scholarly journals Assessing the spatial variability in peak season CO<sub>2</sub> exchange characteristics across the Arctic tundra using a light response curve parameterization

2014 ◽  
Vol 11 (5) ◽  
pp. 6419-6460 ◽  
Author(s):  
H. N. Mbufong ◽  
M. Lund ◽  
M. Aurela ◽  
T. R. Christensen ◽  
W. Eugster ◽  
...  
Keyword(s):  
Spatial Variability ◽  
Response Curve ◽  
Dark Respiration ◽  
Light Response ◽  
Arctic Tundra ◽  
Co2 Exchange ◽  
The Arctic ◽  
Model Parameters ◽  
Light Saturation ◽  
Light Response Curve

Abstract. This paper aims to assess the functional and spatial variability in the response of CO2 exchange to irradiance across the Arctic tundra during peak season using light response curve (LRC) parameters. This investigation allows us to better understand the future response of Arctic tundra under climatic change. Data was collected using the micrometeorological eddy covariance technique from 12 circumpolar Arctic tundra sites, in the range of 64–74° N. The LRCs were generated for 14 days with peak net ecosystem exchange (NEE) using an NEE -irradiance model. Parameters from LRCs represent site specific traits and characteristics describing: (a) NEE at light saturation (Fcsat), (b) dark respiration (Rd), (c) light use efficiency (α), (d) NEE when light is at 1000 μmol m−2 s−1 (Fc1000), (e) potential photosynthesis at light saturation (Psat) and (f) the light compensation point (LCP). Parameterization of LRCs was successful in predicting CO2 flux dynamics across the Arctic tundra. Yet we did not find any trends in LRC parameters across the whole Arctic tundra but there were indications for temperature and latitudinal differences within sub-regions like Russia and Greenland. Together, LAI and July temperature had a high explanatory power of the variance in assimilation parameters (Fcsat, Fc1000 and Psat), thus illustrating the potential for upscaling CO2 exchange for the whole Arctic tundra. Dark respiration was more variable and less correlated to environmental drivers than was assimilation parameters. Thus, indicating the inherent need to include other parameters such as nutrient availability, substrate quantity and quality in flux monitoring activities.

scholarly journals Assessing the spatial variability in peak season CO<sub>2</sub> exchange characteristics across the Arctic tundra using a light response curve parameterization

2014 ◽  
Vol 11 (17) ◽  
pp. 4897-4912 ◽  
Author(s):  
H. N. Mbufong ◽  
M. Lund ◽  
M. Aurela ◽  
T. R. Christensen ◽  
W. Eugster ◽  
...  
Keyword(s):  
Spatial Variability ◽  
Response Curve ◽  
Dark Respiration ◽  
Light Response ◽  
Arctic Tundra ◽  
Co2 Exchange ◽  
The Arctic ◽  
Model Parameters ◽  
Light Saturation ◽  
Light Response Curve

Abstract. This paper aims to assess the spatial variability in the response of CO2 exchange to irradiance across the Arctic tundra during peak season using light response curve (LRC) parameters. This investigation allows us to better understand the future response of Arctic tundra under climatic change. Peak season data were collected during different years (between 1998 and 2010) using the micrometeorological eddy covariance technique from 12 circumpolar Arctic tundra sites, in the range of 64–74° N. The LRCs were generated for 14 days with peak net ecosystem exchange (NEE) using an NEE–irradiance model. Parameters from LRCs represent site-specific traits and characteristics describing the following: (a) NEE at light saturation (Fcsat), (b) dark respiration (Rd), (c) light use efficiency (α), (d) NEE when light is at 1000 μmol m−2 s−1 (Fc1000), (e) potential photosynthesis at light saturation (Psat) and (f) the light compensation point (LCP). Parameterization of LRCs was successful in predicting CO2 flux dynamics across the Arctic tundra. We did not find any trends in LRC parameters across the whole Arctic tundra but there were indications for temperature and latitudinal differences within sub-regions like Russia and Greenland. Together, leaf area index (LAI) and July temperature had a high explanatory power of the variance in assimilation parameters (Fcsat, Fc1000 and Psat, thus illustrating the potential for upscaling CO2 exchange for the whole Arctic tundra. Dark respiration was more variable and less correlated to environmental drivers than were assimilation parameters. This indicates the inherent need to include other parameters such as nutrient availability, substrate quantity and quality in flux monitoring activities.

