武夷山不同海拔植物水分利用效率的变化及其与养分变化的关系

以武夷山不同海拔(600、900、1300、1500、1800、2000和2100 m)的乔木、灌木和草本3种生活型植物为研究对象,观测其水分利用效率和叶片氮、磷养分浓度随海拔的变化趋势,旨在探索海拔梯度间水分、养分变化与植物水分利用效率变化的关系.结果表明: 植物水分利用效率随海拔的增加呈显著上升趋势,乔木叶片δ¹⁸O随海拔变化不显著.总体上看,叶片氮浓度未观测到规律性的变化,高海拔地区的叶片磷浓度显著高于低海拔地区.水分利用效率与叶片磷浓度呈显著正相关,而与叶片氮浓度相关性不显著.不同海拔植物水分利用效率变化主要由光合速率的变化引起,水分状况对植物水分利用效率的影响不显著.海拔梯度间植物叶片磷浓度的差异对光合速率影响显著,进而影响水分利用效率.

Variations of water use efficiency and its relationship with leaf nutrients of different altitudes of Wuyi Mountains,China

We determined the water use efficiency and nitrogen and phosphorus concentrations of plants at different altitudes (600, 900, 1300, 1500, 1800, 2000, 2100 m) in Wuyi Mountains to understand the relationship of water use efficiency with foliar nutrients. The results showed that plant water use efficiency increased with altitude, and the leaf δ¹⁸O of tree showed no significant variance with altitude. On the whole, leaf nitrogen concentration showed no obvious trend, while leaf phosphorus concentration at high altitude was significantly higher than that at low altitude. No significant relationship between water use efficiency and foliar nitrogen concentration was found in this study, but water use efficiency had a positive correlation with foliar phosphorus concentration. In conclusion, the change of water use efficiency was mainly caused by the difference in photosynthetic rate. The effect of water status on plant water use efficiency was not significant. The variances of leaf phosphorus concentrations along the altitudinal gradient may affect photosynthetic rate and in turn the water use efficiency of plant in this area.