Celebrating 20 Years of Forest Watch
FOREST WATCH has made a number of important scientific findings over the past 20 years. Both student biometric data and the spectral tree-health indices document the following:
- White pines respond to summertime (growing season) variations in ozone levels, which vary from year to year.
- Needle health (based on chlorophyll content and moisture levels) is inversely correlated with growing season ozone levels: White pine health is good if ozone levels are low during a growing season. White pine health is poor if needles are exposed to high ozone levels during a growing season.
- Trees growing at coastal locations exhibit poorer health than trees growing inland. Levels of ground-level ozone are higher along the coast and lower inland.
- In the early to mid-1990s (1991-1996) white pine needle health overall was poor, but improved dramatically between 1997 and 1999, corresponding to a significant drop in ozone levels over the same time period (1997-1999);
- Since 2000, needle health has been generally very good, a time period in which regional ozone levels have been significantly lower than the time period from 1991-1996.
What causes the improvement in white pine health?
What causes the decline in ozone levels?
One hypothesis is that air quality is better thanks to the Clean Air Act Amendment of 1990.
There may have been a shift in air and/or ocean circulation patterns over the Gulf of Maine, carrying ozone away from New England.
Is the work of Forest Watch done? No!
Teachers and students are eagerly awaiting Spring 2011 measurements in which they will try to find an explanation for a curious loss of two-year-old needles early in the 2010 growing season. Our UNH Extension foresters believe the needle cast was caused by fungi. Here in the Forest Watch laboratory, we suspect a new atmospheric pollutant, peroxylacetyl nitrate (PAN). Check back for more information as Forest Watch students help with future research on this.