Measurement of tropical rainforest three-dimensional light environment and its diurnal change

A key link to understand the relationship between tropical forest canopy physiology and remote-sensing technology is forest light distribution. Accordingly, we conducted three-dimensional light environment measurements to acquire a quantitative and qualitative understanding of tropical rainforests at Lambir Hills National Park, Sarawak, Borneo, Malaysia, as a typical tropical rainforest region. The aim of this study was to elucidate links between canopy physiological studies and remote-sensing technology, and to investigate the up-scaling capability of canopy processes and mechanisms. Measurements were conducted using a ground-based laser profiler system and terrestrial survey instrument. For understanding qualitative forest characteristics, both reflective and transmissive light measurements were conducted, using photon and quantum sensors and a spectroradiometer. Our results suggest there is no great difference in canopy height, when all trees are mature, are interdependent and are employing the same growth strategies. Photosynthetic active radiation attenuation showed no changes over time.