辽东栎冠层光合生理特性的空间异质性

冠层作为林木与环境因子相互作用最为直接的部分，研究冠层光合作用是分析森林生产力的基础。以北京东灵山辽东栎为对象，利用Li-6400便携式光合仪测定了不同冠层不同方向部位叶片的光合速率和光响应曲线，研究了叶片光合生理特性在冠层空间上的变化。结果表明：在不同冠层和不同方向上，饱和光合速率、光补偿点、光下暗呼吸和表观量子效率均存在差异，随着冠层下降以及从南至北，大多数光合生理特性指标表现出递减趋势。进一步的通径分析结果得出，光强、水气压亏缺、温度是影响不同层次光合速率的主要因子。冠层光合特性的空间异质性研究，对于在冠层水平上揭示植物固碳能力和估算植物生产力具有很重要的意义。

Spatial heterogeneity of photosynthetic characteristics of Quercus wutaishanica canopy

Forest canopy is a direct part of forest interacting with its environment. At the plantation level, there is a huge spatial hetero- geneity of forest canopy. With Quercus wutaishanica, Li-6400 portable photosynthetic system was used to measure the light curves of dif- ferent canopy positions. The results showed that in different canopy positions, there are differences among the physiological indices in- cluding net photosynthetic rate, light saturation point, dark respiration and apparent quantum efficiency. Moreover, with the drop of the canopy position from the south to the north, the majority of indices decreased. Further path analysis showed that vapor pressure deficit, air temperature, photosynthetic active radiation are the main impact factors at different canopy levels.