Thursday, July 24, 2014

Shelton's Oaks and Maples

Oak Trees:  Although there are currently many large oak trees throughout Shelton, once these trees die or fall in a storm, will there be any young oaks to take their place?  Acorns dropped by oaks each fall are an especially important food for wildlife, including deer, squirrels, and turkey. The high fat content allows animals to fatten up for winter, and acorns may be found under the snow all winter when food is scarce.  At Long Hill, none of our six study plots contained oak saplings. Off of Nells Rock Road, there were seven study plots (including the unprotected plot at Eklund) and only three oak saplings found, an average of 0.43 oaks per plot. None of the oaks was very large or vigorous. One was heavily browsed.  In contrast, the plot protected by deer fencing at Eklund had 27 very healthy oaks.

To recap:

Average number of oak saplings per plot
Long Hill: 0
Nells Rock & Eklund (unprotected): 0.4
Eklund (protected): 27

Sugar maple, the quintessential New England tree, is supposed to be the ultimate winner in the textbook "late succession" model of a forest, and in theory should be taking over our forests.  In this model, when a forest first begins growing (after a field is abandoned or most of the trees are felled), it is first dominated by fast-growing, sun-loving species.  These species create shade, so that only the saplings of slow-growing, shade-tolerant species can grow. Sugar maple and beech are such trees. The saplings can persist for many, many years in deep shade, allowing them to eventually take over a forest. Unnaturally high deer numbers upend the classic model however.  Of the 14 plots I've sampled so far in the forest, I haven't found any sugar maple saplings.  (There also weren't any in the protected plot at Eklund, but this was a dry rock hilltop where sugar maple do not grow.)  I do find beech, however, which deer will not eat unless they are starving.

I also haven't found any red maple saplings, except for one within the protected plot at Eklund. Red maples are only moderately tolerant of shade, but they are the most common tree species in Connecticut and highly tolerant of both very dry sites and very wet sites (including swamps).   If you find tree seedlings growing in your garden or gutter, they are mostly likely red maples. Yet I didn't find any red maple saplings in the unprotected study plots. I did find lots of tiny seedlings that had just sprouted this year. They sprout, grow slowly in the shade, and then they get eaten. They just aren't surviving.

Tuesday, July 22, 2014

Deer Browse Assessment - Nells Rock

Assessing the open space off of Nells Rock Road was a pleasure after having witnessed the stripped forest near Long Hill School.  Hikers are still met with a carpet of greenery in at least some locations along Nells Rock Trail and the Paugussett.  It's not all good news, however.  It looks like deer are having a big impact on the species that make up their favorites foods, such as maples, oaks, maple-leaf viburnum, and Jack-in-the-pulpit, which is changing the composition of the forest.

Assessment plot locations off Nells Rock Road
Six 30' x 30' plots were assessed along an East-West line which began 0.2 mile south of Eklund Garden (see map above).  This line was chosen to avoid swamps and cliffs, which are very common in that area. There isn't much elevation change along the transect - it's a plateau.

Plot #1: Next to a swamp
Plot #1 was located next to a large swamp, and was full of sweet pepperbush, an aggressive shrub that grows along the margins of wetlands. Deer don't care much for it to eat, but a pepperbush thicket can provide good cover and there was a deer path through the thicket and deer droppings in the plot. Only two saplings were found between a height of 12" and 7 ft: One oak and one beech.

Plot #2 - A carpet of maple-leaf viburnum
Plots #2 and #3 had lots of maple-leaf viburnum, but most of it was pretty low.  This is a shrub favored by deer.  It wants to be over 4 feet tall, so you don't expect to see it as a low carpet. Although most of the plants are about 6" tall, there are a few taller plants, and these are the ones showing the most browse damage, especially the ones that are 2-3' high. This was a pattern I saw for the rest of the day.  There is plenty of maple-leaf viburnum off Nells Rock Road, but it's being browsed at a rate that is most likely unsustainable, and will eventually disappear (in contrast, I found only one tiny maple-leaf viburnum in the Long Hill Open Space).  It would be interesting to throw up a deer exclosure here and see what happens to the viburnum over a few years.

Maple-leaf viburnum - browse damage

Maple-leaf viburnum - growing back after being nipped.
Plot #2 had two saplings: A beech and a striped maple (which is unexpected in these parts). Plot #3 was at the top of a low knoll and seemed a bit sparse overall, but it had the largest number of tree saplings of all the plots (an oak, 3 beech, a hickory, 5 black cherry, and one unidentified).
Plot #3: More of the same, but with more tree saplings.
Plot #4 was in a boulder-strewn area and dominated by witch hazel (10'-20' high). Only one sapling was found: a witch hazel.
Plot #4: Sparse vegetation on a boulder field

Plot #5: Rocks and ferns
Plot #5 was poorly drained and had some nice highbush blueberry and cinnamon ferns. Zero saplings in this plot. But heading east of Plot #5, the terrain began to drop to the east and the biodiversity shot up.

Plot #6: A lot more diversity here sprinkled amongst the hayscented ferns
Plot #6 at first glance seems to be all hayscented fern. Deer will not eat the fern, leading to what is sometimes called a "fern desert" where deer numbers are high and the fern takes over. But amongst the fronds there were a large number of plant species, not to mention wood frogs and a land snail. Why was the diversity so much higher here?  Not sure, but one reason is likely that the growing conditions are better as the land begins to slope down to the east, with possibly better soil and more moisture. Plants simply grow faster and can handle more browsing pressure. Another factor may be that the ferns are actually protecting some delicate survivors from the deer. Yet another may be simply the foraging patterns of the local deer, who are creatures of habit and keep foraging along the exact same routes day after day, even when there isn't much to eat there.  Then there is the possibility that there is hunting occurring in the large, vacant property located very close by.

