To read about how a neighborhood in Philadelphia went from hills, valleys and creeks to streets, houses and underground conduits, see here:
To read about recent research on what was here before and how it compares to now, see here:
To read the original article, see here:
On the evening of Wednesday the 20th of November, beginning at 7:00PM, the American Entomological Society will have its monthly meeting at the Academy of Natural Sciences, in Philadelphia, and Elena Tartaglia of the Bergen Community College Department of Biology and Horticulture will give a talk about her work, titled “Eat This, Not That: Nectar Foraging Behavior of Hemaris (Sphingidae) on Co-occurring Native Cirsium and Non-native Centaurea (Asteraceae) Inflorescences”.
For more information, see here:
On the evening of Thursday the 21st of November, beginning at 7:30PM, the Philadelphia Botanical Club will have its monthly meeting, and Myla Aronson of Hofstra University will give a talk about her work, titled “Life in the Concrete Jungle: Patterns and Drivers of Biodiversity in the World’s Cities”.
For more information, see here:
If you take a turn onto East Hermit Lane, just off of Henry Avenue after Henry Ave has crossed over going west from East Falls, and go down towards the site of the Kelpius cave, you’ll see on your left, on the east side of East Hermit Lane, a large stand of white pines. Some of them are quite large, over two feet across, and with a canopy dozens of feet above the ground, they tower above the house that’s there. Underneath them there is a ground layer with pokeweed, and jumpseed, and enchanter’s nightshade, and many other herbaceous plants, and there are also beeches and birches coming up in the understory. But the white pines dominate, in terms of the aspect of the stand, and in terms of sheer numbers and size.
This stand is strikingly similar to one along Cresheim Creek, and based on their size, they (the ones along Hermit Lane, that is) were quite likely planted at a similar time as were the ones along Cresheim, and as is clear from the picture below, the Hermit Lane pines were there in 1931 which provides further evidence as to their age, and solidly provides an upper bound (of 1931) to their date of planting.These trees along East Hermit Lane, however, while some of them are on a slope, most of them are not, and the plantings on the level grade are much denser in the above picture than the ones on the percent grade (this difference is also noticeable when you walk among them today), and so, different from the white pines of Cresheim Creek, the Hermit Lane pines probably weren’t planted for erosion control, but perhaps more broadly as part of reforestation efforts of a century ago, to bring back the sylva to Pennsylvania.
As was noted by John M. Fogg, Jr in his “Annotated checklist of plants of the Wissahickon Valley”, published in Bartonia (vol. 59) in 1996: “Although white pines may originally have occurred in the valley, the trees growing here today are the result of recent plantings. A fine grove exists along Hermit Lane near Hermit Street.”
If we look at a map from 1895, we see that this locale (where the white pines are) was privately owned at that time, and though, as we see from a map of 1910, the neighboring lots were part of Fairmount Park by the earliest parts of the 20th century, this particular site (again, where the white pines are) was not. If we assume that these trees were part of park plantings, and not plantings of private property, then this gives a lower bound of 1910 for the year of planting for these trees (given that the property was not part of the park in 1910, as indicated by the maps linked to above), thereby further supporting the argument that these trees date to the vicinity of about a hundred years, again, much like the white pines of Cresheim Creek. And if we look again at that 1931 aerial, above, we see that the stand extends across the path that divides what was private property in 1910 from what was park property at that time. This further implies that the planting was associated with the park, and therefore would postdate the time when that lot became part of the park.
If we look at an aerial photo from 1937, then we see that the stand of white pines is visible, and quite prominent – densely packed in, and of a reasonably appropriate size for stand in its mid-twenties. The second portion across the path is still there, visible in that 1937 photo, too. And if we look at aerials from 1942 or 1957, we see that this stand of white pines is clearly apparent there, along with the portion to the southwest, across the path (it is no longer there today). [to browse more aerial photos, see here: http://www.pennpilot.psu.edu/ ]
Something that we see as we look at these aerials across the 1930s to the 1940s to the 1950s, in addition to the stand itself, is also the wooded areas around it and nearby. And from this we see that as the pines that were planted there grew, that there were wooded areas surrounding them, and they were growing too, until that landscape today yields an appearance of continuity – it is all “the woods”, even if some parts of them look a bit different from one another. And if we walk there today, it can seem like the woods have always been there, in these large expanses, and that they are “natural”, in the sense of not having been made by people, that they just kind of got there on their own and that they keep on going and growing, all on their own. After a century or so, it all just looks like woods, and the kind of woods that we might imagine has always been here.
