Chin J Plan Ecolo ›› 2015, Vol. 39 ›› Issue (12): 1156-1165.

• Orginal Article •

### Dynamics and regulations of ecosystem light use efficiency in a broad-leaved Korean pine mixed forest, Changbai Mountain

ZHANG Lei-Ming1,*, CAO Pei-Yu1,2, ZHU Ya-Ping3, LI Qing-Kang1, ZHANG Jun-Hui4, WANG Xiao-Ling3, DAI Guan-Hua4, LI Jin-Gong5

1. 1Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China
2University of Chinese Academy of Sciences, Beijing 100049, China
3College of Agricultural, Henan University of Science and Technology, Luoyang, Henan 471003, China
4Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China
and 5The Administration Center of Changbai Mountain National Nature Reserve, Yanbian, Jilin 133613, China
• Online:2015-12-01 Published:2015-12-31
• Contact: Lei-Ming ZHANG
• About author:

# Co-first authors

Abstract:

Aims Ecosystem light use efficiency (LUE) reflects the ability of CO2 uptake and light utilization via photosynthesis, which is a key parameter in ecosystem models to evaluate ecosystem productivity. The objectives of this study were to: (1) compare the differences of LUE derived from different methods; (2) elucidate the seasonal dynamics of LUE and its regulatory factors; and (3) evaluate the maximum LUE (LUEmax) and its variability based on eddy-covariance (EC) flux.Methods Using the flux data from an EC tower during 2003-2005 at a broad-leaved Korean pine (Pinus koraiensis) mixed forest, Changbai Mountain, two types of LUE indicators were generated from: 1) the apparent quantum yield (ε) estimated with rectangular hyperbolic curve, and 2) the ecological light use efficiency (LUEeco) calculated as the ratio between gross ecosystem productivity (GEP) and photosynthetically-active radiation (Q).Important findings The seasonal variation of ε and LUEeco appeared a unimodal pattern within a year, with the variations significantly dominated by soil surface temperature and Normalized Difference Vegetation Index (NDVI). A positive correlation between GEP and LUE was found for both ε and LUEeco, with the effect of Q on LUE relatively weak. The increase in diffusion radiation appeared favorable for enhanced LUE. Generally, there was a significant positive relationship between ε and LUEeco, while ε was higher than LUEeco, especially during the mid-season. The annual maximum value of ε and LUEeco was (0.087 ± 0.003) and (0.040 ± 0.002) μmol CO2·μmol photon-1 over the three years, respectively. The interannual variability of LUEmax for ε and LUEeco was 4.17% and 4.25%, respectively, with a maximum difference of >8%, likely resulted from considerable uncertainty in model simulations. Our results indicated that the inversion and optimization of maximum LUE should be taken seriously in the application of LUE models.