---

作 者 ：王秀伟 毛子军

期 刊 ：林业科学 2007年 43卷 11期 页码：43-49

关键词：兴安落叶松；白桦；气体交换；冠层；温度；光合有效辐射；

Keywords:Larix gmelinii, Betula platyphylla, gas exchange, canopy, temperature, PAR,

摘 要 ：

在生长季定期测定兴安落叶松林主要组成树种兴安落叶松和白桦树冠上部、中部和下部叶片的光合作用和呼吸作用。结果表明:兴安落叶松当年生枝针叶在8、9月份最大净光合速率在冠层间差异显著。8月份最高,从上至下分别为13.09、8.63和9.07μmolCO₂·m^-2s^-1。落叶松往年生枝针叶的最大净光合速率在生长季差异不显著,其平均最大净光合速率为8.22μmolCO₂·m^-2s^-1。在整个生长季白桦冠层间的最大净光合速率均差异显著,从上至下,依次为17.56、13.01和9.58μmolCO₂·m^-2s^-1;白桦叶片、落叶松当年生枝针叶和落叶松往年生枝针叶的暗呼吸速率差异随着时间的变化而发生改变,但冠层之间无显著差异。在整个生长季中,白桦叶片、落叶松当年生枝针叶和落叶松往年生枝针叶的暗呼吸速率分别为0.47～1.40,0.83～1.46和0.68～1.63μmolCO₂·m^-2s^-1。2树种的暗呼吸速率与叶片温度显著正相关,与光照不相关。除白桦冠层上层叶片外,光合作用与生长季叶片温度的变化无明显相关性;白桦和落叶松生长季的不同时期冠层气体交换是动态变化的,但变化式样具有种的特异性。

Abstract:

The seasonal photosynthesis and dark respiration (R_d) in the upper, middle and lower portions of the canopy of Larix gmelinii and Betula platyphylla from 34-year-old larch-dominated plantation in northeastern of China were measured. We examined the gas exchange pattern of larch plantation in temporal and spatial variation in canopy-level during the growth season. The results indicated that the maximum net photosynthesis (P_nmax) among upper, middle and lower layers differed significantly for current-year branch needles of L. gmelinii in August and September,respectively, and had highest in August, ranged as 13.09,8.63,9.07 μmolCO₂·m^-2s^-1from upper layer to lower layer. There was no significant difference in P_nmax of previous-year branch-needles of larch among different months during the growth season. The mean of P_nmax was 8.22 μmolCO₂·m^-2s^-1. P_nmax of the birch leaves among the three canopy layers differed significantly throughout the growth season, ranged as 17.56, 13.01 and 9.58 μmolCO₂·m^-2s^-1from upper layer to lower layer. There were changes in R_d differences between the two species during the growth season, but no significant was found among the three layers of the canopy in the two species. During the whole growth season the R_d of birch, current-year and previous-year branch-needles of larch were 0.47～1.40, 0.83～1.46 and 0.68～1.63 μmolCO₂·m^-2s^-1, respectively. Our objective was to examine temporal and spatial variation in canopy-level gas exchange patterns during the growing season, notable positive correlation of R_d with temperature but no obvious correlation with illumination in the two species were found. P_nmax had no significant correlation with leave temperature during the growth season excepted the upper layer leave of larch. The gas exchange of the canopy of the larch and birch was variable depending on growth season with species-specific.

---