Comparison between modified exponential model and common models of light-response curve

2013 ◽  
Vol 36 (12) ◽  
pp. 1277-1285 ◽  
Author(s):  
Wei-Ying CHEN ◽  
Zhen-Yong CHEN ◽  
Fu-Yan LUO ◽  
Zheng-Song PENG ◽  
Mao-Qun YU
Keyword(s):  
Response Curve ◽  
Light Response ◽  
Exponential Model ◽  
Light Response Curve

The Photosynthesis-Light Response Curve

1992 ◽  
pp. 156-191 ◽  
Author(s):  
Richard J. Geider ◽  
Bruce A. Osborne
Keyword(s):  
Response Curve ◽  
Light Response ◽  
Light Response Curve

Environmental Effects on Peppermint (Mentha piperita L.). II. Effects of Temperature on Photosynthesis, Photorespiration and Dark Respiration in Peppermint With Reference to Oil Composition

1980 ◽  
Vol 7 (6) ◽  
pp. 693 ◽  
Author(s):  
RJ Clark ◽  
RC Menary
Keyword(s):  
Environmental Effects ◽  
Dark Respiration ◽  
Co2 Exchange ◽  
Mentha Piperita ◽  
Photon Flux ◽  
Steady Increase ◽  
Light Saturation ◽  
Oil Composition ◽  
Increased Temperature ◽  
Effects Of Temperature

Net CO2 exchange was investigated at several photon flux densities and day temperatures in both 21% and 2% O2. Light saturation occurred between 400 and 500 �Em-2, s-1 in attached, fully expanded leaves of peppermint. Maximum rates of 'apparent' photosynthesis occurred at 20°C. The important determinants of 'apparent' photosynthesis were an increase in 'true' photosynthesis when temperature was increased to 25°C, a steady increase in dark respiration with increased temperature and a rapid increase in photorespiration between 15 and 30°C. Such net CO2 exchange characteristics of peppermint support the photosynthate model proposed to explain environmental effects on oil composition.

The impacts of leaf shape and arrangement on light interception and potential photosynthesis in southern beech (Nothofagus cunninghamii)

2004 ◽  
Vol 31 (5) ◽  
pp. 471 ◽  
Author(s):  
Stephen O. Kern ◽  
Mark J. Hovenden ◽  
Gregory J. Jordan
Keyword(s):  
Flux Density ◽  
Response Curve ◽  
Leaf Shape ◽  
Carbon Assimilation ◽  
Light Response ◽  
Light Interception ◽  
Photon Flux ◽  
Assimilation Rate ◽  
Light Response Curve ◽  
Carbon Assimilation Rate

The impact of differences in leaf shape, size and arrangement on the efficiency of light interception, and in particular the avoidance of photoinhibition, are poorly understood. We therefore estimated light exposure of branches in the cool temperate rainforest tree, Nothofagus cunninghamii (Hook.) Oerst., in which leaf shape, size and arrangement vary systematically with altitude and geographic origin. Measurements of incident photosynthetic photon flux density (PPFD) were made in the laboratory at solar angles corresponding to noon at summer solstice, winter solstice and equinox on branches collected from a common garden experiment. Tasmanian plants showed more self-shading than Victorian plants in summer and equinox. This was related to branch angle, leaf arrangement and leaf shape. Using a modelled light response-curve, we estimated the carbon assimilation rate and the flux density of excess photons at different incident PPFD. Victorian plants had higher predicted assimilation rates than Tasmanian plants in summer and equinox, but were exposed to substantially greater levels of excess photons. Because of the shape of the light-response curve, self-shading appears to reduce the plant's exposure to excess photons, thus providing photoprotection, without substantially reducing the carbon assimilation rate. This is dependent on both regional origin and season.

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