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Title: Information Sheet, Tree Falls and Glover-Archbold Park
Instructors’ Note
A student in Forest Ecology (fall 2002) at Georgetown University (GU), Washington, D.C., produced this report as an individual class project which had a limit of about 20 hours.
Goals of the projects included:
(1) learning about a relatively natural forest (Glover-Archbold Park which is adjacent to Georgetown University, in Washington, D.C.), the “open urban forest” of GU Campuses, and the “urban forest” in residential neighborhoods near GU.
(2) providing information about these subjects to interested parties via the Internet.
These are short projects that lay groundwork for further investigation in their respective areas.
Therefore, these are pilot projects.
To see all 12 of the 2002 projects, please use the keyword 2002FER on this Website.
Projects of future Forest Ecology students might continue lines of investigation of the 2002 projects.
E. M. Barrows and N. Bakkour, instructors
An Assessment of Tree Falls in Glover-Archbold Park, Washington, D.C.
Mary Sandquist
Department of Biology
Georgetown University
Forest Ecology 355, Fall 2002
Introduction
An investigation regarding the location and nature of tree falls in Glover-Archbold Park was conducted with the intention of persuing several aims. The first of these aims was to determine the most probable causes of tree falls in Glover-Archbold Park; the second of these aims was to determine if there were any areas of the Park which seemed to be particularly vulnerable to tree falls; finally, the third of these aims was to ascertain if any specific tree species was predisposed to falling.
Glover-Archbold Park is part of Rock Creek Park in Washington, D.C., extending 2 miles north of the Potomac River at the border of the Georgetown University Main and Medical Campuses. Donated to the city in 1924 by Charles C. Glover and Anne Archbold, this 183-acre park was to be used as a bird sanctuary (Anonymous, 2001). Today, however, it exists predominantly as a nature preserve and recreation area. Washington, D.C., is located in both the Coastal Plain and Piedmont Provinces of the Eastern United States. The Piedmont Province is characterized by its hilly terrain due to the repeated formation and erosion of mountain ranges throughout geological history, while the Costal Plain Province is noted for its low, flat land bordering the Atlantic Coast. (Schmidt, 1994; Stanley, 1989). This park is classified as an angiospermous mesic forest, due to the dominance of angiospermous trees and its proximity to the Potomac River. Common species include oaks, American Beech, Black Walnut, and Eastern Sycamore.
I found it difficult to locate information regarding tree falls in the Eastern United States on the internet; several searches presented no relevant data. However, it can be stated from common knowledge that tree falls in Eastern U.S. forests may be caused by a variety of natural factors. These include lightning strikes, wind, decaying root systems, and mud slides. Trees growing on steep inclines, too, are prone to falling due to the inability of their roots to provide support for their massive aboveground biomass.
Woody vines also may cause trees to fall due to the massive amount of weight that they impose upon their trunks by growing on them. One such woody vine is English Ivy, an invasive, alien species which has recently begun to proliferate in some Eastern U.S. forests. Not only does English Ivy choke out native herbaceous plants, but this woody vine has the ability to harm trees with its weight and competition for sunlight as it winds up tree trunks. Trees may crash to the ground because of the large amount of weight imposed by the wood of this noxious vine (Barrows, 2002).
Materials and Methods
Investigation of the location and nature of recent tree falls in Glover-Archbold Park involved 10 total hours of exploration of the southeastern section of the park. The area of the park was fully investigated by traveling in straight line paths in the east-west direction, covering the width of the park. Observations were documented regarding the nature of the tree fall, its topographical location in the park, its estimated intact height and width, as well as its species. Measurements were made using a standard yard stick.
Results and Discussion
Examination of the accumulated data indicates several trends.
The first of these trends regards the prevalence of tree falls that occur on inclines located within the park. A number of trees seemed simply to topple over, uprooting themselves at their bases, presumably due to the inability of their roots to support their massive weight on such inclines. This is exemplified by the 50% of the total number of trees examined which were designated both “on incline” and “completely uprooted” in the results table.
It also seems that the growth of woody vines on trees, specifically identified as English Ivy, is a major instigator of tree falls in Glover-Archbold Park. A number of trees simply fell over, uprooting themselves at their base, seemingly because of the extensive amount of woody vine twining around their trunks. This type of tree fall is exemplified by the fallen Eastern Cottonwood located along the trail in the park. Presumably in part due to the soft wood characteristic of this species, this tree cracked about 4 feet up from its base leaving part of the trunk is still intact. The recent occurrence of this tree fall can be determined by the freshness of the wood at the split. The entire trunk of the cottonwood is encased in vines of English Ivy, making it easy to determine the cause of this cracking. This appears to be a recently developed problem, given that all of the tree falls due to this strangulation by woody vines were deemed to have occurred within the last few years, some within one year.
