B009-12
The long-term observation of PRI and LUE and phenological changes in a temperate Japanese cypress forest at Kiryu Japan.
Monday, 7 December 2020: 07:33
Virtual
Siyu Chen1, Yoshiko Kosugi1, Tatsuro Nakaji2, Hibiki Noda3, Kenlo Nishida Nasahara4 and Kouki Kikosaka5, (1)Kyoto University, Graduate School of Agriculture, Kyoto, Japan, (2)Hokkaido University, Tomakomai Experimental Forest, Field Science Center for Northern Biosphere, Sapporo, Japan, (3)NIES National Institute of Environmental Studies, Tsukuba, Japan, (4)University of Tsukuba, Tsukuba, Japan, (5)Tohoku University, Sendai, Japan
Abstract:
The light-use efficiency (LUE) of vegetation is one of the most essential parameters in production estimation models for terrestrial ecosystems. LUE generally expressed as the ratio of gross primary production (GPP) to absorbed photosynthetically active radiation (APAR). We utilized the carotenoid-based vegetation index, the photochemical reflectance index (PRI), which is sensitive to changes in carotenoid pigments (e.g. xanthophyll pigments) in live foliage, as a tool to track the photosynthetic activities. We measured and recorded the CO
2 flux data and the micrometeorological data of the temperate Japanese cypress forest from 2014 to 2019. We made use of the digital camera to monitor the canopy phenology changes from 2016 to 2019. The digital camera takes photos in 3 hours interval, the RGB channels of image data were extracted to calculate the RGB chromatic coordinates.
Our findings demonstrated that LUE has a good relationship with the PRI. During the monitoring period, apparent seasonal and diurnal change of the PRI observed at temperate Japanese cypress forest. Furthermore, the PRI was observed that reaches the peak in September and the valley in February. We also found out distinct phenology changes patterns with the phenological analysis results. The gcc showed similar seasonal changes with that of PRI. When the leaves became red, the PRI and the gcc took minimum values. It suggested that leaf reddening phenomena causes the decline of PRI and LUE. Based on the long-term observation results we assume that the air temperature may be a trigger. In the future, we will test this hypothesis by setting 3 ROI (region of interest) in phenological analysis and other new sets of measurements.
