Methodology
What was the new methodology they tested? (Hint: p.1561)
They used the difference in radial growth between male and female trees to determine masting years because male and female trees will allocate more energy to cone production and less to growth at different times.
What masting theory did these results support? (Hint: p. 1567)
The widespread and synchronous reproduction of A. araucana occurs as episodic events of mass seed production followed by periods of low production.
How often does the ENSO occur? (Hint: p. 1567)
Every 3-5 years but with high variability especially considering the changing climate.
Why does their methodology allow them to study a long time range? (Hint: p. 1566)
Using the difference in radial growth between male and female trees decreases confounding variables compared to just using radial growth, so the increased precision allowed them to quantify a wider time range.
Why might plants want to synchronize their reproduction? (Hint: p. 1561)
Synchronized reproduction aids plant fitness through increased pollination efficiency and through the alternating populations of seed consumers with the masting events that enable mass seed establishment.
What does a positive SAM phase mean? (Hint: p. 1567)
A positive phase is when the belt of westerly winds contracts towards Antarctica which results in less intense western winds, higher pressure, and overall less rainfall/increased drought.
What does radial growth tell us about cone production? (Hint: p.1561)
If trees have less radial growth one year, it means they spent energy on other processes, which can include cone production.
Why are these trees synchronizing cone growth in dry years? (Hint: p. 1567)
Trees that produce larger seeds/cone sets during these dry years will have better offspring survival during the wetter El Nino cycle. Trees that produced cones this way were selected through this process which caused such widespread synchrony.
What is hypothesized about future SAM trends given current and projected climate conditions? (Hint: page 1568)
With increased greenhouse gases and the healing of the ozone layer, the positive phases of the SAM will be accelerated, proliferating its resulting climate impacts.