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1.
Mitsuru Hirota Pengcheng Zhang Song Gu Haihua Shen Takeo Kuriyama Yingnian Li Yanhong Tang 《Journal of plant research》2010,123(4):531-541
Characterizing the spatial variation in the CO2 flux at both large and small scales is essential for precise estimation of an ecosystem’s CO2 sink strength. However, little is known about small-scale CO2 flux variations in an ecosystem. We explored these variations in a Kobresia meadow ecosystem on the Qinghai-Tibetan plateau in relation to spatial variability in species composition and biomass. We
established 14 points and measured net ecosystem production (NEP), gross primary production (GPP), and ecosystem respiration
(Re) in relation to vegetation biomass, species richness, and environmental variables at each point, using an automated chamber
system during the 2005 growing season. Mean light-saturated NEP and GPP were 30.3 and 40.5 μmol CO2 m−2 s−1 [coefficient of variation (CV), 42.7 and 29.4], respectively. Mean Re at 20°C soil temperature, Re20, was −10.9 μmol CO2 m−2 s−1 (CV, 27.3). Re20 was positively correlated with vegetation biomass. GPPmax was positively correlated with species richness, but 2 of the 14 points were outliers. Vegetation biomass was the main determinant
of spatial variation of Re, whereas species richness mainly affected that of GPP, probably reflecting the complexity of canopy
structure and light partitioning in this small grassland patch. 相似文献
2.
Sotiris Haliapas Traianos A. Yupsanis Thomas D. Syros George Kofidis Athanasios S. Economou 《Acta Physiologiae Plantarum》2008,30(6):807-815
Petunia × hybrida was grown under high (H), medium (M) and low (L) light intensity [photoperiod; 16 h d−1, photosynthetic photon flux density (PPFD); 360, 120 and 40 μmol m−2 s−1, respectively] as well as under end-of-day (EOD) red (R) and far-red (FR) light quality treatments [photoperiod; 14.5 h d−1, PPFD; 30 μmol m−2 s−1 EOD; 15 min, Control (C) light; without EOD light treatment]. Shoot growth, leaf anatomical and photosynthetic responses
as well as the responses of peroxidase (POD) isoforms and their specific activities following transition to flowering (1–6 weeks)
were evaluated. Flower bud formation of Petunia × hybrida was achieved at the end of the 4th week for H light treatment and on the end of the 6th week for FR light treatment. No flower
bud formation was noticed in the C and R light treatments. H and M light treatments induced lower chlorophyll (Chla, Chlb,
Chla+b) concentrations in comparison to L light. On the other hand R and FR light chlorophyll content were similar to C light.
Photosynthetic parameters [CO2 assimilation rate (A), transpiration rate (E) and stomatal conductance (g
s) values] were higher in the H light treated plants in comparison to M and L light treated plants. A, E and g
s values of R and FR light were similar to C light plants. Leaf anatomy revealed that total leaf thickness, thickness of the
contained tissues (epidermis, palisade and spongy parenchyma) and relative volume percentages of the leaf histological components
were differently affected within the light intensity and the light quality treatments. POD specific activities increased from
the 1st to the 6th week during transition to flowering. Native-PAGE analysis revealed the appearance of four anionic POD (A1–A4) isoforms in all light treatments. On the basis of the leaf anatomical, photosynthetic and plant morphological responses,
the production of high quality Petunia × hybrida plants with optimal flowering times could be achieved through the control of both light intensity and light quality. The
appearance of A1 and A2 anionic POD isoforms could be also used for successful scheduling under light treatments. 相似文献
3.
Taku M. Saitoh Ichiro Tamagawa Hiroyuki Muraoka Na-Yeon M. Lee Yuichiro Yashiro Hiroshi Koizumi 《Journal of plant research》2010,123(4):473-483
We investigated carbon dioxide (CO2) exchange and its environmental response during two years with contrasting climate (2006 and 2007) in a cool-temperate mixed
evergreen coniferous forest dominated by Japanese cedar (Cryptomeria japonica) and Japanese cypress (Chamaecyparis obtusa). The study, which was conducted in a mountainous region of central Japan, used the eddy-covariance technique. Our results
(crosschecked using the common u
* approach and van Gorsel’s alternative approach) showed that annual gross primary production (GPP) and ecosystem respiration
(RE) were at least 6% higher in the dry year than in the wet year, whereas net ecosystem exchange (NEE) was similar in both
years. Without soil water stress, strong light stress or seasonality of plant area index during most of the study period,
the forest had high metabolic activity. GPP and RE differed greatly between the two years, especially in spring (April–May)
and summer (July–September), respectively. The spring GPP difference (>20%) was influenced by different winter air temperatures
and snow melt timing, which controlled photosynthetic capacity in spring, and by different spring light intensities. The annual
NEE differed depending on the evaluation method used, but the mean 2-year NEE estimated by the u
* threshold approach [−3.39 ± 0.11 (SD) MgC ha−1 year−1] appears more reasonable in comparison with results from other forests. 相似文献
4.
