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Protectors of Pine Oak Woods · Current
Issues · Gretta Moulton |
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Clove Lakes Restoration By
Don Recklies, Naturalist Forest Restoration # 180 06-18-11 Once
again weather favored us and Protectors’ 180th Forest Restoration
was sunny and warm with temperatures in the mid 80s.
We met at Clove
Lakes park in order to remove invasive species from newly re-forested
areas, as we did around this time last year.
Most of our regular participants were otherwise engaged - at a
function in another park for the most part - and I did not expect much of a
turn-out, but Barbara Trees, who co-ordinates volunteers for Clove lakes
Park, and Susan Kornacki, who co-ordinates
volunteer services for the Million Tree Initiative, sent a last moment notice
to the new group of Clove Lake stewards alerting them to our presence,
and three members of the current year’s class joined us for the morning
work session, bringing our number up to five. We chose
to work in Area A which is the oldest of the recently replanted areas. I should explain for those of you who
haven’t read the report of our earlier Forest Restoration at Clove
lakes. Several years ago the Natural
Resources Group, the division of NYC Department of Parks and Recreation
tasked with managing invasive species in the city’s parks, began a multi-year
reforestation experiment at Clove Lakes in a highly degraded area. Over a period of several years they
systematically cleared sections of the degraded area with herbicides and
began replanting them with native trees and shrubs. One of these areas was seeded with a close
growing Japanese grass, carefully chosen for its non-invasive qualities, to
see if it would suppress regrowth of invasive species until the trees and
shrubs had grown tall and thick enough to cast their own suppressing shade. (I don’t know how that experiment is
working out, but I’m curious.) The
other areas were depended on active human intervention (here read hand
clipping and pulling) to keep the returning invasives
at bay. This project is still on-going
and has been greatly accelerated by planting large numbers of trees as part
of the Million Tree Initiative, and was the impetus for a series of
stewardship classes at Clove Lakes to train volunteers to recognize unwanted
species in order to be able to remove them from the planted areas. Some seven of our members attended the
first series of these classes, and, although our concern is primarily in the
Greenbelt, our members felt obliged to make some small return for the classes
and implements provided by returning to help with invasive removal, thus the
return to Clove Lakes. We chose to work in the earliest of the planted areas,
and spent our time there pulling up Porcelain Berry, Oriental
Bittersweet, and Japanese Honeysuckle (not omitting Garlic-mustard and
Japanese Knotweed). These edges of
this plot were pretty clear, especially close to the asphalt walkway, but
toward the interior Porcelain Berry had returned with a vengeance, mounding
so thoroughly over saplings and shrubs that they did not so much compete with
them for light as to deprive them of it.
Porcelain Berry (Ampelopsis brevipedunculata)
is a little different from the woody vines we customarily tackle in the
Greenbelt; unlike the twining vines such as bittersweet and honeysuckle which
twist about young saplings and strangle them with a woody ligature, Porcelain
Berry climbs by means of a multitude of green tendrils which wrap about stalk
and stems alike. It is a perennial
vine, but not very woody, and because it doesn’t twine it doesn’t strangle
the tree or shrub it grows upon. It
does, however, grow prolifically, and in a very short time can completely
cover the shrub it grows upon, putting it into deep shade. There’s a subtle distinction for you: this
vine doesn’t strangle, it smothers, but that’s little consolation for the
victims. Our native Catbriar is woody, climbs with tendrils as well and
sometimes takes over clearings, but doesn’t grow nearly as fast and furious
as does Porcelain Berry. Porcelain Berry’s pretty lavender and blue late summer
fruits produce a large quantity of seeds, and wherever it grows the seed bank
in the soil is well provisioned with seeds for years to come (the viability
is a guess on my part; a quick web search only unearthed a statement that the
viability of Porcelain Berry seeds was “variable”). The result is that once this vine gets
established in an area, even after existing vines are killed, there are
hundreds of new sprouts each spring, and they grow fast. One of the NRG’s ideas was that volunteer
tree stewards might be able to pull up these young sprouts starting early in
the year before their roots became well established and the vines more
difficult to uproot. Many vines we
attacked were well developed and so interlaced with other plants that it was
difficult to uproot the entire plant.
In those case we pulled what we could and
clipped the remainder from the base of the tree as far away as we could
reach. In some cases Porcelain Berry
was bending the saplings far over onto the ground, and we wanted release them
and to provide them light by removing the vines from the upper branches. This was difficult to do because the
Porcelain Berry tendrils stubbornly attached the vines to every leaf and
twig. We did the best we could but
often just had to cut the vines and leave the remains to wither on the trees
in the summer heat. To my mind our session at Clove Lakes exemplifies a
problem facing the Department of Parks reforestation efforts. It is relatively easy to get volunteers to
gather to plant trees and shrubs; the activity is attractive - everyone sees
its value and takes great satisfaction from taking part. It is very difficult, however, to find
volunteers to do the sometimes hot, dirty and demanding work of caring for and
policing the previously planted areas, especially when they are rank with
growth and difficult of access. What’s
more, planting can be done once, but the effort to maintain those plants goes
on and on, and requires some dedication.
Yet there are individuals and groups in almost every major city park
that make that commitment, and they should be saluted (and the Protectors who
support our Reforestation Workshops should give themselves a little pat on
the back too). Seeing the enthusiasm of the current stewards at Clove Lakes
Park led me to ruminate about the wisdom and value of various restoration
schemes. The arguments against
invasive removal generally can be reduced to four: undertaking it is too
expensive, it does more harm than good, it will be ultimately unsuccessful,
and finally, as a matter of philosophy, nature can and should be left to take
care of itself. All these points of
view can be variously defended or refuted to create a spectrum of attitudes
toward invasive removal, but I believe that Protectors does not adhere to any
particular stance about restoration efforts, but prefers to examine each
individual instance on its own merits.
The current controversial plan to restore Crookes Point at Great Kills
(which you can read about in Ellen Pratt’s notice in our latest bulletin; I
will not present details here.) is one such instance, and one about which
Protectors has serious reservations. Expense is probably the key issue that mitigates against restoration, especially as we see costs
spiraling higher and higher, drawing the costs of other goods and services
higher in their wake. These
increasingly higher costs dampen enthusiasm for large scale invasive removal
and reduce ongoing activities as budget cuts in parks and preserves force the
allocation of manpower to the bare necessities of maintenance and essential
public services. Reduction of funding
may also play a part in decisions to employ herbicides and non-selective
mechanical eradication in invasive infected areas to the detriment of
existing native species or the larger environment they inhabit. Given budget cuts at the National Park
Service, it wouldn’t surprise me if a large part of the enthusiasm for
restoration at Crookes Point is not due to the availability of plants and
services through the city’s Million Tree Project. At first blush, being able to reforest a
large area with at least a portion of the financing coming from a second
agency invested in planting trees on a tight schedule and happy to have another
agency’s co-operation in doing so would seem a win-win situation for
both. Paradoxically, a lack of
resources may be driving restoration efforts in this case. Whether Draconian methods such as bulldozing and
large-scale spraying of herbicides do more harm than good is debatable, and
there is probably no all-encompassing answer that proves correct in every
instance. We are told that in some
cases a “scorched earth” technique may be the only practical method, such as
when large areas have been taken over by Japanese Knotweed so that there are
almost no other plants growing beneath their cover. Crookes, however, although widely inhabited
by alien species, harbors native plants as well and the mixed plant cover supports a multitude of wildlife. Oriental Bittersweet and Japanese Honeysuckle
abound, as well as Ailanthus and White Poplar trees, but there are also
native Bayberrys, Sumacs and Blackberry. The site itself is an area ill-suited to
drastic restoration plans; it is a sandy area closely surrounded by water,
and herbicides employed there, all water soluble, would
probably find their way into the harbor and bay. Removing the existing cover will expose the
thin layer of soil there to long, hot periods of dessication,
requiring a long period of constant care if new growth is to survive. Then there is also the question about what
it is we are restoring the site to?
