This morning the Pymatuning wetlanders finished up with wetland biogeochemistry and discussed environmental controls on production and decomposition in wetlands. We then went to nearby Hartstown Swamp to learn more plant species in anticipation of Monday’s data collection in the swamp. We also walked to nearby pond to highlight the differences between narrow-leaved cattail (Typha angustifolia, an invasive) and common cattail (Typha latifolia, a native). Although the leaves are generally wider in the native species, there is overlap between the two; therefore, one of the best ways to tell them apart is by looking at the distribution of the male and female flowers on the shoots. In common cattail the male flowers and female flowers are continuos along the stem, or separated by less about half a centimeter of bare stem. In narrow-leaved cattail there is a distinct gap, typically 2-12 cm long, between the two flower types where there is only bare stem. Just to make field identification more fun, there are also hybrids between the two species that are intermediate in both leaf characteristics and the width of the gap between the two flower types (Typha x glauca).
The students then spent the rest of the afternoon pressing their plant collections, working on a wetland hydrology problem set, beginning a biogeochemistry assignment, and starting to prepare for the midterm which is on Wednesday.
Below is a video highlighting some of the fun that we had this week! (a bit low-fi, but the upload speed is very slow here. I’ll replace with a better one after the course is completed)
Stacks and stacks of flattened, dried plants. Each meticulously labeled with a scientific name, collection date, location, habitat details, and other relevant information. Collectively, the over 300 million specimens housed in herbaria throughout the world provide a wealth of information on the world’s botanical diversity and are a rich resource for ecological, taxonomic, and genetic studies. Because location and date are recorded on the specimens, they are an important source of information in studies of past and present plant distribution patterns. DNA can also be extracted from herbarium specimens, and has been used to answer evolutionary and genetic questions. Herbarium specimens have also been used to provide information on changes in plant phenology, i.e., the timing of flowering, fruiting, and other life events, that have occurred over the past couple centuries in response to global change. And they have been used to investigate things that are not directly botanical as well. For examine, leaf damage and other evidence has been used to study changes in herbivory and pathogens. Chemical analyses of herbarium plants have even been used to reconstruct trends in atmospheric pollution. The scientific and educational values of herbaria are varied (for some more examples see here and here), and they will likely be useful for other sorts of investigations in the future.
Index Herbariorum, maintained by the The New York Botanical Garden, provides a global directory of herbaria. Increasingly, information about the specimens housed in these collections has been digitized and compiled into databases so that they can be available for research and education. The process is time consuming and labor intensive, but many herbaria have made all or a good portion of the information about their collections publicly available online. For example, in the northeastern US, the Consortium of Northeastern Herbaria (CNH) provides an integrated portal to search the collections of regional herbaria. Through the CNH portal you can search for records of any species contained in these collections, and if the samples have been georeferenced you can even display the collection locations within Google Maps or Google Earth. For example, here is link to all collections of the the American Chestnut (Castanea dentata) in the database.
The Francis J. Trembley Herbarium at Lehigh University
Recently the herbarium at Lehigh University has been added to the Consortium of Northeastern Herbaria (CNH), although additional specimens are still being entered into the database and many entries still need to be checked. Reorganizing and entering the information about the specimens into a database has been a labor of love, performed by myself and “volunteer” undergraduates (most of the undergraduates that helped had to do this because they missed a course field trip). Data entry has slowly progressed since I first unearthed the herbarium from the basement of Williams Hall in 2010, and is now more than 90% completed. I have added my personal herbarium collection as well, and the Francis J. Trembley herbarium now serves primarily as a teaching resource, although plenty of research opportunities exist. The addition of the herbarium to the CNH makes it more accessible for research, as now this “virtual herbarium” is publicly available.
The collection is small in comparison with the large herbaria of the world (see here for a list of the largest herbaria), only containing about 2200 specimens. However, collectively small herbaria contain a large number of plants; furthermore, small herbaria oftentimes contain important regional collections and the collections of important scientists. The Lehigh University Herbarium includes the collection of Francis Trembley, a pioneering professor of ecology at Lehigh University. His plants were primarily collected from eastern Pennsylvania in the 1930s. The collection represents about 200 plant families and over 500 genera. Below are some figures showing some other characteristics of the collection.
