Featured Research

from universities, journals, and other organizations

Buried leaves reveal precolonial eastern U.S. forests and guide stream restoration

Date:
November 13, 2013
Source:
Penn State
Summary:
Sediment behind milldams in Pennsylvania preserved leaves deposited just before European contact that provide a glimpse of the ancient forests, according to a team of geoscientists, who note that neither the forests nor the streams were what they are today.

Red Oak (left), American Beech (center), Sweet Birch (right). These are fossil leaves removed from the Denlinger Mill study site.
Credit: Wilf Lab/Penn State

Sediment behind milldams in Pennsylvania preserved leaves deposited just before European contact that provide a glimpse of the ancient forests, according to a team of geoscientists, who note that neither the forests nor the streams were what they are today.

"Milldams were built from the late 1600s to the late 1800s in Pennsylvania and other parts of the east," said Peter Wilf, professor of geosciences, Penn State. "We can't get information from historic records on what the area looked like before the dams because recording of natural history didn't really begin until the 1730s and was not detailed."

U.S. census shows that by 1840, tens of thousands of milldams existed in the mid-Atlantic region. About 10,000 of these were in Pennsylvania. In Lancaster County, estimates were one dam for every mile of stream. The abundance of dams in the area altered the landscape dramatically, according to the researchers.

"I see a potential modern day benefit for this research," said Sara J. Elliott, recent Penn State master's degree recipient, currently a research scientist associate atUniversity of Texas Austin, Bureau of Economic Geology. "Attempts to restore precontact environments have been unsuccessful when the effects of milldams were not considered. Understanding the past forest makeup may provide a way to help get a successful and useful reconstruction."

Denlinger's Mill study site. Located on the West Branch of the Little Conestoga Creek in Lancaster County, PA. Arrow indicates dark paleo-wetland soil layer containing fossil leaf deposits, with four plus meters of historical sediment buildup on top.

The researchers looked at samples of 300-year-old leaves buried by sediment that backed up behind Denlinger's Mill in Lancaster County. The leaves came from trees on an outcrop above the dam. Because sediment quickly covered the leaf layer, the leaves that date from before the dam remain intact. When carefully separated and cataloged, the leaves reveal the makeup of the forest near the water's edge before milldams were builtand forests were cleared. The researchers published their findings in today's (Nov. 13) issue of PLOS ONE.

Dorothy J. Merritts, chair, Department of Earth and Environment and Harry W. and Mary B. Huffnagle Professor of Geoscience, and Robert C. Walter, associate professor of geosciences, both of Franklin and Marshall College, who found the fossil leaf mat note that the Denlinger's Mill site was our 'Eureka' moment in the unraveling of this anthropogenic impact story."

"We expected to see evidence for single stream channels that meandered back and forth across the valley bottom landscape for millennia, " they wrote. "Instead, we found that most of the valley bottoms at the time of European contact were dominated by wetland ecosystems with numerous small, stable 'anastomosing' streams."

These branching and reconnecting streams were far different from the steep-banked meandering streams that, since the dams were breached, now cut through the silt deposits created by the dams.

"First we had to uncover the leaf mats and then try to get a sample," Elliott said. "The mats were fragile and delicate, and getting them back to the lab or just transferring them from one container to another was problematic."

Elliott carefully peeled away the leaves, stacked on top of each other in sticky mud and preserving gorgeous detail, to preserve as many pieces as possible. She then treated them in a variety of chemical baths, mounted them between large glass slides and cataloged their species.

"We got a lot of information that was not available from other sources," said Elliott.

The Denlinger's Mill site is unusual because of the rock outcrop and the trees that grow and grew there over the water. The leaves found in the stream bank preserve a snapshot of the trees growing directly above before European settlement, which Elliott then compared to the modern forest makeup.

The researchers found that the precontact forest was overwhelmingly American beech, red oak and sweet birch, similar to modern red oak/beech forests today. But box elder and another maple dominate the current forest that grows above the stream.

"It was intriguing to see samples from American chestnut, which isn't around anymore because of the chestnut blight," said Elliott. "On the whole though, the species are around today, just in different proportions and places."

The researchers think that reconstructing landscapes more along the lines of those that actually existed before the 1700s might be a more successful approach to restoration. Establishment of precolonial-like habitats might also decrease the amounts of nutrients from the legacy sediments that currently flow into the Chesapeake watershed and cause increased algal and plant growth.

"We now know that legacy sediment from the stream banks caused by the milldams is the major source of eutrophication in the Chesapeake area," said Wilf. "Not, as is usually assumed, modern agricultural runoff."


Story Source:

The above story is based on materials provided by Penn State. The original article was written by A'ndrea Elyse Messer. Note: Materials may be edited for content and length.


Journal Reference:

  1. Sara J. Elliott, Peter Wilf, Robert C. Walter, Dorothy J. Merritts. Subfossil Leaves Reveal a New Upland Hardwood Component of the Pre-European Piedmont Landscape, Lancaster County, Pennsylvania. PLoS ONE, 2013; 8 (11): e79317 DOI: 10.1371/journal.pone.0079317

Cite This Page:

Penn State. "Buried leaves reveal precolonial eastern U.S. forests and guide stream restoration." ScienceDaily. ScienceDaily, 13 November 2013. <www.sciencedaily.com/releases/2013/11/131113182545.htm>.
Penn State. (2013, November 13). Buried leaves reveal precolonial eastern U.S. forests and guide stream restoration. ScienceDaily. Retrieved September 19, 2014 from www.sciencedaily.com/releases/2013/11/131113182545.htm
Penn State. "Buried leaves reveal precolonial eastern U.S. forests and guide stream restoration." ScienceDaily. www.sciencedaily.com/releases/2013/11/131113182545.htm (accessed September 19, 2014).

Share This



More Earth & Climate News

Friday, September 19, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Raw: Wildfires in CA Burn Forest Asunder

Raw: Wildfires in CA Burn Forest Asunder

AP (Sep. 18, 2014) — An out-of-control Northern California wildfire has nearly 2,800 people from their homes as it continues to grow, authorities said Thursday. Authorities said a man has been arrested on suspicion of arson for starting the fire on Saturday. (Sept. 18) Video provided by AP
Powered by NewsLook.com
Raw: Elephant Undergoes Surgery in Tbilisi Zoo

Raw: Elephant Undergoes Surgery in Tbilisi Zoo

AP (Sep. 18, 2014) — Grand the elephant has successfully undergone surgery to remove a portion of infected tusk at Tbilisi Zoo in Georgia. British veterinary surgeons used an electric drill to extract the infected piece. (Sept. 18) Video provided by AP
Powered by NewsLook.com
Raw: Scientists Examine Colossal Squid

Raw: Scientists Examine Colossal Squid

AP (Sep. 16, 2014) — Squid experts in New Zealand thawed and examined an unusual catch on Tuesday: a colossal squid. It was captured in Antarctica's remote Ross Sea in December last year and has been frozen for eight months. (Sept. 16) Video provided by AP
Powered by NewsLook.com
Man Floats for 31 Hours in Gulf Waters

Man Floats for 31 Hours in Gulf Waters

AP (Sep. 16, 2014) — A Texas man is lucky to be alive after he and three others floated for more than a day in the Gulf of Mexico when their boat sank during a fishing trip. (Sept. 16) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins