A study on relations of vegetation,climate and soils in Shanxi province,China

Relationships of vegetation, climate and soils in Shanxi plateau wereanalyzed by use of Canonical Correspondence Analysis (CCA). Shanxi province,located at 34°35–40°43 N, 110°15–114°33 E, was divided into a series of rectangular districts of30 latitude by 20 longitude. Areas of vegetation formations and soil types ineach district were measured carefully using fine grain on the vegetation andsoil maps of Shanxi. Climatic data were mean values of 25 years records in eachdistrict. Three data matrices of climate, vegetation and soil were combined byCCA. The results showed that the distribution of vegetation is closely relatedto the variety of climates and to soils distribution.     

Observation of a distinct transition in the mode of interconversion of ring pucker conformers in non-crystalline d-ribose-2'-d from 2H NMR spin-alignment

Internal motions of d-ribose selectively ²H-labeled at the 2 position were measured using solid state ²H NMR experiments. A sample of d-ribose-2 -d was prepared in a hydrated, non-crystalline state to eliminate effects of crystal-packing. Between temperatures of –74 and –60°C the C2–H2 bond was observed to undergo two kinds of motions which were similar to those of C2–H2/H2 found previously in crystalline deoxythymidine (Hiyama et al. (1989) J. Am. Chem. Soc., 111, 8609–8613): (1) Nanosecond motion of small angular displacement with an apparent activation energy of 3.6 ± 0.7 kcal mol^–1, and (2) millisecond to microsecond motion of large amplitude with an apparent activation energy 4 kcal mol^–1. At –74°C, the slow, large-amplitude motion was best characterized as a two-site jump with a correlation time on the millisecond time scale, whereas at –60°C it was diffusive on the microsecond time scale. The slow, large-amplitude motions of the C2–H2 bond are most likely from interconversions between C2-endo and C3-endo by way of the O4-endo conformation, whereas the fast, small-amplitude motions are probably librations of the C2–H2 bond within the C2-endo and C3-endo potential energy minima.     

Reproduction of the calanoid copepod Calanus propinquus in the southern Weddell Sea,Antarctica: observations in laboratory

Reproduction of the dominant Antarctic copepod Calanus propinquus was studied in February–April, 1989 aboard the R.V Dmitry Mendeleev during cruise N° 43 to the Weddell Sea. Single females were kept at 0 °C in the laboratory for 56 days with abundant food concentration (above 300 µg C l^–1 of Platymonas viridis). Females released clutches at night at 2–3 day intervals. Most clutches contained from 10 to 40 eggs, mean 37.3 eggs female^–1. Average carbon content of an egg was 0.37 ± 0.05 µg C. The maximum daily egg production rate of 30–50 eggs female^–1 d^–1 was observed for the first 3 days of the laboratory incubation, corresponding to 3.7–6.2% body C. The state of gonadal development of females showed the decline of the reproductive season in late February. The data suggest that egg laying in the region under study starts in December and lasts until March. The state of ovarian maturation, changes in vertical distribution and biochemical body composition of females suggest the possibility of two-year life cycle in C. propinquus in the southern Weddell Sea.     

Fecundity of Atlantic sturgeon (Acipenser oxyrinchus Mitchill, 1815) captured by the commercial fishery in the Saint John River,New Brunswick,Canada

Knowledge of fecundity in fishes is important for understanding life history, modeling population dynamics, developing fisheries management and determining conservation status. Sturgeon species are known for their high fecundity but to date only two populations of Atlantic sturgeon (Acipenser oxyrinchus Mitchill, 1815) have been examined for this aspect of their biology. The species is protected in most regions of eastern North America but the Saint John River, New Brunswick supports one of the two remaining commercial fisheries in Canada. Sixty females selected by this fishery were sampled for total length, weight, age, gonad weight and egg number. Absolute fecundity ranged from 153,630 to 1,306,626 eggs, with a mean fecundity of 582,832 ± 261,806 eggs. Absolute fecundity exhibited a significant positive relationship to increasing body weight but not to total length or age. Relative fecundity ranged from 129 to 216 eggs/g gonad weight and although it declined with both increasing body size and age the relationships were not significant. The Gonadosomatic Index (GSI) ranged from 1.3% to 27.0% with a mean of 7.8% ± 4.94 SD. Relative fecundity found in this study was higher and mean GSI lower than reported for other Atlantic sturgeon populations and other sturgeon species. Differences were probably due to location of the fishery downstream from spawning sites and selection of pre-spawning females by the commercial fishery.     

