额济纳荒漠河岸胡杨林叶片气孔导度与微环境因子关系的模拟研究

以额济纳荒漠河岸胡杨(Populus euphratica)为研究对象,利用LI-6400光合测定仪于2005年5~9月份观测了胡杨叶片气体交换数据,研究了胡杨叶片气孔导度与光合速率、光合有效辐射与光合速率之间的关系.结果表明:(1)胡杨叶片净光合速率随气孔导度的增大而升高,但当气孔导度增加到一定值后,光合速率的增加变缓慢直至平稳,并主要是非气孔限制因素造成的;Ball-Berry模型(B-B模型)能够很好地描述气孔导度与光合速率之间的关系(R2=0.92).(2)叶片净光合速率随着有效辐射的变化符合非直角双曲线规律(R2=0.99).(3)B-B模型和非直角双曲线光合模型耦合后模拟值与观测值之间存在很好的正相关性(r=0.93),但耦合模型的模拟值还是较实测值偏大.因此,在干旱区还必须考虑水分限制因素对气孔开闭的控制作用,进一步构建适合干旱区生态系统特点的水-碳耦合循环机理模型.

The Simulation of Leaf Stomatal Conductance of Populus euphratica in Desert Riparian Forest in Ejin

The response of photosynthesis of Populus euphratica Oliv.to changes of photosynthetically active radiation (PAR) and the relationship between leaf stomatal conductance and photosynthesis were studied using Li-6400 in Ejin oasis,based on the long-term leaf gas-exchange observations during May to September in 2005.The results showed that:(1)Net photosynthetic rate increases with increasing stomatal conductance (gs) initially,but when gs exceeds a certain value,it will decrease with increasing gs,which was attributed to non-stomatal factors;(2)The relationship between photosynthesis and PAR could be described by a non-rectangular hyperbola;(3)The B-B model could perfectly describe the relationship between the stomatal conductance and photosynthesis (R2=0.92).However,the simulated values of stomatal conductance by coupling a B-B model and a non-rectangular hyperbolic photosynthesis model are slightly greater than the observed values.Thus,it was necessary to consider the influence of water stress on the stomatal conductance in arid zone,and the future research should focus on the mechanism of physiological ecology based on the relationship among water and carbon cycles in terrestrial ecosystem,and try to develop a new water-carbon coupling cycle in arid terrestrial ecosystem.