【作者】 王秀伟；

【导师】 毛子军；

【作者基本信息】 东北林业大学 ， 植物学， 2006， 硕士

【摘要】 植物叶片的光合作用、组织的呼吸以及土壤呼吸等CO₂的变化都会对群落的碳平衡产生影响。本项研究采用叶室气体交换的方法对影响群落碳平衡的关键过程,即地上和地下过程的每个部分分别进行研究,旨在定量地揭示各关键过程在落叶松人工林生态系统碳循环中的作用,结果如下: 1.根据7个光响应模型对白桦叶片、落叶松当年生枝针叶和落叶松往年生枝针叶光响应曲线的拟合结果,通过对决定系数、最大光合速率和呼吸速率估计值的比较,得出模型5（非直角双曲线）和模型6（直角双曲线）对白桦叶片和落叶松针叶的光响应情况描述效果最佳。 2.光照强度的梯度变化引起白桦最大净光合速率成明显的梯度变化,由此可见,白桦叶片对光的依赖性很强。同时,白桦最大净光合速率随月份变化明显,6月初和7月初平均值相对较高,7月初最高,而在8月初和9月初相对较低。落叶松针叶对光照强度的依赖性不如白桦,当年生枝针叶在6月和7月初不同冠层之间最大净光合速率并没有显著差别,而在8月和9月初上层叶片最大净光合速率要显著高于中层和下层;同时当年生枝针叶最大净光合速率随季节变化也比较明显:6月和7月初值基本一致且较低,8月和9月初基本一致且较高;落叶松往年生枝针叶在整个生长季月份之间以及不同冠层间的最大净光合速率基本保持不变。 3.冠层间白桦叶片、落叶松针叶暗呼吸速率差异不显著,月份间的变化明显;月份间暗呼吸速率的变化与叶温的变化基本一致,但是落叶松往年生枝针叶与叶温相关性要好于白桦叶片和落叶松当年生枝针叶。 4.三种叶片类型表观量子效率在冠层间的变化都不显著;在月份间白桦表观量子效率变化不显著,落叶松针叶表观量子效率月份间变化显著,当年生枝针叶表观量子效率最大值出现在7月,往年生枝针叶出现在8月;三种叶片类型总体上白桦叶片表观量子效率最高（除8月外）,而当年生枝针叶表观量子效率的最大值在7月和9月要高于往年生枝针叶。 5.白桦叶片和落叶松当年生枝针叶光补偿点的变化与暗呼吸速率的变化一致,因为光补偿点是光合速率与呼吸速率相等时光合有效辐射的值,所以,白桦叶片和落叶松当年生枝针叶光补偿点的变化是由呼吸速率的变化引起的;由于落叶松往年生枝针叶的呼吸速率不随季节和冠层变化,所以其光补偿点的变化可能是由针叶对光强梯度适应的结果。 6.白桦叶片光饱和点季节的变化不显著,但是冠层间的变化显著:落叶松当年生枝针叶光饱和点冠层、季节间差异显著;落叶松往年生枝针叶光饱和点不受季节变化和不同冠层影响,三种叶片类型光饱和点的变化与其最大光合速率变化基本一致,所以可能是最大净光合速率的变化引起光饱和点的变化。白桦叶片光饱和点低于落叶松,而其最更多还原

【Abstract】 In this research, we studied on photosynthesis and soil respiration of Betula platyphylla Suk. leaves and Larix gmelinii (Rupr.) Rupr. needles in Larix gmelinii plantation. The results showed as following:1. Light-response of Birch leaves, larch current-year and previous-year shoot needles were caculated, using 7 light response models. To compare the estimated values of coefficient of dermination, net maximum photosynthesis and dark respiration, we considered that model 5 and model 6 were most suitable to reflect their light-response.2. Gradients change in light intensity resulted in significantly gradients change of net maximum photosynthesis in birch leaves. It indicated that birch leaves quite depended on light intensity. Also, net maximum photosynthesis of birch leaves obviously changed with seasonal variation. Mean value was relatively high in June and July, which was highest in July, and relatively low in August and September. Larch needles were not dependent on light intensity as birch leaves. Net maximum photosynthesis of current-year shoot needles had no significant differences in different canopy positions, while it was significantly higher in upper than that in middle and lower canopy. Net maximum photosynthesis of current-year shoot needles obviously changed with seasonal variation: the value in June and July was almost the same, and it was higher in August and September. Net maximum photosynthesis of previous-year shoot needles kept stable among different canopy positions and months.3. Dark respiration of birch leaves and larch needles had no significantly differences among different canopy positions, but significantly changed with seasonal variation. The change of dark respiration was almost the same with that of leave temperature. However, the correlation between dark respiration of previous-year shoot needles and leave/needle temperature was better than that of current-year shoot needles birch leaves.4. Apparent quantum yield (AQY) of three leave patterns was stable. It didn’t significantly change with seasonal variation. AQY of larch needles significantly changed with seasonal variation. AQY of current-year shoot needles was highest in July, while previous-year shoot needles in August. AQY of birch leaves was highest as a whole. Maximum AQY of larch current-year shoot needles was higher than previous-year shoot needles.5. Light compensation point (LCP) of birch leaves and larch needles changed with dark respiration, as LCP is the value when photosynthesis is equal to dark respiration. So the change of LCP resulted from dark respiration. Dark respiration of larch previous-year shoot needles didnn’t change with seasonal variation or canopy positions, so the change of its LCP resulted from acclimation to light gradients.6. Light saturation point (LSP) of birch leaves was not affected by seasonal variation, but significantly affected by canopy positions. LSP of larch current-year shoot needles was significantly affected by canopy positions and seasonal variation, while LSP of larch previous-year shoot needles was not affected by them. LSP of three leave patterns changed with their net maximum photosynthesis. So the change of net maximum photosynthesis might result in the change of LSP. LSP of birch leaves was lower than larch needles, while its net maximum photosynthesis was higher than larch needles. This might result from high AQY of birch leaves. It showed that larch needles required more light and was more capable to utilize high light than birch leaves. LSP of different aged shoots also changed significantly. Previou-year shoot needles was significantly higher than current-year shoot. This might relate to needle development.7. Respiration of soil with litter fall was higher than that with no litter fall in the whole growth season. There was no exponential correlation between soil respiration and soil temperature, but linear correlation was more obvious. The correlation of soil with litter fall respiration was better than that with no litter fall. Maximum respiration value of soil with litter fall occurred in August, a bit lower in June and July, lowest in September and October. Respiration of soil with no litter fall didn’t change much with seasonal variation. It was higher in July than that in October.In conclusion, trees’ photosynthesis and respiration changed with canopy positions and seasonal variation. Seasonal variation of soil respiration also obviously changed. So these factors should be considered when estimating carbon balance of a community.更多还原