The life cycle of Laminaria abyssalis (Laminariales,Phaeophyta) in culture

Laminaria abyssalis occurs in deep water in tropical latitudes of the Brazilian coast (19° 23 S, 38° 28 W to 22° 54 S, 42° 13 09 W). Its life cycle has been completed in the laboratory in seven months using different conditions of light and temperature. The gametophytic stage required for growth the low photon flux density of 1.2 ± 0.3 µmol m^–2 s^–1 and 18 °C, while the juvenile and adult sporophytes needed 15 µmol m^–2 s^–1 and 18 °C. The sporophytes became fertile at 23 °C. Our results showed that light and temperature are the main factors regulating the growth and life history of this species under the culture conditions tested.     

The life cycle of Amblyomma neumanni Ribaga, 1902 (Acari: Ixodidae) in the laboratory

A colony of Amblyomma neumanni was started with engorged females collected from cattle in the province of Salta (24° 51S, 65° 33W), Argentina. The larvae and nymphs were fed on rabbits and the adults on calves. The non-parasitic stages were maintained in darkness at 27 ± 1°C and 83–86% RH. The life cycle (pre-feeding period not tested) had a mean duration of 205.7 days. The mean time (days) for the different phases of the cycle were as follows: feeding of females 8.8, pre-oviposition 23.8, oviposition 41.4, minimum egg incubation 76.1, feeding of larvae 8.5, pre-moult to nymphs 16.4, feeding of nymphs 7.9 and pre-moult to adults 22.8. The mean recovery rates of larvae, nymphs and females were 83.8, 85.6 and 89.3%, respectively. The nymphs moulting to females were heavier (8.1 ± 2.34 mg) than those moulting to males (6.0 ± 2.34 mg; p < 0.01), but their range of engorgement weight showed overlap (2.3–16.2 versus 2.2–12.8 mg, respectively). Two gynandromorphs were detected between the nymphs. A comparison of biological parameters of A. neumanni with other American Amblyomma species from mammals is presented. © Rapid Science Ltd. 1998     

Factors affecting egg dimensions and breeding success in the Cory''s Shearwater(Calonectris diomedea) of Selvagem Grande

Summary Eggs of the Cory's ShearwaterCalonectris diomedea borealis of Selvagem Grande (Madeira, 30°09N, 15°52W), show high variability in size and shape between females, while for each individual both are correlated over two seasons. During the first breeding years, females lay larger and more rounded eggs as their experience (number of years since first breeding) increases. Age (number of years since birth) probably has an effect on egg size but adult size has none. No important differences between the two years of study has been observed and no inter-colony variation is apparent. Finally, breeding success is directly linked to egg size but not to egg shape.

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Eigröße und Bruterfolg von Gelbschnabelsturmtauchern(Calonectris diomedea borealis) auf Selvagem Grande

Zusammenfassung Die Größe und Form der Eier des GelbschnabelsturmtauchersCalonectris diomedea borealis von Selvagem Grande (30°09N, 15°52W) variieren zwischen verschiedenen Weibchen erheblich, die einzelnen Weibchen legen jedoch in Folgejahren gleich große Eier. Erfahrenere Weibchen legen größere und rundere Eier. Ältere Weibchen legen größere Eier. Das Alter hat keinen Einfluß auf die Eigröße. Zwischen den beiden Untersuchungsjahren (1996 und 1997) gab es keine Unterschiede, auch nicht zwischen verschiedenen Kolonien. Bruterfolg und Eigröße waren positiv korreliert.

     

Demographic Characteristics of Female Mottled Sculpin, Cottus Bairdi, in the Coweeta Creek Drainage, North Carolina

We quantified: (1) growth rate, (2) length-mass relationships, (3) size- and age-specific fecundity, (4) egg size-frequencies, and (5) size- and age-specific egg diameter relationships for reproductively active female C. bairdi from one of the southern-most extant populations of this species (Coweeta Creek drainage, North Carolina). Gravid females were collected during February and March in 1993–1995, and 1998. Cottus bairdi reached an age of 7+ and 79mm standard length. The youngest and smallest gravid female collected was a 41mm 1+ individual. Mature 1+ females were not uncommon and we collected 21 during our study. All females older than age 2 were mature. Mean fecundity for C. bairdi at Coweeta was 71 eggs (range 9–166 eggs). We found significant positive relationships between fecundity and female length, weight and age. Female length and weight also significantly affected mean egg diameter, although the relationship was not linear. Neither female size or age significantly affected mean maximum egg diameters. Female C. bairdi from the Coweeta Creek drainage possess a unique suite of reproductive characteristics that may represent adaptations to the local selective regime or ecophenotypic variation.     