Four temperature treatments were studied in the climate controlled growth chambers of the Georgia Envirotron: 25/20, 30/25,
35/30, and 40/35 °C during 14/10 h light/dark cycle. For the first growth stage (V3-5), the highest net photosynthetic rate
(P
N) of sweet corn was found for the lowest temperature of 28–34 μmol m−2 s−1 while the P
N for the highest temperature treatment was 50–60 % lower. We detected a gradual decline of about 1 P
N unit per 1 °C increase in temperature. Maximum transpiration rate (E) fluctuated between 0.36 and 0.54 mm h−1 (≈5.0–6.5 mm d−1) for the high temperature treatment and the minimum E fluctuated between 0.25 and 0.36 mm h−1 (≈3.5–5.0 mm d−1) for the low temperature treatment. Cumulative CO2 fixation of the 40/35 °C treatment was 33.7 g m−2 d−1 and it increased by about 50 % as temperature declined. The corresponding water use efficiency (WUE) decreased from 14 to
5 g(CO2) kg−1(H2O) for the lowest and highest temperature treatments, respectively. Three main factors affected WUE, P
N, and E of Zea: the high temperature which reduced P
N, vapor pressure deficit (VPD) that was directly related to E but did not affect P
N, and quasi stem conductance (QC) that was directly related to P
N but did not affect E. As a result, WUE of the 25/20 °C temperature treatment was almost three times larger than that of 40/35 °C temperature treatment. 相似文献
5.
Deepa Dhital Yuichiro Yashiro Toshiyuki Ohtsuka Hibiki Noda Yoko Shizu Hiroshi Koizumi 《Journal of plant research》2010,123(4):519-530
The ecosystem carbon budget was estimated in a Japanese Zoysia japonica grassland. The green biomass started to grow in May and peaked from mid-July to September. Seasonal variations in soil CO2 flux and root respiration were mediated by changes in soil temperature. Annual soil CO2 flux was 1,121.4 and 1,213.6 g C m−2 and root respiration was 471.0 and 544.3 g C m−2 in 2007 and 2008, respectively. The root respiration contribution to soil CO2 flux ranged from 33% to 71%. During the growing season, net primary production (NPP) was 747.5 and 770.1 g C m−2 in 2007 and 2008, respectively. The biomass removed by livestock grazing (GL) was 122.1 and 102.7 g C m−2, and the livestock returned 28.2 and 25.6 g C m−2 as fecal input (FI) in 2007 and 2008, respectively. The decomposition of FI (DL, the dry weight loss due to decomposition)
was very low, 1.5 and 1.4 g C m−2, in 2007 and 2008. Based on the values of annual NPP, soil CO2 flux, root respiration, GL, FI, and DL, the estimated carbon budget of the grassland was 1.7 and 22.3 g C m−2 in 2007 and 2008, respectively. Thus, the carbon budget of this Z. japonica grassland ecosystem remained in equilibrium with the atmosphere under current grazing conditions over the 2 years of the
study. 相似文献
6.
Highly productive papyrus (Cyperus papyrus L.) wetlands dominate many permanently flooded areas of tropical East Africa; however, the cycling of carbon and water within
these ecosystems is poorly understood. The objective of this study was to utilise Eddy Covariance (EC) techniques to measure
the fluxes of carbon dioxide and water vapour between papyrus vegetation and the atmosphere in a wetland located near Jinja,
Uganda on the Northern shore of Lake Victoria. Peak, midday rates of photosynthetic CO2 net assimilation were approximately 40 μmol CO2 m−2 s−1, while night time losses through respiration ranged between 10 and 20 μmol CO2 m−2 s−1. Numerical integration of the flux data suggests that papyrus wetlands have the potential to sequester approximately 0.48 kg C m−2 y−1. The average daily water vapour flux from the papyrus vegetation through canopy evapotranspiration was approximately 4.75 kg
H2O m−2 d−1, which is approximately 25% higher than water loss through evaporation from open water. 相似文献
7.
