scholarly journals Effects of climate variability and functional changes on the interannual variation of the carbon balance in a temperate deciduous forest

2012 ◽  
Vol 9 (1) ◽  
pp. 13-28 ◽  
Author(s):  
J. Wu ◽  
L. van der Linden ◽  
G. Lasslop ◽  
N. Carvalhais ◽  
K. Pilegaard ◽  
...  
Keyword(s):  
Ecosystem Functioning ◽  
Carbon Balance ◽  
Interannual Variation ◽  
Deciduous Forest ◽  
Climatic Variability ◽  
Functional Change ◽  
Model Parameters ◽  
Functional Changes ◽  
Ecosystem Carbon ◽  
Carbon Balances

Abstract. The net ecosystem exchange of CO2 (NEE) between the atmosphere and a temperate beech forest showed a significant interannual variation (IAV) and a decadal trend of increasing carbon uptake (Pilegaard et al., 2011). The objectives of this study were to evaluate to what extent and at which temporal scale, direct climatic variability and changes in ecosystem functional properties regulated the IAV of the carbon balance at this site. Correlation analysis showed that the sensitivity of carbon fluxes to climatic variability was significantly higher at shorter than at longer time scales and changed seasonally. Ecosystem response anomalies implied that changes in the distribution of climate anomalies during the vegetation period will have stronger impacts on future ecosystem carbon balances than changes in average climate. We improved a published modelling approach which distinguishes the direct climatic effects from changes in ecosystem functioning (Richardson et al., 2007) by employing the semi empirical model published by Lasslop et al. (2010b). Fitting the model in short moving windows enabled large flexibility to adjust the parameters to the seasonal course of the ecosystem functional state. At the annual time scale as much as 80% of the IAV in NEE was attributed to the variation in photosynthesis and respiration related model parameters. Our results suggest that the observed decadal NEE trend at the investigated site was dominated by changes in ecosystem functioning. In general this study showed the importance of understanding the mechanisms of ecosystem functional change. Incorporating ecosystem functional change into process based models will reduce the uncertainties in long-term predictions of ecosystem carbon balances in global climate change projections.

scholarly journals Effects of climate variability and functional changes on the interannual variation of the carbon balance in a temperate deciduous forest

2011 ◽  
Vol 8 (5) ◽  
pp. 9125-9163 ◽  
Author(s):  
J. Wu ◽  
L. van der Linden ◽  
G. Lasslop ◽  
N. Carvalhais ◽  
K. Pilegaard ◽  
...  
Keyword(s):  
Carbon Balance ◽  
Deciduous Forest ◽  
Climatic Variability ◽  
Functional Change ◽  
Temperate Deciduous Forest ◽  
Climate Anomalies ◽  
Ecosystem Carbon ◽  
Ecosystem Carbon Balance ◽  
Temperate Deciduous

Abstract. The net ecosystem exchange of CO2 (NEE) between the atmosphere and a beech forest (Sorø, Denmark) showed significant interannual variation (IAV) over 13 years (1997–2009) of observations. The forest sequestered, on average, 157 g C m−2 yr−1, ranging from a source of 32 to a sink of 344 g C m−2 yr−1 in 1998 and 2008, respectively. The objectives of this study were to evaluate to what extent and at which temporal scale, climatic variability (through direct response) and changes in ecosystem functional properties (through biotic response) regulated the IAV in the ecosystem carbon balance. To address this question, we performed correlation analysis between the carbon fluxes and climate variables at different time scales. The response of CO2 exchange to climatic variability was significantly higher at short time scales and the limiting factors changed intra-annually. Combinations of climate anomalies in different periods of the year either intensified or attenuated the aggregated ecosystem responses, implying that the changing distribution of climate anomalies, in addition to the average climate change, could have stronger impacts on the ecosystem carbon balance in the future. A semi empirical model was used to estimate a set of parameter time series for each of the 13 years, which was considered to represent the functional properties of the ecosystem. The climate and parameter time series were applied factorially by year to quantify their relative importance for the IAV in carbon flux. At an annual time scale, as much as 77 % of the IAV in NEE could be attributed to the variation in both photosynthesis and respiration related model parameters, indicating a strong influence of functional change. The possible causes for the observed functional change could not be addressed with the available dataset. This demonstrates the need for more targeted experiments, such as long-term measurements of leaf nitrogen content. Our approach incorporated seasonal variation in the ecosystem status and demonstrated a significant role of biotic factors on the carbon dynamics in a typical temperate deciduous forest. The method can be applied at other sites to explore ecosystem behaviour across different plant functional types and climate gradients. Further, this approach showed how important it is to incorporate functional change in process based models, which could guide model development and consequently reduce the uncertainties in long-term projection of global ecosystem carbon balance.

