Three centuries of insect outbreaks across the European Alps.
Knowledge of the persistence of regular larch budmoth outbreaks is limited in space and time. Although dendrochronological methods have been used to reconstruct insect outbreaks, their presence may be obscured by climatic influences. More than 5000 tree-ring series from 70 larch host and 73 spruce nonhost sites within the European Alps and Tatra Mountains were compiled. Site-specific assessment of growth-climate responses and the application of six larch budmoth detection methods considering host, nonhost and instrumental time-series revealed spatiotemporal patterns of insect defoliation across the Alpine arc. Annual maps of reconstructed defoliation showed historical persistence of cyclic outbreaks at the site level, recurring c. every 8-9 yr. Larch budmoth outbreaks occurred independently of rising temperatures from the Little Ice Age until recent warmth. Although no collapse in outbreak periodicity was recorded at the local scale, synchronized Alpine-wide defoliation has ceased during recent decades. Our study demonstrates the persistence of recurring insect outbreaks during AD 1700-2000 and emphasizes that a widely distributed tree-ring network and novel analysis methods can contribute towards an understanding of the changes in outbreak amplitude, synchrony and climate dependence.
Büntgen
Ulf
U
Swiss Federal Research Institute WSL, Zürcherstrasse 111, 8903 Birmensdorf, Switzerland.
Frank
David
D
Swiss Federal Research Institute WSL, Zürcherstrasse 111, 8903 Birmensdorf, Switzerland.
Liebhold
Andrew
A
Northern Research Station, USDA Forest Service, 180 Canfield St, Morgantown, WV 26505, USA.
Johnson
Derek
D
University of Louisiana, PO Box 42451, Lafayette, LA 70504, USA.
Carrer
Marco
M
Università degli Studi di Padova, Dip. TeSAF, Treeline Ecology Research Unit, Agripolis, 35020 Legnaro (PD), Italy.
Urbinati
Carlo
C
Università Politecnica delle Marche, SAPROV, Forest Ecology and Management, Via Brecce Bianche, 60131 Ancona, Italy.
Grabner
Michael
M
BOKU, University of Natural Resources and Applied Life Sciences, Gregor-Mendel-Str. 33, 1180 Vienna, Austria.
Nicolussi
Kurt
K
Institute for High Mountain Research, Innrain 52, 6020 Innsbruck, Austria.
Levanic
Tom
T
Slovenian Forestry Institute, Vecna pot 2, 1000 Ljubljana, Slovenia.
Esper
Jan
J
Swiss Federal Research Institute WSL, Zürcherstrasse 111, 8903 Birmensdorf, Switzerland.
D000818:Animals; D002980:Climate; D017753:Ecosystem; D005060:Europe; D005843:Geography; D028221:Larix / Q000469:parasitology*; D009036:Moths / Q000502:physiology*; D028222:Picea / Q000469:parasitology*; D013057:Spectrum Analysis; D013696:Temperature; D013997:Time Factors