Tree-ring proxies of larch bud moth defoliation: latewood width and blue intensity are more precise than tree-ring width.

Arbellay E; Jarvis I; Chavardès RD; Daniels LD; Stoffel M

doi:10.1093/treephys/tpy057

Back

Journal article

Tree-ring proxies of larch bud moth defoliation: latewood width and blue intensity are more precise than tree-ring width.

Arbellay E Tree-Ring Lab, Department of Forest and Conservation Sciences, University of British Columbia, 3041-2424 Main Mall, Vancouver, BC, Canada.
Jarvis I Tree-Ring Lab, Department of Forest and Conservation Sciences, University of British Columbia, 3041-2424 Main Mall, Vancouver, BC, Canada.
Chavardès RD Tree-Ring Lab, Department of Forest and Conservation Sciences, University of British Columbia, 3041-2424 Main Mall, Vancouver, BC, Canada.
Daniels LD Tree-Ring Lab, Department of Forest and Conservation Sciences, University of British Columbia, 3041-2424 Main Mall, Vancouver, BC, Canada.
Stoffel M Climatic Change and Climate Impacts, Institute for Environmental Sciences, University of Geneva, Boulevard Carl-Vogt 66, Geneva, Switzerland.

2018-05-23

Published in:

Tree physiology. - 2018

English Reconstructions of defoliation by larch bud moth (LBM, Zeiraphera diniana Gn.) based on European larch (Larix decidua Mill.) tree rings have unraveled outbreak patterns over exceptional temporal and spatial scales. In this study, we conducted tree-ring analyses on 105 increment cores of European larch from the Valais Alps, Switzerland. The well-documented history of LBM outbreaks in Valais provided a solid baseline for evaluating the LBM defoliation signal in multiple tree-ring parameters. First, we used tree-ring width measurements along with regional records of LBM outbreaks to reconstruct the occurrence of these events at two sites within the Swiss Alps. Second, we measured earlywood width, latewood width and blue intensity, and compared these parameters with tree-ring width to assess the capacity of each proxy to detect LBM defoliation. A total of six LBM outbreaks were reconstructed for the two sites between AD 1850 and 2000. Growth suppression induced by LBM was, on average, highest in latewood width (59%), followed by total ring width (54%), earlywood width (51%) and blue intensity (26%). We show that latewood width and blue intensity can improve the temporal accuracy of LBM outbreak reconstructions, as both proxies systematically detected LBM defoliation in the first year it occurred, as well as the differentiation between defoliation and non-defoliation years. This study introduces blue intensity as a promising new proxy of insect defoliation and encourages its use in conjunction with latewood width.

Language