旱柳叶面积指数与光能和水分利用率关系的个体差异

Relationship Between Leaf Area Index and Both Light Use Efficiency and Water Use Efficiency Across Individuals of Salix matsudana

选择张掖市黑河干流边缘的洪泛平原湿地作为试验地,将旱柳(Salix matsudana)分为3个大小等级:I级(d≤250 cm)、II级(250 cm320 cm),运用标准化主轴估计法(SMA),研究了不同大小等级旱柳(Salix matsudana)单株LAI与光能利用率(LUE)、水分利用率(WUE)的相关性。结果表明:随大小等级上升,旱柳冠层叶面积指数、间隙分数阈值、光合有效辐射和气温逐渐增大,空气相对湿度逐渐减少;旱柳高度、叶面积、叶片聚集度、净光合速率、蒸腾速率和WUE持续增大,分枝角度、叶厚度和LUE持续降低,气孔导度呈"倒U型"变化趋势;在大小等级I和III时,旱柳LAI与LUE、WUE分别呈显著负相关(P<0.05)和显著正相关(P<0.05),大小等级II则均呈显著正相关(P<0.05)。中等大小旱柳偏好于折中LAI、LUE和WUE的协调配置策略,大(小)个体植株选择极端LAI和光水利用效率的权衡配置策略,反映了不同个体湿地植物叶片空间分布与资源利用效率的优化配置模式。

The study area was located in the floodplain wetlands of Zhangye city in the Heihe River basin in northwest China(100.40° E,38.98° N).According to d(the cube root of plant volume) at the Heihe flood plain of Zhangye city,Salix matsudana was divided into 3 size classes,small individuals(I,d≤250 cm),medium individuals(II,250 cm320 cm),and standardized major axis(SMA) tests were used to examine the relationship of single plant leaf area index(LAI) with light use efficiency(LUE) and water use efficiency(WUE) of Salix matsudana at 3 size classes.The results showed that with the size classes turned from I to III,LAI,gap fraction threshold,photosynthetic active radiation and air temperature increased,and air relative humidity decreased.The height,leaf area,leaf coverage,net photosynthetic rate,transpiration rate and WUE of Salix matsudana increase,while bifurcation angle,leaf thickness and LUE decreased gradually.Stomatal conductance displayed an ‘inverted U-shaped’ trend.LAI had a positive and negative correlation with LUE and WUE at I and III(P<0.05),respectively,while there were significant positive relationship between LAI and both LUE and WUE at II(P<0.05).Moderate LAI,LUE and WUE were used by medium-sized plant at II,and less or larger LAI and photosynthetic efficiency by which number holds sway above the flux were selected by small or large individual at I and III,which reflected the optimization allocation mode between spatial pattern of leaves and resource use efficiency of wetland plant in different size classes.