Research Report #54 — Living Stumps of Hemlocks (Tsuga canadensis (L.) Carr.)
For many years scientists and naturalists have been studying and observing the flora and fauna of the Shawangunk Ridge. Foremost among them was Daniel Smiley, for whom Mohonk Preserve’s Daniel Smiley Research Center is named. Dan wrote numerous reports summarizing his observations on various topics. This regularly occurring series will feature some of these reports; some hold tremendous scientific value today and just await an interested researcher to follow up, others showcase a quirky sense of humor or highlight an oddity of nature.
A Note from Paul C. Huth, Director of Research Emeritus: At the heart of my long research collaboration and friendship with Daniel Smiley at Mohonk was botany, this concentrating on plant identification and species distribution, and the vegetational history of a nearly 100 square mile Northern Shawangunk Mountains Study Area. This included both field and herbarium projects, entry of our species observations into Dan’s long term Species Card File, and the investigation and documentation of the impacts resulting from nearly 300 years of intense land use of the area.
On 28 March 1974, Dan noticed on a field trip through a Hemlock grove on a northwest-facing slope near Spring Farm, that small stumps of Hemlock trees that had been cut for fence posts some 30 to 40 years earlier, “had some degree of live bark on sides of stump(s) and grown over part of cut surface, for a distance of 1 to 1 3/4 inches. One stump 9 in. diam., 9 in. high with slope cut had live bark.” As our plant research turned to the documentation of Hemlock growth forms (including “bushy”, “multi-stemmed”, and “dense foliage”), we also wanted to investigate the live stumps that Dan had previously recorded. On 28 October 1986, we made a field trip back to the Hemlock grove where Dan had found live stumps 12 years earlier. This was a spectacular stand of Hemlocks on a north-facing slope, some of the mature trees we estimated to reach 80 feet tall. We documented “11 stumps from 3–12 in. (diameter) with live bark. Extensive decay was noted in some of the old wood of the stumps.”
Dan had also recorded additional examples of live stumps. In March 1979, in Mossy Brook, he noted a stump about 8 in. tall and 5 in. diameter, “with a curl of bark over what had been (the) edge of (the much decayed) stump.” In January 1980, another was found in Rhododendron Swamp, a “stump about 7 in., well over grown, (the center) hollow.” In March 1985, a live Hemlock stump was found at Rock Rift, the old cut stump “with bark grown over sapwood, the adjacent heartwood rotted away.” In this case, Dan suggested an “apparent root connection to two adjacent live trees.” In October 1986, Dan found two live Hemlock stumps on the southeast shore of Mohonk Lake, about three feet apart and about 5 in. and 6 in. diameter, the interior of the stumps rotten. Of particular interest, we could see the root from a Hemlock tree about 6 feet away running toward the 6 in. stump.
The sprouting of cut trees has always been of interest both botanically and economically. Historically, the sprouting of cut hardwood or deciduous trees has allowed for relatively quick forest regrowth. In many places on the Mohonk Preserve land, Dan and I could “read” past land use by watching for canopy oak trees with forked or multiple trunks originating at or near the ground indicating they grew from sprouts from a cut stump. Drilling and aging these trunks gave a pretty accurate date of when the previous forest cutting had occurred. Prolific hardwood sprouting from cut stumps in large part drove the 19th-century hoop pole industry, providing hoop stock for shavers and coopers in the assembly of barrels. From the 1887, Second Annual Report of the New York Forest Commission, we get a sense of the resource provided by the sprouting, and resprouting, of American Chestnut stumps, observing “twenty-five to thirty hoop poles to grow from one chestnut stump….”