Klaus S. Larsen Andreas Ibrom Claus Beier Sven Jonasson Anders Michelsen 《Biogeochemistry》2007,85(2):201-213
We measured net ecosystem CO2 flux (F
n) and ecosystem respiration (R
E), and estimated gross ecosystem photosynthesis (P
g) by difference, for two years in a temperate heath ecosystem using a chamber method. The exchange rates of carbon were high
and of similar magnitude as for productive forest ecosystems with a net ecosystem carbon gain during the second year of 293 ± 11 g C m−2 year−1 showing that the carbon sink strength of heather-dominated ecosystems may be considerable when C. vulgaris is in the building phase of its life cycle. The estimated gross ecosystem photosynthesis and ecosystem respiration from October
to March was 22% and 30% of annual flux, respectively, suggesting that both cold-season carbon gain and loss were important
in the annual carbon cycle of the ecosystem. Model fit of R
E of a classic, first-order exponential equation related to temperature (second year; R
2 = 0.65) was improved when the P
g rate was incorporated into the model (second year; R
2 = 0.79), suggesting that daytime R
E increased with increasing photosynthesis. Furthermore, the temperature sensitivity of R
E decreased from apparent Q
10 values of 3.3 to 3.9 by the classic equation to a more realistic Q
10 of 2.5 by the modified model. The model introduces R
photo, which describes the part of respiration being tightly coupled to the photosynthetic rate. It makes up 5% of the assimilated
carbon dioxide flux at 0°C and 35% at 20°C implying a high sensitivity of respiration to photosynthesis during summer. The
simple model provides an easily applied, non-intrusive tool for investigating seasonal trends in the relationship between
ecosystem carbon sequestration and respiration. 相似文献
8.
We compared on eight dates during the ice-free period physicochemical properties and rates of phytoplankton and epipelic primary
production in six arctic lakes dominated by soft bottom substrate. Lakes were classified as shallow ( < 2.5 m), intermediate in depth (2.5 m < < 4.5 m), and deep ( > 4.5 m), with each depth category represented by two lakes. Although shallow lakes circulated freely and intermediate and
deep lakes stratified thermally for the entire summer, dissolved oxygen concentrations were always >70% of saturation values.
Soluble reactive phosphorus and dissolved inorganic nitrogen (DIN = NO3
−–N + NH4
+–N) were consistently below the detection limit (0.05 μmol l−1) in five lakes. However, one lake shallow lake (GTH 99) periodically showed elevated values of DIN (17 μmol l−1), total-P (0.29 μmol l−1), and total-N (33 μmol l−1), suggesting wind-generated sediment resuspension. Due to increased nutrient availability or entrainment of microphytobenthos,
GTH 99 showed the highest average volume-based values of phytoplankton chlorophyll a (chl a) and primary production, which for the six lakes ranged from 1.0 to 2.9 μg l−1 and 0.7–3.8 μmol C l−1 day−1. Overall, however, increased resulted in increased area-based values of phytoplankton chl a and primary production, with mean values for the three lake classes ranging from 3.6 to 6.1 mg chl a m−2 and 3.2–5.8 mmol C m−2 day−1. Average values of epipelic chl a ranged from 131 to 549 mg m−2 for the three depth classes, but levels were not significantly different due to high spatial variability. However, average
epipelic primary production was significantly higher in shallow lakes (12.2 mmol C m−2 day−1) than in intermediate and deep lakes (3.4 and 2.4 mmol C m−2 day−1). Total primary production (6.7–15.4 mmol C m−2 day−1) and percent contribution of the epipelon (31–66%) were inversely related to mean depth, such that values for both variables
were significantly higher in shallow lakes than in intermediate or deep lakes.
Handling editor: L. Naselli-Flores 相似文献
9.
