Marcescence in beech trees

Kaleigh Wood is a senior Environmental Studies in the Rubenstein School at UVM. She enjoys exploring outside, running and cooking.

A couple of weeks ago I was on a stroll through Centennial Woods (CW) for a class assignment. The leaves littered the ground with their colors and gave my steps a pleasant crunchy sound as I made my way deeper into the woods. I looked up to find that most of the trees had shed their leaves. I kept walking and suddenly I was surrounded by this beautiful tree that was still full of its vibrant orange leaves. While I haven't taken dendrology and my tree identification skills are sub-par, I did know this one. The tree that was still holding onto its exciting leaves was an American Beech (Fagus grandifolia). I started to wonder, why do Beech trees hold onto their leaves after all the other deciduous trees let theirs fall?

I went on a run with my trusty running buddy, Lily Morgan, who happens to have a strong passion for trees. I was explaining what I had seen in CW and started to ask her what she knew about the American beech; she started rambling some things in Latin and I quickly stopped her and asked her about the leaves and why they stayed on for so long. She gave me a lesson from Reading the Forested Landscape by Tom Wessels on beech. We found out that beech and oak trees are actually somewhere in between evergreen and deciduous trees, explaining why those tree species can hang on to their leaves throughout  the winter.

We wanted to know more, we found out the genetic reasoning why Beech can hang on to their leaves, but what was the ecological advantage of it? I explored the internet and found an article in Northern Woodlands magazine. The author, Michael Snyder, (who is the Chittenden County Forester in Vermont) explained that some plants will retain dead plant matter, known as marcescence. It turns out there are many theories to the advantages of marcescence. One theory is it’s an adaptive advantage for trees growing in dry and infertile areas (where Beech trees grow!), because if they do not drop their leaves onto the ground they deprive the soil of organic matter which other trees need. Beech and oaks don't need the added nutrients so they  continue to thrive. Keeping leaves on their branches and not on the ground allows them to out-compete other species surrounding them. Additionally oak leaves are high in tannins and reluctant to decompose, further reducing available nutrients to other would-be competitors.

Other advantages of marcescence are, trapping snow which leads to more moisture at the base of the tree, the dead leaves on the limbs protect buds from frost in the winter, and finally the leaves can protect the trees from browsers such as deer and moose. The dead leaves can hide buds so they are less likely to be eaten and are more likely to grow new buds and twigs in the spring. Not only do Beech trees provide CW with great views after most trees have dropped their leaves, but there are also advantages to this interesting adaptation.

Dog Stinkhorn aka Mutinus caninus

Posted by Harrison Balisky. Harrison is an avid outdoorsman, and an Environmental Studies major at UVM set to graduate this spring.

What: I was recently hiking through a wooded area on a class retreat; keeping an eye out for mushrooms and anything else I thought was interesting, when I stumbled upon a pinkish-brown pile of what looked like spongy tubes. I quickly looked at it and dismissed it as trash and continued my walk across a large area of damp mulch woodchips under the cover of some old trees. I was just stepping over a log with some shelf mushrooms attached to it when I encountered more of the spongy tube-like objects, this time almost ending in me crushing them under my foot. They were about as long as my pinky I would say, its spongy like stem having an eerie resemblance to a toy Nerf gun dart. Looking around, I suddenly spied it in several places, growing happily among the wood mulch.

This piece was as light as Styrofoam, with a little brown colored top bit, and had a slimy spongy texture feel to it. I took a quick whiff and encountered a smell that was so putrid; I could only describe it as a smell that was between decaying animal dung and flesh. The smell instantly triggered many of my “about-to-vomit” warning signals. It made ginkgo balls, which are those other notoriously foul-smelling natural fruiting bodies, seem quite appealing. I knew then that I had unwittingly grabbed a piece of fungi that was of total mystery to me. Even my buddy, who was with me that is a forestry major, was completely baffled by it. But I knew right then and there who I could ask that would have the answer, my professor of my Natural History of Centennial Woods class, Teage O'Connor. And sure enough before I even showed him a picture I took of it, he could already tell me from my description of it, that it was a Dog Horn mushroom (Mutinus caninus) in the Stink Horn family.

