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1.
The eddy correlation technique was employed to measure net ecosystem carbon dioxide (CO2) (NEE) and water vapor exchange (LE) over a C3/C4 co-occurring wet temperate Miscanthus-type grassland in the Kanto plain of Japan in the 1999 growing season. The maximal mean canopy height and maximal leaf area index were 1.0m and 5.5, respectively. The daily maximal LE was approximately 540Wm–2. The maximum value of daily accumulative LE was 16.3MJday–1. Daily variation of the decoupling factor () suggests that in the morning LE decoupled with the atmosphere, and the available energy was the major driving force for LE, whereas in the afternoon LE coupled strongly with the atmosphere, and the atmospheric evaporative demand played a critical role in LE. The decline in (from 0.8 to 0.5) with the growing season demonstrates that LE decoupled from the atmosphere in the later growth season. The peak NEE value was 57.4µmolCO2m–2s–1 (the positive value signifies the canopy carbon gain was from the air). The maximal daily integrated NEE was 1.06molCO2m–2day–1 observed during the peak growth stage. A rectangular hyperbolic model was used to describe the relation between daytime NEE and incident photosynthetic photon flux density (PPFD). The net ecosystem CO2 was not light-saturated up to a PPFD level of 2000µmol m–2s–1. The initial slope estimated with the NEE–PPFD response model was approximately 0.042molCO2mol–1photon on average. The canopy light compensation point ranged from 210 to 430µmolm–2s–1 with an average of approximately 310µmolm–2s–1. Both the initial slope and the canopy light compensation point decreased as the canopy senesced. The switch in dominance from C3 to C4 plants played an important role in the canopy fluxes.  相似文献   

2.
The production of erythritol and the erythritol yield from glucose by Torula sp. were improved, in increasing order, by supplementing with 10 mg MnSO44H2O l–1, 2 mg CuSO45H2O l–1, and both 10 mg MnSO44H2O l–1 and 2 mg CuSO45H2O l–1. Mn2+ decreased the intracellular concentration of erythritol, whereas Cu2+ increased the activity of erythrose reductase in cells. These results suggest that Mn2+ altered the permeability of cells, whereas Cu2+ increased the activity of erythrose reductase in cells.  相似文献   

3.
We investigated the carbon dynamics and budget in a grassland of Miscanthus sinensis, which is widely distributed in Japan, over a 2-year period (2000–2001). Plant biomass began to increase from May and peaked in September, then decreased towards the end of the growing season (October). Soil respiration rates also exhibited seasonal fluctuations that reflected seasonal changes in soil temperature and root respiration. The contribution of root respiration to total soil respiration was 22–41% in spring and summer, but increased to 52–53% in September. To determine the net ecosystem production (carbon budget), we estimated annual net primary production, soil respiration, and root respiration. Net primary production was 1207 and 1140gCm–2 in 2000 and 2001, respectively. Annual soil respiration was 1387gCm–2 in 2000 and 1408gCm–2 in 2001; root respiration was 649 and 695gCm–2 in 2000 and 2001, respectively. Moreover, some of the carbon fixed as net production (457–459gCm–2) is removed by mowing in autumn in this grassland. Therefore, the annual carbon budget was estimated to be –56gCm–2 in 2000 and – 100gCm–2 in 2001. These results suggest that the Miscanthus sinensis grassland in Japan can act as a source of CO2.  相似文献   

