What’s an “Ecotone”?

The striking physical features of the Canadian Shield ecosystem, known for bare outcrops of granite rock, of small lakes and thin layer of soil contrast with the St. Lawrence Lowlands ecosystem known for flatter lands, dominated by agriculture and limestone bedrock.[1] These landscapes are well known throughout south-central Ontario, however as ecosystems overlap and transition from one another, they can be characterized as a separate ecosystem, called an ‘Ecotone’.[2] This overlap can be observed in The Land Between and so it is characterized as an ecotone because we can see the ecosystem of the Canadian Shield and the St. Lawrence Lowlands meet each other in this landscape.

Did you know the origin of the word ecotone is of Greek origin, derived from the words “ecology” and “tone” meaning “house” in “tension”? [2] As each ecosystem transitions from one to the other it creates a unique landscape full of cultural and environmental significance, thus an ecosystem of its own. As the origin of the word suggests that these ecosystems are in tension, it can be described better as a natural mosaic and in the Land Between the patchwork is marked with undulations of elevation, changes in forest cover from woodlots to wetlands, rock barrens to meadows, and also a variety and abundance of species. [3,7] In fact, the various habitats present throughout this overlapping landscape results in different species being at their edge of their natural range and thus some of high species diversity in all of Ontario. The Land Between has natural “patchiness”, which is inherent in ecotones. [1] And this region has the highest percentage of intact and connected habitat patches, also known as habitat or beta diversity. The natural mosaic and patchwork that can be visualized through satellite imagery, can provide refuge for species that experience habitat range shifts due to climate change. [6]

The Land Between encompasses over 2400 large lakes. These aquatic ecosystems in this landscape also contain the headwaters for major river systems that flow into the Trent Severn Waterway, through the Ottawa River and find their way into Lake Ontario. [1] The exposed bare rocks seen throughout The Land Between are classified as Precambrian granite and sedimentary Ordovician Limestone. [5] a Along with the rock barrens, the depth of soil is on average less than 15cm across the region. The shallow soils reduce buffering capacity against pollutants from urban-style and residential development along the lakeshores. [1,7] This leaves the water systems sensitive to pollutants as they are highly interconnected. More, is that these waters have high numbers of human and non human beings reliant on them for residence and sustenance.The shorelines are also unique as they too have the “edge effect”, and are Ecotones, but here, where aquatic and terrestrial species can be found living in proximity or dynamic tension. [3]

The biodiversity of the Land Between is at risk as this fragile landscape, and the more vulnerable shores, are becoming highly developed as a result of the rapid growth of lakeshore residential conversions. The degradation of shorelands, adjacent forests and wetland habitats, can cause ripple effects that are long lasting, and which spread throughout the whole food web and aquatic ecosystems because these areas are highly interconnected. [1,6,7] Learning more about how to protect the valuable and beautiful non-human beings is a first step. Here there are species such as the loon, golden winged warbler, 7 native species of Turtle in the region, and also 50 plus additional species that are in jeopardy and who rely on this landscape as a final strong-hold.

The Land Between has many learning resources at your disposal and also has numerous opportunities to volunteer as a Community Scientist. TLB’s biologists provide training to learn how to observe, track and advocate for wildlife too- and all from your backyard! Learn more about how you can volunteer here!

Written by: Shahrzad Gharabaghi, Climate Change Research Specialist

Works Cited:

1. Alley, P., Porchuck, B., & Berman, L. (2014, June). The Land Between as an Ecotone. https://www.thelandbetween.ca/wp-content/uploads/2014/06/The-Land-Between-as-an-ecotone.pdf
2. Ecological Society of America. (n.d.). Ecotone explained. The Ecological Society of America. Retrieved from https://www.esa.org/esablog/about/ecotone-explained/
3. Semlitsch, R. D., & Bodie, J. R. (2003). Biological criteria for buffer zones around wetlands and riparian habitats for amphibians and reptiles. Conservation Biology, 17(5), 1219-1228.
4. Leithead, M. D., Anand, M., & Silva, L. C. (2010). Northward migrating trees establish in treefall gaps at the northern limit of the temperate–boreal ecotone, Ontario, Canada. Oecologia, 164(4), 1095-1106.
5. Liu, K. B. (1990). Holocene paleoecology of the boreal forest and Great Lakes‐St. Lawrence forest in northern Ontario. Ecological Monographs, 60(2), 179-212.
6. Brice, M. H., Vissault, S., Vieira, W., Gravel, D., Legendre, P., & Fortin, M. J. (2020). Moderate disturbances accelerate forest transition dynamics under climate change in the temperate–boreal ecotone of eastern North America. Global Change Biology, 26(8), 4418-4435.
7. Risser, P. G. (1995). The status of the science examining ecotones. BioScience, 45(5), 318-325.