Population structure and dynamics of a neotropical palm in fire-impacted fragments of the Brazilian Atlantic Forest

The demography of the acaulescent palm Attalea humilis was studied from 1996 to 1999 in three forest fragments (1.6, 6.4, and 9.9ha) in southeastern Brazil (22°30–22°33 S, 42°15–42°19 W). A human-induced fire damaged the populations in August–September 1997. Palm density was higher in the medium-sized fragment, where it was concentrated in a single disturbed sector. Population ontogenetic stage structure was dependent on fragment and year, but in general later stages were more abundant than initial ones. Population finite growth rates projected from linear, stage-structured demographic models indicated that the populations were increasing before fire. Population growth rate in the smallest fragment was larger due to a single recruitment event, being most sensitive to changes in survival and growth of seedlings, virgins and the immature, and relatively insensitive to changes in shrinkage and fecundity. Observed growth rates for the entire study period showed that populations remained in equilibrium after fire, but the population in the medium-sized fragment showed a declining tendency. Population structure was resilient to fire, which caused a transitory concentration of individuals in the medium-sized stage. The self-sustainability of the population in the largest, most preserved fragment suggests that habitat-protection measures may suffice to ensure the persistence of populations in small fragments. However, population fluctuations and exclusion from hyper-disturbed sectors in the smallest fragment suggest that reduced fragment area, habitat degradation and human-induced fires can interact to threaten the persistence of even abundant, preadapted to fire, species like A. humilis.     

The life cycle ofAmblyomma parvum Aragao, 1908 (Acari: Ixodidae) under laboratory conditions

A colony ofAmblyomma parvum was started with engorged females collected from cattle in the Province of Salta (25°01 S, 63°56 W), Argentina. The progeny of those ticks were fed on rabbits and the non-parasitic stages maintained at 27±1°C, 83–86% RH in darkness. The life cycle (prefeeding period not evaluated) had a mean duration of 99.6 days. The mean time (days) for the different phases of the cycle were as follows: feeding period of females, 8.0; pre-oviposition period, 5.7; oviposition period, 17.5; minimum incubation period of the eggs, 31.8; feeding period of larvae, 3.2; premoult period to nymphs, 10.9; feeding period of nymphs, 4.7; premoult period to adults, 17.8. The oviposition pattern was typical of an ixodid tick, including a linear relationship between weights of engorged females and the number of eggs laid (r=0.8659). The males increased 18% in weight after feeding on hosts (P<0.01). The mean recovery rates of larvae, nymphs and females were 28.2%, 95.3% and 90.7%, respectively. The nymphs moulting to females were heavier (6.8±0.69 mg) than those moulting to males (3.2±0.29 mg) (P<0.01). A comparison of biological values ofA. parvum with American and non-AmericanAmblyomma species is presented.     

Effects of abscisic acid (ABA) and ABA analogs on freezing tolerance,low-temperature growth,and flowering in rapeseed

Brassica napus and B. campestris are grown in Western Canada in areas subject to unseasonable frosts. At the seedling stage, cultivars of Brassica are very sensitive to frosts of -2° to-5°C, which are either lethal or delay the development of the plant. Seedlings of B. napus and B. campestris, germinated and grown at 10°C (16-h photoperiod), were treated with a foliar spray of either 100 M racemic abscisic acid (ABA), 100 M of various ABA analogs, 0.1% acetone, or were untreated. Freeze tests indicated 2°C of frost tolerance could be gained in B. napus following an application of three ABA analogs. In B. campestris, three analogs also increased freezing tolerance approximately 1.5°C. The analogs 2,3 dihydro ABA and acetylenic divinyl methyl-ABA were effective in both species. Plant fresh weight and dry weight increased in treated plants relative to control or acetone-treated plants after 3 weeks at 10°C. The effect of frost and/or analog treatment on flowering was determined in both species. In B. campestris and B. napus, a mild frost advanced flowering by approximately 2 days compared with nonfrozen control plants. The promotive effect of frost on flowering decreased with increasing severity of the frost. Several of the analog treatments, particularly 2,3 dihydro ABA and acetylenic divinyl ABA, advanced flowering by 2–3 days in both species. The benefit of these ABA analog treatments on flowering was enhanced additionally by a mild frost. Plants treated with either ABA, 2,3 dihydro ABA, 2,3 acetylenic dihydro ABA, or acetylenic divinyl ABA flowered up to 5 days earlier than control plants.     

