Forest Restoration at Field of Dreams
By Don Recklies, Naturalis
Forest Restoration #199, Field of Dreams
For February’s Forest Restoration Workshop five of us assembled in the Field of Dreams Ballfield parking lot opposite the Costco on Forest Hills Road adjacent to the SW entrance of the multi-use (bicycle) path. NYC Parks had suggested that this site might be a good candidate for our workshops, so we had put it into the schedule. Although we already have had several sessions along various areas of the bike trail coming west toward the ballfield, we had not come the entire distance, so this workshop filled the gap.
At first the site didn’t seem promising; close to the ball field the soil is thin, in places barely covering layers of trash and studded by black rings of emerging tires (you may recall Sarah-David’s efforts a few years ago to pull over a hundred tires out of the ground and to the edge of the path for Parks to collect). In the growing season all this is camouflaged by green plants, and in late fall the brown stems of plants not yet broken down by the wind and wet of winter do much the same. Now, however, the camouflage had grown thin and less desirable things were revealed. Along the path we found lots of Japanese Honeysuckle (Lonicera japonica) and other vines, but the trees growing among them were mostly alien Ailanthus (Ailanthus altissima), and many of these vines had been cut before. In a short distance the Ailanthus became mixed with Black Walnut (Juglans nigra), and we found woody twining vines that had not yet been cut. After attending to these we came to a place where we had previously uprooted Princess Tree (Paulownia tomentosa) seedlings growing beside and even on the gravel of the bike path (the Princess Tree, or Empress Tree is a fast growing alien tree escaped from landscaping and quick to colonize sunlit, disturbed areas). There we began to find large clumps of Multi-flora Rose (Rosa multiflora).
We began by uprooting the clumps of Multi-flora Rose growing adjacent to the path, although some clumps proved too large to uproot with the tools we had brought with us. We had with us a medium size weed wrench that worked for most of the rose, but the crowded, multiple stems of a few clusters were too dense for us to get a grip on with the tool, and we had to leave those for a future visit with a saw or a pick. As we saw the need, we ranged off the path to cut European Bittersweet (Celastrus scandens) and Japanese Honeysuckle from saplings and shrubs. Deep spiral grooves in the bark of some were evidence that they had been rescued from the vines before. Although they were somewhat contorted and deformed, they were still alive, a testament to an earlier intervention.
Along the abandoned wood roads adjacent to the path we encountered what I believe were trees planted during the Reader’s Digest Foundation forest restoration grant in the 90’s that impelled Dick Bugler to begin our Restoration Workshops. Numerous of these woods roads crisscrossed the area, here and there intersecting the bike path that, for the most part, follows the original route of the Old Mill Road. To close off some of these no-longer-wanted roads, saplings were planted along the roadways. Here, along an overgrown road still recognizable by the line it traced in the topography of the woods north of the bike path, saplings were planted in groups of three supported by wires to stout stakes on opposing sides. Elsewhere on the opposite hillside we find scattered pairs and isolated trees, usually oaks, that had been planted on roadways that had become now abandoned branches of the Blue Trail, but where we found ourselves on the north side there were trios of Eastern Red Cedar (Juniperus virginiana), what probably was a broadleaf hardwood such as an Oak, and an American Holly (Ilex opaca). I say probably a broadleaf hardwood, because the middle tree of these trios did not survive, the only evidence of their erstwhile presence being the paired stakes that once supported them.
Why the Cedar and Holly survived and not the other tree is a bit of a mystery to me. I suspect that some thorough search in the area might scare up a sample of the missing survivor of the trio and at least let us know what species didn’t make it. We’ll try to watch for a survivor on future visits. This is not to imply that the other trees are doing well, however. Of these the Hollies are probably the healthiest, but the Cedars seem sickly indeed, and just hanging on. A recent scourge of our woodlands, the White-tail Deer, is probably the cause.
I say probably the cause because Eastern Red Cedar can be a “pioneer” tree, a tree that takes advantage of poor soils and newly open spaces to grow fast while light and space is available. Then later, if other trees grow up in its shelter and eventually grow to overtop it, it dies away. Here the Red Cedar is a shrub in the understory of now taller trees, and no doubt suffers from lack of light. However, in every case one sees that their trunks have been severely damaged by deer chewing the bark and rubbing against them to relieve antler itch. Eastern Red Cedar, it seems, is favored by deer in winters when other food is scarce and is much damaged by them in forests of the northeast. The Holly does OK in the shade, and does not seem to be palatable to deer, at least in our area, but many of these Hollies also had swaths of bark rubbed away.
The overpopulation of deer on Staten Island and the degree to which they have browsed away the undergrowth of the wood is much regretted. Staten Island has been unique among the five boroughs of New York City in the extent to which native plant communities have survived. In fact it has been unique in that unlike all the other boroughs, more native species still exist compared to those that have been extirpated. But all that is changing due to the depredation of deer. With no natural enemies – except for that unnatural enemy the automobile – and comfortable wildlife corridors bordered by well tended suburbs that offer even more browsing, their numbers have exploded. A DEC survey in 2008 counted 24 deer on Staten Island, even then a ludicrously low number. At that time I myself had seen herds of four and five deer in widely separated parts of the island, and can’t help but believe that even then the number of deer was up in the 100s.