The eco-physiological responses of three nitrogen-fixing cyanobacteria (N-fixing cyanobacteria), Aphanizomenon gracile, Anabaena minderi, and Ana. torques-reginae, to light were assessed under nutrient saturation. The N-fixing cyanobacteria were isolated into monocultures from a natural
bloom in a shallow colored lake and their growth irradiance parameters and pigment composition were assessed. The different
ecological traits related to light use (μmax, α, I
k) suggest that these N-fixing cyanobacteria are well adapted to low light conditions at sufficient nutrients, yet interspecific
differences were observed. Aphanizomenon gracile and Anabaena minderi had high relative growth rates at low irradiances (ca. 70% of those in high light), low half saturation constant for light-limited
growth (I
k < 9.09 μmol photon m−2 s−1) and high efficiency (α < 0.11 day−1 μmol photon−1 m2 s). Conversely, Ana. torques-reginae showed poorer light competitiveness: low relative growth rates at low irradiances (ca. 40% of those in high light), low α
(0.009 day−1 μmol photon−1 m2 s) and higher I
k (35.5 μmol photon m−2 s−1). Final densities in Aphanizomenon gracile and Anabaena minderi reached bloom densities at irradiances above 30 μmol photon m−2 s−1 with different hierarchy depending on irradiance, whereas Ana. torques-reginae never achieved bloom densities. All species had very low densities at irradiances ≤17 μmol photon m−2 s−1, thus no N-fixing blooms would be expected at these irradiances. Also, under prolonged darkness and at lowest irradiance
(0 and 3 μmol photon m−2 s−1) akinetes were degraded, suggesting that in ecosystems with permanently dark sediments, the prevalence of N-fixing cyanobacteria
should not be favored. All species displayed peaks of phycocyanin, but no phycoeritrin, probably due to the prevailing red
light in the ecosystem from which they were isolated. 相似文献
10.
Phytoplankton productivity and its response to higher light levels in the Canada Basin 总被引:1,自引:0,他引:1
Phytoplankton productivity in the Canada Basin was measured in the late summer season, from mid-September to mid-October 2009,
using a 13C–15N dual tracer technique. To understand potential production changes associated with sea ice melting in the Arctic Ocean, we
examined the effects of light enhancement and nitrate enrichment on the carbon productivity of phytoplankton from the chlorophyll
a maximum layer. The daily carbon productivity in the Canada Basin in 2009 was very low, with a mean of 4.1 mg C m−2 (SD = 3.6 mg C m−2), compared with those reported in previous studies in the region. Among several explanations, the most plausible reason for
the large difference in carbon productivity between this and the previous studies was strong seasonal variation in biomass
and photosynthetic rate of the phytoplankton in the study region. Based on our results from light enhancement and nitrate
enrichment experiments, we found that carbon productivity of phytoplankton in the chlorophyll a maximum layer could be stimulated by increased light condition rather than nitrate addition. Thus, potentially increasing
light availability from current and ongoing decreases in the sea ice cover could increase the carbon production of the phytoplankton
in the chlorophyll a maximum layer and produce a well-developed maximum layer at a deeper depth in the Canada Basin. 相似文献
11.
Large Greenhouse Gas Emissions from a Temperate Peatland Pasture 总被引:2,自引:0,他引:2
Yit Arn Teh Whendee L. Silver Oliver Sonnentag Matteo Detto Maggi Kelly Dennis D. Baldocchi 《Ecosystems》2011,14(2):311-325
Agricultural drainage is thought to alter greenhouse gas emissions from temperate peatlands, with CH4 emissions reduced in favor of greater CO2 losses. Attention has largely focussed on C trace gases, and less is known about the impacts of agricultural conversion on
N2O or global warming potential. We report greenhouse gas fluxes (CH4, CO2, N2O) from a drained peatland in the Sacramento-San Joaquin River Delta, California, USA currently managed as a rangeland (that
is, pasture). This ecosystem was a net source of CH4 (25.8 ± 1.4 mg CH4-C m−2 d−1) and N2O (6.4 ± 0.4 mg N2O-N m−2 d−1). Methane fluxes were comparable to those of other managed temperate peatlands, whereas N2O fluxes were very high; equivalent to fluxes from heavily fertilized agroecosystems and tropical forests. Ecosystem scale
CH4 fluxes were driven by “hotspots” (drainage ditches) that accounted for less than 5% of the land area but more than 84% of
emissions. Methane fluxes were unresponsive to seasonal fluctuations in climate and showed minimal temporal variability. Nitrous
oxide fluxes were more homogeneously distributed throughout the landscape and responded to fluctuations in environmental variables,
especially soil moisture. Elevated CH4 and N2O fluxes contributed to a high overall ecosystem global warming potential (531 g CO2-C equivalents m−2 y−1), with non-CO2 trace gas fluxes offsetting the atmospheric “cooling” effects of photoassimilation. These data suggest that managed Delta
peatlands are potentially large regional sources of greenhouse gases, with spatial heterogeneity in soil moisture modulating
the relative importance of each gas for ecosystem global warming potential. 相似文献
12.
