• 论文与研究报告 •

日本落叶松冠层光合特性的空间变化

1. 林木遗传育种国家重点实验室 国家林业和草原局林木培育重点实验室 中国林业科学研究院林业研究所 北京 100091
• 收稿日期:2017-04-10 修回日期:2019-03-05 出版日期:2019-06-25 发布日期:2019-07-11
• 基金资助:
国家自然科学基金重点项目（31430017）。

Spatial Variation of Photosynthetic Characteristics in Canopy of Larix kaempferi

Xia Guowei, Sun Xiaomei, Chen Dongsheng, Zhang Shougong

1. State Key Laboratory of Tree Genetics and Breeding Key Laboratory of Tree Breeding and Cultivation of National Forestry and Grassland Administration Research Institute of Forestry, CAF Beijing 100091
• Received:2017-04-10 Revised:2019-03-05 Online:2019-06-25 Published:2019-07-11

Abstract: [Objective] [Objective]To better understand the spatial heterogeneity of photosynthetic characteristics in canopy of Larix kaempferi, photosynthetic parameters of needles were measured in different canopy layers. This study could provide a sound theoretical foundation for developing a canopy productivity model and accurately evaluating canopy productivity.[Method] The 8-year-old L. kaempferi was selected as the research material, and the canopy was divided equally into 8 canopy layers according to the canopy length from top to bottom. In each tree, only one south-oriented branch was selected in each layer, and the diurnal change of photosynthesis of needles was measured on each selected branch.[Result] The diurnal change of photosynthetic parameters in most canopy layers was similar. Net photosynthetic rate (Pn), transpiration rate (Tr), value of stomatal limitation (Ls), photosynthetically active radiation (PAR), air temperature (Ta) and vapor pressure deficit (VPD) showed a single peak curve, and the stomatal conductance (Gs) gradually decreased from morning. With the increase of canopy, photosynthetic parameters increased, and specific leaf area reduced, while Ta and VPD increased firstly, and then decreased from high to low position of the canopies. There were significant significant differences (P<0.05) in the photosynthetic parameters and the micro-environmental factors among different canopy layers. The Pn, PAR, Gs, and (Tr) had exponential function relationships with relative canopy height (R2 ≥ 0.94), and the Ta and VPD had quadratic function relationships with relative canopy height (R2 ≥ 0.79). The result of path analysis showed that PAR was a main factor influencing Pn, but the impact of Ta and air humidity was relatively limited.[Conclusion] Photosynthetic effective radiation and photosynthetic activity of mesophyll cells were the main environmental and physiological factors affecting the spatial variation of Pn in L. kaempferi canopy. Pn increased significantly with the increasing canopy, while Pn at the bottom of L. kaempferi canopy was negative, indicating that the part of canopy remained in the state of carbon consumption. Therefore, we suggest that the results can be used as the important indicator for artificial pruning of L. kaempferi larch, and also can be used as the important theoretical basis for developing canopy productivity model and estimating canopy productivity.