Factors affecting oviposition and fecundity in the grain miteAcarus siro L. (Acarina:Acaridae), especially temperature and relative humidity

Oviposition and fecundity in the grain miteAcarus siro were studied at 5–30°C and 62.5–90% RH. At and above 20°C, 80% RH, mating and oviposition occurred soon after emergence, but at lower temperatures and humidities egg laying was progressively delayed from one to several days. Females needed to mate repeatedly in order to achieve maximum egg production, optimum conditions for which were 15°C, 90% RH, where total output per female averaged 435 with a maximum of 858. Oviposition rates were highest at higher temperatures, the mean daily rate at 20 and 25°C, 90% RH, rising to maximum levels of 28/29 eggs per female per day on day six.Oviposition followed clearly defined patterns, favourable conditions producing rapid increases in the mean daily oviposition rate to high peak levels reached at an early stage in the oviposition period. Less favourable conditions resulted in reduced outputs and lower, more uniform rates of egg laying. The mean oviposition period, varying with humidity, fell from 72–122 days at 5°C to 9–13 days at 30°C and the mean incubation period from 42–70 days at 5°C to 3–4 days at 30°C. Egg viability increased with increasing humidity but was little affected by temperature and unaffected by age of the female at time of oviposition.Males tended to live longer than females at most conditions; longevity—depending on humidity—averaging 13–15 days at 30°C and 129–175 days at 5°C. Adult life for females averaged 12–19 days at 30°C and 88–169 days at 5°C. An index of suitability, calculated from egg number, viability and duration of the egg stage and oviposition period, indicated that the most favourable conditions for oviposition and hatching were 20–25°C and 80–90% RH.     

The effect of Mg2+ and Ca2+ on urea-catalyzed phosphorylation reactions

Summary When struvite (MgNH₄PO₄ 6H₂O) is heated with urea at 65–100°C, inorganic pyrophosphate is formed in good yield. Under similar conditions pyro-phosphate is formed much more slowly from ammonium phosphate or hydroxylapatite. The major products formed by the reaction of nucleotides with urea and either ammonium phosphate or hydroxylapatite are derivatives phosphorylated on the 2 or 3 position. With struvite, on the other hand, the main reaction is pyrophosphate bond formation. Yields of up to 25% of uridine diphosphate can be obtained at temperatures as low as 65°C.     

Vegetation history and climate changes in West Equatorial Africa during the Late Pleistocene and Holocene, based on a marine pollen diagram from the Congo fan

Palynological investigation of the marine core, GeoB 1008-3, from near the mouth of the Congo river (6°35.6S/10°19.1E), provides information about the changes in vegetation and climate in West Equatorial Africa during the last 190 ka. The pollen diagram is divided into zones 1–6 which are considered to correspond in time with the marine isotope stages 1–6. Oscillations in temperature and moisture are indicated during the cold stage 6. During stage 5, two cooler periods (5d and 5b) can be shown with an expansion of Podocarpus forests to lower elevations on the expense of lowland rain forest. Extended mangrove swamps existed along the coast in times of high sea level (stages 5 and 1).     

Reproductive isolation between the two forms ofPanonychus akitanus Ehara (Acarina: Tetranychidae)

Crossing experiments were carried out between the stiped-egg form collected from Sapporo (43°04N) and Machida (35°33N), and the stipeless-egg form ofPanonychus akitanus Ehara from Tomakomai (42°37N) and Imagane (42°34N). Intra-form crosses gave a high proportion of female progeny, but inter-form crosses only male progeny, suggesting that fertilization did not take place. The number of eggs laid during the first 10 days of the oviposition period was greater in intra-form crosses than in inter-form crosses (P<0.001). The latter, except for the cross between the Sapporo and the Imagane populations, had similar egg production to virgin females (P<0.05).Mated females showed a greater daily oviposition rate than virgin females. However, the latter drastically increased their oviposition rate after mating with their sons. The two forms are thus reproductively isolated.     