Erica A. H. Smithwick Daniel M. Kashian Michael G. Ryan Monica G. Turner 《Ecosystems》2009,12(5):792-806
Long-term, landscape patterns in inorganic nitrogen (N) availability and N stocks following infrequent, stand-replacing fire
are unknown but are important for interpreting the effect of disturbances on ecosystem function. Here, we present results
from a replicated chronosequence study in the Greater Yellowstone Ecosystem (Wyoming, USA) directed at measuring inorganic
N availability (ion-exchange resin bags) and ecosystem N pools among 77 lodgepole pine stands that varied in age and density.
Inorganic N availability ranged from 0.07 to 3.20 μN bag−1 d−1 and nitrate (NO3−) was, on average, 65% of total resin-sorbed N. Total ecosystem N stocks (live + detrital + soil) averaged 109.9 ± 3.0 g N m−2 (range = 63.7–185.8 g N m−2). Live N was 14%, detrital N was 29%, and soil N was 57% of total stocks. Soil NO3−, total ecosystem N, live N, and detrital N generally increased with stand age, but soil N stocks decreased. Models (AICc) to predict soil N availability and N stocks included soil P, soil Ca, bulk density, and pH in addition to age (adj R
2 ranged from 0.18 to 0.53) and density was included only for live N stocks. Patterns of N stocks and N availability with density
were strongest for young stands (<20 years) regenerating from extensive fire in 1988; for example, litterfall N stocks increased
with density (adj R
2 = 0.86, P < 0.001) but inorganic N availability declined (adj R
2 = 0.47, P < 0.003). Across the complex Yellowstone landscape, we conclude that N stocks and N availability are best predicted by a
combination of local soil characteristics in addition to factors that vary at landscape scales (stand density and age). Overall,
total ecosystem N stocks were recovered quickly following stand-replacing fire, suggesting that moderate increases in fire
frequency will not affect long-term landscape N storage in Greater Yellowstone.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
Author contributions EAHS, MGT, and MGR conceived the study; DMK performed field research; EAHS and DMK oversaw laboratory analyses and analyzed
data; EAHS wrote the paper. 相似文献
13.
Agu Laisk Eero Talts Vello Oja Hillar Eichelmann Richard B. Peterson 《Photosynthesis research》2010,103(2):79-95
Fast cyclic electron transport (CET) around photosystem I (PS I) was observed in sunflower (Helianthus annuus L.) leaves under intense far-red light (FRL) of up to 200 μmol quanta m−2 s−1. The electron transport rate (ETR) through PS I was found from the FRL-dark transmittance change at 810 and 950 nm, which
was deconvoluted into redox states and pool sizes of P700, plastocyanin (PC) and cytochrome f (Cyt f). PC and P700 were in
redox equilibrium with K
e = 35 (ΔE
m = 90 mV). PS II ETR was based on O2 evolution. CET [(PS I ETR) − (PS II ETR)] increased to 50–70 μmol e− m−2 s−1 when linear electron transport (LET) under FRL was limited to 5 μmol e− m−2 s−1 in a gas phase containing 20–40 μmol CO2 mol−1 and 20 μmol O2 mol−1. Under these conditions, pulse-saturated fluorescence yield F
m was non-photochemically quenched; however, F
m was similarly quenched when LET was driven by low green or white light, which energetically precluded the possibility for
active CET. We suggest that under FRL, CET is rather not coupled to transmembrane proton translocation than the CET-coupled
protons are short-circuited via proton channels regulated to open at high ΔpH. A kinetic analysis of CET electron donors and
acceptors suggests the CET pathway is that of the reversed Q-cycle: Fd → (FNR) → Cyt cn → Cyt bh → Cyt bl → Rieske FeS → Cyt f → PC → P700 →→ Fd. CET is activated when PQH2 oxidation is opposed by high ΔpH, and ferredoxin (Fd) is reduced due to low availability of e− acceptors. The physiological significance of CET may be photoprotective, as CET may be regarded as a mechanism of energy
dissipation under stress conditions. 相似文献
14.
Measurement of net ecosystem production and ecosystem respiration in a Zoysia japonica grassland,central Japan,by the chamber method 总被引:1,自引:0,他引:1
Dhital Deepa Muraoka Hiroyuki Yashiro Yuichiro Shizu Yoko Koizumi Hiroshi 《Ecological Research》2010,25(2):483-493
Measuring light, temperature, soil moisture, and growth provides a better understanding of net ecosystem production (NEP),
ecosystem respiration (R
eco), and their response functions. Here, we studied the variations in NEP and R
eco in a grassland dominated by a perennial warm-season C4 grass, Zoysia japonica. We used the chamber method to measure NEP and R
eco from August to September 2007. Biomass and leaf area index (LAI) were also measured to observe their effects on NEP and R
eco. Diurnal variations in NEP and R
eco were predicted well by light intensity (PPFD) and by soil temperature, respectively. Maximum NEP (NEPmax) values on days of year 221, 233, 247, and 262, were 2.44, 2.55, 3.90, and 4.17 μmol m−2 s−1, respectively. Throughout the growing period, the apparent quantum yield (α) increased with increasing NEPmax that ranged from 0.0154 to 0.0515, and NEP responded to the soil temperature changes by 44% and R
eco changes by 48%, and R
eco responded from 88 to 94% with the soil temperature diurnally. NEP’s light response and R
eco’s temperature response were affected by soil water content; more than 27% of the variation in NEP and 67% of the variation
in R
eco could be explained by this parameter. NEP was strongly correlated with biomass and LAI, but R
eco was not, because environmental variables affected R
eco more strongly than growth parameters. Using the light response of NEP, the temperature response of R
eco, and meteorological data, daily NEP and R
eco were estimated at 0.67, 0.81, 1.17, and 1.56 g C m−2, and at 2.88, 2.50, 3.51, and 3.04 g C m−2, respectively, on days of year 221, 233, 247, and 262. The corresponding daily gross primary production (NEP + R
eco) was 3.5, 3.3, 4.6, and 4.6 g C m−2. 相似文献
15.
Ecosystem Metabolism in Piedmont Streams: Reach Geomorphology Modulates the Influence of Riparian Vegetation 总被引:1,自引:0,他引:1
We measured the impact of riparian zone vegetation on ecosystem metabolism in paired forested and meadow reaches on 13 streams
in southeastern Pennsylvania and Maryland, USA. Metabolism estimates were based on open-system measurements of dissolved oxygen
changes, with reaeration determined from propane evasion. Daily gross primary productivity (GPP) in meadow and forested reaches
averaged 2.85 and 0.86 g O2 m−2 d−1, respectively, at water temperatures of 12°C or greater when the forest canopy was developed and 1.74 and 1.09 g O2 m−2 d−1, respectively, at temperatures below 12°C when the canopy was bare. Community respiration (CR24) also was greater in meadow reaches than in forested reaches, averaging 5.58 and 3.57 g O2 m−2 d−1, respectively, in the warm season and 4.87 and 2.88 g O2 m−2 d−1, respectively, during the cold season. Thus, both meadow and forested reaches were heterotrophic. Forested reaches were always
wider and nearly always shallower than companion meadow reaches. When ecosystem function was assessed per unit of stream length,
the difference in average GPP between meadow and forested reaches was reduced from three-fold to 1.9-fold in the warm season,
and mean GPP was greater in the forested reaches during the cold season. Mean CR24 per meter stream length was greater in forested reaches during both seasons. Even though riparian shading reduced primary
productivity per unit area of streambed, the greater stream width of the forested reaches counteracted that reduction in part.
Thus, when rates of ecosystem function were expressed per length of stream, differences between reaches were always smaller
than when expressed per area, and activity per unit stream length was sometimes greater in forested reaches than in meadow
reaches. 相似文献
16.
Hong-Yang Zhu Hong Xu Xiao-Yan Dai Yang Zhang Han-Jie Ying Ping-Kai Ouyang 《Bioprocess and biosystems engineering》2010,33(5):565-571
A new yeast, isolated from natural osmophilic sources, produces d-arabitol as the main metabolic product from glucose. According to 18S rRNA analysis, the NH-9 strain belongs to the genus
Kodamaea. The optimal culture conditions for inducing production of d-arabitol were 37 °C, neutral pH, 220 rpm shaking, and 5% inoculum. The yeast produced 81.2 ± 0.67 g L−1
d-arabitol from 200 g L−1
d-glucose in 72 h with a yield of 0.406 g g−1 glucose and volumetric productivity
Q\textP Q_{\text{P}} of 1.128 g L−1 h−1. Semi-continuous repeated-batch fermentation was performed in shaker-flasks to enhance the process of d-arabitol production by Kodamaea ohmeri NH-9 from d-glucose. Under repeated-batch culture conditions, the highest volumetric productivity was 1.380 g L−1 h−1. 相似文献
17.
