Marcescence and senescence in a submediterranean oak (Quercus subpyrenaica E.H. del Villar): photosynthetic characteristics and nutrient composition |
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Authors: | A. ABADí A,E. GIL,F. MORALES,L. MONTAÑ É S,G. MONTSERRAT,J. ABADÍ A |
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Affiliation: | Departamento de Nutrición Vegetal, Estación Experimental de Aula Dei, Consejo Superior de Investigaciones Científicas (C.S.I. C.), Apdo 202, 50080 Zaragoza. Spain;Unit of Forest Resources, Servicio de Investigación Agroalimentaria-Diputación General de Aragón, Apdo 727, 50080 Zaragoza, Spain;Department of Functional Ecology and Biodiversity, Instituto Pirenaico de Ecología, Consejo Superior de Investigaciones Científicas (C.S. I. C.), Apdo 202, 50080 Zaragoza, Spain |
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Abstract: | We have studied some characteristics of marcescent leaves (withered retained leaves) and senescent leaves in Quercus subpyrenaica, a tree species that plays a major role in the climatic transition forests between temperate and mediterranean environments in north-eastern Spain. Leaves were taken from the upper and lower halves of the tree crown, both in the south- and north-exposed parts of the tree. Leaves receiving low photosynthetic photon flux density (PPFD) undergo autumnal senescence, which is associated with decreases in photosynthetic pigments and decreases in the chlorophyll a to chlorophyll b ratio. Leaves receiving higher PPFD underwent senescence at a later date. Leaves situated in the upper, south-exposed part of the tree, which receive the highest PPFD, showed no signs of senescence and remained photosynthetically active for a longer period of time, marcescence occurring suddenly at the end of the season. Marcescence is unlikely to cause an improvement in nutrient recycling, since the removal of nutrients proceeded similarly in marcescent and senescent leaves. Marcescence may increase the time-span of the assimilation capacity for a significant period of time during September and October, when high light intensities and mild temperatures occur. The phenomena triggering marcescence may be related to low temperatures. |
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Keywords: | Quercus subpyrenaica chlorophyll fluorescence marcescence nutrition oak photosynthetic pigments senescence |
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