植物生态学报 ›› 2022, Vol. 46 ›› Issue (8): 904-918.DOI: 10.17521/cjpe.2021.0416

所属专题: 碳水能量通量

• 研究论文 • 上一篇    下一篇

散射辐射对中国东部典型人工林总初级生产力的影响

刘沛荣1, 同小娟1,*(), 孟平2, 张劲松2, 张静茹1, 于裴洋1, 周宇2   

  1. 1北京林业大学生态与自然保护学院, 北京 100083
    2中国林业科学研究院林业研究所国家林业局林木培育重点实验室, 北京 100091
  • 收稿日期:2021-11-16 接受日期:2022-02-19 出版日期:2022-08-20 发布日期:2022-04-28
  • 通讯作者: 同小娟
  • 作者简介:*(tongxj@bjfu.edu.cn)
  • 基金资助:
    国家自然科学基金(31872703);国家自然科学基金(31570617);国家重点研发计划(2020YFA0608101)

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)

摘要:

散射辐射是影响森林碳吸收的重要因子。然而, 有关生态系统总初级生产力(GPP)对散射辐射响应机理的理解仍有限。该研究利用中国东部6个人工林生态系统2019-2020年观测的碳通量数据和气象数据, 估算了散射辐射, 区分了直接辐射和散射辐射条件; 基于直角双曲线方程获取了不同辐射条件下生态系统光响应参数; 量化了GPP对散射辐射和直接辐射变化的响应; 采用偏相关方法分析了光照和环境因子对GPP日变化的贡献, 旨在探究生长季散射辐射对人工林生态系统GPP的影响机理。研究表明: 散射辐射增加可以有效促进冠层光合作用, 初始量子效率(α)和光合有效辐射(PAR)为1 000 μmol·m-2·s-1时的GPP (P1000)分别提高了47%-150%和2%-65%。与直接辐射条件相比, 散射辐射条件下的PAR每增加1 μmol·m-2·s-1, GPP增加0.86%-1.70%, 森林植被类型和站点物候变化会影响这一过程, 具有较低归一化植被指数(NDVI)的樟子松(Pinus sylvestris var. mongolica)和油松(Pinus tabuliformis)人工林GPP随单位PAR增加的变化量的增量(0.86%-1.00%)明显低于其他人工林站点的增量(1.04%-1.70%), 且植被NDVI与P1000存在显著正相关关系。在低光照时, PAR控制生态系统平均总初级生产力(GPPa)的变化; 在中等至高光照时, 散射辐射比例(DF)是影响GPPa的主要因子。在中等光照时, 散射辐射对应的光合作用接近于高光照时太阳辐射对应的光合作用, 且杉木(Cunninghamia lanceolata)、杨树(Populus spp.)、栓皮栎(Quercus variabilis)和华北落叶松(Larix gmelinii)在中高DF (≥0.5)时的GPPa比低DF (<0.5)高出27%-50%, 油松和樟子松在中高DF时的GPPa比低DF约高出2%。散射辐射条件下, 散射光合有效辐射(PARdif)解释了GPP变化的16%-45%, 气温(Ta)和饱和水汽压差(VPD)解释了杉木、栓皮栎和华北落叶松林GPP变化的10%-19%。在散射辐射条件下, 人工林在Ta为15-25 ℃和VPD为0-1 kPa时P1000最大。

关键词: 人工林, 散射辐射, 总初级生产力, 饱和水汽压差

Abstract:

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