Excess nitrogen affects the frost sensitivity of the inner bark of Norway spruce

Abstract

-The sensitivity to frost in the living inner bark of trees have been hypothesised to be influenced by acid rain and N deposition through changes in nutrient balance and carbon metabolism. At the Skogaby experimental site, situated in southern Sweden, Norway spruce in control plots, plots fertilized with ammonium sulphate and plots fertilized with mineral nutrients except N were compared in this respect. Frost sensitivity was measured by electrolytic leakage and expressed as an index of injury. The results showed increased sensitivity to frost in the bark of trees treated with continuous applications of ammonium sulphate for 11 years. This was probably not only a direct effect of high nitrogen availability, but also caused by insufficient levels of other nutrients due to the rapid growth and changes in soil chemistry induced by the addition of ammonium sulphate. Mainly Mg and K seemed to be of importance for retaining a good frost resistance, supporting the hypothesis that nutrient imbalances increases the risk for development of frost related bark lesions in southern Sweden.carbohydrates / index of injury / nutrient status / Picea abies / Skogaby / stem damage Résumé -Effets d'un excès d'azote sur la sensibilité au froid de l'écorce interne de l'Epicéa. On a émis l'hypothèse selon laquelle la sensibilité au froid de la partie vivante interne de l'écorce des arbres serait influencée par les pluies acides et les dégâts azotés, par suite de changements de l'équilibre d'azote et du métabolisme du carbone. À la station expérimentale de Skogaby, située en Suède méridionale, on a comparé le comportement, sous cet angle, de l'épicéa dans un dispositif comportant des parcelles fertilisées avec divers nutrients à l'exclusion d'azote, ainsi que des parcelles témoins. La sensibilité au froid a été évaluée par des mesures de conductivité électrolitique, et exprimée par un indice de l'importance des dommages observés. Les résultats montrent une sensibilité accrue au froid de l'écorce des arbres traités d'une manière continue pendant 11 ans avec du sulfate d'ammoniac. Cela est probablement dû, non seulement à l'effet direct d'une importante disponibilité en azote, mais aussi à un niveau insuffisant de celle des autres nutrients, cela résultant d'une croissance plus rapide ainsi que de modifications des équilibres chimiques du sol induits par l'apport du sulfate d'ammoniac. Le rôle de Mg et K semble particulièrement important pour assurer une bonne résistance au froid, ce qui appuie l'hypothèse selon laquelle des déséquilibres entre nutrients augmentent le risque de lésions de l'écorce dans le sud de la Suède.hydrates de carbone / indices de dommages / statut de nutrient / Picea abies / Skogaby / dégâts sur les tiges

Tree growth as indicator of tree vitality and of tree reaction to environmental stress: a review

“…Growth of woody tissues may be competing with production of defensive compounds (Baier et al 2002, Waring 1987 and thus increased growth due to change in environmental conditions could mean reduced defence against pathogens or insect attacks. Increased growth due to increased nitrogen depositions may also reduce the frost and drought resistance of trees (Jonsson et al 2004). However, other long-term studies on fertilizer experiments record increased growth and increased indicators of tree vitality in fertilized plots (Wargo et al 2002, Weetman et al 1997, Flu¨ckiger and Braun 1995, Filip et al 1992, Waring et al 1992, Proe et al 1992, Spiecker 1990).…”

Frost sensitivity and nutrient status in a fertilized Norway spruce stand in Denmark

“…Due to the correlation between the concentrations of P and K, it is difficult to attribute the difference in frost sensitivity to either P or K. The frost sensitivity of Norway spruce bark, also measured as an index of injury, has been related to low levels of P, Mg and K in needles and bark (Jönsson et al, 2001;Jönsson et al, 2004). Also low hardiness status of Norway spruce needles has been related to low levels of P and Mg in needles (Jönsson et al, 2001).…”

Tracing the Impact of Adverse Environmental Conditions on the Frost Sensitivity in Trees

“…In field studies, an increased sensitivity to frost of Norway spruce bark has been related to a poor nutrient status (Jönsson et al, 2001;Jönsson et al, 2004a;Jönsson et al, 2004b). Also, the sensitivity to frost in the bark of beech trees has been related to the concentrations of nutrients (Jönsson, 2000b), and connected to the nutrient status of the forest soil (Jönsson, 2000c).…”