School of Plant Science, University of Tasmania, Hobart, Tasmania 7001, Australia.
Tree Physiol. 2010 Aug;30(8):957-68. doi: 10.1093/treephys/tpq057. Epub 2010 Jul 2.
We examined spatial and temporal dynamics of foliage respiration in canopies of dominant and suppressed Eucalyptus globulus trees to better understand processes regulating foliage respiration in a young fast-growing stand. Temperature response functions and seasonal measures of respiration (measured at a reference temperature of 15 °C, R₁₅) were studied for approximately 1 year to (i) examine controls on respiration as a function of canopy position, foliar nitrogen and non-structural carbohydrate concentrations and (ii) assess the capacity for thermal acclimation within E. globulus canopies. The short-term temperature response of respiration varied both with canopy position and seasonally. Area-based R(15) measurements declined with increasing canopy depth and were strongly related to foliar N concentrations, especially in upper-canopy positions. R₁₅ was negatively correlated with the average temperature of the preceding 14 days, a pattern consistent with thermal acclimation. In suppressed canopies, R₁₅ was higher than that at similar canopy heights in dominant trees. Similarly, foliar concentrations of non-structural carbohydrates were also relatively higher in suppressed canopies than dominant canopies, providing support for a substrate-based model of leaf respiration. Our data highlight the dynamic nature of foliar respiration within E. globulus canopies, which contrasts with the generally simplistic representation of respiration within most process-based models.
我们研究了主导和抑制桉树树冠中叶片呼吸的时空动态，以更好地了解在快速生长的年轻林分中调节叶片呼吸的过程。我们研究了约 1 年的时间来研究温度响应函数和呼吸的季节性测量值（在 15°C 的参考温度下测量，R₁₅），以（i）检查树冠位置、叶片氮和非结构性碳水化合物浓度对呼吸的控制作用，以及（ii）评估桉树树冠内的热适应能力。呼吸的短期温度响应随树冠位置和季节而变化。基于面积的 R(15)测量值随树冠深度的增加而下降，与叶片 N 浓度密切相关，尤其是在上层树冠位置。R₁₅与前 14 天的平均温度呈负相关，这与热适应一致。在抑制性树冠中，R₁₅高于主导树木中相似树冠高度的 R₁₅。同样，非结构性碳水化合物在抑制性树冠中的叶片浓度也相对高于主导树冠，为叶片呼吸的基于基质的模型提供了支持。我们的数据突出了桉树树冠内叶片呼吸的动态性质，这与大多数基于过程的模型中普遍存在的简单呼吸表示形成对比。