4.
Behavioral and physiological responses to hypoxia were examined in three sympatric species of sharks: bonnethead shark Sphyrna tiburo, blacknose shark, Carcharhinus acronotus, and Florida smoothhound shark, Mustelus norrisi, using closed system respirometry. Sharks were exposed to normoxic and three levels of hypoxic conditions. Under normoxic conditions (5.5–6.4mg l–1), shark routine swimming speed averaged 25.5 and 31.0cm s–1 for obligate ram-ventilating S. tiburo and C. acronotus respectively, and 25.0cm s–1 for buccal-ventilating M. norrisi. Routine oxygen consumption averaged about 234.6 mg O2kg–1h–1 for S. tiburo, 437.2mg O2kg–1h–1 for C. acronotus, and 161.4mg O2 kg–1 h–1 for M. norrisi. For ram-ventilating sharks, mouth gape averaged 1.0cm whereas M. norrisi gillbeats averaged 56.0 beats min–1. Swimming speeds, mouth gape, and oxygen consumption rate of S. tiburo and C. acronotus increased to a maximum of 37–39cm s–1, 2.5–3.0cm and 496 and 599mg O2 kg–1 h–1 under hypoxic conditions (2.5–3.4mg l–1), respectively. M. norrisi decreased swimming speeds to 16cm s–1 and oxygen consumption rate remained similar. Results support the hypothesis that obligate ram-ventilating sharks respond to hypoxia by increasing swimming speed and mouth gape while buccal-ventilating smoothhound sharks reduce activity.  相似文献   

5.
Annual nitrogen and phosphorus budgets for the whole North Sea taking into account the most recent data available were established. The area considered has a total surface of approximately 700,000km2 and corresponds to the definition by OSPARCOM (Oslo and Paris Commission) with the exclusion of the Skagerrak and Kattegat areas. Input and output fluxes were determined at the marine, atmospheric, sediment and continental boundaries, and riverine inputs based on river flows and nutrient concentrations at the river–estuary interface were corrected for possible estuarine retention. The results showed that the North Sea is an extremely complex system subjected to large inter-annual variability of marine water circulation and freshwater land run-off. Consequently, resulting total N (TN) and P (TP) fluxes are extremely variable from 1 year to another and this has an important influence on the budget of these elements. Total inputs to the North Sea are 8870±4860kTNyear–1 and 494±279kTPyear–1. Denitrification is responsible for the loss of 23±7% of the TN inputs while sediment burial is responsible for the retention of only of 2±2% of the TP input. For TN, due to the large variability on marine and estuarine fluxes, and to the uncertainty related to the denitrification rate, it was concluded that the North Sea could either be a source (1930kTNyear–1) or a sink (1700kTNyear–1) for the waters of the North Atlantic Ocean. For TP it was concluded that the North Sea is mostly a source (–4 to 52kTPyear–1) for the waters of the North Atlantic Ocean.  相似文献   

6.
Inoculation of sugar mill by-products compost with N2-fixing bacteria may improve its quality by increasing total N and available P. Compost was inoculated with Azotobacter vinelandii(ATCC 478), Beijerinckia derxii (ATCC 49361), and Azospirillumsp. TS8, each alone and all three together. Numbers of all N2-fixing bacteria in compost declined from an initial population of 5×105cellsg–1 during incubation. The population of Azotobacter declined to approximately 2×102cellsg–1 and the population of Beijerinckia and Azospirillum declined to approximately 9×103 and 3.5×104cellsg–1 respectively, at day 50. Inoculation with N2-fixing bacteria increased acetylene reduction, total N by 6–16 and available P by 25–30% in comparison to the uninoculated control. Increasing the N content and P availability of compost increases its value and there may be additional benefit from providing N2 fixing bacteria.  相似文献   

7.
Strain H-984 of G. fujikuroi grown for 38h in a shake flask with medium containing 20g glucose l–1, 3g yeast extract l–1, 2.5g NH4NO3 l–1, 0.5g KH2PO4 l–1, 0.1g MgSO4 l–1, 1g CaCO3 l–1, and inoculated into a bioreactor with medium containing 60g glucose l–1; 1g NH4Cl l–1; 3g KH2PO4 l–1 and 1.5g MgSO4 l–1 produced 1100mg gibberellic acid l–1.  相似文献   