And more broadly, looking around Philadelphia today, along the Wissahickon or the Pennypack, or in the wooded areas of West Fairmount Park or Juniata Park, or throughout so many of the many other parkland areas currently in Philadelphia, we see forests, and it can seem some times as though that it how it has always been.
Certainly, when William Penn arrived here in the 17th century there were woods woods woods and more woods, filled with all kinds of trees. But by the 20th century, these had been cut over, multiple times (see page 39, here, for more about this), and also just prior to and at that time (the late 19th and into the 20th century, that is) was a period of incredibly extensive development across Philadelphia, and therefore wooded areas were being rapidly cleared to accommodate housing, and also businesses and industry – the economic drivers of a thriving city. This period was an intense time for this – there was roughly a doubling of the population of Philadelphia between the 1850s and 1890 (according to US Census data), when we went from about a half a million to about a million people, and then the population roughly doubled again, until we hit about two million people in the mid-20th century, and one need not imagine the impact this would have on the woods, this massive population expansion. We can also see this expansion of urbanization in the reduction of farms and farmland here - we go from 824 farms in Philadelphia in 1910, to 423 in 1920, to 381 in 1925 (data from the 1925 Census of Agriculture), which represented a reduction in farm acres in Philadelphia from 30,488 acres, to 17,408 acres, to 15,971 acres at each of those steps (Philadelphia’s total land acreage is about 82,000). By the 1950s, this had declined yet more, to 76 farms (5,024 acres) in 1954, and 53 (3,465 acres) in 1959; as of the latest census of ag, in 2007 there were 17 farms comprising a total of 262 acres. (for more historical ag census data, see here: http://agcensus.mannlib.cornell.edu/AgCensus/homepage.do, and for current and more recent: http://www.agcensus.usda.gov/index.php; specifically for Pennsylvania: http://www.agcensus.usda.gov/Publications/2007/Full_Report/Volume_1,_Chapter_2_County_Level/Pennsylvania/)
At the height of our deforestation rate, in the mid-19th century, a wooded site in our region would be cut about every 25 years (for a 4% (that is, 1/25, or one out of every twenty-five years) deforestation rate). These woods that were being trimmed on the scale of decades were or had been cut to clear land for development, and for farmland, and to build houses (and for other lumber needs, like furniture or cabinets and what-have-you), and also for firewood, wood being the dominant energy source in the US pretty much through to the end of the 19th century, as can be seen in figure one, here), and so it’s not like there would have been a single episode of cutting at a site as land was cleared and houses were built from those trees that were cut, and then everything then would have commenced back to growing into woods again, but deforestation was a continuous local process at that time, due to energy needs, as well. [They were also cut for other reasons, even amidst revolution, as John Thomson Faris relates in his 1932 Old gardens in and about Philadelphia and those who made them: '...in 1782, the Corporation of Philadelphia ordered that all trees in the streets of the city be cut down, because "they obstructed the prospect and passage through the public streets, lanes, and alleys,...disturbed the water-courses and foot-ways by the extending and increasing of the roots." Then it was felt that they were apt to "extend fire and obstruct the operation of the fire engineers." Then, with rare humor, the additional indictment was given: "They were not affected to the government because they remained with the enemy when they had possession of the city!" ' .... Faris goes on to write that "Fortunately the strange law was repealed in season to save some of the trees that were the glory of the streets of the city."]
By the late 19th century, the deforestation rate had slowed a bit, to about 2%, but that still means we’d expect stands to be at most about 50 years old at that time, in the late 19th and early 20th century, which is the time when we see the oldest portions of the lands that are now forested in Fairmount Park becoming the natural areas that we now know them as.
