Evergreen broadleaf greenness and its relationship with leaf flushing, aging, and water fluxes

Remote sensing capabilities to monitor evergreen broadleaved vegetation are limited by the low temporal variability in greenness signal. With canopy computed from digital repeat photography (PhenoCam), we investigated how related seasonal changes leaf age and traits as well variation of trees’ water fluxes (characterized sap flow conductance). The results showed that sprouting leaves mainly responsible for rapid increase green chromatic coordinate (GCC) spring. We found statistically significantly differences spectral properties among different ages. Specifically, mean GCC young was 0.385 ± 0.010 (mean SD), while mature old 0.369 0.003, 0.376 0.004, respectively. Thus, dynamics can be explained age. Sap conductance both a combination environmental drivers (96% 87% variance explained, respectively). In particular, air temperature vapor pressure deficit (VPD) most variance, Besides, is an important explanatory variable may because represent ontogeny information. conclude PhenoCam used identify flushing trees, which carries information about traits. it helpful better estimating constraints fluxes.