8.
Planktonic microbial interactions in the central basin of Lake Baikal were examined on a summer day in 1999. The subsurface maxima of bacterial abundance and chlorophyll concentration were recorded at the same depth, whereas the vertical distribution of heterotrophic nanoflagellates was the inverse of those of bacteria and picophytoplankton. Release of extracellular organic car-bon (EOC) from phytoplankton was estimated by the NaH14CO3 method as 2.4µgCl–1day–1. Bacterial production (4.3µgCl–1day–1), estimated in a bottle incubation experiment using size-fractionated water samples, exceeded the EOC released. Thus, other supplying sources of organic matter are needed for the bacterial production. Grazing (2.6µgCl–1day–1) was also estimated in the experiment and accounted for 60% of the bacterial production. This is the first report on the microbial food web in the central basin of Lake Baikal.  相似文献   

9.
Uptake kinetics of nitrogen derived from sewage–seawater mixtures (2.5–20% v/v effluent) were determined in the laboratory for Ulva rigida (Chlorophyceae) native from Bahía Nueva (Golfo Nuevo, Patagonia, Argentine). In terms of nitrogen concentration, experimental enrichment levels varied between 53.7 and 362.3M of ammonium and between 0.77 and 6.21M of nitrate+nitrite. Uptake rates were fitted to the Michaelis–Menten equation, with the following kinetic parameters: ammonium: Vmax = 591.2molg–1h–1, K s=262.3M, nitrate+nitrite: V max=12.9molg–1h–1, K s=3.5M). Both nutrients were taken up simultaneously, but ammonium incorporation was faster in all cases. The results show a high capability of Ulva rigida to remove sewage-derived nitrogen from culture media. In the field, most of the nitrogen provided by the effluent would be tied up in algal biomass, supporting low nitrogen levels found at a short distance away from the source.  相似文献   

10.
A new indigenous soil bacterium Pseudomonas sp. growing on phenol and on a mixture of phenol, toluene, o-cresol, naphthalene and 1,2,3-trimethylbenzene (1,2,3-TMB) was isolated and characterized. Phylogenetic analysis suggested its classification to Pseudomonadaceae family and showed 99.8% DNA sequence identity to Pseudomonas pseudoalcaligenes species. The isolate was psychrotroph, with growth temperatures ranging from ca. 0 to 40 °C. The GC–MS structural analysis of metabolic products of phenol degradation by this microorganism indicated a possible ortho cleavage pathway for high concentrations (over 200 mg L–1) of phenol. Biodegradation rates by this species were found to be three times more effective than those previously reported by other Pseudomonas strains. The effect of temperature on phenol degradation was studied in batch cultures at temperatures ranging from 10 to 40°C and different initial phenol concentrations (up to 500mgL–1). Above 300mgL–1 of initial phenol concentration no considerable depletion was recorded at both 10 and 40°C. Maximum degradation rates for phenol were recorded at 30°C. The biodegradation rate of phenol was studied also in the presence of additional carbon sources (o-cresol, toluene, naphthalene, 1,2,3-TMB) at the optimum growth temperature and was found significantly lower by a factor of eight in respect to the strong competitive inhibition between the substrates and the more available sources of carbon and energy. The Haldane equation =m S/(KS+S+S2/KI) was found to best fit the experimental data at the optimum temperature of 30°C than the Monod equation with kinetic constants m=0.27h–1, KS=56.70mgL–1, KI=249.08mgL–1.  相似文献   

11.
This paper presents a large data set on carbon isotope composition (13C) of modern soils which were collected under the main vegetation communities along an altitude of 1250–5500m above sea level in the Qinghai-Tibetan Plateau. The 13C values of 198 samples range from –28.6 to –15.1 versus PDB and exhibit a clean relation to different vegetation communities from forest (–25.9±1.2) to shrub (–24.7±1.4), steppe (–23.1±1.3), alpine meadow (–23.6±0.7), alpine desert steppe (–21.3±1.6), and alpine desert (–18.9±2.5). We attributed the observed variability in 13C values to that the mean annual precipitation (MAP) and the mean annual temperature (MAT) are the main factors controlling the distribution of vegetation types in the Tibetan Plateau, which causes the change in carbon isotope composition of modern soils at any given altitude. The result of both linear and nonlinear regression analyses also confirms that MAP and MAT are the major factors affecting the 13C values of surface soils. In the absence of favorable moisture and temperature conditions, low pCO2 alone is not sufficient to cause the distinct changes in carbon isotope composition of modern soils in the Tibetan Plateau. This study provides some fundamental information on the carbon isotope composition of terrestrial carbon pools and bears some practical significance for the use of carbon isotope data to document vegetation changes and environmental conditions of the high plateau in the past.  相似文献   