That is to say that Fairmount Park was still quite young, by arboreal standards, as the 20th century arrived and moved forward – the oldest parts of it were on the order of a half century old at that time (dating to roughly the mid-19th century, that is), and many large parts were still coming to the city as the 20th century rolled on (for example, like the Pennypack, whose land starts being acquired by the city in 1905, and of course the site upon which the Hermit Lane pines now stand comes to the city around this time), and so the woods of Fairmount Park that we see now, filled with enormous tulip poplars and oaks and pines, and hemlocks, too, would have been pretty young at that time, and nowhere near as full as what we see today.
I’m not aware of any stands in Philadelphia that are older than 100 to 150 years old, and this is pretty well in line with the historical data outlined above. This is not to say that there aren’t individual trees that are older than that, as we know that there certainly are ones much older than this (e.g, in Hunting Park), or even some groupings of older trees (e.g, if you go along the rocky hilltop trail along the Wissahickon, just north from the Henry Ave. Bridge, there’s some wonderfully old chestnut oaks growing among the rocks overlooking the Wissahickon there that, based on their size, quite clearly predate the late 19th century), but I’m not aware of any substantial stands of trees in Philadelphia that predate the late 19th century.
And so we see in the first half of the 20th century a low of the areal extent of the forestation of Philadelphia – the woods had been cut over multiple times by then, and older stands that might have been found in less populated areas, perhaps distant out in the far northeast, or way out in the wilds of west Philadelphia, both dry and wet, were being cut down for the development that accommodated our growing population, and the current grandeur of Fairmount Park was still a young sylva at the time, not yet grown to the size that we see now.
In the 1930s especially, it appears, Philadelphia had few forested areas – development had extended to parts of city that still had wooded spots, and Fairmount Park had not yet become the well forested agglomeration of sites that we know today. Though it can seem difficult today to believe that our green city was once so unwooded, an illustrative anecdote of this is provided in Richard Miller’s paper, “the Breeding Birds of Philadelphia”, in volume 51, number 7 of the Oologist (“for the student of birds, their nests, and eggs”), published in 1933, where he notes of the American Crow that it is “Common, but slowly decreasing, due chiefly to destruction of woods.” (I also note that the Red-Bellied Woodpecker, a bird of forests and woodlands, is not listed in Miller’s paper – this is a bird that I commonly see now, along the Wissahickon, and elsewhere (e.g, at Bartram’s Garden, on the 5th of April 2013), which calls to the increase of trees in Philadelphia, I note; this is a bird whose range has expanded northward generally in the past decades, I also note; NB: notes are good).
Nowadays, so far as I am aware, no one fears for the crows due to lack of woods, and in this we can see the change from then to now – today there are wooded areas throughout the city, from Cobbs to the Poquessing, and so many places in between, where there are not just trees, but forests, and woodlands. Our landscape has changed drastically from a century ago – the woods we see now have grown since then, and what were once open areas are now wooded. Of course, the opposite has also occurred – what were once wooded areas now are not, and are now populated by buildings or streets or mown parks (sometimes this happened with quite a bit of opposition, as the fight over “Sherwood Forest” prior to it being cleared illustrates), and so it’s not like the woods have all grown up everywhere throughout Philadelphia, but as those wooded areas were being cleared, elsewhere parklands grew, and weren’t then cut again to clear the land, or for timber and fuel, and so we see this striking change throughout the landscape, from a hundred years ago to today.
There is, I should say, also continuity through time here – hemlocks have been here and are here now. And many other plants, animals and fungi have been documented to have been here in the past and remain here to this day. These include plants that are parasitic upon other plants – these persist as well, such as Conopholis americana, or Squaw-root, noted by Keller and Brown (1905) with a locality of “Wissahickon”, and that Barton (1818) noted as “Parasitic. On the authority of Mr. Bartram, I have introduced this plant, never having met with it myself. He says it grows in the woods near Philadelphia. Perennial. July.” (however, in Norman Taylor’s 1915 Flora of the Vicinity of New York, which includes Philadelphia, he lists Conopholis americana for PA as “Bucks, Delaware, and Chester Counties” (that is, not Philadelphia); he also calls it “A rare and local plant” and its habitat as “In rich woods, usually at the bases of oak trees… Rare”). [one wonders if this plant's populations have grown more abundant in the past hundred years due to expansion of oak populations which grew due to decrease in population of their main competitor, the American chestnut, which decreased due to the introduction of the fungus Cryphonectria parasitica, the causative agent of the chestnut blight, doesn't one?]