Greenhouse gas fluxes from the eutrophic Temmesjoki River and its Estuary in the Liminganlahti Bay (the Baltic Sea) 总被引:2,自引:0,他引:2
Hanna Silvennoinen Anu Liikanen Jaana Rintala Pertti J. Martikainen 《Biogeochemistry》2008,90(2):193-208
We studied concentrations of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) in the eutrophic Temmesjoki River and Estuary in the Liminganlahti Bay in 2003–2004 and evaluated the atmospheric fluxes
of the gases based on measured concentrations, wind speeds and water current velocities. The Temmesjoki River was a source
of CO2, CH4 and N2O to the atmosphere, whereas the Liminganlahti Bay was a minor source of CH4 and a minor source or a sink of CO2 and N2O. The results show that the fluxes of greenhouse gases in river ecosystems are highly related to the land use in its catchment
areas. The most upstream river site, surrounded by forests and drained peatlands, released significant amounts of CO2 and CH4, with average fluxes of 5,400 mg CO2–C m−2 d−1 and 66 mg CH4–C m−2 d−1, and concentrations of 210 μM and 345 nM, respectively, but N2O concentrations, at an average of 17 nM, were close to the atmospheric equilibrium concentration. The downstream river sites
surrounded by agricultural soils released significant amounts of N2O (with an average emission of 650 μg N2O–N m−2 d−1 and concentration of 22 nM), whereas the CO2 and CH4 concentrations were low compared to the upstream site (55 μM and 350 nM). In boreal regions, rivers are partly ice-covered
in wintertime (approximately 5 months). A large part of the gases, i.e. 58% of CO2, 55% of CH4 and 36% of N2O emissions, were found to be released during wintertime from unfrozen parts of the river. 相似文献
18.
A comparison of water and carbon dioxide exchange at a windy alpine tundra and subalpine forest site near Niwot Ridge,Colorado 总被引:1,自引:1,他引:0
Peter D. Blanken Mark W. Williams Sean P. Burns Russell K. Monson John Knowles Kurt Chowanski Todd Ackerman 《Biogeochemistry》2009,95(1):61-76
Eddy covariance measurements of the surface energy balance and carbon dioxide exchange above high-elevation (3,480 m above
sea level) alpine tundra located near Niwot Ridge, Colorado, were compared to simultaneous measurements made over an adjacent
subalpine forest over two summers and one winter, from June 9, 2007 to July 3, 2008. The surface energy balance closure at
the alpine site averaged 71 and 91%, winter and summer, respectively, due to the high wind speeds, short turbulent flux footprint,
and relatively flat ridge-top location of the measurement site. Throughout the year, the alpine site was cooler with higher
relative humidity, and had a higher horizontal wind speed, especially in winter, compared to the forest site. Wind direction
was persistently downslope at the alpine site (summer and winter, day and night), whereas upslope winds were common at the
forest site during summer daytime periods. The latent and sensible heat fluxes were consistently larger in magnitude at the
forest site, with the largest differences during summer. The horizontal advective flux of CO2 at the alpine site averaged 6% of the net ecosystem exchange (NEE) during summer nights (5% during summer daytime), and was small in relation to the high wind speeds, relatively flat site,
and weak sources of CO2 upwind of the site. The magnitudes and diurnal behavior of the alpine NEE calculated using three methods; eddy-covariance, friction velocity filter, and with advection and storage calculations, gave
similar results. The period of net CO2 uptake (negative NEE) was 100 days at the alpine site with a net uptake of 16 g C m−2, compared to 208 days at the forest site with a net uptake of 108 g C m−2, with initiation of net uptake coinciding with air temperatures reaching +10°C. Winter respiration loss at the alpine site
was 164 g C m−2 over 271 days, compared to 52 g C m−2 over 175 days at the forest site, with the initiation of net loss coinciding with air temperatures reaching −10°C at each
site. 相似文献
19.
