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

Abstract

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.

Carbon allocation in fruit trees: from theory to modelling

“…These models, considering light interception at the scale of the whole crown, do not bring relevant information for addressing carbon partitioning at an infra-crown scale. Models splitting foliage into 3D cells (List and Küppers 1998;Röhrig et al 1999;Sinoquet et al 2001) give useful information about the spatial distribution of light interception but with only indirect association between light interception and plant topology. Alternatively, some FSPM light models simulate light interception at the scale of individual plant entities such as shoots (e.g., LIGNUM: Perttunen et al 1996) or elementary organs, such as leaves, internodes or fruits (Yplant: Pearcy and Yang 1996;Vegestar: Adam et al 2004;MMR: Dauzat and Eroy 1997;Nested Radiosity: Chelle and Andrieu 1998).…”

How can calibrated research-based models be improved for use as a tool in identifying genes controlling crop tolerance to environmental stresses in the era of genomics-from an experimentalist's perspective

“…The plant needs to be broken down into phytomers, tissues (cambium), stems, and fruits or fruit parts and roots. The British Growth Analysis method with its LA, LAI, dry mass (M), and dM/dt, dA/dt is no longer of much help by itself and must be integrated with McCree (1974) equation for estimating respiration and with Monsi and Saeki (1953) and Röhrig et al (1999) within crop canopies light interception models to provide useful software if possible. Modellers must test their rules and priorities against what plants do in the real world under similar stresses.…”

Assessing the Impact of Canopy Structure Simplification in Common Multilayer Models on Irradiance Absorption Estimates of Measured and Virtually Created Fagus sylvatica (L.) Stands

“…Studying the light distribution within a forest canopy is possible using radiation transfer models, provided that the stand architecture and leaf optical properties are adequately described [2]. These radiation transfer models simulate the effect of canopy geometry and structure on light interception and can link individual leaf light capture to gross photosynthetic assimilations [3][4][5][6][7]. However, because of the difficulties in acquiring detailed stand structure information, most of these models simplify the canopy structure, by using either big-leaf models [8][9][10] (single leaf assumption), or multi-layer models [11][12][13][14] (homogeneous horizontal and vertical layers containing the same amount of leaf area).…”

“…At the same time, scientists have incorporated three dimensional canopy elements [27,28] to assess light interception inside a canopy either by using cubic units that were either filled or empty with leaf area [5], or by using field measurements and Monte Carlo simulations of canopy gap fraction and LAI to examine the interaction of beam radiation with clumped forest canopies [25]. However, the contribution of explicit geometric canopy models compared to different multilayer canopy simplifications in calculating irradiance absorption and therefore surface radiation balance has not yet been thoroughly assessed and quantified.…”