The third most common instigator of tree falls in Glover-Archbold Park is hypothesized to be natural forces such as lightning and wind. Given the great heights of the trees which were cracked many feet up from their bases, as well as examination of the nature of the splits, it is entirely possible that both lightning and wind played significant roles in the cause of these tree falls.
Acknowledgement
I would like to thank Kyle Brown for “protecting” me in the woods, all of my friends, for still loving me despite the loser that I have become, and Dr. Edward Barrows and his faithful assistant Noura Bakkour, who have helped me to be able to identify more trees than I ever thought I would know.
Literature Sited
Anonymous. 2001. Trail Guide: Glover-Archbold Park. Internet File. http://www.washdc.ord/trail4.html
Barrows, E. M. 2002. Information Sheet, English Ivy. Internet File. http://biodiversity.georgetown.edu/index.htm
Schmidt, M. F., Jr. 1994. Maryland’s Geology. Tidewater Publishers, Centreville, Maryland.
Stanley, S.M. 1989. Earth and Life Through Time. Second Edition. W. H. Freeman and Company, New York.
Table 1. Tree falls in
Glover-Archbold Park, Washington, D.C., 2002*
| Species |
Location in park |
Estimated diameter (feet) |
Estimated original height (feet) |
Nature of fall |
Site in forest |
Estimated time of fall in 2002
or years ago |
| |
|
|
|
|
|
|
| Eastern Sycamore |
8 |
4 |
40 |
completely uprooted |
on incline |
15–20 |
| |
|
|
|
|
|
|
| Eastern Sycamore |
9 |
4 |
40 |
completely uprooted |
on incline |
15–20 |
| |
|
|
|
|
|
|
| Musclewood |
11 |
1 |
30 |
cracked 15 feet up |
on incline |
3 February |
| |
|
|
|
|
|
|
| Eastern Sycamore |
12 |
3 |
30 |
cracked 30 feet up |
on incline |
7 May |
| |
|
|
|
|
|
|
| oak |
13 |
2 |
50 |
completely uprooted |
on incline |
10 |
| |
|
|
|
|
|
|
| Musclewood |
14 |
1 |
20 |
cracked at base |
on incline |
5 March |
| |
|
|
|
|
|
|
| American Beech |
15 |
1 |
50 |
completely uprooted |
on incline |
At least 20 |
| |
|
|
|
|
|
|
| oak |
16 |
3 |
50 |
completely uprooted |
on incline |
15–20 |
| |
|
|
|
|
|
|
| American Beech |
20 |
2 |
25 |
cracked halfway |
on incline |
5 March |
| |
|
|
|
|
|
|
| Eastern Sycamore |
21 |
5 |
50 |
completely uprooted |
on incline |
10 July |
| |
|
|
|
|
|
|
| oak |
22 |
7 |
100 |
cracked 60 feet up |
on incline |
3 February |
| |
|
|
|
|
|
|
| Musclewood |
24 |
1 |
50 |
completely uprooted |
on incline |
10 July |
| |
|
|
|
|
|
|
| Black Walnut |
1 |
2 |
50 |
completely uprooted |
extensive woody vines growing on it |
5 March |
| |
|
|
|
|
|
|
| Black Walnut |
2 |
2 |
50 |
completely uprooted |
extensive woody vines growing on it |
5 March |
| |
|
|
|
|
|
|
| Young Black Walnut (10-20 years old) |
7 |
0.5 |
30 |
completely uprooted |
extensive woody vines growing on it |
Within 1 year |
| |
|
|
|
|
|
|
| Cottonwood |
10 |
2 |
75 |
partially cracked 4 feet up |
extensive woody vines growing on it |
Within a few months |
| |
|
|
|
|
|
|
| American Beech |
17 |
2 |
75 |
completely uprooted |
in dense woody vine growth |
15–20 |
| |
|
|
|
|
|
|
| Ash-leaved Maple |
23 |
3 |
40 |
completely uprooted |
in dense woody vine growth |
1 |
| |
|
|
|
|
|
|
| White Ash |
3 |
1 |
30 |
completely uprooted |
on level ground, fell on nearby trees |
7 May |
| |
|
|
|
|
|
|
| American Beech |
18 |
5 |
100 |
cracked 15 feet up |
on level ground |
5 March |
| |
|
|
|
|
|
|
| Eastern Sycamore |
19 |
3 |
30 |
cracked halfway |
on level ground, near stream bed |
10 July |
| |
|
|
|
|
|
|
| Musclewood |
4 |
1 |
30 |
just fell over |
small root system, rocky area |
15-20 |
| |
|
|
|
|
|
|
| Musclewood |
5 |
1 |
30 |
just fell over |
small root system, rocky area |
15–20 |
| |
|
|
|
|
|
|
| American Beech |
6 |
1 |
30 |
just fell over |
small root system, rocky area |
15–20 |
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