Headwater streams are key sites of nutrient and organic matter processing and retention, but little is known about temporal
variability in gross primary production (GPP) and ecosystem respiration (ER) rates as a result of the short duration of most
metabolism measurements in lotic ecosystems. We examined temporal variability and controls on ecosystem metabolism by measuring
daily rates continuously for 2 years in Walker Branch, a first-order deciduous forest stream. Four important scales of temporal
variability in ecosystem metabolism rates were identified: (1) seasonal, (2) day-to-day, (3) episodic (storm-related), and
(4) inter-annual. Seasonal patterns were largely controlled by the leaf phenology and productivity of the deciduous riparian
forest. Walker Branch was strongly net heterotrophic throughout the year with the exception of the open-canopy spring when
GPP and ER rates were co-equal. Day-to-day variability in weather conditions influenced light reaching the streambed, resulting
in high day-to-day variability in GPP particularly during spring (daily light levels explained 84% of the variance in daily
GPP in April). Episodic storms depressed GPP for several days in spring, but increased GPP in autumn by removing leaves shading
the streambed. Storms depressed ER initially, but then stimulated ER to 2–3 times pre-storm levels for several days. Walker
Branch was strongly net heterotrophic in both years of the study, with annual GPP being similar (488 and 519 g O2 m−2 y−1 or 183 and 195 g C m−2 y−1) but annual ER being higher in 2004 than 2005 (−1,645 vs. −1,292 g O2 m−2 y−1 or −617 and −485 g C m−2 y−1). Inter-annual variability in ecosystem metabolism (assessed by comparing 2004 and 2005 rates with previous measurements)
was the result of the storm frequency and timing and the size of the spring macroalgal bloom. Changes in local climate can
have substantial impacts on stream ecosystem metabolism rates and ultimately influence the carbon source and sink properties
of these important ecosystems. 相似文献
20.
Solar‐induced chlorophyll fluorescence is strongly correlated with terrestrial photosynthesis for a wide variety of biomes: First global analysis based on OCO‐2 and flux tower observations 下载免费PDF全文
Xing Li Jingfeng Xiao Binbin He M. Altaf Arain Jason Beringer Ankur R. Desai Carmen Emmel David Y. Hollinger Alisa Krasnova Ivan Mammarella Steffen M. Noe Penélope Serrano Ortiz A. Camilo Rey‐Sanchez Adrian V. Rocha Andrej Varlagin 《Global Change Biology》2018,24(9):3990-4008
Solar‐induced chlorophyll fluorescence (SIF) has been increasingly used as a proxy for terrestrial gross primary productivity (GPP). Previous work mainly evaluated the relationship between satellite‐observed SIF and gridded GPP products both based on coarse spatial resolutions. Finer resolution SIF (1.3 km × 2.25 km) measured from the Orbiting Carbon Observatory‐2 (OCO‐2) provides the first opportunity to examine the SIF–GPP relationship at the ecosystem scale using flux tower GPP data. However, it remains unclear how strong the relationship is for each biome and whether a robust, universal relationship exists across a variety of biomes. Here we conducted the first global analysis of the relationship between OCO‐2 SIF and tower GPP for a total of 64 flux sites across the globe encompassing eight major biomes. OCO‐2 SIF showed strong correlations with tower GPP at both midday and daily timescales, with the strongest relationship observed for daily SIF at the 757 nm (R2 = 0.72, p < 0.0001). Strong linear relationships between SIF and GPP were consistently found for all biomes (R2 = 0.57–0.79, p < 0.0001) except evergreen broadleaf forests (R2 = 0.16, p < 0.05) at the daily timescale. A higher slope was found for C4 grasslands and croplands than for C3 ecosystems. The generally consistent slope of the relationship among biomes suggests a nearly universal rather than biome‐specific SIF–GPP relationship, and this finding is an important distinction and simplification compared to previous results. SIF was mainly driven by absorbed photosynthetically active radiation and was also influenced by environmental stresses (temperature and water stresses) that determine photosynthetic light use efficiency. OCO‐2 SIF generally had a better performance for predicting GPP than satellite‐derived vegetation indices and a light use efficiency model. The universal SIF–GPP relationship can potentially lead to more accurate GPP estimates regionally or globally. Our findings revealed the remarkable ability of finer resolution SIF observations from OCO‐2 and other new or future missions (e.g., TROPOMI, FLEX) for estimating terrestrial photosynthesis across a wide variety of biomes and identified their potential and limitations for ecosystem functioning and carbon cycle studies. 相似文献