Trent University
MyTrent
  • Academics
    • Undergraduate Programs
    • Graduate Programs
    • Trent Online
    • Summer Courses
    • Continuing Education
    • Study Abroad
    • Academic Calendar
    • Academic Timetable
    • Academic Skills Centre
    • Academic Advising
    • Library
    • Centre for Teaching and Learning
  • Admissions
    • Undergraduate
    • Thinking of Applying
    • Already Applied
    • Received an Offer
    • Accepted My Offer
    • Graduate
    • International
    • Indigenous
    • Returning to Trent
    • Transfer
  • Services & Support
    • Academic Advising
    • Academic Skills Centre
    • Administrative Departments
    • Alumni Services
    • Athletics
    • Campus Security
    • Careerspace
    • Colleges
    • Communications
    • Conferences
    • Financial Aid
    • Financial Services
    • Health & Wellness
    • Indigenous Services
    • Information Technology
    • International Students
    • Learning Support
    • Parking
    • Printshop
    • Recruitment
    • Registrar's Office
    • Residence & Housing
    • Student Clubs
    • TrentU Card
  • Research
    • Research at Trent
    • Research Centres
    • Find an Expert
    • Resources
  • Give to Trent
  • About Trent
    • About Trent
    • Careers
    • Giving to Trent
    • Governance
    • How to Find Us
    • Media
    • News & Events
    • President's Office
    • Staff Directory
    • Trent Facts
    • Contact Us
  • Campus Locations
    • Peterborough
    • Durham GTA
    • Online
  • Future Students
    • Undergraduate
    • Thinking of Applying
    • Already Applied
    • Received an Offer
    • Accepted My Offer
    • Graduate
    • International
    • Indigenous
    • Returning to Trent
    • Transfer
  • Current Students
  • Alumni
  • Trent Forward: COVID-19 Info
  • Apply
  • Visit
  • Give
  • Map
  • Careers
  • Directions
  • Library
  • Site Map
  • Bookstore
Skip to main content Home
  • Peterborough
  • Durham GTA
  • Online
  • MyTrent
MENU
Trent University
News and Events
  • Latest News
  • Trent Experts
  • For Media
  • For Faculty and Staff
  • Publications
  • Contact Us
  1. Trentu.ca
  2. News and Events

Deforestation in 19th Century Altered Lake Ontario Nutrients

March 6, 2020
Share This Story

Research by Trent University postdoctoral fellow reveals nitrogen composition changed as logging became widespread

Research by Trent University postdoctoral fellow Dr. Eric Guiry

Changes in logging and land management practices in the 19th century caused a profound ecological shift in one of the world’s largest freshwater ecosystems according to new research by Trent University postdoctoral fellow Dr. Eric Guiry published in the journal Limnology and Oceanography.

Nitrogen levels in Lake Ontario increased as a result of widespread deforestation across its watershed after at least 800 years of relatively stable levels. The new research shows this balance suddenly shifted when forests were cleared, the land became more vulnerable to erosion, and nitrogen-rich soils washed into the lake.

“Shifting a lake’s nutrient balance, of which nitrogen is a key component, can have significant effects on the health of the plants and animals that live within it,” says Dr. Guiry.

“We know that humans have had an impact on the lake for a long time, and we've known that runoff from forestry and agriculture were an important part of that. Our data allowed us to tightly control the timeframe over which we can see it happening, which helps understand which activity caused the problem.”

Dr. Guiry uncovered this relationship using stable isotope analysis of archaeological fish bones to reconstruct the lake’s historic nitrogen cycle. Trent’s first-ever Banting postdoctoral fellow in Archaeology—a research position funded by all three of Canada’s research councils—Dr. Guiry analyzed the amount of the element nitrogen-15 in the bones of lake trout, Atlantic salmon and whitefish specimens from a number of sites along Lake Ontario’s shores and within its watershed. The oldest among them dated to approximately 980 AD.

Using information about where and when fish specimens were caught, Dr. Guiry was able to identify that after centuries of stability, the level of nitrogen-15 in Lake Ontario began to rise in the 1830s. The findings show that even the largest lakes can be sensitive to human impacts over short timespans.

During the 19th century, the population near the lake was growing. People living in cities like Toronto and Kingston would have been impacting the lake too, but it would have been more localized.

“The increase in nitrogen levels happened on a lake-wide scale, so it had to be broader than just one city,” explains Dr. Guiry. “Widespread industrialization could have caused it, but that had not happened yet, so the cause must have been something occurring across a large area. That was deforestation.”

Indigenous people had long used fire to clear land in the area, and early settlers had cleared forests for their farms. However, the scale of logging in the watershed during that period was unprecedented.

“Originally, when farmers cleared their fields, they often took precautions to avoid nutrient loss in their soils. They would leave stumps behind and wait to start plowing to try to use nutrients without affecting the soil,” says Dr. Guiry.

“As logging increased and more land was cultivated, people started to plow and remove stumps, rocks, and barriers that might have kept more nutrients in the soil. That’s when you start to have large-scale loss of soil nutrients through increased runoff.”

Find other stories about: Ecology, Ecological Restoration, Research

Share This Story

You Might Also Like

Graphic reads "Trent Beat Making Headlines". The graphic includes six images of: a painting of Thomas Symons, a person holding a phone, Dr. Dawn Lavell Harvard, Dr. David Beresford, Dr. Marguerite Xenopoulos, and a person holding flying squirrels.old

Trent Beat

Image of Kerri Mozessohn, sitting in Bata library, smiling at the camera.

An Inspired Journey: Transfer Student Dives into the World of Undergraduate Research

Image of Sandra Dueck looking at the camera.

Educating a New Generation of Police Leaders

Trent University logo
Challenge the Way You Think

Trent University respectfully acknowledges it is located on the treaty and traditional territory of the Mississauga Anishinaabeg. We offer our gratitude to First Peoples for their care for, and teachings about, our earth and our relations. May we honour those teachings.

Peterborough

1600 West Bank Drive
Peterborough, ON Canada, K9L 0G2

Toll Free: 1-855-MY-TRENT

Campus Map

Durham Greater Toronto Area

55 Thornton Road South
Oshawa, ON Canada, L1J 5Y1

Phone: 905-435-5100

Campus Map

Social Media Directory
  • Contact
  • Directions
  • Site Map
  • Accessibility
  • @ Copyright 2023 Trent University