There is no certain figure about how many deer any particular natural area can support. Various states managing their deer population, usually for hunting, have come up with numbers of 17 to 21 deer per square mile. Staten Island comprises 58 square miles, but try as I might I could find no figures for how much of that area was forest and grassland suitable for deer. Finally I resorted to NYCOASIS maps in order to estimate what portion was forest and grassland. My best guess was well under 50% of which much woodland was in the form of tiny woodlots scattered in residential areas, and much of the remainder was phragmites marsh. If we figured that 20 deer per square mile might be allowable – a pretty high estimate for isolated suburban woodlands – this would suggest a carrying capacity of 580 deer, but that would be true only if the natural areas were mostly contiguous, which they are certainly not. And it must be considered that these estimates of deer carrying capacity are not necessarily estimates of the how many deer a forest can support without endangering its biodiversity, but of how many deer a woodland might support while keeping the deer healthy, not necessarily the forests.
Deer, like people, favor certain foods, and for the most part avoid eating things alien. Year after year they select from the native species, usually avoiding alien imports, further tilting the balance against the plants they favor until the continued existence of those plants is in jeopardy. We should be concerned because we value some of these plants highly (in fact, we should value them all, but as is usually the case, the handsome and beautiful garner most of our attention). The Maryland Native Plant Society has sounded a warning about the fate of the Pinxter Azalea, that shrub that is a wonder of the spring blooming season in our woodlands. The Pinxter can probably survive being browsed occasionally, but as the number of deer continue to grow and browsing becomes continuous they will begin to disappear from the understory. If unchecked, we will soon be left with a ground layer of herbs and ferns and an upper layer of saplings and trees that hangs down only as far as the reach of a standing deer, as can be seen in many New Jersey forests.
In the late 1990’s Susan Stout, a silviculturist for the USDA Forest Service sounded an alarm based on her perception of what was happening in Pennsylvania woodlands. She pointed out was what already obvious – that Pennsylvania’s woodlands were not naturally regenerating – and that the cause was the overabundance of deer exacerbated by the elimination of the deer’s historical predators, Game Commission laws curtailing the hunting season, and the expansion of deer favorable habitat that followed widespread harvesting of timber in the late 1800’s. She referred to a study of old growth forest reserves through the thirties and forties describing the steady disappearance of the deer browsed Hobbiebush Viburnum (Viburnum alnifoliurn – not a species we find on Staten Island) in the Tionesta Scenic and Research Area, and noted that “today” (around 1990) only one of these plants remained all of its 4000 acres. She noted that several studies correlating deer density to biodiversity suggested that the density should be no more that 10 to 20 deer per square mile, and that the most devastating impacts of deer on their habitat occurred in the early years of deer overabundance.
We may have already passed a tipping point for whatever rare plants may yet survive in our woodlands, and what makes the lack of an effective deer control policy in our woods even more dire is that once deer have defoliated a woodland, the woodland may not necessarily regenerate after the deer have been removed. Of special concern are the plants of the herb and shrub layer. Often when deer have browsed an area it turns to fernland or becomes populated with plants such as Asters that deer do not prefer. After the deer have browsed an area for successive seasons the seed bank that might replenish the former spring wildflowers becomes impoverished, and unmolested by deer, the ferns begin to shade out seedlings of the more slow-growing trees and shrubs. We tend to think of ferns as delicate lacy indicators of moist, shady woods, but ferns can be indeed sturdy, competitive plants. After all, they have managed to survive since before the days of the dinosaurs, so they must have a good survival mechanism. We often see large swaths of Hay-scented Fern in shady woods. The dense layer of fronds serves to stanch the growth of seedlings that try to sprout beneath them, and once formed those fern areas seldom display spring wildflowers or any abundance of tree seedlings.
Our overpopulation of deer must be addressed soon. During the deep snows of several years ago the deer wintering at Clay Pit Ponds State Park Preserve killed almost all of the evergreen seedlings in the restricted area close to the old shooting range. Visitors could see a distinct browse line in the pines where they had consumed foliage as high as they could reach. And as recently as three years ago they browsed about half of the White Pine saplings that had been planted close to the junction of the bicycle trail in LaTourette. One might think that the seemingly recent trend to less severe winters would relieve deer pressure on our woodlands, but mild winters that make foraging easier and reduce deer mortality result in even larger herds that our woodlands cannot support. NYS is aware that making it easy for deer does them no favors; though experience the state found that feeding the deer in winter contributed to unsupportable numbers of survivors and that crowding of deer in areas where they could artificially find food made more easy the spread of disease through the herds. For this reason (and to prevent deer being lured to bait and feed for hunting purposes) in 2010 it was made illegal to feed wild deer in NYS.
