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Gori Y.,FEM IASMA Edmund Machinery Foundation | Camin F.,FEM IASMA Edmund Machinery Foundation | Porta N.L.,FEM IASMA Edmund Machinery Foundation | Carrer M.,University of Padua | Battisti A.,University of Padua
Forest Ecology and Management | Year: 2014

This paper focuses on carbon and oxygen stable isotopes in conjunction with tree-ring chronologies to investigate the short- and long-term effects of the spruce web-spinning sawfly Cephalcia arvensis Panzer defoliation on Picea abies. We found massive growth loss and significantly different carbon and oxygen stable isotope patterns associated with insect feeding; while carbon isotope values increased, oxygen isotope values decreased in the defoliated trees. We also observed a difference in isotope composition between defoliated and control trees prior to the defoliation, indicating that some abiotic factors may have predisposed the trees to the insect attack. With respect to isotope theory, carbon and oxygen isotope patterns could be explained by both an increase in photosynthetic rate and a resort to starch reserves following insect feeding. Overall, these findings contribute to our understanding of how trees respond to insect attack. © 2014 Elsevier B.V. Source

Gori Y.,FEM IASMA Edmund Machinery Foundation | Cherubini P.,Swiss Federal Institute of forest | Camin F.,FEM IASMA Edmund Machinery Foundation | La Porta N.,FEM IASMA Edmund Machinery Foundation
European Journal of Forest Research | Year: 2013

Tree-ring patterns of Picea abies (L.) Karst. both unaffected and affected by Heterobasidion parviporum were analysed in three mature stands located at different elevations in the Eastern Alps. The main objectives were (1) to clarify the role of climatic conditions on infected trees; (2) to estimate indirect volume losses due to the prolonged presence of the fungus within the wood. The low elevation site showed the highest growth decline in the last decade, whereas all infected trees at medium and high elevation showed a slow growth decline over many decades. We hypothesise that infection could be dated over 80 years at the highest site. Fungal attack made P. abies more susceptible to drought stress at low elevation site. Both infected and healthy P. abies at medium and high elevation showed similar climate-growth relationships, suggesting that the same driving environmental factors influence their growth. At low elevation, H. parviporum was seemingly more aggressive, causing a more rapid decline, decreasing the ability of host trees to cope with drought and, in some cases, inducing cambial activity to stop. P. abies at higher elevation, however, exhibited a very slow decline and no sign of increasing water stress since the influence of climate on tree growth was the same for both infected and healthy trees. © 2013 Springer-Verlag Berlin Heidelberg. Source

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