Searching for specimens in the herbarium
To search for specimens in the herbarium, go here. You can search by collector last name, genus, species, location, or other fields. For example, here is a link to all the specimens collected by the herbarium’s namesake, Francis Trembley, and here is a link to all of the specimens he collected in the old Lehigh Arboretum (see here for more information on the arboretum). Or perhaps you want to know what specimens were collected in Pennsylvania, New Jersey….or even Alaska. Or maybe you are interested in plants of the Okefenokee Swamp in Georgia, or you are student in my wetland ecology field course 🙂 and want to see what species have been collected in Pymatuning Creek Marsh in western Pennsylvania. Of course, you can also search the entire CNH database, including Lehigh’s collection and other regional herbaria, by going here.
Future plans and new specimens
The remaining specimens in the herbarium will hopefully be made “virtual” in the coming months. Samples from the Northeast will also be georeferenced so that they can be plotted geographically, and eventually images of the herbarium sheets will be uploaded. At this point, few attempts to update taxonomy have been made and the specimens are organized based on the original species identifications. However, it appears that synonyms can be searched through the portal, although I have not experimented with this yet.
Of course, new collections will also be added. Plant collecting is a great way to learn plant identification, and archiving the specimens in herbaria contributes to our knowledge of the world’s botanical diversity. And besides, there is just something fulfilling about standing on a full plant press, pulling the straps to tighten it, and feeling the crunch of cellulose compression beneath your feet.
“It is interesting to contemplate a tangled bank, clothed with many plants of many kinds, with birds singing on the bushes, with various insects flitting about, and with worms crawling through the damp earth, and to reflect that these elaborately constructed forms, so different from each other, and dependent upon each other in so complex a manner, have all been produced by laws acting around us. . .” – Charles Darwin
Where is the tangled bank?
Snippets of what little I could recall of the above quote from Charles Darwin bounced around my head as I read labels on some herbarium specimens.
My task was to reorganize this collection of carefully flattened and labeled dried plants, to make it more useful as a teaching resource.
According to the labels on these particular specimens, they were collected from the “Tangled Bank.” No other location information was given. Where was this place? What was its significance? The labels indicated that they were all collected by a person named David J. Mazsa. Maybe I could track this person down…
Finding David Mazsa
Google is amazing. Within a minute of searching, I found a person by the name of David Mazsa with a degree from Lehigh Unversity. Perhaps he was the collector? I sent him an email and received a prompt response….
“You are in luck- I am the guy you are looking for.
“Tangled Bank” is the sloped area right behind Williams Hall. Dr. Trembley had an idea to allow that mowed and manicured area to proceed through natural succession and become a “tangled bank” (I think the term is from Charles Darwin). Dr. Trembley convinced Lehigh to stop mowing and allow the area to begin to revert to it’s more natural state. In his view this would be so much more attractive and diverse than the mowed lawn. I honestly do not remember the exact chronology but my best guess is that they stopped mowing some time in 1967 and my samples were from the following year but I am not sure. Dr. Trembley found some money for me to work on the bank and take samples to record changes in the plant species distributions. I am amazed to learn that I left a mark! I graduated from Lehigh in 1969 and although I visited Dr. Trembley once or twice afterwards, I don’t know how long the project lasted or what additional data was collected.
Dr. Trembley was one of the people responsible for my career path. I was born and raised in Bethlehem and he wrote a lot in the local newspapers. He was one of the reasons I chose Lehigh. He was a combination of an old time naturalist who loved the diversity of living things and was eternally curious about how they interacted. Walking on a field trip with him was like having a window to the world of nature. We hung on his every word and loved his stories. But he was also politically astute and he was in the middle of Environmentalism of the 60s and 70s.
He taught Ecology with a set of note cards that were at least thirty years old. When we asked him if it was boring teaching the same stuff over and over again, he noted that the Ecology material was much the same, but the students changed every year and his interaction with them made it different every year. I have just finished my 40th year as a high school teacher and now I understand how right he was about the difference in students from year to year.
I also remember that our grade in Ecology was determined by a semester exam and that the question was “Describe life in, on, and around inland waters.” Although that was the only science course at Lehigh that I didn’t ace (I got a B I think), That course and Dr. Trembley are certainly one of the big reasons I have spent much of my life teaching and working toward making the world a more sustainable place.
