in E. camaldulensis than in E. globulus. the importance of formation of adventitious roots in flooding tolerance is emphasized.Research supported by the College of Agricultural and Life Sciences, University of Wisconsin, Madison; CEPEC (Cacao Research Center), Bahia, Brazil; and BMBRAPA (Brazilian Research Institute), Brasilia, Brazil     

Different population size change and migration histories created genetic diversity of three oaks in Tokai region,central Japan

Journal of Plant Research - To understand genetic diversity in focal species, it is important to consider the possibility of speciation with gene flow, especially in species with porous genomes...     

荒漠生境油蒿根围AM真菌多样性

为了阐明荒漠生境主要植被油蒿(Artemisia ordosica)根围AM真菌多样性, 2007年8月从毛乌素沙地和腾格里沙漠选取榆林、盐池、研究站和沙坡头4个样地, 按0–10、10–20、20–30、30–40、40–50 cm 5个土层采集油蒿根围土壤样品, 研究了油蒿根围AM真菌物种多样性和生态分布。在分离的4属28种AM真菌中, 球囊霉属(Glomus)16种, 无梗囊霉属(Acaulospora)7种, 盾巨孢囊霉属(Scutellospora)4种, 多孢囊霉属(Diversispora)1种。4个样地的共同优势种为摩西球囊霉(G. mosseae), 共同常见种为双网无梗囊霉(A. bireticulata)和网状球囊霉(G. reticulatum), 共同稀有种为缩球囊霉(G. constrictum)。地球囊霉(G. geosporum)仅出现在盐池, 蜜色无梗囊霉(A. mellea)、帚状球囊霉(G. coremioides)、浅窝无梗囊霉(A. lacunosa)和宽柄球囊霉(G. magnicaule)仅出现在研究站, 黑球囊霉(G. melanosporum)仅出现在榆林。盐池与研究站样地AM真菌种类最多, 榆林样地孢子密度最大, 沙坡头样地种类和孢子密度显著偏低。总体上, 孢子密度、分离频度、相对多度和重要值依Glomus >Acaulospora > Scutellospora> Diversispora呈现显著减小趋势。结果表明, 油蒿与AM真菌之间有良好共生性, 这对进一步利用菌根生物技术维护荒漠生态系统结构的完整性具有重要意义。     

A leukocyte culture and chromosome preparation technique for avian species

Summary A technique for avian leukocyte culture and chromosome analysis is described. The method is simple and allows karyotypic analysis by a variety of chromosome banding methods. It is applicable to a wide variety of species and may be useful in determining the genetic sex of monotypic species in captivity or for population studies of specimens in the wild. This work was supported by Medical Research Council (Canada) Grant MA-4655. B. M. B. is a recipient of a Medical Research Council Fellowship.     

Effects of film-forming and silicone antitranspirants on four herbaceous plant species

Summary Effectiveness of antitranspirants in reducing transpiration was studied in the laboratory in an attempt to evaluate their potential for conservation and reallocation of soil moisture. Film-forming antitranspirants caused about a 50% reduction of transpiration and photosynthesis in all species. Effectiveness decayed slowly over 10–14 days. Effectiveness of the silicone antitranspirant was very short-lived. Water use efficiency was slightly improved following film-forming antitranspirant treatment of three species. Mixing antitranspirants altered their effects.Research supported by the Bureau of Land Management in Cooperation with the Office of Water Research and Technology, United States Department of the Interior (OWRT Grant B-099)     

Role of enemy release and hybridization in the invasiveness of Impatiens balfourii and I. glandulifera

Journal of Plant Research - Comparative studies with taxonomically and geographically paired alien species that exhibit different degrees of success in their invasions may help to identify the...     

Review of Indo-Pacific species of the scorpionfish genus Scorpaena (Teleostei: Scorpaenidae), with descriptions of two new species from the west coast of Australia

Ichthyological Research - A taxonomic review of Indo-Pacific species of the scorpionfish genus Scorpaena resulted in the recognition of 21 valid species (including 2 subspecies and 2 new species)...     

Mechanisms of drought-induced dissipation of excitation energy in sun- and shade-adapted drought-tolerant mosses studied by fluorescence yield change and global and target analysis of fluorescence decay kinetics

Photosynthesis Research - Some mosses stay green and survive long even under desiccation. Dissipation mechanisms of excess excitation energy were studied in two drought-tolerant moss species...     

The influence of climate and population density on Buxus hyrcana potential distribution and habitat connectivity

Journal of Plant Research - Changes in environmental factors, human impact, and interactions between them accelerate the extinction of woody species. Therefore, conservation programs are needed to...     

Effects of light conditions on growth and defense compound contents of Datura inoxia and D. stramonium

Journal of Plant Research - We examined the effects of light conditions on plant growth and production of defense compounds in the toxic species Datura inoxia and D. stramonium. Specifically, we...     

Models of competition in the chemostat with instantaneous and delayed nutrient recycling

Two models for competition of two populations in a chemostat environment with nutrient recycling are considered. In the first model, the recycling is instantaneous, whereas in the second, the recycling is delayed. For each model an equilibrium analysis is carried out, and persistence criteria are obtained. This paper extends the work done by Beretta et al. (1990) for a single species.Research partially supported by the Natural Sciences and Engineering Research Council of Canada, Grant NSERC A4823Research carried out at the University of Alberta while on a Canada-China Scholarly Exchange Program     

Larvae and juveniles of three gobiid species of the genus Priolepis

Ichthyological Research - Larvae and juveniles of three species in the family Gobiidae were described based on reared material; Priolepis borea survived to post-settlement, and Priolepis cincta and...     

Zinc and Metallothionein in the Development and Progression of Dental Caries

Biological Trace Element Research - Chronic oxidative stress and reactive oxygen species (ROS) in oral cavity as well as acidic pH on dental enamel surface due to the metabolic activities of...     

Description of two new species of Bassozetus (Ophidiiformes: Ophidiidae) and a redescription of Bassozetus robustus Smith and Radcliffe 1913

Ichthyological Research - Two new deepwater assfish species, Bassozetus trachibranchus and Bassozetus squamosus, are described from the 29 western Atlantic and four western Indian and western South...     

Connectivity and variation among estuaries in recruitment and population demographics of Sillago ciliata

Ichthyological Research - Sillago ciliata is widely distributed in estuarine and nearshore coastal waters along the Australian east coast where it is a key target species in recreational and...     

Interaction of livestock grazing and rainfall manipulation enhances herbaceous species diversity and aboveground biomass in a humid savanna

Journal of Plant Research - Understanding of the interaction of livestock grazing and rainfall variability may aid in predicting the patterns of herbaceous species diversity and biomass production....