Showing posts with label Princeton University grounds. Show all posts
Showing posts with label Princeton University grounds. Show all posts

Saturday, September 18, 2021

Butler Tract Meadows Restoration?

This is the story of what can go wrong if you plant a native meadow and then don't take care of it. Princeton University has been installing some native meadows, and some have done a lot better than others.

Just off of South Harrison Street, framed by Sycamore Rd and Hartley Ave, are some meadows that were planted in 2016 following the university's demolition of the Butler apartments. It was a well intended succession from graduate housing to native meadow, and when I took a look in 2019, the meadows were still hosting diverse native wildflowers. 

Two years later, these signs appeared: 
"Butler Tract Meadows is under an invasive management program for this year."

For most of the summer, it wasn't clear what that meant. The signs appeared early in the growing season, but I could find no sign of any action. 


This photo tells the story of what happened to the native meadow over the course of five years. The usual nonnative invasive species moved in and began to dominate, with mugwort foremost among them. The white flowering plant on the left is Japanese knotweed, which can form large monocultures as well. Bamboo is getting a foothold in the lower lefthand corner of the photo, and in the distance can be seen the sproutings of black locust, a native tree that nonetheless can move aggressively into native grasslands. 

Sericea lespedeza (L. cuneata) is another super-aggressive nonnative. Newer on the Princeton scene, it can rival mugwort in its capacity to displace diverse native plants, for instance along the gasline right of way that crosses the Princeton Ridge. 
And here's crown vetch, which climbs over everything around it. Both crown vetch and Sericea lespedeza were planted extensively along freeways to control soil erosion, reducing one environmental harm while creating another. 

I did notice a few native species still present, including this wild senna. The only practical means of shifting the balance back to the native species on this scale is through use of herbicides. Some people lump all herbicides together and pronounce them evil poisons--an indiscriminate rejection borne of their often indiscriminate use. But there are many kinds and many formulations, some far safer than others, and the aim as with medicines for people is to use as little as possible, in a targeted way. 

The way to reduce the use of herbicides is to be proactive and intervene early to kill the invasives when they are still few in number. That would have been something to do from the beginning, back when a more targeted, minimalist approach was possible. 

My friend Basha who lives across from the Butler Tract told me they had finally done some spraying. A week later, I took a look. Here you can see the black locust tree sprouts turning brown while many other invasive plants appear untouched.
This big patch of mugwort shows some sign of dieback, but pretty uneven results thus far.
I'm guessing that patch in the background of this photo was crown vetch. In the foreground is probably common cinquefoil (Potentilla simplex), which is native but a very rapid spreader.

It will be interesting to see how this goes. My experience is that institutions have always understood that lawns and landscaping take ongoing care, but they have yet to grasp that more naturalistic areas like meadows also need ongoing intervention. At the Butler Tract, they seem to be trying to figure out what that means.

Friday, September 27, 2019

Urban Succession--Butler Apartments Turned Into Meadows

Normal urban succession proceeds from grassland to shrubland to woodland, then to a climax community of houses and lawns. Near the corner of Sycamore and South Harrison Street, a much different sort of succession took place three years ago. The Butler Apartments had stood here since they were built in 1946 in a scramble to house returning veterans, then were later turned into graduate housing. Seventy years later, they were torn down and turned into meadows--real meadows, not some development called The Meadows that names itself after what no longer exists. The scattered trees give the place a savanna-like look, and the preserved infrastructure of streets and fire hydrants serve as a deluxe means to appreciate and care for the plantings.

At the urging of my friend Kurt, I finally paid a visit. I happened to be teaching a 16 year old to ride a bike, so we parked the truck on Sycamore and explored this ultra safe biking territory.

When creating meadows, it's common to scatter "wildflower seed" with species that create a burst of color the first year, but are not native to the area. Surprisingly, this planting reflects closely the local flora, and has been flourishing with all the rain this year. A few of the usual invasive species have gotten small footholds, but the meadows are still dominated by a diversity of natives.

What follows here is a sampling of the plant diversity that can now be found there, and will help with identification for anyone who goes there. In this photo, a maple is turning color early, and doing a dance with a powerline that may or may not still carry electricity.

Korean dogwoods, leftover plantings that still adorn the streets, offer edible fruit at many of the corners.

The white clouds of late-flowering thoroughwort set off the more colorful wildflowers nicely.

Common milkweed sometimes caters to the needs of monarch caterpillars.


Oxeye sunflower, which is common in seed mixes though I've never seen it growing wild.

Grasses to be encountered are Indian grass, switchgrass, purple top, and this shorter one that matured earlier in the year, which is looking like a robust version of wild rye.

In the background is mugwort, a highly invasive species that would likely continue displacing natives if this site is kept as meadow.

I call this frost aster.

Various goldenrods.

This is looking like Japanese hops--an invasive vine, though not nearly as invasive as the kudzu-like porcelainberry, which hopefully has not gotten established here.

Mistflower (wild ageratum) is a native occasionally found in the wild. It grows low to the ground, and can survive only along the edges, given all of its tall competitors here. Eupatorium coelestinum in latin.