I hope I helped identify the location for you. Thanks for bringing back some very fond memories.
So the “tangled bank” is the slope behind Williams Hall!
Of course! This is the only non-manicured place on the Asa Packer campus. And before the Department of Earth & Environmental Science moved from Williams Hall into the STEPS building, my office used to face it. For five years I looked directly out my window at the “tangled bank.” And I agree with Trembley, it is more beautiful and diverse than a mowed lawn. An aerial photograph from 1971 shows that much of the slope was still characterized by low-growing vegetation four-years after they stopped mowing.
After David’s email, I also found mention of the “Tangled Bank” in a book on the history of education at Lehigh University (Yates 1992, page 238):
“The biologist Fran Trembley was speaking and writing on the dangers of technology long before the subject became popular with the general public. In 1951 he had his title changed to professor of ecology. Students flocked to his classes. In order that they might have a nearby spot in which to study ecosystems, he asked that the slope above Williams Hall be left in a wild state – a tangled bank, he called it, using a term coined by Darwin. The administration complied with the request and put up a sign, “Tangle Bank,” to identify the place.”
Today, the “tangled bank” is a small, diverse woodlot, with an overstory that includes tulip poplar (Liriodendron tulipifera), American beech (Fagus grandifolia), black cherry (Prunus serotina), several species of maples (Acer spp.), as well as several other deciduous species. Various shrub species occur throughout, particularly along the margins, and poison ivy (Toxicodendron radicans) and Virginia creeper (Parthenocissus quinquefolia) are common. It is a very different place than it was in 1968. A few more photographs are below (click on one to view as slides).
What can students learn from the tangled bank?
This fall, students in general ecology (EES-152) at Lehigh University, will revisit Trembley’s “tangled bank.” Forty-seven years of ecological succession have passed since the mowing was stopped, and because of David Mazsa’s collections we know many of the pioneer species that grew on slope after just one year.
Students in the ecology class will complete a botanical inventory of the slope, and the data will be used to introduce and explore the topic of secondary succession. Furthermore, the students will use modern databases to research and compare information on the functional traits (e.g., seeds per plant, energy content per seed, growth habit, mode of dispersal) of plants in early succession versus mid-succession (i.e., today). We will report our results on this blog later in the fall semester!
Trembley’s last lesson.
Unfortunately, this will probably be the last lesson taught by Trembley’s “Tangled Bank.” A renovation of Williams Hall is planned to begin later this year, and as part of this effort the area will be relandscaped…removing the “tangle” from the bank.
Perhaps only this ecologist would be saddened by such a thing.
On July 30th 1935, Francis Trembley walked along the north-facing slope of South Mountain above the campus of Lehigh University. Dr. Trembley was a biology professor, and he stopped along the road to collect some goldenrod and several other herbaceous plants that were in flower at this time. He then likely entered a semi-open area on the southern side of the road that was carefully planted with clusters of different tree species. There, in a plot of land only about 11 acres in size, he probably observed over 90 of the tree species native to Pennsylvania, and as many as 200 types of North American trees (Emery 1915, Hall 1951). At least 20 species of oaks were represented alongside maples, pines, basswood, beech, yellow buckeye, tulip poplar, red spruce, and many others (Hall 1951). This museum of trees resulted from the foresight and passion of another Lehigh biology professor, Robert Hall. Dr. Hall was instrumental in acquiring the land for the university in 1908, and he designed and oversaw the plantings, which were apparently positioned on the property to broadly reflect botanical relationships (Hall 1951). This “informal park,” as Hall envisioned it, was the Lehigh University Arboretum. By all accounts, it was one of the finest university arboretums in the country.
On that day in July, Trembley probably also walked a bit further east past the arboretum, where he would have observed a young, wedge-shaped forest that was meticulously divided into a series of 42 experimental plots. Initially established and planted in 1915, the plots included over 20 tree species native to North America and Europe. Some plots were planted with a single species and others a mixture of two species. This was the Lehigh University Forest Plantation. Set up as a forestry experiment to assess what economically valuable species would grow best on the rocky, thin soils of South Mountain and similar areas in Pennsylvania, the value of the experiment was highlighted by the President and Vice-President of the University, Henry Drinker and Nat Emery, at a speech to the Pennsylvania Forestry Association in 1915. However, by the end of the 20th century both the arboretum and the forest plantation would be almost completely forgotten…engulfed by the surrounding forest.
