Hey all! Here I am to give an update of my project.
As the title suggests, tree coring gives you sore arms. Tree cores and aerial photography dominate my day to day. The cores are telling an interesting story: the forest was disturbed more than once. By analyzing general patterns in the rings, several occasions where increased growth and suppression are obvious. Some of these years directly coincide with known disturbances such as the Hurricane of 1938. However, not all of the events coincide with known disturbances. Whether these events are site-specific or cover the regional area is yet to be told.
Geo-referencing and creating a scale for the 1940’s aerial photography has proven frustrating and quite difficult. After multiple failed attempts at superimposing the gridding system over the aerial photography, I figured out the most appropriate method. Believe it or not, I went old-school and superimposed the grid with an acetate layer. Not only was it easier, but it kept the process simple and eliminated distortion inherent in geo-referenced products. I documented about 710 trees with substantial length – long enough to measure with Vernier calipers. Using the scale produced by geo-referencing the aerial photos, I was able to estimate the length of each tree bole. Using allometric equations based on the dominant species of a northern hardwoods forest, total fallen biomass can also be estimated.
Logging camp somewhere on the north facing slopes. Photo courtesy of C. Cogbill.
DISCLAIMER: I must confess that I never planned on harping down the exact number of fallen biomass and carbon, but rather produce a range of possibility. The methods used produce considerable uncertainty, but when the uncertainty is considered throughout the process, a viable range of possibilities can be produced.
Based on the results I have now, I can confidently state multiple preliminary conclusions.
To begin: there were multiple recorded and multiple unrecorded disturbance events in the study area.
Secondly: The Hurricane of 1938 felled a significant amount of biomass (and carbon), possibly proportional of up to 25% of the previous standing forest.
Thirdly: The 1900-1920 logging event was not particularly severe in the study area.
Four: Don’t core Hemlocks; they’re usually a waste of your time.
Five: Tree size is never an accurate representation of age. If a Spruce is big – core it. If Spruce is small – core it. I recently sanded and counted a 144 year old spruce core, barely reaching 2” in length. If you see a decent Spruce, core it because you never know how old it is.
What happened in Watershed 6? Photo courtesy of C.Cogbill.
Further conclusions will be posted soon.