What I have been hearing from most people through my searches is that they don't seem to like Dog Horn, something about the smell. Go figure. But when I first came across the Elegant Stinkhorn, as I described in my experience above, I would soon come to find why some of the other common names for it are Devil's Dipstick, Devil's Horn, Devil's Stinkpot, and Dog Penis. The foul smell of the fungus coupled with its cornucopian shape is what’s appropriately used for the origin of its common name stinkhorn. The
more pejorative names are probably based on its strange appearance. I’m not going to lie about what I really thought when I first saw it. What kind of shroom is that? Along with looking at it and thinking What is this disgusting mushroom that looks like a…Well put it this way it might be inappropriate to say what I thought it looked liked at first but I’m sure you can figure that out. Elegant may be seen in reference to its simplicity, almost artistic simplicity, however suggestive it still may be.

Ecological Notes: According to Simon & Schuster’s guide to Mushrooms, the Dog Stinkhorn grows from a white or pale yellow “egg” and is covered by a decaying slime. What’s not surprising to me is that the edibility of the mushroom is listed as “of no interest”. It also depicts that the slime attracts flies, which pick up the mushroom’s spores and deposit them elsewhere that helps to spread this mushroom around. There's no real polite way of saying it: I think stinkhorns are fairly on the grosser side when it comes to mushrooms, and after smelling it I think I could say their stink is so potent you should be able to smell them before you see them.

The Continuing Saga of Squirrels and Walnuts

*** Starting this week my UVM students will be posting occasionally in response to the prompt: Find something in the woods that you've never seen before and figure out what its story is. So look for that!

What: Last week Clay and I found a dead gray squirrel (Sciurus carolinensis) on the sidewalk. It was a pretty good mystery as to how the squirrel had died. I skinned it with my Crow's Path kids and before we did the autopsy we couldn't detect any broken bones from getting hit by a car (plus it was about 10' from the road). The squirrel was a full grown male (just about the most enormous squirrel I've seen), and we thought maybe it could have eaten poison from a nearby house, fallen out of a tree, got hit by a bike or chomped by a cat/dog. We couldn't find any evidence of blunt trauma from getting hit by something, but when we pulled the skin up above the neck we could finally see two chomp marks that hadn't pierced the skin (so no external blood) but were most likely what killed this little critter.

You can notice in the two photos below the difference between the rear (left) and the front feet (right). The difference in color is due to the constant assault of the squirrels on the walnuts (see my previous post on how it stains their face and paws). I love looking up close at squirrels to see all the little differences between individuals, and this little guy, with a lone black chin hair popping out, was no exception. It also had orange staining its whole belly, probably from eating walnuts and then grooming its belly (around its crotch was particularly orange, which was amusing).

Ecological notes: With the kids we noted that the rear foot was flexible in almost all directions and could rotate just about 180 degrees. I was telling the kids that the squirrels will hanging from a tree hanging down with their feet rotated back behind them. I've also noticed that when they leap to a branch they rotate their feet so that they're hanging below their body and the bottoms are facing the direction they're going. As they hit the branch their rotated feet catch their body and grip onto the branch as they then rotate around to face forward and propel them in their next jump. Amazing! Another thing to note is that animals have larger feet where they hold most of their weight. Gray squirrels hold most their weight in their butts, so have larger rear feet. Same with raccoons, possums, beavers, etc. Dogs (think about pitbulls here) have larger front feet to support their broad chests and big torsos.

Where: Burlington

Feet & all those dead squirrels

What: I was driving home from Sterling College last night and I hit a young male red squirrel (Tamiasciurus hudsonicus). I felt terrible, but at least it died immediately. I scooped it up and brought it to my CCV Natural History course today to skin with my students. It was neat to be able to see the paw prints up close, to be able to see the palm pads in such detail. All rodents (even beavers, muskrats, mice, voles, capybaras) have five toes in the rear and four in the front. Red squirrels spend a lot more time on the ground relative to grays (Sciurus carolinensis). On the ground, the front feet of reds tend to be offset far more than grays. Think about an animal who spend all that time "perched" on a branch with its feet side by side - when it runs along the ground its front feet keep that side-by-side pattern as seen below.

Red Squirrel                  Gray Squirrel
(ground dwelling)         (tree dwelling)
 H     H          H      H       /\
     f              f  f         ||  H = hind
   f                             ||  f = front

This of course is a tendency and not always true. So in general animals that spend more time on the ground tend to follow the pattern or red squirrels, with front feet landing offset, and animals that spend more time in trees, like gray squirrels, land with feet side-by-side. One of the things reds are doing with all that time spent on the ground is harvesting mushrooms. Look in a stand of hemlocks for mushrooms lodged in the crotch of a branch, left out by red squirrels to dry for a winter supply.

