Photosynthesis of Vascular Plants: Assessing Canopy Photosynthesis by Means of Simulation Models

Beyschlag, Wolfram; Ryel, Ronald J.; Caldwell, M. M.

doi:10.1007/978-3-642-79354-7_20

Cited by 8 publications

(4 citation statements)

References 34 publications

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“…Nutrient uptake per unit root length also increases with increasing temperature if plant growth is not limited by other factors (BassiriRad et al, 1993 ;BassiriRad, 2000). These results are certainly not surprising, given what we know about the relationship between temperature, photosynthesis and shoot growth (Beyschlag et al, 1993 ;Schwartz et al, 1997). However, as Fitter et al (1998) recently discussed, there is sometimes little correlation between field temperatures and root growth.…”

Section:  mentioning

confidence: 89%

Responses of tree fine roots to temperature

et al. 2000

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Soil temperature can influence the functioning of roots in many ways. If soil moisture and nutrient availability are adequate, rates of root length extension and root mortality increase with increasing soil temperature, at least up to an optimal temperature for root growth, which seems to vary among taxa. Root growth and root mortality are highly seasonal in perennial plants, with a flush of growth in spring and significant mortality in the fall. At present we do not understand whether root growth phenology responds to the same temperature cues that are known to control shoot growth. We also do not understand whether the flush of root growth in the spring depends on the utilization of stored nonstructural carbohydrates, or if it is fueled by current photosynthate. Root respiration increases exponentially with temperature, but Q "! values range widely from c. 1.5 to 3.0. Significant questions yet to be resolved are : whether rates of root respiration acclimate to soil temperature, and what mechanisms control acclimation if it occurs. Limited data suggest that fine roots depend heavily on the import of new carbon (C) from the canopy during the growing season. We hypothesize that root growth and root respiration are tightly linked to whole-canopy assimilation through complex source-sink relationships within the plant. Our understanding of how the whole plant responds to dynamic changes in soil temperature, moisture and nutrient availability is poor, even though it is well known that multiple growth-limiting resources change simultaneously through time during a typical growing season. We review the interactions between soil temperature and other growth-limiting factors to illustrate how simple generalizations about temperature and root functioning can be misleading.

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Section:  mentioning

confidence: 89%

Responses of tree fine roots to temperature

et al. 2000

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“…The scenario calculations outline the capability of the model to analyze canopies ranging from a closed canopy to individual plants. Especially in heterogeneous canopy architectures, the influence of a neighboring plant varies with its distance and azimuthal orientation (Beyschlag et al, 1995) Thus, the model can give valuable information in situations where light distribution within the canopy is important, such as the evaluation of different planting patterns or the estimation of light interception in a multispecies canopy.…”

Section: Resultsmentioning

confidence: 99%

“…However, calculations become more complicated when exceeding simple geometric descriptions for the foliage envelope. Modified and extended versions of this model have been applied to tree stands (Grace et al, 1987; Wang and Jarvis, 1990) and to tussock grass canopies (Ryel et al, 1993) The approach was also extended to calculate light interception in a mixed species stand (Beyschlag et al, 1995)…”

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confidence: 99%

A Three‐Dimensional Approach to Modeling Light Interception in Heterogeneous Canopies

1999

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The accuracy of plant growth models depends strongly on a precise calculation of radiation uptake. Numerous approaches exist to estimate light absorption in spatially heterogeneous canopies, but these either have restrictions with respect to canopy structure or involve complex and inflexible calculations. The objective of this study was to develop a simulation tool to assess radiation penetration into canopies that should (i) give details on light absorption in heterogeneous canopy architectures and (ii) comprise simple and easily adaptable routines. In the model, the complete canopy volume is subdivided into cubic units that are either empty or filled with leaf area. Leaf area can be distributed in an arbitrarily chosen geometric solid positioned anywhere in the model domain. Transmission through the cubes is calculated by following the path of solar rays from the top of the canopy to ground level. Daily canopy absorption is calculated separately for direct and diffuse radiation, taking reflection and scattering of the direct beam into account. Using only a few readily obtainable parameters, a close agreement between simulated and measured canopy transmission of a cauliflower (Brassica oleracea var. botrytis L.) crop was found (r2=0.97) Comparing different canopy structures ranging from single‐plant canopies to a closed canopy gave detailed information on the absorption characteristics and the distribution of light absorption in individual plants. Results for closed canopies and row crops were consistent with those of earlier models. It is thus useful as a reference model to identify possible simplifications in the quantification of light interception by heterogeneous crops.

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“…Simulation conditions are for mid-latitude clear skies in summer. (Ryel et al 1990) canopy structure are difficult to do experimentally (Beyschlag et al 1994;Ryel and Beyschlag 1999). The results from these simulations indicate that, even when the total leaf area index (LAI) of the two component species is identical and remains unchanged, a 10% reduction in the vertical distribution of leaf area for one of the species can reduce its relative light capture in mixture by 20-60% (Fig.…”

Section: Uv-b Radiation and Plant-plant Interactionsmentioning

confidence: 96%