Publication details
Tree-ring isotopes from the Swiss Alps reveal non-climatic fingerprints of cyclic insect population outbreaks over the past 700 years
| Authors | |
|---|---|
| Year of publication | 2023 |
| Type | Article in Periodical |
| Magazine / Source | Tree Physiology |
| MU Faculty or unit | |
| Citation | |
| Web | https://doi.org/10.1093/treephys/tpad014 |
| Doi | http://dx.doi.org/10.1093/treephys/tpad014 |
| Keywords | dendroecology; deuterium; ecophysiology; insect defoliation; insect outbreak; plant-pathogen interaction; stable isotope; tree physiology; tree-ring cellulose; Zeiraphera griseana |
| Description | Recent experiments have underlined the potential of delta H-2 in tree-ring cellulose as a physiological indicator of shifts in autotrophic versus heterotrophic processes (i.e., the use of fresh versus stored non-structural carbohydrates). However, the impact of these processes has not yet been quantified under natural conditions. Defoliator outbreaks disrupt tree functioning and carbon assimilation, stimulating remobilization, therefore providing a unique opportunity to improve our understanding of changes in delta H-2. By exploring a 700-year tree-ring isotope chronology from Switzerland, we assessed the impact of 79 larch budmoth (LBM, Zeiraphera griseana [Hubner]) outbreaks on the growth of its host tree species, Larix decidua [Mill]. The LBM outbreaks significantly altered the tree-ring isotopic signature, creating a H-2-enrichment and an O-18- and C-13-depletion. Changes in tree physiological functioning in outbreak years are shown by the decoupling of delta H-2 and delta O-18 (O-H relationship), in contrast to the positive correlation in non-outbreak years. Across the centuries, the O-H relationship in outbreak years was not significantly affected by temperature, indicating that non-climatic physiological processes dominate over climate in determining delta H-2. We conclude that the combination of these isotopic parameters can serve as a metric for assessing changes in physiological mechanisms over time. |