Reexamine China’s terrestrial ecosystem carbon balance under land use-type and climate change

2021 ◽  
Vol 102 ◽  
pp. 105275
Author(s):  
Jiasheng Li ◽  
Xiaomin Guo ◽  
Xiaowei Chuai ◽  
Fangjian Xie ◽  
Feng Yang ◽  
...  
Keyword(s):  
Climate Change ◽  
Land Use ◽  
Carbon Balance ◽  
Terrestrial Ecosystem ◽  
Land Use Type ◽  
Ecosystem Carbon ◽  
Ecosystem Carbon Balance

Functional changes in adenylyl cyclases and associated decreases in relaxation responses in mesenteric arteries from diabetic rats

2005 ◽  
Vol 289 (5) ◽  
pp. H2234-H2243 ◽  
Author(s):  
Takayuki Matsumoto ◽  
Kentaro Wakabayashi ◽  
Tsuneo Kobayashi ◽  
Katsuo Kamata
Keyword(s):  
Mesenteric Artery ◽  
Diabetic Rats ◽  
Functional Change ◽  
Water Soluble ◽  
Mesenteric Arteries ◽  
Diabetic Rat ◽  
Adenylyl Cyclases ◽  
Camp Production ◽  
Functional Changes ◽  
Rat Mesenteric Artery

To assess the functional change in adenylyl cyclases (AC) associated with the diabetic state, we investigated AC-mediated relaxations and cAMP production in mesenteric arteries from rats with streptozotocin (STZ)-induced diabetes. The relaxations induced by the water-soluble forskolin (FSK) analog NKH477, which is a putative AC5 activator, but not by the β-adrenoceptor agonist isoproterenol (Iso) and the AC activator FSK, were reduced in intact diabetic mesenteric artery. In diabetic rats, however, Iso-, FSK-, and NKH477-induced relaxations were attenuated in the presence of inhibitors of nitric oxide synthase and cyclooxygenase. To exclude the influence of phosphodiesterase (PDE), we also examined the relaxations induced by several AC activators in the presence of 3-isobutyl-1-methylxanthine (IBMX; a PDE inhibitor). Under these conditions, the relaxation induced by Iso was greatly impaired in STZ-diabetic rats. This Iso-induced relaxation was significantly attenuated by pretreatment with SQ-22536, an AC inhibitor, in mesenteric rings from age-matched controls but not in those from STZ-diabetic rats. Under the same conditions, the relaxations induced by FSK or NKH477 were impaired in STZ-diabetic rats. Neither FSK- nor A-23187 (a Ca2+ ionophore)-induced cAMP production was significantly different between diabetics and controls. However, cAMP production induced by Iso or NKH477 was significantly impaired in diabetic mesenteric arteries. Expression of mRNAs and proteins for AC5/6 was lower in diabetic mesenteric arteries than in controls. These results suggest that AC-mediated relaxation is impaired in the STZ-diabetic rat mesenteric artery, perhaps reflecting a reduction in AC5/6 activity.

scholarly journals In Situ Estimation of Carbon Balance of In Vitro Sweetpotato and Tomato Plantlets Cultured with Varying Initial Sucrose Concentrations in the Medium

2002 ◽  
Vol 127 (6) ◽  
pp. 963-970 ◽  
Author(s):  
Chieri Kubota ◽  
Makiko Ezawa ◽  
Toyoki Kozai ◽  
Sandra B. Wilson
Keyword(s):  
Carbon Balance ◽  
Ipomoea Batatas ◽  
Dry Weight ◽  
Photon Flux ◽  
Sugar Uptake ◽  
Relative Contribution ◽  
Carbon Balances ◽  
Species Specific

The effects of initial sucrose (suc) concentrations in the medium (S0) on the carbon balance and growth of sweetpotato [Ipomoea batatas (L.) Lam. `Beniazuma'] and tomato (Lycopersicon esculentum Mill. `HanaQueen') plantlets were studied under controlled environmental conditions. Plantlets were cultured with 0, 7.5, 15, or 30 g·L-1 of S0 under high photosynthetic photon flux (160 to 200 μmol·m-2·s-1) and CO2 enriched (1400 to 2050 μmol·mol-1) conditions. Net photosynthetic rate per leaf area (Pl) decreased and dry weight per plantlet (Wd) increased with increasing S0, but did not differ significantly between S0 of 7.5 to 30 g·L-1 for sweetpotato or 15 to 30 g·L-1 for tomato. Carbon influxes and effluxes of the plantlets by metabolism of medium suc and/or photosynthesis, and respiration were estimated based on measurements of in situ and steady state CO2 exchange rates and sugar uptake during culture. At S0 from 7.5 to 30 g·L-1, photosynthesis was responsible for 82% to 92% and 60% to 67% of carbohydrate assimilation for sweetpotato and tomato, respectively. Estimated carbon balances of plantlets based on the estimated and actual increases of moles of carbon in plant tissue demonstrated that in situ estimation of carbon balance was reasonably accurate for sweetpotato at S0 of 0 to 15 g·L-1 and for tomato at S0 of 0 g·L-1 and that the actual contribution of photosynthesis for tomato at high S0 might be lower than the values estimated in the present experiment. Results showed that initial suc concentration affected the relative contribution of photosynthesis on their carbon balances and that the responses were species specific. The failure of validation at S0 in a range specific to each species suggested the need for further study on carbon metabolism of in vitro plantlets cultured with sugar in the medium.

scholarly journals Determinants of terrestrial ecosystem carbon balance inferred from European eddy covariance flux sites

