Báo cáo khoa học: The decline of a Pinus nigra Arn. reforestation stand on a limestone substrate: the role of nutritional factors examined by means of foliar diagnosis

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Báo cáo khoa học: "The decline of a Pinus nigra Arn. reforestation stand on a limestone substrate: the role of nutritional factors examined by means of foliar diagnosis" Original articleThe decline of a Pinus nigra Arn. reforestation stand on a limestone substrate: the role of nutritional factors examined by means of foliar diagnosis Enrico Cenni, Filippo Bussotti Lorenzo Galeotti Laboratory of Applied and Forest Botany, Department of Plant Biology, University of Florence, Piazzale delle Cascine 28, I 50144 Florence, Italy (Received 6 June 1997; accepted 26 November 1997)Abstract - The Austrian black pine reforestation projects on Monte Morello, near the heavily pop-ulated metropolitan area of Florence (Italy), have been affected for many years now by a severedecline consisting of widespread crown yellowing. To investigate the causes of this declinefoliar diagnosis methods were used to monitor the nutritional status of ten trees, sampling andanalysing every year, between 1989 and 1992, the current year needles (c), needles from theprevious year (c+ I) and from the year before that (c+2). The parameters examined were both chem-ical (nitrogen, sulphur, magnesium, potassium, calcium, manganese, iron and lead) and mor-phological (needle length, flat projection, dry weight, specific dry weight and water content). Thefindings show a considerable calcium accumulation as the needles age, accompanied by anincrease in dry weight and specific dry weight, as well as a marked antagonism to manganese. Theinfluence of the nearby metropolitan area of Florence is suggested by the accumulation of lead.(© Inra/Elsevier, Paris)afforestation / calcium / iron / leaf / manganese / Pinus / nigra subsp. nigra senescencechlorosisRésumé - Le dépérissement des reboisements de Pinus nigra Arn. sur substrat calcaire ; lerôle des facteurs nutritionnels étudiés à l’aide du diagnostic foliaire. Les reboisements de pinnoir d’Autriche dans le Monte Morello, près de l’importante zone urbaine de Florence (Italie) sontaffectés depuis maintenant plusieurs années d’un sévère dépérissement consistant en un jaunis-sement très fréquent des couronnes. Pour étudier les causes de ce dépérissement, des méthodesd’analyse foliaire ont été utilisées pour suivre l’état nutritionnel de dix arbres échantillonnés etanalysés chaque année entre 1989 et 1992, en prenant en compte les aiguilles de l’année (c), lesaiguilles de l’année précédente (c+1) et les aiguilles âgées de 2 ans (c+2). Les paramètres étudiésétaient chimiques (azote, soufre, magnésium, potassium, calcium, manganèse, fer, plomb) mor-* Correspondence and reprintsE-mail: fbussotti@cesitl.unifi.itphologiques (longueur des aiguilles, surface projetée, poids sec spécifique et teneur en eau). Lesrésultats montrent une accumulation considérable de calcium avec l’âge des aiguilles accompa-gnée par un accroissement du poids sec et du poids spécifique, ainsi qu’un antagonisme marquédu manganèse. L’influence de l’agglomération voisine de Florence est suggérée par l’accumulationde plomb. (© Inra/Elsevier, Paris)reboisement / calcium / fer / sénescence foliaire / manganèse / Pinus nigra subsp. Nigra /chlorose located in1. INTRODUCTION urbanized densely they are a (more than1 million inhabitants). area Thus, any conclusions drawn as to their In the first half of this century, several ecological stability or instability could bespecies of conifers were widely used in a valid contribution in guiding the deci-Italy to reforest areas where the sions of the city’s administrators on theautochthonous forest vegetation normally fate and management of these stands.consists of broadleaved trees. The purposeof these reforestation projects was usuallyeither timber production or hydrogeolog-ical protection. Pinus nigra Am., with all 2. MATERIALS AND METHODSits various subspecies, thanks to itsremarkable ecological flexibility, was one 2 ...