Rear feet, five toes, long flat foot

Front foot, 4 toes, smaller dexterous digits

Ecological notes: Red squirrels spend this time of year in search of a territory to defend over the winter, when food resources are drastically reduced. Fall dispersal of yearlings is always a rough time for animals, with lots and lots more road kill this time of  year than at others. Below are the feet I got from a raccoon (Procyon lotor) that was road kill just north of Stowe. I surprised at how much fat was stored up in the tail.

Raccoon feet (rear feet on outside, front on inside)

Where: North Wolcott along the Wild Branch

Wind and walnuts

What: Finally got around to adding photos. Will post again on Friday. What a beautiful windstorm we had last Tuesday night. Of course this was easy to write from the comfort of my home, free of the flying debris and desiccating winds. Walking around the next morning there was so much debris that had blown down and I imagine that too early fall storms like this take its toll on plants and the still-developing fruits and nuts of things like apples, oaks, and walnuts. These windstorms are probably more helpful for deer and turkey that can't climb trees to get access to apples. The red squirrels (Tamiasciurus hudsonicus; "tamias" means hoarder) seemed extra pissy about it. In about 5 minutes I had collected a 5-gallon bucket's worth of walnuts, that's 5-gallons worth of walnuts the alpha red squirrel could no longer defend from the gray squirrels and beta red squirrel. In the last week since the wind knocked the walnuts down, the red squirrel has seemed less insistent about waking up at dawn to claim his territory, as though the wind was blown from his sails.

Ecological notes: We usually get these gusty Fall storms later on in the season, typically in November. Most of the debris on the ground is likely a result of all the leaves still on the trees, which catch the wind and want to be carried away. By November the leaves have fallen and the wind has a much less dramatic effect on the trees.

A uninfected husk (left) and one hosting a healthy colony of husk fly (right).

Black walnuts (Juglans nigra) have a thick outer husk that's filled with juglone (the same allelopath - toxic chemical - found in the roots that hinders the growth of other species). The chemical stains your hands (and can dye fabrics anything from an earthy yellow to a deep green); it also stains the mouths of squirrels this time of year. The walnut husks that have black on the outside have been colonized by a fly whose larvae eat the husk but leave the nut in tact. I cracked the one below open and found one larvae and two pupae (the shiny dark brown cylinders in the photo to the right).

 

Gladys eating the walnut husk fly maggots (Rhagoletis sp.)

The shell of the walnut is super tough and sharp (apparently used as an industrial abrasive). It's got a complex labyrinth of groves and channels that the nut fits into, making it difficult to get out large chunks of the "meat" (see photo at top). So it's a lot of work to get at the meat, but if you have lots of time, well worth the patience as it's delicious! It has a sweet minty flavor to it.

Where: All over Vermont

Other notes: Callan and I drove back from Fairfax last Tuesday night. Before we left we heard spring peepers (Pseudacris crucifer, formerly Hyla crucifera) calling. The roads were filled with frogs crossing back and forth. When I got home I was greeted by a chorus of gray treefrogs (Hyla versicolor). The wet weather has brought the young amphibians out in droves. At the fall equinox, the ratio of light to dark during a day is the same as it is during the spring equinox (March 21), which is roughly the time that amphibians first start singing. One theory is that the fall chorus of frogs is from confused young males that are cuing in to daylength.

Praying mantis

What: Meryl & Julia spotted a hitchhiker in our house today - it apparently came in on one of my sweatshirts. This adult female European mantis (Mantis religiosa) was a blast to watch. They're visual predators, focusing right now on all these late summer, early fall insects like crickets and grasshoppers fattening up for a late breeding season. They move slowly and awkwardly through lawns, relying on camouflage and stealth to ambush their prey. Their "praying" arms are really vicious graspers that clasp onto a prey and don't let go. Here, the lady is just using those forelegs to hold a rear leg that it was cleaning.

Ecological notes: Mantises mate in the fall and lay their eggs in a frothy mess (called an ootheca) that hardens. Eggs overwinter and hatch in the late spring. This time of year they're fattening up stores for laying all those eggs. Oh, and apparently it's a myth that they eat the bridegroom. That only happens in captive settings. They're pretty finicky when it comes to visual stimuli so a lab setting, where they're in a glass case results in some weird behavior. In the video, she responded to my movement, but seemed relatively unperturbed when I stomped my feet against the ground to try and elicit a response. The creepy part was that she was watching me, intently. I think it's extra obvious because she could move her head, but it felt like she was studying me - it reminded me of Muldoon, the Aussie hunter in Jurassic Park, who says of the raptors: "That one... when she looks at you, you can see she's working things out."

