Back Bay Forest Weather Response

This is the dune trail, located close to the visitor center. The dunes provide a dynamic habitat that is greatly affected by tides, wind, and salt spray from the ocean. This area is also susceptible to drought.

We use increment borers to obtain tree core samples. This safely extracts a small sample from the tree without causing any harm.

Using the National weather service data we compared historic precipitation trends to the growth of the specific trees found in this ecosystem.

The blue pins represent live oaks and the green represent loblolly pines.

This is a photograph of a year of growth in a live oak tree. The circles in the photo are the xylem structure. Xylem are hollow tube spaces that allow water to flow up a tree. There is research that states that live oaks are one of the most difficult trees to study. This is because they don't have tree rings at all but rather a density change in the xylem structure.

There is an obvious difference between the two species of trees found in this ecosystem. The pine has brown and yellow patterning that is distinguishable tree ring growth. The live oak has very subtle changes in xylem density which are difficult to see even under a microscope. Both trees can be used for dendrochronology research but this species of pine is more commonly used because they are easier to read.

5-PDT is a loblolly pine with a diameter of 12 inches. The sample collected dates back to 1984. Using the historical weather data, we compared the rate of growth to the amount of precipitation in that year.

2004, 2008, and 2018 are all years where there was a significant drop in the trees growth as well as the precipitation rate for that year.

In 1984, 1993, and 1990, there were spikes in growth this correlates with the historic weather data. This indicates that there was more precipitation in those years allowing the tree to grow.

1-LODT is a loblolly pine with a diameter of 14 inches. The sample collected dates back to 1992. Using the historical weather data we compared the rate of growth to the amount of precipitation in that year.

1992 , 1994, 2004 and 2010 are years where there are spikes in this tree's growth. These spikes relate back to how there was more precipitation in those years according to the National Weather Service data.

1996, 2000, 2004 and 2006 are all years where there was less rainfall from the historic data and less growth shown in this live oak.

Now we will investigate the second study site; the green hills, located on the south end of Back Bay National Wildlife Refuge.

This is the Green Hills study site 2, located located on the west dike near A Pool. The Maritime Forest provides a habitat that is inland and on the bay side of the barrier island.

The growth compared to the weather data may be varied by a few years due to the challenges of reading the samples of live oaks with no growth rings and pines that have false rings. More research can be done to verify these findings.

False rings occur in Loblolly pines and some other tree species but not all. They can form when there is an abrupt change in weather. These false rings if misidentified can interfere with data collection.

7-LOMF is a live oak with a diameter of 14 inches. The sample collected dates back to 1963.

In years 1963, 1996 and 2009, there were spikes in the live oaks growth along with more precipitation recorded in those years.

In years 1970 and 1976, there were drops in rate of tree growth. This correlates with less precipitation recorded in those years from the National Weather Service.

2-PMF is a live oak with a diameter of 21.5 inches. The sample collected dates back to 1965.

1967, 1983 and 2017 are years where there were spikes in this pines growth with more precipitation recorded in those years.

1969, 2005 and 2008 are years when there were drops in the rate of tree growth. This correlates with less precipitation recorded in those years from the National Weather Service.

In this study we also wanted to include a comparison between the two species, but found there was little to no difference in how the loblolly pines and live oaks respond to different levels of precipitation.