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.

Invasive Aliens and Alien UFO

A splendid late summer view of my preserve's meadows

A former member of my land stewardship staff, Mike, moved on five years ago to become the land manager at a preserve owned by another land conservancy in our area.  I consider Mike a colleague, and I contacted him when Temple University (where I am an adjunct faculty member) needed an individual to teach a class on invasive organisms.  It was a match made in heaven (both for Mike and Temple), and Mike is now teaching the class for a second year.

Mike (second from right) holding forth on restoration strategies

On Thursday, September 17, Mike brought his students to my preserve to examine invasive plants (no shortage of them here, unfortunately) and our organization's restoration projects.  I spent the morning outside (a rarity for me) accompanying the class as we walked about three miles through the preserve.

Handling (carefully!) an American chestnut burr

One of our stops was a reforestation area planted in 1994.  We incorporated pure American chestnut trees into the reforestation project, and now the trees are 30 feet tall and producing fruits (more appropriately called burrs).  The trees are all infected with the non-native chestnut blight fungus, but they are pumping out burrs like crazy nonetheless.  The burrs are really prickly and painful to hold; I don't know how squirrels manage to get them open.

Preparing for liftoff

After the walk, Mike brought out his drone to show the students how these devices can be useful for examining the landscape from the air.  He flew the drone about one mile away and returned it to the launch site, a tour that took 9 minutes.  The drone has the capacity to fly for about 18 minutes on one battery charge.

UFO spotted over the preserve

Mike remotely piloted the drone to fly over the meadows and woodlands of the preserve, and then to circle the tower on the right (one mile distant) in the image above.  All the while, the drone was sending back remarkably clear video that Mike recorded on his iPad.  He promised to share the video with me; if he does so, I will post it later.

Class Field Trip

High School Park Restoration Manager Kevin (bearded, far left) with students

On Friday, November 7, I accompanied my Ecological Restoration students from the University of Pennsylvania on a field trip to High School Park in one of Philadelphia's "inner ring" suburbs.  I've written about High School Park in several earlier posts.  The park is the site of the municipality's original high school, which was abandoned when a new school was built in another location, fell into decrepitude, and was finally razed.  Since then, the 11-acre park has been adopted by a "Friends" group, which has been working to restore the riparian woodlands, up-slope forests, and hilltop plateau with native plants.

Stairs leading from former athletic fields to the hilltop location of the old school

Our guide for the trip was the Friends' Restoration Manager, Kevin.  Although the site is small, it is overrun with invasive plants.  Because the park is public property, Kevin is not authorized to use herbicides.  In addition, he has no help other than volunteers that he can cajole into working.  In my opinion (and experience), he's fighting a losing battle, but he is supremely dedicated to the work and to the Friends.

Along a mid-slope forest trail

Because the park is located in an "inner ring" suburb, its infrastructure is old.  The sewer line following the creek that runs along the north edge of the park is leaking, and the municipality must replace it.  Next spring, the municipality's contractor is going to excavate a massive trench alongside the creek and through a major portion of the park to install a new 5-foot concrete sewer pipe.  Any work that Kevin has accomplished to date there will be destroyed.  I'd find such a setback really disheartening, but Kevin sees the silver lining in these storm clouds because the construction will require streambank restoration and he thinks the park could actually end up better than it is now.

I'll withhold judgement until I get a chance to see the work.

Pretty Perfect Weekend Field Trip

I'm teaching ecological restoration at the University of Pennsylvania this term as an Adjunct Professor.  It's a class for graduate students, and I have taught it every other fall term since 1992 - that's 22 years now, about as long as some of my youngest students have been alive.

I'd like to take the students on a lot of field trips.  The more that they can get out in the field to see actual restoration work, the better.  But UPenn is very near the heart of Philadelphia and it's hard to get to a site, take a tour, and get back to campus in the allotted 3-hour class period.  So, I always offer a weekend field trip to my preserve.  We did the trip this last weekend.

Many of the students are foreign nationals, and most don't own cars, so they use the regional rail network to get near my preserve, and then Kali and I pick them up at the train station.  Yesterday's trip started off badly - a 60-year-old man walking on the railroad tracks was struck and killed by a train (it happens more often than you might imagine; most victims are suicides), which delayed the start of the trip by one hour.  But the students all finally arrived and we enjoyed two hours of nearly perfect early autumn weather.