As yet no effective deer control has been proposed for Staten Island. In some other areas deer herds are periodically culled by hunting, but this solution is not always effective and would present an obvious problem in a heavily urbanized area such as Staten Island (although some county parks in Westchester and many in New Jersey, for instance, have bow hunting seasons for deer, and firearm hunting as well if the area is sufficiently isolated for such practices to be safe). This presents a great problem for natural resource wildlife managers; if hunting should be allowed it must be restricted to safe areas and the most capable and careful hunters. How would one restrict hunting in the patchwork of woods and wood corridors that make up Staten Island’s natural areas? Moreover, sooner or later there is bound to be a hunting accident, a public relations nightmare for whoever might be in charge. How else might we keep their numbers down? Trapping and relocating excess numbers of deer is sometimes suggested as a humane alternative, but think of the expense! How could we persuade local government to fund such an endeavor given all the other calls upon the public purse? And just where might these excess deer be relocated – to some deer retirement farm? Trying to capture and release large numbers of deer in some other natural area would certainly arouse a NIMBY response.
Contraception is sometimes proposed as an alternative, but that approach is beset with many technical and economic difficulties. Lacing feed with contraceptives is problematic because it is a not very targeted method; how does one keep the contraceptive away from other animals? (One issue among many is that deer meat is sometimes introduced into the food supply, so either a contraceptive safe for human consumption must be used, or there must be some way to insure that the treated deer cannot make their way to areas where they might be hunted.) Darting the deer with contraceptive syringes might seem feasible, but would be a very expensive method. Until recently, in order that the contraceptive be effective each doe would have to be darted twice each season. How could one insure that enough deer on Staten Island were treated twice to control the population given that the DEC couldn’t even get a reasonable handle on the number of deer actually present? To illustrate how deep the devil is embedded in these details, consider that contraceptives tried elsewhere did prevent does from conceiving, but also lengthened the period in which they were sexually attractive to males and increased the risk of collisions between automobiles and sex-crazed bucks. And those sex-driven bucks posed a hazard, not only on the roadways, but also to people they might encounter in the woods. The danger from deer is not just Lyme disease and defoliation.
In regard to danger to humans, the economics of deer-automobile collisions is eye-opening. State Farm, along with other insurance analyses it provides, periodically publishes statistics about the frequency and cost of deer-automobile collisions. Interestingly enough, recent figures indicate the danger of such collisions has slightly decreased (State Farm was astute enough to suspect that the reason for this was that the economic downturn resulted in fewer miles on the road, not fewer deer that might intersect with cars). However, the average cost of each collision, at the time of the 2011 report, had risen to $3,305 (logically, as automobiles become more complicated and expensive, so do repair costs). Nationally the yearly cost of deer and moose collisions totaled over 4 billion dollars, and this does not even consider the emotional and physical cost to those involved, or the 200 yearly deaths such collisions cause. Where deer populations are high the chances of such a collision are not small. For example State Farm estimated that in 2011 the yearly chance of a driver hitting a deer in West Virginia was 1 in 53! I wonder how the risk is growing for Staten Island drivers, and how the increasing cost of deer-automobile collisions will be shared among us? Controlling the number of Staten Island deer would be a good thing both for us and the environment.
There is some optimism that non-lethal deer control might be employed in the future. Recently the National Wildlife Research Center announced the development of a new contraceptive that has few of the drawbacks of prior drugs. The new contraceptive, GonaCon, is said to not cause treated animals to become unsafe for human consumption, is effective in single injectable doses and does not adversely affect the length of the breeding season and cause unwanted recurring sexual activity. That said, the drug still must be injected, requiring capture of the deer for treatment or the employment of skilled marksmen to dart them in the field. And, although the drug is said create long lasting infertility, “long-lasting” means about 75% effective the first year and 47% the second. One doubts that such a “C” grade would be efficient enough to save our woods. Critics say that given its effective rate somewhere between 90 to 100% of the total deer population would have to be treated just to stabilize a deer population, much less reduce it. Should it prove even possible, this more effective contraceptive solution would still seem to be an very expensive proposition to implement. None-the-less, it seems promising, and the NWRC has announced that it continues research in an attempt to develop an ingestible version of the drug.
A version of the drug that could be widely administered by luring the deer to feed could do much to stabilize the deer population on Staten Island, but would probably not serve to reduce it. The costly option of capture and relocation or the lethal option of permitting deer hunting would probably be necessary as well, but the “Bambi” effect will probably militate against employing one option, and our limited public purse will militate against the other. For now it seems that we have little choice other than to watch our woodlands being eaten away. Striking as it is to see on the trail the flash of white tails in the woods as an alarmed string of deer flees to a safer place, I see it all too often on Staten Island, and I see as well torn and ripped stems of browsed understory plants almost everywhere I go. It’s nice that our woodlands are accommodating to larger wildlife like deer, but I just wish there weren’t so darned many of them. DfR 3-17-13