Deodar Tree Rings Reveal 378-Year Climate Shift and Rising Geohazards in Himachal Pradesh

Deodar trees (Cedrus deodara) in Batseri, Kinnaur (Himachal Pradesh) show a long-term shift from wetter spring conditions during the Little Ice Age (LIA) to progressively drier conditions after 1757 CE.

• Recent decades show a rise in spring drought years, captured in the narrowing or altered growth rings.

Reconstructing 378 Years of Moisture History

• Tree-ring analysis has enabled scientists to reconstruct:
  • A 378-year record (1558–2021 CE) of spring moisture conditions.
  • A 168-year record (1853–2021 CE) of rockfall activity in the region.
• This makes the Batseri dataset one of the most detailed natural archives for western Himalayan climate variability.

Tree Rings as Natural Archives

• Tree rings are yearly growth layers formed in the trunk.
• They provide clues about:
  • Tree age
  • Past climatic conditions such as rainfall and drought
  • Historical geohazard events like rockfalls, landslides, and extreme weather
• Tree-ring analysis (dendrochronology) is widely used, including by archaeologists to estimate construction dates of ancient structures using timber patterns.

Role of Western Disturbances

• Tree growth in Batseri is particularly sensitive to spring moisture (February–April).
• This moisture largely depends on winter precipitation brought by Western Disturbances (WDs).
• Variability in WDs significantly impacts:
  • Drought frequency
  • Snow accumulation
  • Soil moisture
  • Vegetation growth

Climate Variability and Geohazards

• Findings show strong links between regional/global climate fluctuations and rockfall activity, which has intensified due to drying conditions.
• This highlights the increasing vulnerability of Himalayan regions to:
  • Rockfalls
  • Landslides
  • Slope instability

Need for Early Warning and Forest Management

• Study underscores the importance of:
  • Monitoring forest ecosystems
  • Strengthening early warning systems for geohazards
  • Integrated disaster risk management
• Understanding long-term climate patterns helps improve prediction of future hazard events.

Sources: PIB & NOAA