Analyzing the canopy light distribution among different poplar genotypes using terrestrial laser scanner and the GreenLab model

Crown architecture determines the leaf distribution, light interception and biomass production of trees in a high-density plantation. Light distribution and interception affect leaf photosynthesis and biomass production. The precise analysis of the light distribution in crown architecture is meaningful for ideotype breeding and genotype selection in forests. In the present study, five genotypes (namely, 6, 14, 97, 111 and 171) with significantly different crown architectures and biomass production were selected and analyzed using a terrestrial laser scanner (TLS). The branch characteristics that determine the crown structure were extracted from TLS point clouds. Geomagic Studio (2012, 3D system, USA) and Geomagic Spark (3D system, USA) software were used to measure these branch traits. Light response curves of leaves in the upper, middle and lower crown layers was measured using a portable photosynthesis system (LI-6400 XT, OPEN 6.1, Ecoteck, USA) and were used for deriving the leaf response to the photosynthetic photon flux density (PPFD). Using the GreenLab model, the visualized crown of each genotype was simulated according to the measured parameters of the branch traits, which were used to simulate and analyze the distribution of leaf irradiance and leaf photosynthesis in canopy. According to The results, genotype 171 showed the highest light interception and biomass production among the five monitored genotypes, which is consistent with the results obtained in the field observations. Thus, we concluded that genotype 171 is the ideal genotype and could be used for energy and wood fiber production and cultivation in high-density plantations.