Scaling leaf photosynthesis to canopy in a mixed deciduous forest. II. A simulation study for two growing seasons

1997 ◽  
Vol 62 ◽  
Author(s):  
R. Samson ◽  
S. Follens ◽  
R. Lemeur
Keyword(s):  
Forest Canopy ◽  
Deciduous Forest ◽  
Growing Season ◽  
Limiting Factor ◽  
Canopy Photosynthesis ◽  
Growing Seasons ◽  
Mixed Deciduous Forest ◽  
Leaf Level ◽  
Big Leaf Model ◽  
Leaf Model

The  model as described in Samson et al. (1997) (FORUG model) is validated at the  leaf level, and seems to simulate well the canopy rates for the different  species and the different considered layers in the canopy. The highest  instantaneous canopy photosynthesis rates are found for oak, the lowest for  beech. The total amount of carbon assimilated during the growing season was  highest for oak and ash and lower for beech and amounted respectively 10.9,  11.0 and 10.3 ton C ha-1 y-1 for the growing season 1996. The carbon uptake was higher  during the growing season 1997 due to a higher mean daily temperature, and a  higher amount of incoming PAR. For bole respiration the maximum rate for both  growing seasons amounted 3.6 µmol m-2  S-1. Integrated over the  growing season the total bole    respiration amounted 4.5 and 4.3 ton C ha-1 y-1 for respectively the growing season 1997 and 1996. At high  temperatures and high PPFD, temperature becomes a limiting factor for Net  Canopy Photosynthesis (NCP). A total forest canopy has, just as leaves, a  curvilinear reaction on PPFD. This finding allowed to construct a one-layer  or 'big leaf' model which simulated-the NCP as well as did the multi-layer  FORUG model. However a multi-layer model for simulating the NCP is preffered  as it allows more simpler incorporation or adaptation of parameters.

Scaling leaf photosynthesis to canopy in a mixed deciduous forest. I. model description

1997 ◽  
Vol 62 ◽  
Author(s):  
R. Samson ◽  
S. Follens ◽  
R. Lemeur
Keyword(s):  
Temperature Dependence ◽  
Quercus Robur ◽  
Deciduous Forest ◽  
Growing Season ◽  
Model Description ◽  
Canopy Photosynthesis ◽  
Leaf Photosynthesis ◽  
Layer Model ◽  
Mixed Deciduous Forest ◽  
Leaf Level

A  multi-layer model (FORUG) was developed, to simulate the canopy  photosynthesis of a mixed deciduous forest during the growing season.  Measured photosynthesis parameters, for beech (Fagus  sylvatica), oak (Quercus  robur) and ash (Fraxinus  excelsior), were used as input to the model. This  information at the leaf level is then scaled up to the level of the canopy,  taking into account the radiation profiles (diffuse and direct PAR) in the  canopy, the vertical LAI distribution, the evolution of the LAI and the  photosynthesis parameters during the growing season, and the temperature  dependence of the latter parameters.

scholarly journals Transport-driven aerosol differences above and below the canopy of a mixed deciduous forest

2021 ◽  
Author(s):  
Alexander A. T. Bui ◽  
Henry W. Wallace ◽  
Sarah Kavassalis ◽  
Hariprasad D. Alwe ◽  
James H. Flynn ◽  
...  
Keyword(s):  
Long Range ◽  
Forest Canopy ◽  
Deciduous Forest ◽  
Vertical Gradient ◽  
Organic Aerosol ◽  
Long Range Transport ◽  
Transport Mechanisms ◽  
Aerosol Composition ◽  
Range Transport ◽  
Mixed Deciduous Forest

Abstract. Exchanges of energy and mass between the surrounding air and plant surfaces occur below, within, and above a forest's vegetative canopy. The canopy also can lead to vertical gradients in light, trace gases, oxidant availability, turbulent mixing, and properties and concentrations of organic aerosols (OA). In this study, a high-resolution time-of-flight aerosol mass spectrometer is used to measure non-refractory submicron aerosol composition and concentration above (30 m) and below (6 m) a forest canopy in a mixed deciduous forest at the Program for Research on Oxidants: Photochemistry, Emissions, and Transport tower in northern Michigan during the summer of 2016. Three OA factors are resolved using positive matrix factorization: more-oxidized oxygenated organic aerosol (MO-OOA), isoprene-epoxydiol-derived organic aerosol (IEPOX-OA), and 91Fac (a factor characterized with a distinct fragment ion at m/z 91) from both the above- and below-canopy inlets. MO-OOA was most strongly associated with long-range transport from more polluted regions to the south, while IEPOX-OA and 91Fac were associated with shorter-range transport and local oxidation chemistry. Overall vertical similarity in aerosol composition, degrees of oxidation, and diurnal profiles between the two inlets was observed throughout the campaign, which implies that rapid in-canopy transport of aerosols is efficient enough to cause relatively consistent vertical distributions of aerosols at this scale. However, four distinct vertical gradient episodes are identified for OA, with vertical concentration differences (above-canopy minus below-canopy concentrations) in total OA of up to 0.8 μg/m3. The magnitude of these differences correlated with concurrent vertical differences in either sulfate aerosol or ozone. These differences are likely driven by a combination of long-range transport mechanisms, canopy-scale mixing and local chemistry. These results emphasize the importance of including vertical and horizontal transport mechanisms when interpreting trace gas and aerosol data in forested environments.

scholarly journals Atmospheric measurements of the terrestrial O<sub>2</sub> : CO<sub>2</sub> exchange ratio of a midlatitude forest