12.
To clarify consistency in the size of carbon pool of a lowland tropical rainforest, we calculated changes in above-ground biomass in the Pasoh Forest Reserve, Peninsular Malaysia. We estimated the total above-ground biomass of a mature stand using tree census data obtained in a 6-ha plot every 2years from 1994 to 1998. The total above-ground biomass decreased consistently from 1994 (431Mgha–1) to 1998 (403Mgha–1) (1Mg=103 kg). These are much lower than that in 1973 for a 0.2ha portion of the same area, suggesting that the the total above-ground biomass reduction might have been consistent in recent decades. This trend contrasted with a major trend for neotropical forests. During 1994–1998, the forest gained 23.0 and 0.88Mgha–1 of the total above-ground biomass by tree growth and recruitment, respectively, and lost 51.9Mgha–1 by mortality. Overall, the biomass decreased by 28.4Mgha–1 (i.e. 7.10Mgha–1·year–1), which is almost equivalent to losing a 76-cm-diameter living tree per hectare per year. Analysis of positive and negative components of biomass change revealed that deaths of large trees dominated the total above-ground biomass decrease. The forest biomass also varied spatially, with the total above-ground biomass density ranging 212–655Mgha–1 on a 0.2-ha basis (n= 30 subplots, 1998) and 365–440Mgha–1 on a 1ha basis. A large decrease of the total above-ground biomass density (>50Mg per ha per 2years) in several 0.2-ha subplots contributed to the overall decrease in the 6-ha total above-ground biomass. In the present study, we discuss the association between forest dynamics and biomass fluctuation, and the implication for carbon cycling in mature forests with emphasis on forest monitoring and assessments of soil and decomposition systems.  相似文献   

13.
Hawaii's dry forests are among the most endangered of all ecosystems in the archipelago. Invasion of alien plant species into these ecosystems is one of the most significant threats to on-going efforts to preserve and restore Hawaii's remaining dry forests. Comparing the physiological performance of alien and native species can offer causal explanations behind the relative success of alien plant invasions within Hawaiian dry forests and elsewhere. We compared maximum rates of net CO2 assimilation, water-use efficiency (WUE), daily carbon gain, and leaf morphology for three native and two alien shrubby species growing within 1-m2 plots under two natural light (sub-canopy shade relative to open full sunlight) treatments. Maximum rates of net CO2 assimilation were similar between alien and native species (8.15 vs. 7.12molm–2s–1, respectively), however, native plants exhibited lower stomatal conductance and higher instantaneous WUE than alien plants in all treatments (0.13molm–2s–1 and 72.36mol CO2mol H2O–1 against 0.23 and 58.78, respectively). Alien plants had approximately 65% more aboveground biomass than native plants. This result may reflect differential seed production and seed bank viability between native and alien species. We found an overall strong, positive correlation between species-specific physiological traits and final species aboveground biomass. Based on this type of information we can predict species-specific boundaries across light gradients, and focus restoration efforts accordingly.  相似文献   

14.
Production of acetyl esterase (EC 3.1.1.6) by Fusarium oxysporum strain F3 was enhanced by optimization of growth conditions. Under optimal conditions, activities as high as 0.89U/ml of culture medium were obtained. The culture filtrate was equally active on p-nitrophenyl acetate and acetylxylan. The enzyme produced 71% deacetylation of acetylxylan in 2h at 40C. Activity was optimized at pH6.5 and at 55C. The respective Km values for p-nitrophenyl acetate and acetylxylan were 0.25mM and 1.05% (w/v) and the Vm values were 0.65 and 0.43mol acetate/min/mg protein.  相似文献   

