A Holocene landscape dynamic multiproxy reconstruction: How do interactions between fire and insect outbreaks shape...

Area of Science:

• Paleoecology
• Forest Ecology
• Entomology

Background:

• Boreal forests are shaped by disturbances like fire and insect outbreaks.
• Long-term dynamics of spruce budworm (Choristoneura fumiferana (Clem.)) (SBW) and its interaction with fire are poorly understood.
• Traditional proxies for insect outbreaks have limitations.

Observation:

• A new proxy, lepidopteran scales, was used alongside macrocharcoal and plant macrofossils to reconstruct Holocene ecology.
• Lepidopteran scales proved more robust than traditional proxies for detecting insect outbreaks.
• 87 significant peaks in scale abundance were identified over the last 10,000 years.

Findings:

• SBW outbreaks occurred more frequently throughout the Holocene than previously estimated.
• Fire history showed a more fire-prone early and late Holocene, with reduced fire frequency in the mid-Holocene.
• A generally inverse relationship was observed between fire frequency and insect outbreaks over the Holocene.

Implications:

• This study provides a more comprehensive understanding of long-term boreal forest dynamics.
• The findings highlight the complex interplay between different disturbance regimes in shaping forest ecosystems.
• The robustness of lepidopteran scales as a proxy opens new avenues for paleoecological research.