Wasn’t the site formerly a rocky and sandy island dotted with seaside
grasses, sedges and a few salt-tolerant shrubs? The environment is hostile and what trees
were there before must have been small, sparse and tolerant of spray from the
bay. If anything, shouldn’t that state be the aim of restoration there? One could take the position that unless success can be
assured the natural environment would be served best by not employing such
extreme measures. Invasive plants, by
the nature of their lack of natural enemies, their fast growth and
reproductive rates, and - often - tolerance of a wide variety of growing
conditions, can often return with a vengeance after a plot has been
cleared. At Clove lakes, for example,
if in the future sufficient resources are not available to maintain areas
cleared of invasives it may prove that those areas
should not have been cleared at all.
Only time will tell if there is enough commitment to see it
through. This is probably a key to the
whole restoration debate: if the outcome ultimately is un-successful, should
an attempt at invasive removal be made at all? If we agree that invasive species are too
widespread to be entirely eradicated, shouldn’t we just throw in the towel
and watch as a new balance of native and alien species is achieved? Assuming, as I do, that climate change is
occurring, that southern species will continue to move into our locality and
that more and more species from southern Europe and Asia will find their way
here, shouldn’t we just step back and watch while nature adjusts itself? I myself can’t completely agree. Human activity is the root cause of most of
the problems of alien invasives in our natural areas,
and I believe that human intervention can correct or at least ameliorate some
of those problems. What are our other
options? Should we just admit, for
example, that Garlic-mustard will continue to advance along the trails in the
Egbertville Ravine and that our descendants will
eventually have to be content with viewing native wildflowers such as
Virginia Waterleaf and Doll’s Eye in botanical gardens? (By the way, I have just read an abstract
from a recent study done in New Zealand that implicates botanical gardens as
the source of more than half of the noxious invasive plants that have been
released to plague the modern world. Those plants escaped, however, mostly
between 1800 and 1950.) Or should we
accept that the serpentinite barrens on Staten Island
will all disappear by being covered over by encroaching shrubs or, as seems
to be happening below Moses Mountain, by the alien Devil’s Walking
Stick? We don’t really know what the
future will bring, but we do know from present experience that alien twining
vines strangles saplings in the Greenbelt and that invasive
plants such as Garlic-mustard tend to propagate and penetrate along
used trails, and that these things can be attacked on a small scale by
individuals or groups. I have no
illusions that invasive plants can be totally removed from the Greenbelt, or
for that matter from any other of our natural areas. But I have seen numerous sapling strangled
by alien vines, and numerous, larger trees displaying the scars where someone
has previously cut away the strangling vines.
These trees would not be standing had not park employees or volunteers
like us not made the effort to remove the vines when the saplings were
young. And I still find Doll’s Eye
along the White Trail in Egbertville Ravine where
Dick Buegler and I cleared Garlic Mustard several
years ago. The Garlic Mustard is
coming back strongly and needs to be cleared away again, but for now colonies
of Doll’s Eye are still there. We can’t foresee the long range results of small scale
invasive removal efforts such as we try to do in the Greenbelt, but I am
persuaded that they can do little harm, and certainly cannot but help the
native flora survive the onslaught of invasive species along the trails. I have been looking at a Wisconsin Department
of Natural Resources website which tallies invasive plants of concern in that
state - a document containing many suspects familiar to us - and lists
control methods, and noted that the writers recommended a strategy of
prioritizing restoration efforts. http://dnr.wi.gov/invasives/pdfs/WI%20inv%20plant%20field%20guide%20web%20version.pdf Rather than attack the core concentrations
of invasive plants, they suggest that much can be accomplished by attacking
smaller, isolated, outlying infestations, thus preventing further spread with the least investment of
resources. As more resources are
available, they can be applied to suppressing the perimeter of core
infestations. Scouting and removing
outliers of invasive plants along the Greenbelt trails would be a good role
for knowledgeable volunteers. Who
knows, perhaps in the future better, more effective methods of suppressing
alien plants and protecting native species will be developed; in the meantime
we have to do the best we can to preserve what we now have.
DfR 07-06-2011
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©2011 PPOW