Friday, July 11, 2014

Deer Browse Assessment at Eklund Garden

Plot #1 - Inside the deer exclosure at Eklund Garden
Back in 2009, a fence was installed to protect Eklund Garden from deer.  The fencing was installed so that it would not be visible from the garden itself, back in the trees, and that has created an opportunity to compare what the plants look like on either side of the fence now. Much of the fence was installed were there was an abrupt change in the terrain, making comparisons pointless, but at the top of the hill each side of the fence is pretty much identical.  This type of terrain is agreeable to oaks and pines, two plants favored by browsing deer, especially in winter.
Healthy oak sapling inside the deer exclosure, Plot #1
I set up two 30' x 30' foot plots, one on each side of the fence (side by side) and recorded all the plants growing in each. Of special importance are the oaks and pines taller than 12", but less than an inch in diameter or about 7 feet in height.  Trees shorter than 12" may have just recently germinated from seed (especially oaks), or may be very old and just keep resprouting after being eaten to the ground (maples can do this - a 6" sugar maple may be twenty years old).  Taller trees are not vulnerable to deer because their foliage is too high for deer to reach. 

Healthy White Pines inside the deer exclosure, Plot #1
There were lots of saplings of this size in Plot #1, and they all looked pretty healthy, including: 14 white oak, 13 red oak, 10 white pine, 2 black cherry, 1 spruce, and 1 red maple, all within 90 s.f. of land. The plot was affected by a trail going through it, a log pile, and a brush pile where nothing could grow.  There were also 6 Pink Ladyslipper, one of which had successfully bloomed, as well as blueberry or huckleberry, mountain laurel, lots of moss, Canada mayflower, grass, poison ivy, and lots of little tree seedlings (a few dozen oaks, hickory, lots of red maple, white pine, and spruce.)  On to the other side of the fence.  

Plot #2 - Outside the deer exclosure
Plot #2 was very similar in turns of terrain and sunlight (maybe a bit more sun).  At first glace, the two sides don't seem very different. But upon closer inspection, the plant composition is strikingly different. Where Plot #1 had a total of 27 oak saplings between the height of 1 and 7 feet, Plot #2 had only one oak, and that oak was heavily browsed.  I did manage to count seven oak seedling (less than 12"). The acorns are sprouting, they just aren't getting very tall (a sprouting acorn can reach a height of 6 or 8" almost immediately). 

The only oak sapling taller than 12" in Plot #2. 
As for white pines, another deer favorite, where there had been 10 healthy pines in the first plot, there were five in the second plot, and all five were very heavily browsed and stunted. Deer browse on twigs in the winter when there is nothing else to eat, giving the sapling some time to regenerate during the summer, but if a sapling is browsed too often, it will first become stunted and then finally die.

White pine resprouting after being nipped in Plot #2.
Other plants were not affected by the deer, including some black cherry saplings, blueberry, mountain laurel, Canada mayflower, black swallowwort (invasive), and plenty of moss.  Two plants were present but seemed undersized: sarsaparilla and marginal woodfern. And there were two ladyslippers, but each only had one leaf. 

After assessing these two plots, I took a walk along the rock ridge looking for oak saplings between one and seven feet in height. For the first 15 or 20 minutes all I found were seedlings (<12"), even though there was plenty of sun for them to grow, but continuing south and west I did begin to see a few taller saplings, finding more and more as I headed south. Not sure why. There could simply be more deer wintering in the vicinity of Eklund Garden (winter is when they tend to nip saplings, not in the summer), or more hunting pressure towards the south end of the park (where I have rec'd complaints of a deer stand on City open space).