Population structure and dynamics of Pinus taiwanensis Hayata at Songyang county,Zhejiang Province,China

Pinus taiwanensis is a widely distributed species in the southeastern China (Zhejiang, Anhui, Hubei, Human, Jiangxi, Fujian, Taiwan provinces) at an elevation of 700–2000 m. This pine is a pioneer in forest succession and is often used as a species for afforestation in this region at an elevation above 700 m. This study was carried out at Guanshanyuan, Zhejiang province, at a latitude of N 28° 18, a longitude of E 119° 16 and an altitude of 800–1502 m above sea level. On the basis of a census of all individuals of Pinus taiwanensis at different successional stages and various habitats, age structure, spatial pattern, density, biomass of population and their dynamics were described. Considering the population dynamics throughout the successional process, three phases could be recognized. Until about 9–10 years after Pinus taiwanensis invaded the stands, the density of population was increased by the recruitments along with increase of the mean tree weight and population biomass (phase I). Thereafter, the population was in full density state, the biomass of population and the mean tree weight increased exponentially, while the density was decreased drastically by the self-thinning and the invasion of other broad-leaved trees (phase II). The –3/2 power law of natural thinning was applicable to the populations in this phase. When the broad-leaved trees reached the canopy, although the mean tree weight increased slowly, the density and biomass of Pinus taiwanensis population decreased gradually (phase III) until the population senesced and retreated from the successional series completely. The population dynamics of Pinus taiwanensis during the successional process was in common with pioneer species in forest succession. At some special habitats such as rocky steep slopes and ridges, however, Pinus taiwanensis population could form such an edaphic climax community that the population density, biomass and the mean tree weight in phase III could be in a stable state for very long period.     

Fish populations in the Paraná River: Lentic environments of Diamante and San Pedro Areas (Argentine Republic)

Data on the fish populations of lentic water bodies of the Lower Paraná River in the Diamante and San Pedro areas (33°40–31°55 S, 59°40'–60°40 W), sampled during 1971 are given. Limnological characteristics such as surface area and depth of ponds, water turbidity, and plant cover are included. Differences in fish population size, structure, specific diversity, dominance, and biomass of particular species are established between two areas in a dry season.     

Annual primary productivity of an antarctic continental lake: Phytoplankton and benthic algal mat production strategies

Primary production in Watts Lake, Vestfold Hills, Antarctica (68°36S, 78°13E), was measured from March 1981 to February 1982. Phytoplankton production peaked in autumn and spring, with a September maximum (340 mgC m^–2 d^–1), then declined in summer and was not detectable in winter. Benthic algal production peaked in summer at 74 mgC m^–2 d^–1), Production strategies differed, with the more efficient phytoplankton adapted to growth at low light, while benthic production increased with increasing light in summer. Estimation of annual production was 10.1 gC m^–2 and 5.5 gC m^–2 for the phytoplankton and benthos respectively.     

Plankton and hydrochemistry of Lake Futalaufquen (Patagonia,Argentina) during the growing season

Plankton communities and hydrochemistry of an oligotrophic lake occupying a glacial valley in Argentinian Patagonia (42 °49S; 71 °43W) were studied. Monthly samples at three stations integrated from 0 to 50 m and stratified samples at the site of maximum depth, were taken during the growing season. Transparency was always controlled by glacial silt, and not by phytoplankton. Lake water belongs to the calcium-bicarbonate type, with low conductivity (24 µS cm^–1), and poor buffering capacity. Forty-five phytoplankton taxa were found. Mean phytoplankton density was 49 cells ml^–1 and mean biomass 69 µg l^–1. N:P relationships, inorganic nitrogen exhaustion in the photic layer, and correlations between nutrients and phytoplankton density suggests nitrogen as the main limiting factor. Fifteen zooplankton species were found. Mean zooplankton density was 12.2 ind. l^–1 and mean biomass 22.9 µg l^–1. Diatoms and Boeckellidae were the dominant planktonic groups. Morphometry and hydrological factors were responsible for horizontal heterogeneity in phytoplankton and chemical variables.     

Pre-moult foraging trips and moult locations of Emperor penguins at the Mawson Coast

The movements of nine breeding adult emperor penguins Aptenodytes forsteri from two colonies, Auster (67° 23S 64° 04E) and Taylor Glacier (67° 28S 60° 54E), were determined by satellite telemetry on their pre-moult foraging trips. While preparing for their annual moult the penguins travelled for 22–38 days and reached distances of up to 618 km from the colony. Six of the nine tracked penguins were followed to three different moult locations all to the west of their breeding colonies and near other known emperor penguins colonies, such as Kloa Point (66°38S, 59°23E) and Fold Island (67°17S, 59°23E). Sea-ice conditions changed throughout the tracking period; as the birds travelled north the sea-ice contracted south.