Tree rings record annual growth and the environment in which the tree has lived now a new study by Cameron Lee and Matthew Dannenberg that employed machine learning shows that air masses surrounding the tree also make a significant impact. Source: Timberbiz
Tree-ring widths depend on the weather a particular tree experiences and are a direct indicator of tree growth and tree health. Often, the relationship between tree rings and weather are described using temperature, precipitation, or drought indices. However, a tree is exposed not just to temperature and/or precipitation alone, but to all weather elements acting together, which can be defined as an air mass.
In this research article titled Frequencies of Multivariate Air Masses Drive Tree Growth, the authors explored how air masses impact tree growth at over 900 locations across the Northern Hemisphere.
They found that tree-ring widths are significantly related to the frequency of certain air masses, especially a Dry and Warm air mass, and a Humid and Cool air mass.
Further, they found that air masses often affect tree growth more strongly than temperature and precipitation alone, up to a year prior to when the tree ring grew. Air mass information could therefore help in forecasting tree/forest health.
Key points in their study were:
- Tree-ring widths are significantly related to variability in air mass frequency (number of daily occurrences) in the year preceding growth
- The air masses that impact tree-ring widths the most are dry, dry-warm, and humid-cool air masses, especially in relatively hot locations
- Air mass models explain more variability in tree-ring widths than models based on temperature and precipitation for most sites and species
The paper can be found at https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022JG007064
