Chin J Plant Ecol ›› 2022, Vol. 46 ›› Issue (8): 904-918.DOI: 10.17521/cjpe.2021.0416

Special Issue: 碳水能量通量

• Research Articles • Previous Articles     Next Articles

Effect of diffuse radiation on gross primary productivity of typical planted forests in eastern China

LIU Pei-Rong1, TONG Xiao-Juan1,*(), MENG Ping2, ZHANG Jin-Song2, ZHANG Jing-Ru1, YU Pei-Yang1, ZHOU Yu2   

  1. 1School of Ecology and Nature Conservation, Beijing Forestry University, Beijing 100083, China
    2Key Laboratory of Tree Breeding and Cultivation of State Forestry Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing 100091, China
  • Received:2021-11-16 Accepted:2022-02-19 Online:2022-08-20 Published:2022-04-28
  • Contact: TONG Xiao-Juan
  • Supported by:
    National Natural Science Foundation of China(31872703);National Natural Science Foundation of China(31570617);National Key R&D Program of China(2020YFA0608101)


Aims Diffuse radiation is one of the important factors affecting forest carbon uptake. However, the response of gross primary productivity (GPP) of planted forest ecosystems to diffuse radiation in China is still unclear. We explored the effects of diffuse radiation on GPP at 6 plantation ecosystems in eastern China during the growing season.

Methods Based on carbon flux data and meteorological data during the growing season of 2019-2020, we estimated the diffuse radiation and identified the direct and diffuse conditions. The important light response parameters of plantation ecosystems were obtained by the rectangular hyperbolic curve. Meanwhile, we quantified the variations of GPP responding to diffuse and direct radiation. The contribution of light and environmental factors to the diurnal variation of GPP was analyzed by partial correlation method.

Important findings Diffuse radiation can effectively promote canopy photosynthesis. The values of light response parameter canopy quantum efficiency (α) and photosynthesis at photosynthetically active radiation of 1 000 µmol·m-2·s-1 (P1000)increased by 47%-150% and 2%-65%, respectively. Compared with direct sky conditions, GPP increased by 0.86%-1.70% in response to 1 μmol·m-2·s-1 enhancement of photosynthetically active radiation (PAR) under diffuse sky conditions, which was affected by forest type and vegetation phenology. In diffuse skies, the increment of the variation of GPP under increasing per unit PAR (0.86%-1.00%) at Pinus sylvestrisvar. mongolica and P. tabuliformissites with lower normalized difference vegetation index (NDVI) value was significantly lower than other plantation sites (1.04%-1.70%), and there was a significant positive correlation between NDVI and P1000. Under low light level, PAR controlled the averaged gross primary productivity (GPPa), but diffuse fraction (DF) mainly regulated GPPain middle and high light level. The photosynthesis corresponding to diffuse radiation under moderate light was roughly equal to photosynthesis corresponding to total radiation under high light. Under middle light conditions, the GPPa value in medium and high DF (≥0.5) at Cunninghamia lanceolata, Populusspp., Quercus variabilis and Larix gmeliniiwas about 27%-50% higher than under low DF condition (<0.5), and the GPPa value at high DF was about 2% more than under low DF conditions at Pinus sylvestrisvar. mongolica and P. tabuliformis sites. Under diffuse radiation conditions, diffuse photosynthetically active radiation (PARdif) explained 16%-45% of the variation of GPP. Air temperature (Ta) and vapor pressure deficit (VPD) explained 10%-19% of the variation of GPP at Cunninghamia lanceolata, Quercus variabilis and Larix gmelinii sites. Under diffuse radiation conditions, the P1000 will be the highest when Ta is 15-25 °C and VPD is 0-1 kPa.

Key words: plantation, diffuse radiation, gross primary productivity, vapor pressure deficit