Return to High School Park

High School Park Stewardship Manager Kevin preparing a dogwood live stake

A year ago, I brought my undergraduate Landscape Restoration students to High School Park, a 10-acre municipal park in a Philadelphia suburb that a non-profit "friends" organization adopted in order to re-establish native ecosystems on the site of the community's old high school.  At the end of our field trip in 2013, as I was preparing to leave, a young man came by walking his dog and we struck up a conversation.  It turned out that this fellow, Kevin, was enrolled in the graduate landscape architecture program at the university where I serve as an adjunct instructor, and that he had just applied for the part-time Stewardship Manager position at High School Park.

I needed some part-time help in my preserve, so I asked Kevin to call me if he found that he had some time.  Kevin got the job at High School Park, and he did some restoration work for me, too, all while trying to finish his Master's degree (which he will do next month).  So, when it came time for a field trip this year, I asked Kevin to escort my students - graduate students this year - around the park, which we did on a drizzly, cold April 3 morning.

An introduction to the restoration work

We spent a lot of time in the floodplain of Tookany Creek, which forms the northern border of the park.  Like all the streams in the Philadelphia suburbs, Tookany is a "flashy" stream that roars after rains and then dries up to nearly a trickle between storms.  Water quality is "impaired," a polite term for terrible.  The streambanks are constantly eroding, and much of the work in the park is dedicated to trying to stabilize them as best as possible. 

Considering options for streambank restoration in an urban watershed

The municipality has spent a lot of money installing "cribs," telephone poles anchored into the streambank and filled with soil, then planted with trees and shrubs.  The cribs hold for a while, but inevitably the stream begins to erode behind the structures, which usually results in a catastrophic failure during a major flood.  In the lower right of the image below, the upstream end of one of the cribs is visible.  If it doesn't receive some attention soon, that crib is doomed.

Downstream view of Tookany Creek with crib 

Though spring is finally getting underway here in the northern Piedmont, only a few flowers have dared to blossom yet.  One that is not so shy is lesser celandine, an invasive buttercup that carpets our urban and suburban floodplains excluding native spring ephemerals.  Though the plant flowers profusely, ecologists believe that tiny bulbettes attached to the tops of the roots are actually more responsible for its spread than are its seeds.  Because he plant favor floodplains, the bulbettes detach from the mother plant and wash downstream during floods, establishing new colonies.  

Lesser celandine (Ranunculus divaricata)

The site of the demolished high school on a plateau above the creek has been converted to a meadow.  Though the "friends" have tried twice to create a meadow dominated by native species, the meadow consists mostly of non-native, invasive weeds.  The repeated failure can be attributed to the fact that the building was bulldozed into its basement, leaving a calcium-rich, high pH substrate for plants that prefer low pH soils.  In addition, the layer of topsoil spread over the site was far too shallow to support most native species.  Scheduling difficulties with the planting contributed to the failure.  And, finally, becaue the park is public property, the private "friends" group cannot apply herbicides that might help keep the weeds in check.   

At the edge of the "native" meadow

Kevin also has to beg for help from the municipality's parks department, which has mowing equipment that the "friends" group cannot afford.  While the park employees try to be helpful, sometimes they act more like "cowboys" more adept at mowing large expanses of turf.  Two weeks ago, the park guys mowed down shrubs planted at the edge of the meadow - another setback.

Colorful stakes failed to prevent the parks "cowboys" from mowing shrubs

At the end of our tour, Kevin showed the group some "planting logs" he invented to try to speed-up the development of a riparian shrub layer.  Kevin creates a "burrito" of mulch and soil wrapped up tightly in burlap, and then he inserts dogwood cuttings into the logs.  He keeps the burritos moist, which encourages the dogwood cuttings to develop roots.  Then, he takes the rooted logs down to the streambank and secures them with more dogwood cuttings in an effort to jumpstart a stabilizing shrub cover.

A burlap planting log

How Kevin will secure the rooted logs onto the streambank

Restoration Setback Courtesy of Hurricane Irene

The creek at 8:30 a.m. Sunday.  Though it had only been about three hours 
after the crest of the flooding,the creek had already subsided significantly--
a typical "flashy" urban stream.
 

In our heavily urbanized watershed, restoration is always going to be a challenge.  There are non-native invasive plants lurking in backyards and untended corners of commercial properties.  White-tailed deer find refuge from hunters in those same pockets of green, and then make their way under cover of darkness into the preserve to eat the trees.  Perhaps the biggest problem, though, is that every storm brings a new wave of flooding, and hurricanes like Irene create so much havoc on the floodplain that it's difficult to get trees firmly enough established to withstand the onslaught of the next big flood.

