Liu Qiang, Dong Li Hu, Li Feng Ri, Li Xiang
Northeast Forestry University, Harbin 150040, China.
Ying Yong Sheng Tai Xue Bao. 2016 Sep;27(9):2789-2796. doi: 10.13287/j.1001-9332.201609.008.
Based on a 14-year-old planted Larix olgensis in the Maoershan Forest Farm, Heilongjiang Province in 2014, the spatial heterogeneity of photosynthetic indicators, environmental factors and photosynthetic physiological parameters were analyzed, meanwhile the relationship between net photosynthetic rate (P) and other indicators were studied. Results showed that in the vertical direction, P, stomatal conductance (g) and transpiration rate (T) were higher in upper than middle and lower canopy significantly, intercellular CO concentration (C) increased in the sequence of upper < middle < lower canopy. Photosynthetic active radiation (PAR) decreased from outside of upper to inside of lower canopy significantly, vapor pressure deficit (VPD) and needle leaf temperature (T) in upper canopy were respectively higher than in middle and lower canopy significantly, while relative humidity (RH) showed no significant difference with spatial location. The mean value of maximum P(P), dark respiration rate (R), light compensation point (LCP) and light sa-turation point (LSP) followed the pattern of upper > middle > lower canopy and decreased by 32.7%, 55.8%, 80.2% and 51.6% from upper to lower canopy respectively. Apparent quantum yield (AQY) in lower canopy was 1.2 and 1.3 times as much as that of middle and upper canopy, respectively. In the horizontal direction, P, g, T, PAR and VPD were significantly higher from outside to inside in the upper crown, but C and RH showed no significant diffe-rence. The mean value of P, R, LCP and LSP declined by 0.4%, 37.7%, 42.0% and 16.4% from outside to inside, on the contrary, AQY was 0.7% higher from inside to outside. C was the main physiological impact factor for P, and PAR was an important environmental factor that had the most obvious influence on P, especially in weak light region. Therefore, spatial heterogeneity should be considered necessarily when simulating and/or predicting the tree canopy photosynthesis.
基于2014年在黑龙江省帽儿山实验林场种植的14年生落叶松，分析了光合指标、环境因子和光合生理参数的空间异质性，同时研究了净光合速率（P）与其他指标之间的关系。结果表明，在垂直方向上，树冠上层的P、气孔导度（g）和蒸腾速率（T）显著高于中层和下层，胞间CO₂浓度（C）则呈上层＜中层＜下层的顺序增加。光合有效辐射（PAR）从树冠上层外侧到下层内侧显著降低，树冠上层的水汽压亏缺（VPD）和针叶温度（T）分别显著高于中层和下层，而相对湿度（RH）在空间位置上无显著差异。最大P（Pmax）、暗呼吸速率（R）、光补偿点（LCP）和光饱和点（LSP）的平均值呈树冠上层＞中层＞下层的规律，从上层到下层分别下降了32.7%、55.8%、80.2%和51.6%。下层树冠的表观量子效率（AQY）分别是中层和上层树冠的1.2倍和1.3倍。在水平方向上，树冠上层从外侧到内侧的P、g、T、PAR和VPD显著升高，但C和RH无显著差异。P、R、LCP和LSP的平均值从外侧到内侧分别下降了0.4%、37.7%、42.0%和16.4%，相反，AQY从内侧到外侧高0.7%。C是影响P的主要生理因子，PAR是对P影响最明显的重要环境因子，尤其是在弱光区域。因此，在模拟和/或预测树冠光合作用时，必须考虑空间异质性。
