27 Jul Looking back on the beaver project
My personal objective during this internship was to study the foraging ecology of beavers. By observing the beavers’ herbivory patterns along transects while noting what they choose to take and where, we can compare what is available to what they have eaten and get a better idea of their dietary habits. Looking into the browse patterns and regeneration issues side by side will give us a better overall idea of their connection.
And so, my portion of work surrounded vegetation sampling. The process for this part of the beaver project entailed completing three transect samples located at Crosby farm regional park.
By putting these transect lines between the two bodies of water near the Crosby Farms site, we can establish a gradient of how far into the forest the beaver will forge from their lodges near the water’s edge.
We managed to multitask and do two different surveys throughout the transect lines. The first was to examine foraging patterns. After we flagged out the transects route, we followed the 100 meter tape from point to point, while looking at trees within a meter space on either side of the tape. We would note any trees that showed signs of herbivory, and list what kind of animal did it. Deer herbivory would usually appear towards the tops of saplings, while beaver left more clear cuts at what we referred to as beaver height, around 3.5 feet or lower. On more mature trees they would often leave obvious signs of girdling.
For our second survey, we studied tree regeneration. At 100, 400, 700, and 1100 meters, we would stop at each respective point and do variable radius plots. Using a prism to establish which trees were “in” or “out” of the sample, we would take trees that were in and note the type of tree, DBH (diameter at breast height), overall health of the tree, and if there were any signs of herbivory.
Since these were the first transects that anyone had sampled for the beaver projects herbivory study, it was both fun and challenging to get down the general methodology. Finding what worked and what didn’t work was super rewarding and will be used in future sampling for different areas around the Mississippi.
As for results, since we just finished the transects last week,it’s hard to have any concrete conclusions from our work- we are expected to have preliminary results by 2025.
What we know now is that the answers are going to be complex. From a survey in 2021, we can assume beaver populations in the Mississippi are not uniform and the NPS corridor hosts a lot of heterogeneity. Therefore, we cannot expect a uniform effect from beavers throughout the park, and need to posture the research accordingly.
Ultimately, more time and hard work will be needed to determine the ecological impacts that beaver have on tree regeneration.
I had so much fun on this project. I collaborated with some awesome folks who helped further my understanding of field methods and plant ID tremendously! I feel very grateful for the opportunity to participate.