Floodwaters toppled trees protected in plastic shelters on the creek floodplain.

Our last hurricane was Floyd in 1999, so our trees have had 12 years to put down roots deep enough to remain in place. Unfortunately, between the highly competitive non-native porcelain-berry vines (Ampelopsis brevipedunculata) and the fact that many of the planted trees are growing in broken shade (cf., out in full sunlight), they tend to grow slowly.  Few had achieved a stature to allow them to stand up to floodwaters that nearly rivaled Floyd's.  So, more planting is in order over the next few years.  The pattern has become discouraging and more than a little bit disheartening.

The approach to the second-oldest stone arch bridge in the county, built in 1817.

Formerly a municipal road along the creek and now closed and  incorporated into the preserve trail system.

I don't think the municipality wept any tears about giving up the rights to this perennially flood-prone road.

For a time, the wetland (pond on the right of image) and the creek were one.

At normal flows, the wetland is 10 feet above the level of the creek.

After filling the wetland basin (left side, out of image), the creek washed away the split rail fence

and moved debris against this bench cemented deeply in the ground.

Bench and flood debris from a different angle.  Historical note: the log jammed against the bench is hollowed out.  It is a wooden water pipe used by mill workers in the mid-1800's to bring sweet water from a spring on the the hillside above the creek to one of the many water-powered mills on the banks of the creek.  Even in the mid-19th century, the creek's water had become so fouled that the mill workers needed a source of clean water.  The wooden pipe was excavated from the mucky bottom of the wetland when we restored the wetland pond a few years ago.

Part of a bird blind formerly located on the edge of the wetland.

Flood debris lodged against an access gate.

Carrifran Wildwood

In 2000, I attended the Society for Ecological Restoration's conference held in Liverpool, England that year. In the exhibitors' hall, I came across a display set up by Scotland's Borders Forest Trust (BFT), a non-profit organization that had just adopted a grassroots volunteer coalition called the Wildwood Group which had the audacious idea of re-creating a native forest in a valley that had been denuded and devastated by sheep and goats for centuries. Staffing the BFT's exhibit was Hugh Chalmers, whose title was Project Officer; Hugh was the on-the-ground man directly responsible for implementing the vision of the Wildwood Group. I was so captivated by Hugh's description of the project that (1) his inspiring vision literally choked me up as we were speaking, and (2) I sent BFT all of my remaining British pounds when I left England, and I have been a BFT member and supporter ever since.

In 2009, BFT published The Carrifran Wildwood Story, and I have prepared a review of the book that will appear in the journal Ecological Restoration. Here's a draft of my review.

The Carrifran Wildwood Story

Myrtle and Philip Ashmole, with members of the Wildwood Group. 2009. Jedburgh, Scotland, UK: Borders Forest Trust. Paper, £15. ISBN 978-0-9534346-4-0. 224 pages.

What does it take to turn an ecologically “green desert” into a diverse, native deciduous forest—especially when the templates available to serve as guides are, at best, tiny ecosystem fragments with uncertain management and land use histories stretching back centuries? This was the daunting task faced by the all-volunteer Wildwood Group working in the harsh Southern Uplands of Scotland as they sought to acquire an entire watershed and “re-create…an extensive tract of mainly forested wilderness with most of the rich diversity of native species present in the area before human activities became dominant.” The Carrifran Wildwood Story, published to commemorate the tenth anniversary of the planting of the first trees on the site on New Year’s Day, 2000, in the “Millennium Grove” documents the project’s complete history from conception and land acquisition through the reforestation of nearly the entire 1,640 (665 ha) Carrifran Burn watershed.

The book is a popular (not scientific) account—highly readable, well-written, and lively. Nevertheless, the authors do not short-change the essential climatologic, edaphic, hydrologic, topographic, botanic and ethnographic characteristics of the region and the site that underpin the project. In this sense, the Wildwood Group’s planners were following the footsteps of visionary environmental landscape architect Ian McHarg (1969), who advocated for developing as thorough an understanding of a locale as possible prior to undertaking any action on the ground.

