摘要
比较研究了海南岛尖峰岭热带山地雨林上层乔木盘壳栎 (Castanopsis patelliformis(Chun) Chun)叶片光合作用对高 CO2浓度的短期响应。用 L i- 6 4 0 0 (L i- cor,Inc.,USA)便携式光合作用测定系统外置 CO2 气源 ,程序控制 CO2 处理浓度为35 0μmol/ mol及其加倍浓度 ,测定叶片光合速率的日变化进程 ,并通过光合作用相关响应曲线计算主要光合参数。结果表明 ,CO2 浓度倍增可使盘壳栎植株阳性叶净光合速率平均提高 75 % ,光饱和光合速率提高 6 5 % ,气孔导度降低 2 8%～ 73% ,水分利用效率提高 4 3%～ 70 % ,光补偿点升高近 7μmol/ (m2· s) ,饱和点提高 10 0 μmol/ (m2·s) ,表观量子产量提高 6 1% ,反映出 CO2浓度升高可提高植物的光合生产力。叶片光合作用日变化趋势在高 CO2
The responses of tropical plants to CO_2 enrichment are interest in view of the global increase in CO_2 levels. In this research we measure and analyze the short-term responses of photosynthesis diurnal courses and photosynthetic light response in sun leaves of the canopy species Castanopsis patelliformis. The measurements were made with Li-6400 (Li-cor, Inc., USA) portable photosynthesis system, where CO_2 was controlled at ambient (350μmol/mol) and elevated (700μmol/mol) concentrations respectively, during a continuous 3-day period in April, 2000. This is the dry season in the tropical mountain rain forest of Jianfengling, Hainan Island. An empirical model of photosynthetic light response was then constructed to predict the daytime carbon gain by fitting measured data into a non-rectangular hyperbola nonlinear model with the following parameters: the light-saturated photosynthetic rate (Asat), the light-saturated constant (K, equal to the PPFD, which is required to produce one-half of the light-saturated photosynthetic rate), apparent quantum yield (φ, the initial slope of the curve) and dark respiration rate (Rd). The results suggest that plants photosynthetic ability can be enhanced as the short-term responses to CO_2 enrichment, with elevated CO_2 stimulating an apparent quantum yield increase of 61% in our analysis. Elevated CO_2 also increased the light-saturated photosynthetic rate by 65% and the daily average net photosynthetic rate by 75%. Under elevated CO_2, the light saturation point increased by 100μmol/(m^2·s) and the light compensation point reduced by 10~20μmol/(m^2·s). Water use per unit carbon fixation was decreased by 42%~69%, while stomatal conductance was reduced by 28%~73%.A complete understanding of the effects of increases in atmospheric CO_2 concentration on forest ecosystems in real environments is dependent on the comprehension of the complex canopy light environment, as well as the interactions of light with CO_2.
出处
《生态学报》
CAS
CSCD
北大核心
2004年第8期1622-1628,共7页
Acta Ecologica Sinica
基金
国家自然科学基金重大资助项目 ( 3 98993 70 )
科技部和国家林业局全国重点野外科学观测试验站资助项目 ( 2 0 0 1-0 8)。~~
关键词
CO2浓度倍增
光合特性
盘壳栎
热带山地雨林
海南岛
elevated CO_2
light response of photosynthesis
Castanopsis patelliformis
tropical mountain rain forest
Hainan island
Jianfengling