Crown vetch is an invasive just beginning to show up.

This is looking like a tickseed sunflower (Bidens)--an annual that can get large and showy, but also can be a bit weedy.

It's been a good year for partridge pea, another native that tends to be rare in the wild but performs really well in these meadow seedmixes.

These monarchs are fueling up at a New England aster waystation prior to making their annual journey to a mountain range in Mexico for the winter.

Pokeweed, also called inkberry for its dark berries. In springtime, there's a way to harvest and prepare "poke salad" so that it is edible, but not the berries.

Other typical wildflowers to look for are wild bergamot, mountain mint, and wild senna.

Eventually this meadow could be shaded out by trees or undone by new construction or the expansion of a few nonnative species, it is currently a great example of a meadow packed with mostly native species growing in balance. Thanks to my friend Kurt for finally getting me over there.

Tuesday, December 06, 2016

A Modern Times Moment With Persimmons

There's a scene in Modern Times where Charlie Chaplin's fantasy of domestic bliss includes reaching out the window to pluck some grapes. A cow comes to the back door to supply milk. Nature is cleverly tended to put its bounty within arm's reach.

I think of that scene every time I bicycle over Princeton University's graceful Streicker Bridge above Washington Road, ever since I noticed some native persimmon trees rising up alongside the bridge. They were planted intentionally, like Chaplin's grapes, and each year they've gotten higher, pressing their leaves and fruits closer to the fencing .

Posts from 2014 documenting the persimmon trees' rise can be found here and here, and a 2015 post is entitled "Close but no persimmon".

There's a catalpa growing within reach as well, but that's not as appetizing, somehow.

This year, the long awaited casual Chaplinesque reach was finally possible. Heading to a university soccer game, I'd check their progress.

The fencing is a real deterrent, though, as if Chaplin's dream of domestic bliss were set in a high-crime neighborhood where all the windows were barred.

At last, time and fruit seemed ripe. But wait, one problem. It's a persimmon. Can't they be astringent in the extreme? So much expectation, only to have a very pucker-mouthed ride home.

The soccer season passed less than gloriously into history, the leaves fell. A few persimmons remained on the tree, but out of reach.

Giving it one last try, I gave up on the fruits coming to me and went down below the bridge to see what lay on the ground. There, preserved on top of a leaf, was one ready to taste. It was sweet, without a hint of astringency, delicious beyond all expectation.

Sometimes dreams don't play out the way you imagined, but they can still come true.

Saturday, November 26, 2016

Norway Maples, and Seeing the Future

One purpose of this blog is to help people to look at nature now and see where it's headed. Every gardener imagines the harvest while planting the seeds. In science, one extrapolates from past and current trends to predict the future. With practice, one can look at a woodland and see not only the present but past and future as well. As a land manager, one envisions two futures--one without intervention, one with. Because we've altered local habitats so much--through altered hydrology, past farming, introduced species, banishment of important forces like fire and predators like mountain lions and wolves--intervention can help restore functionality that no longer happens naturally.

Autumn is the easiest time to divine a woods' future, because each species shows its colors, making trends easy to spot. For instance, learn the Norway maple's brand of yellow this time of year, and you'll start seeing them all over town. Unpalatable to deer, they rise unnoticed until they become full-sized trees, mostly along backyard fencelines.

That's what's happening on a larger scale in the hidden valley between the Princeton University chemistry building and Washington Road. That mix of yellow and lingering green indicates that the Norway Maples are taking over the top of the valley,

and extending downstream. This is the perfect time of year to see the extensive invasion by this nonnative tree. Why have I on multiple occasions urged the university grounds staff to cut or girdle these trees, despite their attractive yellow in autumn?

The problem is an ecological one. This forest, one of Princeton's oldest, is steadily shifting from native trees that feed local wildlife to nonnative vegetation that does not. As the shade-tolerant Norway Maples push up into the native canopy above, their competition for water and nutrients weakens the giant oaks and black gums, hastening their decline and increasing their susceptibility to wind storms. Young native trees--preferred by deer and less shade tolerant--can't compete with the Norway Maples, which grow quickly, green up sooner in spring and drop their leaves later in the fall. This photo shows a 1-2 centuries old oak with a sea of Norway maples rising underneath.

Fortunately, most Princeton woodlands have not been invaded by Norway maple, though it would be worth it for land managers to take a walk through the woods to see if they are starting to get established elsewhere in Princeton's open space.

Except in that Washington Rd. gorge woods, they have proven invasive only in people's yards, showing highly localized invasiveness much like Japanese maples and Rose of Sharon. This photo, taken along North Harrison Street, shows the classic problem with ignoring the silent ascent of Norway maples, in this case under a powerline. Chances are they grew unnoticed by the homeowner, and now will require repeated pruning to keep them from threatening the wires.

At least the half of the tree closer to the street shades the pavement in the summer,

but another annoying aspect of the species--their dense shade and aggressive roots that leave little sun or water for the lawn--has made it impossible to grow grass on the steep slope.

Like climate change and the nonpoint pollution of our waterways, the Norway maple silently transforms the world, undermining food chains and biodiversity, while our attention is elsewhere.