Seasonal dynamics of light-use efficiency in Artemisia ordosica shrubby desert

ObjectiveLight-use efficiency (LUE) is a key parameter to evaluation the ecosystem productivity, which shows the efficiency of vegetation photosynthesis transforming absorbed energy into organic dry matter. In order to improve the ecosystem productivity estimation and prediction accuracy of Artemisia ordosica shrubby desert , this paper studied the seasonal dynamics of LUE and the regulation mechanism of environmental factors for Artemisia ordosica shrubby desert.

MethodWe used eddy covariance measurements in growing season (from May to October) in 2014 to analyze the net carbon exchange, photosynthetically active radiation, temperature, and moisture dynamics and the relationship between influential factors and light-use efficiency at different temporal resolutions of Artemisia ordosica shrubby desert in northern China.

ResultAt diurnal scale, LUE showed a significant trough trend, reaching the lowest (0.000 8−0.002 4 μmol/μmol) at 14:00. Canopy conductance (g_s) and photosynthetically active radiation were the main factors in affecting LUE at diurnal scale. At the seasonal scale, LUE began to rise rapidly in May and reached its peak (0.002 5 g/MJ) in September, then gradually decreased. The monthly average of LUE was between 0.000 9 and 0.002 5 g/MJ. Soil N content, canopy conductance and photosynthetically active radiation were the most factors in regularizing LUE at seasonal scale.

ConclusionThe light-use efficiency for Artemisia ordosica shrubby desert has obvious diurnal and seasonal dynamics. At seasonal scale, increasing soil N content can promote the ecosystem primary productivity (GEP), so as to increase LUE. The results can improve the accuracy of ecosystem productivity model and provide an important reference for the sustainable management of the desert ecosystem and the restoration of the sandy area.