15.
The present study demonstrates a procedure for the rapid development of a high number of somatic embryos from embryogenic suspension culture. This method might be efficient for mass propagation of Phnix dactylifera L. Embryogenic callus placed in liquid medium with 10–5M ABA yielded an average 72 embryos per 100ml of culture medium within 2months, while those placed on solid medium yielded an average of 33, 20 and 16 embryos per 100ml of culture medium respectively for 10–7, 10–6 and 10–5 M ABA after 4months. The combination of 2,4-DIchlorophenoxyacetic acid (2,4-D) (4.5×10–7M), glutamine (6.7×10–4M), and ABA (10–5M) (L8 liquid medium) showed a beneficial effect on somatic embryos production compared to 2,4-D and glutamine alone, while this combination significantly (p<0.05) increased the accumulation of storage proteins (144 and 138mgg–1 DW respectively for Jihel and Bousthami noir cultivars) in somatic embryos. The somatic embryos which underwent maturation on medium containing only 4.5×10–7M 2,4-D and 10–5M ABA (L6 liquid medium) accumulated more sugars (292 and 265mgg–1 DW respectively for Jihel and Bousthami noir) than those matured on any other liquid medium. Histological studies revealed that somatic embryos (developed in L6 and L8 liquid media) accumulated less reserve compounds (proteins and sugars) than zygotic embryos. The addition of activated charcoal (0.25 and 0.5gl–1) and phytagel® (2.5gl–1) to the germination medium may be useful for enhancing the germination of Phnix dactyliferasomatic embryos.  相似文献   

16.
The biomass of summer forage and their contributions were surveyed to show that litterfall supported a high-density population of sika deer (Cervus nippon Temminck) in summer on Nakanoshima Island, Toya Lake, Japan. In July 1974, the grassland had the highest productivity among understory vegetations (228±55kgha–1: mean±SE). In deciduous forests, palatable plants occupied only 0.1% of the biomass of 0.872±0.366kgha–1, and deciduous leaves within the reach of deer (=220cm at height) produced 0.208±0.070kgha–1. However, litterfall during this period had the highest productivity, 28.7± 5.3kgha–1. The deer consumed litterfall (75.6% in dry weight), short grasses (17.2%), deciduous forest understory (4.1%), deciduous leaves within the reach of deer (3.0%) and conifer plantation under story (0.1%). It is suggested that the high-density deer population would be maintained by litterfall through the year instead of browsing in deciduous forests, which has been overlooked.  相似文献   

17.
Saccharomyces cerevisiae-based ethanol fermentations were conducted in batch culture, in a single stage continuous stirred tank reactor (CSTR), a multistage CSTR, and in a fermentor contaminated with Lactobacillus that corresponded to the first fermentor of the multistage CSTR system. Using a glucose concentration of 260 g l–1 in the medium, the highest ethanol concentration reached was in batch (116gl–1), followed by the multistage CSTR (106gl–1), and the single stage CSTR continuous production system (60gl–1). The highest ethanol productivity at this sugar concentration was achieved in the multistage CSTR system where a productivity of 12.7gl–1h–1 was seen. The other fermentation systems in comparison did not exceed an ethanol productivity of 3gl–1h–1. By performing a continuous ethanol fermentation in multiple stages (having a total equivalent working volume of the tested single stage), a 4-fold higher ethanol productivity was achieved as compared to either the single stage CSTR, or the batch fermentation.  相似文献   

