Mid-Summer Update

This post will be an update from my first post about this summer’s research. Thus far, we have been able to collect tree ring cores and the information about the trees from the TRAYLS group. We have created the Google Earth interactive site that houses this information and is accessible to anyone. We have also added other tree information from Lauren Oakes’s study site and Pleasant Island. We are working on adding data points from Ben Gaglioti’s study site at La Perouse Glacier.

The cores arrived in the mail and were mounted and sanded. The samples came from mountain hemlock and Sitka spruce trees. We were able to create graphs from the data and do some comparing between tree species.

Graph 1. Representing the ring width indices. The black line represents samples so the higher it goes, the more samples overlap during that time. The year 1808 is marked in the graph because of its volcanic events and cooling (Cameron et al., 2006). Although the location of the eruption is unknown, ice cores indicate an eruption occurring from certain chemicals found inside the ice.

In graph 1, the blue line rises to its highest peak around 1880. This means that the rings indices is at the highest point. The tree rings would be thickest indicating the most growth would be happening during this time in all of the overlapping samples.

Graph 2. Representing the ring width indices. Again, the black line represents samples so the higher it goes, the more samples overlap during that time.

In graph 2, the blue line rises to its highest point at about 1900. After this, the line takes a nosedive and drops continuously till 2000. From both graphs, we can speculate what the past environments could have been like. This work is important because it has rarely been studied before. This work can be added to the known information about Alaskan Trees and the history of the area.

Figure 1. An image of the reaction wood in a mountain hemlock sample. Reaction wood means that there was stress imposed on the tree. The darker wood grows to help recover from the stress. Some examples of stress could be wind, weather, or even a bear stepping on a tree as its growing (see below). The tree compensates for the lean in its main stem by putting on denser reaction wood.
Figure 2. Here is an image showing some examples of what the tree and tree cookie would look if the tree has reaction wood.
Figure 3. Showing the two species of samples compared to one another. The Sitka spruce has wider rings and the Mountain Hemlock has thinner rings. Resin ducts (arrows) are seen in the Spruce.