And there are plants that we still have, but in very different places, as we can read from Bayard Long’s 1922 paper in Rhodora (vol. 24), “Muscari comosum a new introduction found in Philaelphia” [the common name for this plant is grape hyacinth]:
“The collector of the specimen of Muscari comosum, Miss Adelaide Allen, fortunately was able to designate exactly where it had been obtained, as the spot lay along the familiar route from her home to school. Through her kindness, and the interest of Dr. Keller, we learned that it grew along the sides of a dyke, running in to South Broad Street from outlying farm houses, near League Island Park, in the southern portion of Philadelphia. This area consists in large measure of the extensive alluvial flats and marshes of the lower Delaware, more or less intersected by ditches. The region is not yet built up to any extent and the more elevated portions are frequently occupied by truck-farms. The southern extension of Broad Street, with its trolleys, offers one of the chief lines of travel in this particular locality, and the nearby farms often obtain access thereto by dykes laid down over the low meadows and more impassable places. These dykes are continually augmented by the dumping of ashes and rubbish down their sides. [note that the Dr. Keller mentioned above is the same Keller of 'Keller and Brown', mentioned previously]
In such a habitat from a detailed sketch map furnished by Miss Allen the Muscari was found growing.”
This plant persists from then, as is noted by John M. Fogg, Jr in his “Annotated checklist of plants of the Wissahickon Valley”, published in Bartonia (vol. 59) in 1996: “Muscari botryoides. Grape-hyacinth. Introduced and naturalized from Europe. Occasional in woods and clearings. Thomas Mill Road.”
In the overall change of Philadelphia’s ecosystem over the centuries, many of the moving parts have remained, though they may have shifted gears a bit.
This succession, the change in urban ecosystems through time, is not, as is illustrated by the Hermit Lane pines, strictly a passive process. It is, or at least can be, actively facilitated by people and their (or “our”, I should say, since we are all people) management – by planting those white pines, for erosion control or for reforestation, this altered the pattern of succession that we would have seen otherwise, from what we most likely would have seen, or at least what I’d expect to see, which would be a stand of tulip poplars, that would’ve now had trunks about a meter across and would now be just about reaching the end of their lifespan, to this massive stand of white pines that we see today. This occurred not by chance, but by human intervention, and is the reason that what we see today is there as it is.
By looking at these old photos and maps, by reading old reports and census documents, by understanding landscape ecology and succession, we can see how what was done before has brought about what is here today – we can see the enormous changes that have affected our city, and often be quite surprised at just what those changes were and how they came about.
It can be surprising to realize that Philadelphia has more dense forest today than it did a hundred years ago, and also then to learn the other impacts this brings about, on birds, as mentioned above, and also on water quality, among other environmental factors. And it is key to realize that this did not happen by chance; ecology in cities is due directly to actions by people, and always has been, for a very long time, as we see from those pines that were planted a century ago. We are part of these ecosystems, and thoughtful decisionmaking, such as that in the Philadelphia Parks and Recreation’s recently released Parkland Forest Management Framework, is needed for making these decisions in a way that will be amenable to all of us in and for Philadelphia, both now and in the years, decades, and centuries to come.
On Thursday, the 24th of October, Elizabeth McLean, author and garden historian, will lecture “on how we are now so used to getting plants from all over the world that we tend to take it for granted: roses from South America, Granny Smith apples from Australia. But this was not always the case. From the familiar lilac to the exotic Dove tree and the vibrant blue poppy, intrepid plant explorers have historically risked their lives to enrich our gardens.”
For more information, see here:
A new report on urban biodiversity was released this month. For a press release on it from the UN Environmental Programme, see here:
And for more: