Comment on Relationships between single tree canopy and grass net radiations

摘要

Pereira et al. [Pereira, A.R., Green, S., Villa Nova, N.A., 2007. Relationships between single tree canopy and grass net radiations. Agric. Forest Meteorol. 142 (1), 45-49] have proposed an empirical relationship between whole tree canopy net radiation and grass net radiation as a function of tree leaf area. In this work, I show that the relationship does not hold for either isolated trees or trees in orchards. A simple model of tree interception is used to analyze the scaling up of radiation interception by isolated trees while a published radiation interception model is used for trees in canopies. The two models are able to predict some of the data presented by Pereira et al. and explain the main causes of variation. For isolated trees radiation interception is proportional to leaf area but the coefficient is much higher than that found by the authors. For trees in orchards, net radiation absorbed might be calculated as a function of intercepted radiation using available models.