How do we know that Trembley went up to the arboretum on that day in 1935? The plants that he collected on the edge of the arboretum are archived in the Lehigh University Herbarium. In fact, the discovery of the herbarium specimens is what first sparked our interest in relocating the arboretum.
The History of the Arboretum
In 1951, Robert Hall finished a manuscript entitled “History of the Lehigh University Arboretum,” and although he clearly doubted that it would have much use to anyone, he filed it away in the University library. The document contains much of what we know about the arboretum – how and why it was established, the role of the adjacent nursery and seedbeds, the adjacent forest plantation, and the many challenges he had to overcome. It might sound like dull reading, but it isn’t. In fact, the second half is a bit of a political thriller. Well, perhaps not a thriller, but it does provide a fascinating window into university politics of the early 1900s. Other sources of information on the arboretum include a brief statement in the 1910 yearbook regarding the purchase of the land, various articles in the student newspaper (The Brown and White) which mention or describe the arboretum, and two publications in the journal “Forest Leaves,” which was published by the Pennsylvania Forestry Association.
Archives of the student newspaper reveal that the arboretum played practical, educational, and cultural roles for the university and students until sometime in the 1950s. For example, the arboretum and associated nursery provided replacement trees after the American chestnut blight eliminated the chestnut trees on the main area of campus (Brown & White, March 10, 1916) and it was a continual source of trees for the rest of campus in the 1920s and 1930s. Students and faculty also went to the arboretum and forest plantation to learn, observe, admire, and even have a little fun. Francis Trembley used the arboretum for his classes. An open-air theater within the arboretum, referred to as Top ‘o The Mountain theater, was used for plays during the summer session in the 1930s (Brown and White, Sept 26, 1936). And for fun, mischievous Lehigh students occasionally swapped the labels on the trees (Brown & White, Oct 6, 1943). Lehigh students were apparently just as wild and crazy then as they are today!
The last mention of the arboretum in the student paper was an anecdotal mention in 1954, and Robert Hall seems to have recognized the declining interest in the arboretum in his 1951 manuscript:
“The last time I saw it, the arboretum looked like a monument to neglect – grass uncut, limbs stretching out over the road. It had seemingly been years since any car had tried the road.”
“What is the condition of the arboretum today? I do not know. If I were not seventy-nine years old I would climb up there and see.” – R.W. Hall
When Hall wrote those words in 1951, a new forest was likely already sprouting within the spaces between the carefully planted trees. Priorities change. Human memories fade. There were no more plays at Top ‘o The Mountain Theater. The students stopped moving the tree labels. The arboretum disappeared from campus maps.
Rediscovering the trees
The arboretum and forest plantation were relocated in the fall of 2011, and the story of this rediscovery was recently told in the Lehigh Alumni Bulletin (see here). Luckily for us, both the arboretum and the plantation land are still forested and have not been extensively disturbed by development. These areas of campus, and the trees that are on them, provide a potentially rewarding scientific opportunity to better understanding the legacy of a planting and reforestation experiment. Furthermore, they represent an opportunity for the Lehigh community to reconnect with the history of the university and explore our changing values and priorities.
The Lehigh Experimental Forest Plantation
The forest plantation was less commonly mentioned in the student newspaper, although the archives reveal that it was occasionally mistaken to be just another name for the arboretum. Given that its mission was scientific, it is not surprising that it received less attention. Although two articles on the experimental forest plantation were published, it appears that it was forgotten about quickly.
