Vinca, Garlic Mustard and an Eastern Cottontail

What: The patch of woods behind my house (dominant trees are black walnut, slippery elm, boxelder, and and Norway maple, with black cherry, honeysuckle, and common buckthorn in the understory and that is literally all) has about three different herbaceous plants growing in the understory and they form near monocrop patches. The first is Vinca spp. (or periwinkle), which I have growing in dense, impenetrable thickets closest to the walnut (walnuts have juglone in their roots which is known to inhibit growth of other plants). Farther away is a 1-2' tall forest of garlic mustard. The scilla, which I already posted about has pretty much gone through its life cycle before the garlic mustard is up.

Ecological notes: I've long just attributed this overwhelming abundance of garlic mustard and vinca to the fact that this is a heavily disturbed area and so non-native exotics like garlic mustard would thrive. The Vinca was probably ground cover from an ornamental planting. There's virtually no leaf litter (all that's there is from this year) due to an over abundance of earthworms (Lumbricus terrestris), the soils are pretty darn sandy, and there's lots of browsers and not a lot of predators.

But I've also been noticing more and more a rabbit in my backyard. The rabbit's an Eastern cottontail, Sylvilagus floridanus, which, for Vermont, is an introduced species that has largely outcompeted the native New England cottontail. We don't really ever get foxes or other rabbit predators and so I think that the rabbit population might be big enough to essentially be controlling the herbaceous layer. I see them eating violets, dandelion, the grasses, and my blueberry shrubs, but they have entirely avoided the garlic mustard and vinca.

Where: My backyard! Sandy soils, an old plowed field (abandoned in the 70s).

Other notes: I tasted a periwinkle flower and it was okay at first and then had a taste reminscent of black licorice but much worse. I haven't seen any really browse sign on them at all so stuff seems to pretty well avoid it.

More little leaves

What: So in response to Ryan's comment about sugar maples being considerably later than their breathren to leaf out I set out to document some of the later-to-burst buds. A loose pattern I thought I found was that the later species to bud out seem to be the ones that are more shade tolerant. But my sample is too small to make anything other than a very gross generalization (and probably not that correct). I also didn't notice whether or not there's a difference between individuals in the canopy and individuals in the understory. I couldn't find great data on the order of when species leaf out (Project Bud Bursts data set isn't that great) so looks like I'll have to keep investigating.

I know that there is variation within a population due to small-scale climatic features. In the posting on dandelions I described finding dandelions that had gone to seed earliest in south-facing spots adjacent to buildings or rocks. Trees in similar warm areas tend to leaf out earlier. I followed up on the shade-tolerance piece and didn't find a whole lot pertinent to leafing out. It is pretty well established that a woody species' shade tolerance is most relevant in the seedling/sapling stages. The following table is condensed from Humbert et al.'s 2007 paper "A shade tolerance index for common understory species of northeastern North America". It gives ranks each species from 1-9, with 9 being the least tolerant of shade and 1 being the best, an X means that it has a wide range of tolerances. The real table has more trees, lots of herbaceous plants and even some mosses and liverworts.

Latin name	Common name	Shade tolerance index
Abies balsamea	Balsam fir	3
Acer pensylvanicum	Striped maple	3
Acer rubrum	Red maple	5
Acer saccharum	Sugar maple	4
Acer spicatum	Mtn maple	5
Alnus incana ssp. rugosa	Speckled alder	7
Betula alleghaniensis	Yellow birch	5
Betula papyrifera	White birch	7
Comptonia peregrina	Sweet fern	7
Cornus alternifolia	Alt leaf dogwood	4
Cornus canadensis	Bunchberry	X
Corylus cornuta	Witch hazel	4
Fagus grandifolia	American beech	2
Fraxinus nigra	Black ash	5
Larix laricina	Tamarack	9
Ledum groenlandicum	Bog Labrador tea	7
Lonicera canadensis	Fly honeysuckle	X
Myrica gale	Sweetgale	8
Ostrya virginiana	Hophornbeam	X
Picea glauca	White spruce	4
Picea mariana	Black spruce	X
Pinus resinosa	Red pine	8
Pinus strobus	White pine	6
Populus balsamifera	Balsam poplar	9
Populus grandidentata	Big-tooth aspen	9
Populus tremuloides	Quaking aspen	9
Prunus pensylvanica	Pin cherry	9
Prunus serotina	Black cherry	8
Prunus virginiana	Chokecherry	X
Quercus rubra	Red oak	7
Salix discolor	American willow	8
Salix humilis	Prairie willow	9
Sambucus racemosa	Red elderberry	5
Taxus canadensis	Canada yew	2
Thuja occidentalis	White cedar	3
Tsuga canadensis	Hemlock	3
Ulmus americana	Elm	6
Vaccinium angustifolium	Lowbush blueberry	7

The other columns that I would like to see in here would be simple vs compound leaf, ring-porous vs diffuse porous, successionary stage, and dry vs wet habitat preference, freezing killing temperature, herbivore pressure, leaf drop date, flowering date, furthest north latitude, center of evolutionary group's range, among others. So it's a start, but for now mostly just pretty pictures and a cool table.