There were 4 saplings observed in this plot: one hickory and 3 ash trees.

Many of the most vulnerable plants, like Jack-in-the-pulpit, were small and not flowering, but hiding in the ferns. Here's a sampling:

Plot #6: Hogpeanut, hayscented fern

Plot #6: False Solomon Seal

Plot #6: Maple-leaf viburnum forming berries

Plot #6: Jack-in-the-Pulpit (small)

Plot #6: Wild geranium, poison ivy, and sensitive fern

Plot #6: Doll's Eye Banebery

Plot #6: Enchanter's Nightshade
Heading back to the car, I noted the vegetation growing along Nells Rock Trail. There were a few Jack-in-the-Pulpit, but all were small and none were flowering (flowering Jack-in-the-Pulpit is sometimes used as an indicator of the deer population).  There were also some asters, but there were all very heavily browsed (see photo below).  This plant should be over a foot tall by now and starting to form flower heads. Instead, these asters have all been cropped low and may not be able to reproduce this year. These is something also very evident at Eklund Garden, where the asters are cropped closely outside the deer fence but proliferate inside the fence.

Nells Rock Trail: White Wood Asters, heavily browsed

Friday, July 18, 2014

Deer Browse Assessment - Klapik Open Space

Large oaks in the open space
The Long Hill open space known as Klapik Farm has been assessed for deer browse impacts, and the results are disturbing.  In a nutshell, no trees are successfully reproducing in this open space except for beech, which deer don't like, and even the beech are showing browse damage. Moreover, the beech may not be truly reproducing that well, since the trees are infested with beech bark disease and some of the "saplings" may actually be clonal shoots thrown up by the roots of dead or dieing trees. Once these root shoots reach a certain height, they too may succumb to beech bark disease.

The Klapik property is series of hayfields and woods located in the southeastern part of town, just south of Long Hill School. Many deer, turkey, and coyote are seen in the hayfields, which provide abundant summertime forage, while the woods provide acorns that allow deer and other animals to fatten up for the winter. The woods are full of oak, hickory, ash, birch, maple, and beech trees. The deep shade and oak leaf litter create difficult growing conditions for many plants, so it can be assumed that plants grow slowly under these conditions and are less able to tolerate deer browsing.

Six plots were inventoried, one every 200 feet in an east-west transect across the wood part of the open space.  Each plot was 30'x30'.   Of special interest were tree saplings above 12" and below 7' (those vulnerable to browsing). 

Plot locations. Laurel Wood Drive is at the bottom

Plots 1-5 each contained between 2 and 12 beech saplings between the height of 12" and 7 feet, and no other tree species.  Many of the beech had been browsed, which is not usually seen. Plot #6, located near the edge of the hayfield, had more diversity overall and had one beech (browsed), one black cherry (browsed), and one birch.

As for shrubs and wildflowers, there is only very sparse cover by a small number of deer resistant plants, such as mountain laurel and Canada mayflower. Most of the forest floor is not vegetated, and woods are very open and easy to see through and walk through.

Plot #1: Note the browse line about 4 feet up
Plot #2. Again, very brown below a level of 4 feet (the browse line).

Plot#3 - More brown than green

Plot #4. A large beech in the center has toppled and nearly all the green below 4 ft is
comprised of beech shoots, likely from the roots of the fallen tree.

Plot #5 - lots of brown
The sixth plot was significantly greener from the other five plot, although much of the greenery was in the form of invasive barberry and multiflora rose. This plot was located near the base of the drumlin where groundwater likely seeps out and there may be more sunlight, allowing plants to grow more aggressively and survive repeated browsing. The thorns of barberry and rose also provide some protection for more vulnerable species. This plot had one beech sapling (browsed), one black cherry sapling (browsed), and one birch sapling. These are all relatively deer-resistant species.

Plot #6, looking much greener due to additional moisture and light as well as the
presence of thorny plant like Japanese barberry

Although the first five plots looked pretty barren, upon a close examination, I did find a few vulnerable plant species hanging on. For example, there was a tiny 4" maple-leaf viburnum in Plot #2 that showed signs of repeated browsing. This shrub is more often three or four feet high with white flowers and dark blue berries that people often notice along the trails at Shelton Lakes. Here in the Long Hill open space all I could find was a rare sprig a few inches high.

Browsed 4" Maple-Leaf Viburnum shrub, normally several feet tall

And there was the Pink Lady Slipper in Plot #1, chewed up but surviving. At Shelton Lakes, we see the blooms nipped off (which prevents them from reproducing), but we don't see the leaves being eaten.

Browsed Pink Lady Slipper
 In Plot #5 there was a highbush blueberry, although it showed a lot of browse damage.
Browse damage - Highbush Blueberry
The winning species in this property was perhaps the Canada mayflower. It was scattered everywhere. Highly resistant to deer, and adapted to dry, acidic soil and deep shade, this plant is doing quite well.

Canada mayflower was found in every plot
The biggest surprise was the extent to which beech is being browsed. This is not something you normally see, and reflects deer that are very hungry during the winter (the time of year when deer eat the ends of twigs).
Browsed beech, which is a "starvation food."

The future: Because tree saplings are not able to survive, eventually, the taller and older oaks will reach the end of their lifespan or be toppled in a storm, and the forest will be dominated by the younger birch and beech trees which now grow alongside the oaks. The loss of acorns will have profound impacts on wildlife. Birch and beech will likely dominant the forest for some time, but eventually the birch, which is not reproducing currently, will be lost as well, and only beech will be left.

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).