2007 ◽  
Vol 34 (1) ◽  
Author(s):  
Markus Reichstein ◽  
Dario Papale ◽  
Riccardo Valentini ◽  
Marc Aubinet ◽  
Christian Bernhofer ◽  
...  
Keyword(s):  
Eddy Covariance ◽  
Carbon Balance ◽  
Terrestrial Ecosystem ◽  
Ecosystem Carbon ◽  
Ecosystem Carbon Balance

scholarly journals Adaptive functional change of the contralateral kidney after partial nephrectomy

2017 ◽  
Vol 313 (2) ◽  
pp. F192-F198 ◽  
Author(s):  
Se Young Choi ◽  
Sangjun Yoo ◽  
Dalsan You ◽  
In Gab Jeong ◽  
Cheryn Song ◽  
...  
Keyword(s):  
Renal Function ◽  
Partial Nephrectomy ◽  
Functional Change ◽  
Functional Changes ◽  
Contralateral Kidney ◽  
Before And After ◽  
Group 2 ◽  
American Society ◽  
American Society Of Anesthesiologists ◽  
Group 1

Partial nephrectomy aims to maintain renal function by nephron sparing; however, functional changes in the contralateral kidney remain unknown. We evaluate the functional change in the contralateral kidney using a diethylene triamine penta-acetic acid (DTPA) renal scan and determine factors predicting contralateral kidney function after partial nephrectomy. A total of 699 patients underwent partial nephrectomy, with a DTPA scan before and after surgery to assess the separate function of each kidney. Patients were divided into three groups according to initial contralateral glomerular filtration rate (GFR; group 1: <30 ml·min−1·1.73 m−2, group 2: 30–45 ml·min−1·1.73 m−2, and group 3: ≥45 ml·min−1·1.73 m−2). Multiple-regression analysis was used to identify the factors associated with increased GFR of the contralateral kidney over a 4-yr postoperative period. Patients in group 1 had a higher mean age and hypertension history, worse American Society of Anesthesiologists score, and larger tumor size than in the other two groups. The ipsilateral GFR changes at 4 yr after partial nephrectomy were −18.9, −3.6, and 3.9% in groups 1, 2, and 3, respectively, whereas the contralateral GFR changes were 10.8, 25.7, and 38.8%. Age [β: −0.105, 95% confidence interval (CI): −0.213; −0.011, P < 0.05] and preoperative contralateral GFR (β: −0.256, 95% CI: −0.332; −0.050, P < 0.01) were significant predictive factors for increased GFR of the contralateral kidney after 4 yr. The contralateral kidney compensated for the functional loss of the ipsilateral kidney. The increase of GFR in contralateral kidney is more prominent in younger patients with decreased contralateral renal function.

scholarly journals Effects of a windthrow disturbance on the carbon balance of a broadleaf deciduous forest in Hokkaido, Japan

2015 ◽  
Vol 12 (23) ◽  
pp. 6837-6851 ◽  
Author(s):  
K. Yamanoi ◽  
Y. Mizoguchi ◽  
H. Utsugi
Keyword(s):  
Forest Management ◽  
Carbon Balance ◽  
Deciduous Forest ◽  
Carbon Sink ◽  
Ecosystem Respiration ◽  
Gross Primary Production ◽  
Co2 Flux ◽  
White Birch ◽  
Eddy Covariance Method ◽  
Area Index

Abstract. Forests play an important role in the terrestrial carbon balance, with most being in a carbon sequestration stage. The net carbon releases that occur result from forest disturbance, and windthrow is a typical disturbance event affecting the forest carbon balance in eastern Asia. The CO2 flux has been measured using the eddy covariance method in a deciduous broadleaf forest (Japanese white birch, Japanese oak, and castor aralia) in Hokkaido, where incidental damage by the strong Typhoon Songda in 2004 occurred. We also used the biometrical method to demonstrate the CO2 flux within the forest in detail. Damaged trees amounted to 40 % of all trees, and they remained on site where they were not extracted by forest management. Gross primary production (GPP), ecosystem respiration (Re), and net ecosystem production were 1350, 975, and 375 g C m−2 yr−1 before the disturbance and 1262, 1359, and −97 g C m−2 yr−1 2 years after the disturbance, respectively. Before the disturbance, the forest was an evident carbon sink, and it subsequently transformed into a net carbon source. Because of increased light intensity at the forest floor, the leaf area index and biomass of the undergrowth (Sasa kurilensis and S. senanensis) increased by factors of 2.4 and 1.7, respectively, in 3 years subsequent to the disturbance. The photosynthesis of Sasa increased rapidly and contributed to the total GPP after the disturbance. The annual GPP only decreased by 6 % just after the disturbance. On the other hand, the annual Re increased by 39 % mainly because of the decomposition of residual coarse-wood debris. The carbon balance after the disturbance was controlled by the new growth and the decomposition of residues. The forest management, which resulted in the dead trees remaining at the study site, strongly affected the carbon balance over the years. When comparing the carbon uptake efficiency at the study site with that at others, including those with various kinds of disturbances, we emphasized the importance of forest management as well as disturbance type in the carbon balance.

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