2019 ◽  
Vol 19 (13) ◽  
pp. 8687-8701 ◽  
Author(s):  
Mark O. Battle ◽  
J. William Munger ◽  
Margaret Conley ◽  
Eric Sofen ◽  
Rebecca Perry ◽  
...  
Keyword(s):  
Large Scale ◽  
Carbon Budget ◽  
Forest Canopy ◽  
Deciduous Forest ◽  
Carbon Sink ◽  
Atmospheric Measurements ◽  
Global Carbon Budget ◽  
Mixed Deciduous Forest ◽  
The Mean ◽  
Global Carbon

Abstract. Measurements of atmospheric O2 have been used to quantify large-scale fluxes of carbon between the oceans, atmosphere and land since 1992 (Keeling and Shertz, 1992). With time, datasets have grown and estimates of fluxes have become more precise, but a key uncertainty in these calculations is the exchange ratio of O2 and CO2 associated with the net land carbon sink (αB). We present measurements of atmospheric O2 and CO2 collected over a 6-year period from a mixed deciduous forest in central Massachusetts, USA (42.537∘ N, 72.171∘ W). Using a differential fuel-cell-based instrument for O2 and a nondispersive infrared analyzer for CO2, we analyzed airstreams collected within and ∼5 m above the forest canopy. Averaged over the entire period of record, we find these two species covary with a slope of -1.081±0.007 mol of O2 per mole of CO2 (the mean and standard error of 6 h periods). If we limit the data to values collected on summer days within the canopy, the slope is -1.03±0.01. These are the conditions in which biotic influences are most likely to dominate. This result is significantly different from the value of −1.1 widely used in O2-based calculations of the global carbon budget, suggesting the need for a deeper understanding of the exchange ratios of the various fluxes and pools comprising the net sink.

scholarly journals Contrasting Rhizospheric and Heterotrophic Components of Soil Respiration during Growing and Non-Growing Seasons in a Temperate Deciduous Forest

Forests ◽  
2018 ◽  
Vol 10 (1) ◽  
pp. 8 ◽  
Author(s):  
Zhen Jiao ◽  
Xingchang Wang
Keyword(s):  
Soil Respiration ◽  
Deciduous Forest ◽  
Growing Season ◽  
Heterotrophic Respiration ◽  
Temperate Deciduous Forest ◽  
Northern Forest ◽  
Growing Seasons ◽  
Temperate Deciduous ◽  
Total Soil Respiration ◽  
Annual Period

The contributions of heterotrophic respiration (RH) to total soil respiration (RS) for the non-growing season, growing season, and annual period are 84.8%, 60.7%, and 63.3%, respectively.Few studies have partitioned RS into its rhizospheric (RR) and heterotrophic components throughout the year in northern forest ecosystems. Our objectives were to quantify the contributions of non-growing season and heterotrophic respiration. We conducted a trenching experiment to quantify RR and RH in a temperate deciduous forest in Northeast China over two years using chamber methods. Temperature sensitivities (Q10) for RS and for RH were both much higher in the non-growing season (November to April) than those in the growing season. The Q10 for RS was higher than Q10 for RH in both seasons, indicating a higher temperature sensitivity of roots versus microorganisms. Mean non-growing season RS, RH, and RR for the two years were 94, 79 and 14 g carbon (C) m−2, respectively, which contributed 10.8%, 14.5%, and 4.5% to the corresponding annual fluxes (869, 547 and 321 g C m−2 year−1, respectively). The contributions of RH to RS for the non-growing season, growing season, and annual period were 84.8%, 60.7%, and 63.3%, respectively. Using the same contribution of non-growing season RS to annual RS, to scale growing season measurements, to the annual scale would introduce significant biases on annual RH (−34 g C m−2 yr−1 or −6%) and RR (16 g C m−2 yr−1 or 5%).We concluded that it was important to take non-growing season measurements in terms of accurately partitioning RS components in northern forests.

scholarly journals Atmospheric measurements of the terrestrial O<sub>2</sub> : CO<sub>2</sub> exchange ratio of a mid-latitude forest

2018 ◽  
Author(s):  
Mark O. Battle ◽  
J. William Munger ◽  
Margaret Conley ◽  
Eric Sofen ◽  
Rebecca Perry ◽  
...  
Keyword(s):  
Fuel Cell ◽  
Large Scale ◽  
Carbon Budget ◽  
Forest Canopy ◽  
Deciduous Forest ◽  
Atmospheric Measurements ◽  
Global Carbon Budget ◽  
Mixed Deciduous Forest ◽  
Global Carbon ◽  
Photosynthesis And Respiration

Abstract. Measurements of atmospheric O2 have been used to quantify large-scale fluxes of carbon between the oceans, atmosphere and land since 1992 (Keeling, 1992). With time, datasets have grown and estimates of fluxes have become more precise, but a key uncertainty in these calculations is the exchange ratio of O2 and CO2 associated with terrestrial photosynthesis and respiration. We present measurements of atmospheric O2 and CO2 collected over a six-year period from a mixed deciduous forest in central Massachusetts, USA (42.537° N, 72.171° W). Using a differential fuel-cell based instrument for O2 and a non-dispersive infrared analyzer for CO2, we analyzed an airstream collected within and ~6 m above the forest canopy. Averaged over the entire period of record, we find these two species covary with a slope of −1.058 &amp;pm; 0.006 moles of O2 per mole of CO2. If we limit the data to values collected on summer days within the canopy, the slope is −1.01 &amp;pm; 0.01. These are the conditions in which biotic influences are most likely to dominate, suggesting that this slope is our best estimate of αB. This result is significantly different from value of 1.1 widely used in O2-based calculations of the global carbon budget, suggesting adjustments of these O2-based flux estimates may be in order.

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