Macinnis-Ng Catriona, McClenahan Kate, Eamus Derek
Institute for Water and Environmental Resource Management, Department of Environmental Sciences, University of Technology, Sydney, NSW 2065, Australia.
Institute for Water and Environmental Resource Management, Department of Environmental Sciences, University of Technology, Sydney, NSW 2065, Australia. Corresponding author; email:
Funct Plant Biol. 2004 Jun;31(5):429-439. doi: 10.1071/FP03194.
Convergence in leaf traits across biomes demonstrates generality in plant functioning. Relationships between hydraulic architecture and photosynthesis are less well studied. We investigated convergence in minimum leaf water potential (Ψ), conductivity per sapwood area (k), Huber value (Hv) and xylem embolism and photosynthesis in four habitats across two seasons (summer and winter) in the Sydney region in heathland, woodland (ridge-top), woodland (below-ridge) and mangrove. Seasonality strongly influenced all parameters in all habitats. Winter Ψ values were lower than those for summer in the heathland and both woodland habitats but summer Ψ values were lower than those for winter in the mangrove. Summer k values were higher than winter values in all habitats, while Hv was higher in winter than summer for all habitats. Loss of conductance due to xylem embolism was larger in summer than winter in eight of 11 species. We also investigated relationships between the hydraulic parameters across habitats. There was a strong, significant inverse correlation between log-transformed Hv and log-transformed k, which held across the seasons. There were significant inverse correlations between Ψ and xylem embolism, which held within seasons but not across seasons. We found a strong, significant positive correlation between k and Ψ also within seasons but not across seasons and a significant negative correlation between xylem embolism and k for winter but only a weak negative correlation between xylem embolism and k for summer. We believe the seasonal patterns and relationships in hydraulic architecture and water relations are driven by the cost of efficient sapwood. This is demonstrated by the negative correlation between photosynthetic rate and k in winter.
不同生物群落叶片性状的趋同表明了植物功能的普遍性。关于水力结构与光合作用之间的关系，研究较少。我们调查了悉尼地区石南灌丛、林地（山脊顶部）、林地（山脊下方）和红树林这四个栖息地在两个季节（夏季和冬季）的最小叶片水势（Ψ）、边材面积比导率（k）、胡伯值（Hv）、木质部栓塞和光合作用的趋同情况。季节性对所有栖息地的所有参数都有强烈影响。在石南灌丛和两个林地栖息地中，冬季的Ψ值低于夏季，但在红树林中，夏季的Ψ值低于冬季。在所有栖息地中，夏季的k值高于冬季，而所有栖息地冬季的Hv均高于夏季。在11个物种中的8个物种中，木质部栓塞导致的导度损失在夏季大于冬季。我们还研究了不同栖息地水力参数之间的关系。经对数转换后的Hv与经对数转换后的k之间存在强烈且显著的负相关，且这种关系在各个季节均成立。Ψ与木质部栓塞之间存在显著的负相关，这种关系在季节内成立，但在不同季节间不成立。我们还发现，k与Ψ在季节内也存在强烈且显著的正相关，但在不同季节间不成立；木质部栓塞与k在冬季存在显著的负相关，但在夏季，木质部栓塞与k仅存在微弱的负相关。我们认为，水力结构和水分关系的季节性模式及关系是由高效边材的成本驱动的。这在冬季光合速率与k的负相关中得到了体现。