Henry Drinker elicited the help of others in the establishment of the forest plantation. Joseph Rothrock, the first president of the Pennsylvania Forestry Association, and Simon Elliott of the Forestry Reservation Commission, were called on to assist in its design (Emery 1915). Seedlings, all the same age and less than about six inches tall, were densely planted in the plots in 1915. It was meant to be a natural experiment with little to no intervention after the the initial planting, and it appears that no additional management was performed. In fact, Rothrock assessed the experiment after 5 years and noted that several tree species had already established naturally (i.e. without planting) within the plots, including black birch (Betula lenta), black oak (Quercus velutina), and black cherry (Prunus serotina). The latter two species were also planted in several plots. The total number of each species that were planted was as follows:
- 600 Basswood (Tilia americana)
- 300 Black cherry (Prunus serotina)
- 300 Black oak (Quercus velutina)
- 400 Bur oak (Quercus macrocarpa)
- 100 Elm (Ulmus americana)
- 400 European larch (Larix europa)
- 100 Grey birch (Betula populifolia)*
- 100 Hemlock (Tsuga canadensis)
- 300 Honey locust (Gleditsia triacanthos)
- 500 Jack pine (Pinus banksiana)
- 500 Norway spruce (Picea abies)
- 100 Pin oak (Quercus palustris)
- 500 Pitch pine (Pinus rigida)
- 100 Red spruce (Picea rubens)
- 400 Scotch pine (Pinus sylvestris)
- 400 Sugar maple (Acer saccharum)
- 600 Tulip poplar (Liriodendron tulipifera)
- 400 Western yellow pine (Pinus ponderosa)
- 700 White ash (Fraxinus americana)
- 300 White oak (Quercus alba)
- 500 White pine (Pinus strobus)
Like most science of the time, Rothrock’s assessment of the forest plantation after five years of growth was very qualitative. He attempted to summarize both the relative height and general health of the planted species. He noted that 1919 was a locust year (he was likely referring to cicadas), and that the hardwoods, particularly the oaks, suffered extensive damage. Although cicadas are not usually a problem for adult trees, their egg laying can damage small trees. He also noted that several species were damaged by fire, which apparently was common at the time on South Mountain (Rothrock 1920). In fact, the arboretum had a fire break around its perimeter (Hall 1951).
Although Rothrock’s assessment was qualitative it still provides a nice picture of the changes that occurred in those first few years. Some clear winners and losers were emerging by this time. In general, conifers initially did better than the hardwoods. Hemlock, elm, and honey locust all perished quickly. Tulip poplar, basswood, white oak, and ponderosa pine were all alive but not faring well, as several of these species were hit hard by cicadas and/or fire. A number of species were moderately successful, including sugar maple, white ash, and white pine; however, the tallest growing and healthiest trees were the european larches, scotch pines, and jack pines. Black birch, which wasn’t planted but colonized the site naturally, and black cherry were also doing quite well after five years. Although much slower growing, the spruces were thriving. Of course, Rothrock recognized that his report only captured a small piece of a long-term experiment – an experiment that would continue to play out for decades to come:
This experimental tree plantation was the beginning of a practical scientific experiment, so far unique in this country, which is bound in ten, twenty and fifty years to be productive of information of great value to the forestry interests of Pennsylvania and of the country at large. – J.T. Rothrock
A century of change
Fast forward nearly 100 years. What happened? Did Rothrock’s initial observations forecast what the forest would look like today? How many of the planted species survived? How did natural ecological succession play out against this backdrop of plantings? How did plant and animal invasions of the past century impact this unusual forest? Were some plots more susceptible to invasion than others? If Rothrock, Elliott, Drinker, or Hall had had the ecological knowledge of today, could they have predicted what the area would look like in 2012? How do other ecosystem characteristics and processes (e.g., soil characteristics) vary in the different plots today? What other legacies of the plantings exist? Given knowledge of the past, present-day patterns, and forecasts of the future, what might this forest look like in another 100 years? Students at Lehigh University are now investigating these and other questions, using this unique experiment as a natural laboratory. Stay tuned for the results.
The Epitome, Lehigh University Yearbook, 1935. Download here.
The Epitome, Lehigh University Yearbook, 1910. Download here.
All Brown and White articles mentioning the arboretum can be downloaded here.
Hall, R.W. 1951 (1945-51). History of the Lehigh Arboretum. Download here.
Emery, N.M. 1915. A demonstration tree plantation at Lehigh University. Forest Leaves 15: 56-58. Download here.
Rothrock, J.T. 1920. The demonstration tree plantation at Lehigh University. Forest Leaves 18: 9-13. Download here.