A Day in the Field
Today was a day of data collection--a long day of data collection in a 16-hectare plot. Basically, it's easy to do, but time consuming. First you go to the designated place in the grid of markers. In the first photo, you see a line of PVC pipes staking the forest. These mark the SW corner of each 10m x 10m sub-plot. The second photo shows how the PVC stakes are tagged with coordinates of the X-Y coordinates of the sub-plot. They were set using precise GPS technology, so the positions are correct.
We just set the measuring tapes and estimate the positions of the centers of plants within 5 cm. On a slope, though, it is possible to measure more than 10 m and still be within the sub-plot. Fortunately, the spreadsheet contains informations on the contour of the earth so that corrections can be made during data analysis, and we just write down what is on the measuring tape.
The next step is to measure the diameter of the plant at breast height (DBH). A special walking stick with a mark at 1.30 m is used to determine the location for the DBH measurement. Calipers would not do the trick since most tree trunks are not perfectly round in cross-section. In the field of forestry, the standard way to account for these irregularities is to
measure the circumference and convert to diameter. There are special tapes used for this purpose with different scales on the two sides, as shown in the photo. You should be able to confirm that the upper tape is the photo takes pi into account.
The next step is to mark the plant. If the DBH is less than 8.0 cm, the tag is tied on, which allows for rapid growth. If the plant is bigger, though, the tag is nailed on, with the nail sloping a bit so that gravity keeps the tag from touching the tree, as shown at right. (Click on the image to see it more clearly.) 
From time to time in the future, it will be necessary to loosen the tied tags and pull the nails out a bit to accommodate growth. If this maintenance is forgotten, the tree can envelop the tag, as the tree at left is threatening to do. Finally, we had to identify the plant species, describe its health, and note the degree to which it is able to obtain direct light.
As a bonus today, we got to climb a tower that is measuring solar radiation above the canopy to compare with similar measurements on the forest floor. (I suggested that they call this research group the "Soleil du SERC" which seemed to be a welcome suggestion, probably since this place is filled with wonderful, driven, somewhat-dorky academics--like a graduate school.) The views were great, and the climb was worth it, even though the tower swayed quite a bit.
On the way back from tree mapping, we noticed a strange pattern on a tree. It turns out that this pattern is evidence of the presence of a particular bird--the yellow-bellied sap sucker. This bird obviously displays that obsessive, compulsive behaviors are not limited to human beings. Later, in the dorm, we were treated to a talk on the science of climate change, presented by Dr. Dan Stover, who is the Earthwatch director at SERC. I'll be receiving his presentation file to share with you later.
After cooking and eating, it was time for sleep. The Blogger servers were uncooperative last night, so I had to wait until this morning to post.
posted by Dr D @ 7:45 PM
6 Comments:
Is the the yellow-bellied sap sucker at all harmful to the trees? The plethora of holes it is making does not seem beneficial to the tree.
I am really excited to read Dr. Stover's presentation. I think it will be very interesting to hear the facts from someone who has collected some of the most recent data. Melanee Sprenkel Period 6
Why does the the yellow-bellied sap sucker attack trees in this way, are they able to gain any nutrients through the sap that they are not able to find elsewhere? And does the bird specifically attack this type of tree, or have you seen the pattern elsewhere?
Also, what is the significance of measuring the circumference of the trees at breast-height as opposed to elsewhere? Hope the trip is going well
Evan Lorenzen per 6
Does the yellow-bellied sap sucker only attack certain types of trees and is it a native species? The holes on the tree appeared to be very deep and looked like they hurt the trees ability to protect itself from disease and or other harmful insects. Also by measuring the solar radiation above and below the canopy what does that show you about climate change and its affects on the environment?
I don't understand how the tree can "eat" the tags placed on them. I know that the trees are growing so they get closer to the tag, but wouldn't they just fall off? Also, these trees must grow very fast if there is already evidence of a tag being consumed by a previously marked tree. Taylor Nelson P3
First of all, I would like to know how scared you were on that SWAYING tower above the canopy? Well, I would also like to ask if the abundance of holes these yellow-bellied birds make causes damage to the tree now or even future damge to the tree as a result of depleating its protective bark external shell.I am also curious to know how big of a difference in canopy radiation there is from the top to the bottom of the canopy and the effects these radiation differences have on the animals and trees. Lastly Doctor D., have you seen any signs of invasive species in the forest during your stay?
I hope the oscillations of the swaying tower did not have a huge magnitude (and I hope that I just made sense!). Are any insects that are affecting the trees like in Colorado, or is the moisture of the habitat prominent enough that the trees have enough sap to defend themselves? Is the yello-bellied sap sucker as dangerous to the trees in the North East temperate forest as the pine beatle in the coniferous forest?
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