Main content area

Effects of simulated herbivory on photosynthesis and N resorption efficiency in Quercus pyrenaica Willd. saplings

Fernando, Silla, Marina, Fleury, Sonia, Mediavilla, Alfonso, Escudero
Trees 2008 v.22 no.6 pp. 785-793
Quercus pyrenaica, carbon, herbivores, insect larvae, leaf area, leaves, net assimilation rate, nitrogen, nitrogen content, photosynthesis, resorption, saplings, senescence
We examined the effects of simulated folivory by caterpillars on photosynthetic parameters and nitrogen (N) resorption efficiency in Quercus pyrenaica saplings. We analyzed the differences between intact leaves in control plants, punched leaves in damaged plants, and intact leaves in damaged plants. We then established two levels of simulated folivory: low ([almost equal to]13% of the leaf area of one main branch removed per plant) and high ([almost equal to]26% of the leaf area of one main branch removed per plant) treatments. No differences were found in net assimilation rate and conductance between either leaf type or treatment during the most favourable period for photosynthesis. However, the N content was lower in punched than in intact leaves, and as a result PNUE was higher in damaged leaves from treated trees. In leaf-litter samples, N mass was significantly higher in punched than in intact leaves in treated plants, and LMA was significantly higher in damaged than in intact leaves of both the treated and control plants. Consequently, N resorption efficiency was around 15% lower in damaged leaves as compared with intact leaves from treated and control plants. Mechanical injury to leaves not only triggered no compensatory photosynthetic response to compensate a lower carbon uptake due to leaf area loss, but also affected the resorption process that characterizes leaf senescence.