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Dr. Doug Larson
Professor Emeritus

 Dr. Doug Larson



Why is it that plants can survive in extreme environments that are largely unsuitable for humans? I had an opportunity to address this question by working on the tundra near Hudson's Bay when I was an undergraduate then graduate student at McMaster University. This work provided a partial, physiologically-based answer to the question. After I joined the Botany Department of the University of Guelph, I expanded the scope of my investigations to include other processes and habitats. Now I use an ecosystem approach, concentrating on cliff and alvar environments in eastern North America, to unravel the web of complex physiological, morphological and behavioural mechanisms used by plants to thrive in these hostile environments.

My work has been well received by my colleagues, other educators and the public at large. I have received a number of awards, including the Ralph Sherwood Conservation Award, the Friends of the Escarpment Award, Canadian Wildflower Society Conservation Award, and Rolex Awards Honourable Mention. My findings also receive considerable coverage on television, radio, newspapers and magazines and I am asked regularly give talks to groups.

I am a member of the Canadian Botanical Association and Sigma XI. I have served on the Ontario Scientific Advisory Committee for Old Growth Forests and I have been an associate editor of the Canadian Journal of Botany.


B.Sc. - McMaster University
Ph.D. - McMaster University


Cliff Ecology Research Group

My Cliff Ecology Research Group consists of graduate students, research associates and summer students who join me in trying to understand the ecology of an entire 'place' known as a cliff. By studying cliffs from as many perspectives as possible we hope to gain a better understanding of how an ecosystem works than is possible using traditional approaches. Cliffs are relatively discrete and biologically unproductive which simplifies our task. To date, we have shown that cliffs have many interesting characteristics, including the fact that they support the least disturbed and oldest forest ecosystem in North America. Some of our current projects are described briefly below.

Plant invasion and habitat heterogeneity on cliffs and other rocky terrain
(Jeremy Lundholm, PhD candidate)

This project tests the hypothesis that habitat heterogeneity limits habitat invasion by exotic species.

Habitat-dependent plant invasion
(Margy deGruchy, MSc graduate)

This research examines the relationship between the abundance of alien plants in a habitat and its productivity.

Effect of rock climbing on cliff vegetation and snails (Michele McMillan, MSc graduate)

The structure of biotic communities on and off routes used by rock climbers are being compared to provide a basis for the formulation of new land-use policies.

Endolithic and epilithic organisms
(Uta Matthes, Research Associate)

This project examines the structure and function of the community of organisms found attached to, and inside of, rocks on cliffs.

Ancient trees on the Niagara Escarpment
(Pete Kelly, Research Associate)

The locations of ancient trees are being mapped to provide an inventory of the tree component of this ancient forest.

Restoration ecology of Niagara Escarpment landforms
(Uta Matthes, John Gerrath, Margy deGruchy)

In this area, we are trying to understand the initial site conditions for disturbed limestone plateaus, cliff edges, cliff faces and talus slopes. We are also trying to use this information to facilitate restoration of these sites.

Selected Publications


Larson, D.W., Matthes, U. and Kelly, P.E. 2000. Cliff Ecology. Cambridge University Press, UK.

This book provides a summary of our current understanding of ecological structure and function of cliffs around the world.

Chapters in Books

Larson, D.W., Matthes-Sears, U. and Kelly, P.E. 1999 The Niagara Escarpment Cliff Ecosystem. In: Savanna, Barrens and Rock Outcrop Plant Communities of North America. Eds: R. Anderson, J. Fralish and J. Baskin. Cambridge University Press, UK. pp. 362-374

This chapter puts the Niagara escarpment cliff ecosystem into context by comparing it to other hostile environments in North America.

Booth, B.D., and Larson, D.W. 1999. Impact of language, history and choice of system on the study of assembly rules. In: Assembly Rules. Eds: E. Weirher and P. Keddy. Cambridge University Press, UK. pp. 206-229

This chapter takes a critical look at the concept of assembly rules and concludes that it is an important and well known concept that has recently been given a new name.

Research Papers

McMillan, M., Nekola, J. C., and Larson, D. W. 2002. The effects of rock climbing on the vegetation of the Niagara Escarpment in Southern Ontario, Canada. Cons. Biol. (2002).

This study used a careful experimental design to determine the effects of rock climbing on the structure of cliff biotic communities. The impact of rock climbing was significantly negative in all areas where rock climbing might occur.

deGruchy, M., Matthes, U., Gerrath, J. A. and Larson, D. W. 2001. Natural recovery and restoration potential of severely disturbed talus vegetation at Niagara Falls: assessment using a reference system. Rest. Ecol. 9:311-325.

This paper defines the pre-restoration species composition and distribution patterns in the Niagara Gorge. It shows that the conditions are wholly different from the conditions that apply on naturally-occurring talus slopes of the escarpment.

Larson, D. W. 2001. The paradox of great longevity in a short-lived trees species. Experimental Gerontology 36:651-673.

This paper presents a comprehensive analysis of the factors that lead to exceptional longevity in what is supposed to be a short-lived tree species.

Matthes, U. and Larson, D. W. 2001. Light attenuation by limestone rock and its constraint on the depth distribution of endolithic algae and cyanobacteria. Int. J. Plant Sci. 162: 263-270.

This paper presents the first quantitative analysis of the influence of rock type on the attenuation of light that supports populations of endolithic organisms living in the Niagara Escarpment.


In my teaching I emphasize the dynamic and progressive aspects of science. In intermediate and senior-level ecology courses (BIOL*3010 and BIOL*4110) I lead students through the planning and execution of laboratory and field exercises to test ecological theory. Most recently, I have been teaching a new fourth year course in restoration ecology (BIOL*4060) that uses some of my experience in this field.

At the graduate level, we discuss current topics in ecology (BOT*6301) and philosophical decisions made in the everyday practice of science (BOT*6404). These approaches reflect my belief that knowledge gained by physical and mental participation is more permanent than knowledge gained by other means.

In recognition of my teaching, I have received the College of Biological Sciences Teaching Award.

Past Grad Students

Richardson, Paul (PhD)
Stabler, Cassandra (MSc)