Almost all deciduous trees, when cut, can send up sprouts from their crowns and stumps in varying numbers. These include Shawangunk species like Sugar and Red Maple, White Ash, American Beech, American Chestnut, oaks, aspens, Paper and Yellow Birch, and unfortunately more recently from introductions, like Ailanthus. Deciduous stump sprouting can be very attractive to browsers like White-tail Deer. However, stump sprouting is seldom seen in coniferous species, and then “is limited to a few species”. This is especially true if cut low to the ground, below any live limbs. Dan and I had noticed that young Hemlock trees, that had been totally defoliated by Gypsy Moth larvae in the large outbreaks in the 1970’s and 1980’s, couldn’t regrow their needles or sprout and ultimately died when adjacent deciduous trees had the ability to regrow their leaves.
In preparing this report, we looked into the references available in the Daniel Smiley Research Center library and subject files and found four references documenting living stumps after a tree had been cut. The earliest appeared in the “Botanical Gazette” in 1899, by Frank Haines Lamb, where he reports “a broken stub (of fir)….without leaves or branches…appear(s) entirely lifeless until cut into with an axe… showing they are covered with living bark and beneath that a living woody tissue very hard and with a grain of very fine and intricate burl.” “Investigation has shown that they are connected with one of the main roots of the parent.”
In 1927, Professor Frederick S. Page wrote an article in the Journal of Forestry (25:687–690), reporting on live stumps of Hemlock and White Pine found “in Hanover, New Hampshire, that lived for many years…(those of Hemlock) were observed during the fall of 1925 in a stand where a thinning was made during the preceding winter. Also in Ithaca, New York, thirteen living hemlock stumps were counted on an area of less than half an acre.” “Examination of three hollow hemlock stumps at Hanover showed that they grew on the average 33.3 years after cutting and that the annual rings averaged .021 cm. in thickness.” “Root grafts were not diﬃcult to find on the larger stumps.”
In our Shawangunk examples of living stumps, we didn’t “excavate to explore the locations of root graphs,” nor did we drill any of the stumps with an increment borer in an attempt to determine the age of the living wood. However, later drilling of the stumps proved impossible because of the decay of the wood in the original stump.
In the 1964 issue of Torreya (91(3):233–234), Donald W. Davidson and Roger M. Davis reported on their “additional finds of 116 living Tsuga canadensis stumps, in four stands,” in northern New Jersey. This, bringing a total of 118 “intact living stumps” documented in two papers. They propose that “there has been a great deal of disturbance…. for a long period of time, resulting from intensive use of the area for recreation. This disturbance is believed to be the basis for the extensive occurrence of these living stumps in this area… Such examination of stumps in hemlock stands suggests that this is by no means an uncommon phenomenon…. ”
In July 1991, Mohonk Preserve Research staﬀ, unfortunately, made the first discovery of the invasive and very impactful Hemlock Woolly Adelgid on Mohonk Preserve lands. Between July and the end of the year, Hemlock stands in the area of Spring Farm, Old Canaan Road, Cragswood Road, Mossy Brook, and along the Duck Pond Trail, were found to be infested with this new insect. A “rare few were found in the area of Hemlocks west of the Knolls Road junction with Mohonk Road, across from the ‘live bark on stumps’ plot….”. Subsequently, most stands of Preserve Hemlocks, attacked by adelgids, were also found to be heavily impacted by spider mites and elongate hemlock scale, collectively causing in most cases heavy needle loss and tree death. Now, nearly three decades later, most of our classic Hemlock stands, like that along Laurel Ledge Road, for example, have been decimated.
Recently, I checked two of the stands where Hemlock live stumps had been documented. At the one on the G.M. Ayres Lot, near Spring Farm, first noted by Dan 45 years ago, and that we had revisited and documented in 1986, I sadly found the Hemlock stand devastated. Where we had noted “a fine grove of Hemlocks… some of the Hemlock trees we estimated to be 80 ft. tall,” I found the trees in the grove either standing dead or the few still alive with chlorotic needles comprising their thin tops. What about the previously documented live stumps? A search revealed that nearly half of them are now dead, their bark loose or gone. Remarkably, most of the others were still alive with firmly attached apparently viable bark. But, with the major decline of the stand, even natural root grafting won’t likely sustain their survival for much longer. We will have to watch and see.