A study in croziers (fiddleheads)

What: 1) The wood fern had totally colonized an old stump (possibly white pine, as much of the pine had been logged in that area in recent history). 2) Ostrich fern is past its peak with just a few scattered fiddleheads - or croziers - still furled enough to harvest. The rest were almost entirely unfurled, but still only about 1-2' tall. 3) Someone had harvested some of the cinnamon fern and its sap had congealed into this hard jelly type crust on the broken stem. I think I might have mis-labeled an interrupted fern as cinnamon fern in a previous post. The two next to each other shows a pretty clear contrast in the color of fuzz coating each species. Cinnamon fern is the oranger of the two. Ryan showed me a photo of a white fuzzed fiddlehead with clear sporangia on the middle pinnae of one of the fiddleheads (Cathy Paris pointed this out to him). 4) The hay-scented fern reminded me of comedy and tragedy. These grow in a pretty dense patch under the powerlines. 5) Sensitive fern seems to be awfully red. I forgot to take note if there was more red on ones in the open than ones in shade. Next time I'm out...

Wood frogs, green frogs, and toads!!

What: Both toads and wood frogs "singing" today in Centennial Woods. The wood frog eggs that I've been watching for the past few weeks hatched about 10 days ago and I was able to grab a few photos of the tadpoles today. They seemed to be congregating at a log near the surface of the water possibly for warmth.

Ecological notes: I first noticed the eggs on March 25th, so it took about 23 days for the eggs to hatch.

Where: I noted in my last post on the eggs that the beavers had flooded the area, raising the water table, and creating this little standing pool. The beavers had moved upstream few weeks ago and haven't worked on their lower dam. If they do decide to work on the dam and raise it about 4" it will raise the water enough to connect this pool to the brook and the fish will probably wipe out the tadpoles.

Beavers in Centennial Woods

What: Our first rains in ages!! And that new rain seemed to be a bit too much for the beavers of Centennial Woods. The rain started on Saturday night and continued well into today (Monday). I was out yesterday and the lower dam (which burst in January and was repaired in February) blew out by about 1pm. Sometime later on Sunday the upper dam blew out. Luckily over the last week they had built a new dam in between that kept up a channel about 3' deep. 

Ecological notes: The water was awfully murky from the heavy siltation due to all the rains. Not only was this the first rain in a while, but the temperature has dropped considerable. I watched the beavers from about 4:30 to 8:30 and by the end I could see my breath pretty clearly. Since the beavers are right next to the trail, it was neat to watch how they respond to dogs and hikers. They definitely perceived the hikers with dogs well before those without. It also took the beavers less time to return to baseline following a hiker without a dog. Hikers with dogs were less likely to notice the beavers. Everyone was definitely enthused about the beavers though and it was great to get to share their excitement.

And I'm still trying to wrap my head around why the beavers will slap their tail. It's not as easy as they do it when they feel threatened and to ward of would-be-predators. I think they will do it to communicate to others over longer distances. This one slapped its tail while it was on one side of the bridge and the other two beavers were upstream. It was as though it were saying, "Hey don't forget about me, I'm down here where all the people are (there were 8 of us at one point)." It seems to also serve as an indication of investigation, as with the chickadees, "Chicka-dee-dee" call they make when they get close to people. It seems like they're saying, "I"m going to go investigate something, would you check in with me in a little bit to make sure I'm still alright." I've seen beavers make this sound to nothing in particular before they headed upstream out of eyesight of other beavers.

Where: Middle terrace of the beaver dam under the Velco powerlines.

Other notes: Twas also a great afternoon for birds. Saw a pair of geese land in the retention pond, a Cooper's Hawk, flicker, and phoebe skirting the edge of the pond, winter wrens singing, and lots of cardinals, robins, song sparrows, grackles, and red-winged blackbirds. Surprised I haven't seen more nests yet - I'll have to spend some more time tracking individual birds. And no sign of Ryan's ruby-crowned kinglets today.