Abstract: The study on the light use efficiency in the upper, middle, and lower canopy layers of Zea mays stand showed that the photosynthetically active radiation (PAR) intercepted by the entire canopy was 87.7% of the total incident, and the interception rate in middle and upper layers was as much as 75%. Within the range of visible spectra, the interception rate was in the sequence of upper layer>middle layer>lower layer. The diurnal variations of the three layers leaf temperature had a similar trend, and the differences among the layers were mainly related to canopy microclimate. The variations of non-photochemical quenching coefficient (q_N) were in accordance with those of leaf temperature, photochemical quenching coefficient (q_P), and photosynthetic rate (P_n). There was a trade-off tendency between the energies used for photochemical reactions and heat transformation.

Key words: Subalpine coniferous forest, Ecological process, Artificial restoration, Species diversity, Picea asperata