The potential for using Larix decidua ring widths in reconstructions of larch budmoth (Zeiraphera diniana) outbreak history: dendrochronological estimates compared with insect surveys.
Authors:  C. Rolland ⁽¹⁾, W. Baltensweiler ⁽²⁾, V. Petitcolas.

• TITRE: Utilisation des largeurs des cernes de croissance du Mélèze (Larix decidua) pour reconstruire l'historique des attaques de la Tordeuse grise du mélèze (Zeiraphera diniana): comparaison d'une reconstruction dendrochronologique avec un suivi des populations d'insectes.
• LANGUAGE English
• SPECIES Larix decidua, Picea abies, Pinus cembra, Zeiraphera diniana
• SITES French Alps (Briançonnais, tarentaise, Maurienne)
• ABSTRACT

	Trees - Structure and Function  Publisher: Springer-Verlag Heidelberg ISSN: 0931-1890 (Paper) 1432-2285 (Online) DOI: 10.1007/s004680100116 Full text of this article here (for subscribers).
	Issue: Volume 15, Number 7 Date:  October 2001 - Pages: 414 - 424

ABSTRACT:   In the Alps, larch (Larix decidua Mill.) forests show periodic discolouration due to larch budmoth (LBM) outbreaks (Zeiraphera diniana Guénée, Lepidoptera: Tortricidae). Tree defoliation causes severe reductions in radial growth, visible in tree rings. This paper aims at reconstructing LBM outbreak history, and critically examining the potential for using dendrochronological data by comparing tree-ring estimates with insect surveys. The occurrence of LBM outbreaks was investigated using 249 cores from larch growing near the timberline in three regions of the French Alps (Briançonnais, Maurienne, and Tarentaise). Years with an abrupt decrease in radial growth (-40%) were considered as negative pointer years reflecting the potential impact of LBM. The comparison with three non-host conifers (Norway spruce, stone and mountain pines) permitted us to distinguish growth reductions in larch due to climatic effects from those due to defoliation by LBM. The dendrochronological data were matched with information reporting conspicuous discolouration in old forestry reports or recovered from systematic field observations. Twenty-two outbreaks are discernible within the period 1800-1983. A peak reduction in larch growth occurred at intervals of 8.86-1.01 years in the following years: 1801, 1811, 1820, 1830, 1838, 1846, 1857, 1867, 1875, 1884, 1892, 1901, 1909, 1918, 1926, 1936, 1945, 1953, 1963, 1972, 1980, and 1987. Our objective method based on ring measurements and comparison with non-host trees was compared with qualitative techniques based on the visual detection of conspicuous latewood anomalies. Larch in the Briançonnais (which experiences a continental climate) are infested first, whereas the Tarentaise region exhibits a much weaker impact of LBM. Complete tree recovery was observable 3 years after outbreak peaks.

KEYWORSD: Dendroecology, European larch, Picea abies (L.) Karst, Pinus uncinata Mill ex Mirb., Pinus cembra L.

CONTACT:

⁽¹⁾ Laboratoire des Ecosystèmes Alpins, Centre de Biologie Alpine, B.P. 53 X, 38041 Grenoble Cedex 9, France
⁽²⁾ Blumenbergstrasse 9, 8634 Hombrechtikon, Switzerland.