18.
This study examined macronutrient input from pollen in two naturally regenerating pine stands in southeast Korea. Durham gravity pollen collectors were used to measure pine pollen deposition and the macronutrients in the collected pine pollen were analyzed. In 1998, pine pollen deposition began just before 18 April and lasted for approximately 2weeks. Total pine pollen deposition differed between the two sampling sites; 27.5kgha–1 was collected from the mature stand and 17.7kgha–1 was collected from the young stand. The values for nutrient deposition from pine pollen are 549gha–1 N, 78gha–1 P, 240gha–1 K, 45gha–1 S and 22gha–1 Mg at the mature stand and 353gha–1 N, 51gha–1 P, 151gha–1 K, 27gha–1 S and 14gha–1 Mg at the young stand, suggesting that nutrients from pine pollen contribute to forest nutrient cycling. The pine pollen deposition values obtained from our study (17.7–27.5kg–1ha–1year–1) are approximately 1/115–180-fold that of pine litterfall in Korea. If we take pollen nutrients into account, the contribution rate of pollen to the annual nutrient input is very high in our study (N 1/30, P 1/5, K 1/9 that of litterfall). Macronutrient deposition from pine pollen is concentrated temporally in spring. Although the annual contribution of nutrient mass by pollen is small compared to that of litterfall, the rapid turnover rate of pollen nutrients combined with episodic deposition suggests that pollen may play a disproportionate role in temperate pine forest nutrient cycling.  相似文献   

19.
Lake Puma Yumco is a typical alpine lake (altitude 5030m) located in the pre-Himalayas of Tibet, China, and this study was the first limnological investigation ever conducted on it. Lake Puma Yumco (28°34N, 90°24E) has the following morphometric properties: maximum length 31km, maximum width 14km, mean width 9km, shoreline 90km, surface area 280km2, and shoreline development 1.5. Transparency was approximately 10m, even in the thawing season. The extinction coefficient of the lake water was calculated as 0.15m–1. Annual maximum transparency was estimated from the depth of the Chara zone to be 30m. Dissolved oxygen was 7mg O2 l–1 and showed saturated values, and salinity was 360mgl–1. The chemical type of the lake water was Mg-Ca-HCO3-SO4, and it was slightly alkaline in character. Total nitrogenous nutrients (sum of ammonia, nitrite, nitrate, and urea nitrogen), phosphate, and silicate were extremely low at 1, 0.02, and 9µM, respectively. Dissolved organic carbon, nitrogen, and phosphorus concentrations were 160, 11, and 0.08µM and the molar ratio was calculated as 2100:140:1. Chlorophyll a concentration was 0.2mgm–3. Phytoplankton and zooplankton were dominated by Aphanocapsa sp. and Diaptomidae. Both nitrogen and phosphorus appear to be the limiting parameters for phytoplankton growth. Organic carbon and nitrogen contents in lake sediments were low and the sediments contained a large amount of CaCO3. The grain size of sediment was that of silt-sand in most cases. The present results indicate that the pre-Himalayan alpine freshwater Lake Puma Yumco is an ultraoligotrophic lake.  相似文献   

20.
Petitpierre E  Garnería I 《Genetica》2003,119(2):193-199
The chromosomes of ten species of Cyrtonus and the genome sizes of six are surveyed. Among the total of 15 chromosomally studied species, 11 have 2n=28 chromosomes and a 13+Xyp male meioformula, three have 2n=40 and 19+Xyp and one 2n=46 and 22+Xyp. All but one species with 28 chromosomes show only metacentric or submetacentric chromosomes, whereas the species with 40 and 46 chromosomes display some telocentrics or subtelocentrics, that are probably derived from the former by centric fissions. However, since the number of major chromosome arms is strikingly higher in these latter species (NF=70 and 78) than in the 28-chromosome species (mostly NF=56), other chromosomal rearrangements such as pericentric inversions or heterochromatin accretions could also be involved. The genome sizes display a narrow range, from 1C=0.6–1.22pg, and they are not significantly correlated with the chromosome numbers. Some possible factors implied in the rough chromosomal evolution of Cyrtonus are discussed in relation to a few other genera of the subfamily Chrysomelinae.  相似文献   

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