The book is divided into 12 roughly chronological chapters, each introduced by a brief outline of the topics addressed in the chapter. The first two chapters provide an overview of the conception of the project. The Wildwood Group visionaries imagined purchasing a small catchment whose native vegetation had been severely depleted by centuries of intensive sheep and goat grazing, and then restoring native forest to the watershed. The third and fourth chapters review the Wildwood Group’s five-year efforts to locate and raise money to purchase a suitable watershed—first in the Scottish Borders (the counties bordering England) and then, when a suitable site could not be located there, a bit further north in the Southern Uplands. A thorough and comprehensive overview of planning for the restoration, including evaluating the current conditions in the drainage, examining the prehistoric palynological record, and identifying contemporary woodland sites that could serve as models and sources of propagules for a re-created forest is the subject of chapters 5-7. The decade-long planting program carried out by forestry contractors and a large cadre of dedicated volunteers is covered in chapters 8-11. Finally, since forest restoration by its very nature requires centuries to complete, the twelfth chapter chronicles the encouraging short-term changes observed in the valley over the first decade and projects the site’s ecological trajectory into the future.

The Wildwood Group adopted the evocative name Carrifran Wildwood for their initiative. Carrifran, freely translated as “seat of ravens” or “raven’s crag,” has many local spellings and pronunciations, none of which, apparently, were the ones ultimately adopted by the Wildwood Group (which calls the valley CarriFRAN). Recognizing that readers outside Scotland may not be familiar with local topographic and geographic terms, the authors thoughtfully included a glossary of “descriptive words with various origins” on page 52, though the list is not comprehensive. For example, the authors frequently use the word cleugh but don’t define it (a cleft in a hill or a ravine). In addition, readers may want to keep a bookmark lodged between pages 68 and 69 to make frequent reference to the unfamiliar place names and planting sections shown on the excellent site map.

Among the facets of this project that struck me most strongly were the historic rights and privileges afforded the public with which the Wildwood Group had to contend. The Carrifran Wildwood was established on private property owned by the Borders Forest Trust (the official nonprofit entity that served as an umbrella group managing the Carrifran Wildwood as well as many community forestry projects). Nonetheless, the Wildwood Group had to confront issues that stand in stark contrast to the few constraints faced by restorationists working on private property in North America. For example, while the Wildwood Group always envisioned that “access will be open to all,” the group was forced to enclose the entire Carrifran watershed with perimeter fencing to exclude wild roe deer, domestic sheep, and feral goats. In the process of protecting the newly planted trees, the fence excluded “hillwalkers”—hikers who enjoy the privilege of traipsing freely over private property throughout Britain. In addition, once the fence was in place, the Group had to remove the feral goats that roamed throughout the hills. The rural residents of the Southern Uplands expected to encounter goats, and their exclusion from the Wildwood through a combination of live capture and relocation and (in the case of a few highly elusive individuals) lethal sharpshooting, proved controversial. In his Foreword to the book, Professor Aubrey Manning notes that,“…it must have been very demanding of the tolerance and forbearance of the local people, of planners and statutory bodies like Scottish National Heritage and the Forestry Commission and of charitable trusts. A lot of persistent persuasion will have been involved and this story is set out here in a fascinating way” (page 3).

Excluding hikers with a fence would cause few problems in North America; in fact, hikers here need to secure permission before entering private property. Similarly, in most cases, North American landowners have the right to control feral animals on their own property and also may be able to control wild populations like deer if landowners can document that the animals are causing economic loss or hardship.

Another difference between the restoration efforts at Carrifran and those in many parts of temperate North America was the lack of non-native invasive plant species that needed to be managed in the Scottish project. To be sure, the trees planted at Carrifran had to compete with dense patches of native bracken fern (Pteridium aquilinum), which the Wildwood Group was forced to manage mechanically and chemically. Forest restorationists working in eastern North American woodlands with very high white-tailed deer densities often must contend with a similar situation when the ground layer vegetation has been decimated by browsing, leaving only a dense cover of unpalatable hay-scented ferns (Dennstaedtia punctilobula). However, the absence of the fast growing introduced vines, lianas, and shrubs that can overtop saplings planted in eastern North America during a single growing season made me almost wish that bracken was my greatest challenge in establishing new woodland.

The book is thoughtfully designed and visually appealing. The designer restricted the text to two-thirds of each page, and then devoted the remainder of the page to full-color photographs, maps, and blue-background sidebars that explore the details of subjects mentioned in the accompanying text. The sidebars also occasionally contain poetry, evocative watercolor reproductions, and anecdotes and testimonials contributed by Wildwood Group members who were integral to the project’s success.

The book will appeal most directly to deciduous forest restorationists working in the temperate zones. However, the detailed account of the ecological planning that took place before a single tree was introduced onto the site should be of interest to all restorationists. And, those of us who fancy ourselves to be stewards of the earth will find ample inspiration in the audacity and execution of this truly visionary project.

Reference

McHarg, I. L. 1969. Design with nature. Philadelphia: The Falcon Press.