Tuesday, October 18, 2016

Wissahickon Part 1: Houston Meadows

Bumblebee on goldenrod
Last Saturday (October 15) was an absolutely perfect early autumn day, with temperatures in the upper 60s, crystal clear blue skies, and very low humidity.  I packed Kali into the car and we drove over to the north-westernmost neighborhood in Philadelphia called Roxborough for a hike in the 1,800-acre Wissahickon Valley Park, Philadelphia's largest and best-known park.  Our goal that day, in addition to just getting some exercise, was to inspect Houston Meadows, a restoration project undertaken by the city's Department of Parks and Recreation as part of an ongoing series of natural lands restorations throughout the city's larger parks.
Trail through goldenrod and little bluestem
A few aspens; there are others growing nearby at the edge of the meadow
Native little bluestem (Schizachyrium scoparium)
To my mind, the Houston Meadows project was not a straightforward "winner."  During the early part of the 20th century, the meadows had been an active farm before urbanization expanded outward to the very edges of the city limits.  When the farm was incorporated into the park, the land became fallow and quickly reverted to herbaceous old-field habitat - a "wildflower meadow" in common parlance.  This habitat was extraordinarily attractive to birds and butterflies that needed such habitat, and Houston Meadows became a birders paradise maintained by fires set periodically by neighborhood hoodlums.
Bluebird box on meadow slope
All was well until houses were built up to the very edge of the park, and then the field fires had to be suppressed.  This fire suppression allowed natural succession to kick in and trees and woody vegetation, formerly killed by the fires, began to creep into the meadows, changing the land first to a thicket and then to a young woodland.  The birds and lepidopterans could no longer find appropriate habitat and abandoned Houston "Meadows."
Goldenrod (Solidago spp.), boneset (Eupatroium perfoliatum) and native grasses
With support from a philanthropic foundation, the city decided to try to restore the meadow habitat and attract the birds back.  So, they brought in heavy equipment to clear the trees in the young woodlands, and they seeded the land with early concessional meadow species and native grasses.    

The result has been mixed in my opinion.  First, I have to admit that I don't know if the "target" birds have returned to the meadows.  If they have, they've "voted with their wings" and given the restoration their approval.  But, if the birds haven't returned, the project cannot automatically be dubbed a failure because (1) they birds may not have "found" the meadows yet, (2) the habitat may not have developed enough to interest the birds, or (3) the restored field really might not be suitable habitat.

This section of the meadows almost looks "western," with a big rock and conifers
Where the herbaceous vegetation has gotten established, the meadows are lush, productive and beautiful.  But Parks and Recreation seems (to me, anyway) to have left too many trees in the midst of the fields.  Hawks and other raptors perch in these trees and prey on the meadow-nesting birds.

In addition, the meadows are small and fragmented.  Some meadow-nesting birds seem to need 160 acres of grassland habitat to breed successfully, and these fields are nowhere near that large.  Other species, especially species that like brushy habitat, may be the first ones to recolonize the site.  To my eye, the habitat looks perfect for birds that like scrubby, brushy habitat.
Deer exclosure fencing
Parks and Recreation also included a deer exclosure as part of the project, but it is in a wooded corner of the meadows.  I don't know the motivation for excluding deer from a meadow project, but perhaps they were trying to expand a section of woodland and not develop meadow here.


Mark P said...

I wonder who managed the restoration project. Maybe they needed more input from people with a better understanding of the requirements.

The shot with the large stone does look like a scene from somewhere out West.

robin andrea said...

I really appreciate seeing this and reading your commentary on it. I like your analysis and how you evaluate the efforts to restore this habitat. I would never notice the details that you see, and I am enlightened by your knowledgeable perspective. Thank you for that.

Scott said...

Mark: The fellow who manages the Houston Meadows project is actually a former employee of mine. He knows his stuff. I'm just afraid that the vagaries and constraints of city politics may have gotten in the way of making this a great project.

By the way (apropos nothing), the first time I visited this site, just before restoration work was to begin, I got a terrible case of chiggers. It's the only time I've ever gotten chiggers in the East, and none of my colleagues who were with me in the fieled that day got the buggers. My luck!

Scott said...

Robin Andrea: Thank you for your kind comments. I've been doing this for 28 years now, so I'd better at least appear to know what I'm doing!