Where: My backyard

Other notes: For adult praying mantises, females have much larger thoraxes and their wings are never longer than their bodies, while males are more slender and their wings are longer than their bodies are.

The Diversity of Squirrels (in my backyard)

Notch-o on my roof

What: After my last post I decided I wanted to really get a handle of who is who in my backyard. It's pretty obvious who Captain Death is, since he has but one ear, but there are about 4 other gray squirrels that also use my yard at various points throughout the day. Another one has a large cyst like thing on its left side, making it another easy one to ID. The lady above has a pair of notches on her ears, presumable from a male biting them during their odd little courtship routine.

A while back I thought it would be a fun challenge to see how many wild animals I could touch. It becomes pretty obvious pretty quick that the easiest way to win an animal over is through its stomach, whether it's downy woodpeckers, woodchucks, beavers, or chickadees. So in the spirit of feeding wild animals and in order to get a better handle on the rascally little squirrels I set up a feeder in the middle of my yard. This way I can see them out in the open and watch them long enough to start to discern unique features that will allow me to recognize each individual (gender, size, coloration, scars, tail length, etc.). Next step will be to name them.

FIELD GUIDE TO THE SQUIRRELS OF 56 LATHAM CT:
1. Squirrel has one ear: Captain Death
1b. Squirrel has two ears
      2a. Has large cyst (or whatever it is) on left side: Lumplestiltskin
      2b. Does not have cyst on left side
            3a. Both ears notched: Notch-o
            3b. Both ears not notched
                  4a. One ear notched (has scraggly tufts on back): Tufts
                  4b. No notches in ear: Youngyun

Tufts

Tufts, showing those clumps of scraggly fur on back

Youngyun with a walnut I set out for her

Youngyun with feet extended backwards (grays can rotate rear feet 180o)

Where: My backyard (but could just as easily be yours)

Other notes: I've noticed that their mouths all seem to be a bit darker these days, probably from the non-stop chewing of walnut husk. My hands are stained for a couple of weeks after handling walnuts, and I imagine it sticks just as well to fur as to skin.

Captain Death

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What: In college I started Ye Olde Lovable Li'l Scamps Feeding Clubbe (Y'olls FC). We collected stale bread from the dining halls and spent lunch hour on the quads hand feeding the squirrels. After a few days we could easily recognize one squirrel from the other by personality as well as by physical scars on each animal (more than not had some sort of visible scar on its face). It turns out squirrels lead a pretty tough life. One in particular, who we called Captain Death, had a large scar cutting diagonally down across his face. He was certainly the most skittish, but once we earned his trust he was the one that would approach first and stay the longest. Each time a new person joined us, Captain Death had to be won over again.

Many of the females had ragged ears or other signs of the hazards of living. Males with aggressively court females and defend access to them (see my post from May 7 for more on that). I assume that many of the scars on the squirrels were from squirrel-to-squirrel interactions during breeding season. Once we had the chance of watching a red-tailed hawk swoop down and steal a squirrel off the ground. The hawk was successful and we then watched it eat the squirrel. I imagine that not every attempt ends this way and that many a squirrel lives to climb another tree, hide another acorn, a scar as wide as a talon bears witness to the fact that squirrels are prey.

Well this morning my mom, Callan, and my sister were outside when they spotted this sad little earless squirrel. He was happily (well, as happily as he could have been) cleaning the husk from a walnut from the shell. I've been finding walnuts hidden everywhere around my backyard. The gash runs from his eye (barely visible in some of the photos) back towards his left ear (you can easily tell it's a male in the photo below), which is noticeably absent. The wound looks fresh and I haven't seen this scar before so I'm assuming it happened in the last couple of days (there's no blood on the fur, so it at least had a chance to clean that off).

Ecological notes: The squirrel was eating a walnut from our tree. This has definitely been a bumper year for walnuts and a red squirrel (Tamiasciurus hudsonicus) has been fiercely defending it, trying in vain to fend off the grays from stealing a snack.

Where: We spotted the squirrel on one of the wonders of the modern world of Latham Ct (the Silver Maple in my driveway).