The weather this month has been up and down like a yo-yo: A low of 6oF on February 2, highs in the 50s and 60s for six days, then a low of 14oF on February 9. During those warm days the sap started running in the trees. I wouldn’t have noticed except …
On February 10 during a walk in Schenley Park I found flash-frozen sap on the damaged trees. At top, a fallen red oak made a red-orange waterfall. Below, a small amount of sap in a fungi-encrusted tree dripped like orange ribbons.
Sap runs and freezes inside healthy trees, too. We just can’t see it.
If you live in the City of Pittsburgh and visit our parks you’ll want to participate in this survey, available now through April 2019.
Pittsburgh has 165 parks sprinkled throughout our neighborhoods from small playgrounds to regional parks — Schenley, Frick, Riverview, Highland and the future Hays Woods. The City’s goal is to have well maintained parks within a 10-minute walk of every resident.
Perhaps you’ve noticed that infrastructure is crumbling in many of them. The park system gets big donations for capital improvements (bricks & mortar) but not for maintenance, so we have new buildings like the Frick Environmental Center but deteriorating playgrounds, landscape and trails. How do we fix that inequity and how much will it cost?
Hackberry fruits, pictured at top, are drupes similar to cherries and peaches with fleshy fruit surrounding a central pit. The fruit is thin and the pits are large so we rarely eat hackberries but birds love them.
The pits in cherries and peaches are made of wood (or something like it) but hackberry pits are made of stone: calcium carbonate inside a lattice framework. When Hope Jahren used Xray diffraction on the crushed lattice material its composition came up “opal.”
When I found this out I searched for the pits under hackberry trees in Schenley Park. At this time of year the fleshy purple fruit is gone, only the white pits remain. Here’s what I found, one whole, one opened. The exterior is a network of tiny raised lines.
The pits don’t look like opal and probably never will. You’d have to use acid to remove the calcium carbonate (the white stuff of seashells) and then examine the remaining latticework under a microscope. There’s a tiny bit of opal in there.
And so I wonder: How does a tree put opal in its drupes? I don’t know, but here are the raw materials:
[The rock] Opal is formed from a solution of silicon dioxide and water. As water runs down through the earth, it picks up silica from sandstone, and carries this silica-rich solution into cracks and voids, caused by natural faults or decomposing fossils. As the water evaporates, it leaves behind a silica deposit. This cycle repeats over very long periods of time, and eventually opal is formed.
Last Sunday, October 7, it felt like summer when Steve Tirone and I went looking for Armillaria in Schenley Park. We didn’t find any honey mushrooms but Steve found an amazing insect along the Beacon-Bartlett meadow trail.
This praying mantis (possibly Tenodera sinensis) was not alone. When we paused to take photographs, we saw another mantis perched nearby and a third one flew away from us. Gigantic flying bug!
Fall is mating time for praying mantises. The adults will die but their egg masses will survive the winter. Here’s what the egg sac looks like. Don’t take one home until you’ve read these Praying Mantis Egg Sac instructions. They will hatch in your house!
Last weekend was a busy time for praying mantises, hanging out in Schenley Park.
Yesterday morning this oak was intact as we searched it for warblers in Schenley Park. Last evening three Duquesne Light trucks were parked below it, fixing the wires it hit when a big chunk fell on Bartlett Street.
Here’s what broke (photo below). Most of the tree still stands but I wouldn’t be surprised if DPW chops it down now that it “misbehaved.”
This is not the only 100-year-old oak that’s fallen in the park in recent weeks. This oak fell across the Falloon Trail in July …
… and this one fell last week at the edge of Overlook Drive.
None of the crashes were caused by strong wind. The trees just broke and fell. The Fallon and Overlook trees had root rot, caused by Armillaria fungus. (See below for more on the Bartlett tree.)
You can see it inside this fallen trunk: black sheets of old Armillaria and white sheets of mycelium, the new growth, in the center.
If this stump was damp on a warm, very dark night (impossible in Schenley Park) the fungus would glow in the dark — a phenomenon called foxfire.
We usually don’t know that a tree is infected but the fungus will give us a hint this month. Armillaria produces fruit in autumn that we call honey mushrooms. (Here’s a USDA photo of one species, Armillaria tabescens.)
If you find honey mushrooms at the base of a tree, that tree is infected.
Unfortunately there’s a lot of Armillaria in Schenley Park. I’ll look for mushrooms this month to find out who’s in trouble.
NEWS about the Bartlett tree: The branch that fell on Bartlett Street was hollow — probably not Armillaria but it was bad nonetheless. Here’s a photo of the thickest part of the branch after it was chopped up.
Despite the Great Race road closures, eleven of us met at Bartlett Shelter this morning for a walk in Schenley Park. The air was chilly but the birding was good because the north wind brought us new migrants.
I took the group photo, above, at the end of the walk because we were distracted from the start. There were warblers in the trees above us! Cape May, Black-throated Green, Magnolia and Blackpoll.
Ultimately we saw 23 species + an unidentifiable flycatcher (listed as Empidonax sp). We were surprised to find no thrushes or sparrows so we crossed the road beyond our cars to find two song sparrows at the end. Still no thrushes other than robins.
Best find for the day: Mushrooms! My favorite was spectacularly orange but I’m saving it for late October.
And here’s another mushroom. Do you know what it is? (I don’t remember.)
Thanks to all for coming out today. My last scheduled walk for the year will be on October 28 at Duck Hollow.
At the end of September the weather’s fine and there’s plenty to see outdoors. Goldenrod and asters are blooming but everything else has gone to seed, fruit, and nuts. This is great news for chipmunks.
Join me for a bird and nature walk in Schenley Park on Sunday, September 30, 8:30a – 10:30a.
Meet at Bartlett Shelter on Bartlett Street near Panther Hollow Road. We’ll see birds, fall flowers, fruits, seeds, acorns and busy chipmunks.
Dress for the weather and wear comfortable walking shoes. Bring binoculars and field guides if you have them.
Before you come, visit my Events page in case of changes or cancellations.