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• 作者：Gauslaa ; Yngvar ; Solhaug ; Knut Asbj&oslash ; rn
• 刊名：Lichenologist
• 出版年：2000
• 出版时间：May, 2000
• 年：2000
• 卷：32
• 期：3
• 页码：271-289
• 全文大小：1.99 M

文摘

Abstract: The annual course of irradiance was recorded at two vertical and even-aged neighbouring Quercus stems, one rich in L. pulmonaria, one without. Irradiance never exceeded 610μmol photons m⁻²s⁻¹at the L. pulmonaria site, whereas the L. pulmonaria -deficient site could experience 2h daily 2000μmol photons m⁻²s⁻¹, and 6h above 1000μmol photons m⁻²s⁻¹during a clear day in early spring. Thalli of L. pulmonaria were transplanted to these two stems. During the first 40 days (April–May), transplants at the L. pulmonaria -deficient site developed severe chlorophyll degradation, and a substantial reduction in maximal PS II efficiency (F_V/F_M) even when measured after a 48-h recovery period at low light intensity. Extensive bleaching was formed along light-exposed sides of the tiny ridges on the upper side. Subsequent to this damage, F_V/F_Mgradually rose to nearly normal levels during the following year. This apparent recovery was probably mainly due to irreversible loss of damaged chlorophyll, but also to some level of acclimation. No damage was observed in control transplants on the L. pulmonaria -rich tree, which were the only transplants gaining sufficient growth for new attachment to the new substratum during the 397-day transplantation period. Nevertheless, a fine-scale, but highly significant seasonal variation in F_V/F_Mof control transplants reflected variations of even low irradiance levels. F_V/F_M, as measured after a 48-h recovery period at low light intensity, is an efficient method for recording permanent high light damages at and shortly after damage is formed. However, F_V/F_Mis not a useful estimator of chronic long-term damage.