Fleck Isabel, Grau Daniel, Sanjosé Magí, Vidal Dolors
Unitat de Fisiologia Vegetal, Departament de Biologia Vegetal, Facultat de Biologia, Universitat de Barcelona, Diagonal 645, 08028, Barcelona, Spain.
Oecologia. 1996 Feb;105(3):286-292. doi: 10.1007/BF00328730.
Ecophysiological differences related to photosynthesis were compared in holm oak Quercus ilex leaves from undisturbed holm-oak vegetation, resprouts after fire and resprouts after tree-fell. No significant differences in any parameter measured were observed between the two kinds of resprout throughout the first growing season following disturbance. Resprouting leaves showed lower carbon isotope discrimination (Δ) and intercellular CO concentration (p ), and higher photosynthesis, leaf conductance and transpiration rates than leaves from undisturbed stands. Nitrogen, soluble protein content and ribulose bisphosphate carboxylase (RuBPCase) activity were 88%, 96% and 45% higher respectively, in both kinds of resprout. The results indicate that photosynthetic capacity, rather than stomatal conductance, is the limiting factor in photosynthesis in resprouts, Chlorophyll content and chlorophyll a/b ratio did not differ between resprouts and undisturbed leaves, indicating that the observed differences were not a result of differences in light environment during leaf development. Leaf mass per area (LMA), was 80% higher in the resprouts, and was negatively related (r=-0.86) to Δ and positively related (r=0.87) to N content. Enhanced carbon assimilation after disturbances resulted in higher water use efficiency, as indicated by lower Δ values in the resprouts. We conclude that the cause of defoliation was not relevant in the physiology of the resprouts, suggesting the importance of underground organs.
对来自未受干扰的圣栎植被、火灾后萌生苗以及树木砍伐后萌生苗的圣栎（Quercus ilex）叶片中与光合作用相关的生理生态差异进行了比较。在干扰后的第一个生长季节，两种萌生苗在任何测量参数上均未观察到显著差异。与未受干扰林分的叶片相比，萌生叶片的碳同位素分馏（Δ）和胞间CO₂浓度（p）较低，而光合作用、叶片导度和蒸腾速率较高。两种萌生苗中的氮、可溶性蛋白质含量和核酮糖二磷酸羧化酶（RuBPCase）活性分别高出88%、96%和45%。结果表明，光合能力而非气孔导度是萌生苗光合作用的限制因素。萌生苗和未受干扰叶片之间的叶绿素含量和叶绿素a/b比值没有差异，这表明观察到的差异不是叶片发育期间光照环境差异的结果。萌生苗的单位叶面积质量（LMA）高出80%，并且与Δ呈负相关（r = -0.86），与氮含量呈正相关（r = 0.87）。如萌生苗中较低的Δ值所示，干扰后增强的碳同化导致了更高的水分利用效率。我们得出结论，落叶的原因与萌生苗的生理无关，这表明地下器官的重要性。
