Clove Lakes Restoration
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.