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June 9, 1998

Mr. Donald Barber
Vice-President, Friends of the Cawthra Bush & Greater Mississauga Area
Station B, Box 1054,
Mississauga, ON, L5G 2P6

Dear Mr. Barber,

Thank you for your fax of 3 June 1998. The problems you described are indeed widespread and under documented. My own study is still in the stages of being prepared for a submission to an academic journal. I provide a synopsis for you:

In eastern Ontario forests, increased fragmentation has caused edge effects to increase in severity. This means that the micro-climate around the forest edge is altered and the interior of the forest also is subjected to environmental conditions that normally would be associated with edge habitat. These edge effects tend to self perpetuate because they allow invasive species to colonize sites, out-compete species that prefer shady, moist, and wind-free habitats, and thereby kill off regeneration of tree seedlings or understorey herbs (for example). This frees up more habitat suitable for the invasives and they advance further into the forest. Simultaneously, the changes in micro-climate and habitat structure indirectly affect organisms such as insects that pollinate plants. My study focused on a beetle that pollinated sharp-lobed hepatica. The larvae of this beetle cannot survive in a dry, sunny area and die when edge effects alter the micro-climate. When this happens, the hepaticas lose their sole pollinator and resort to selfing (inbreeding) that eventually can cause severe mutations and eliminate local populations. The problem ran be serious as hepatica is not as vulnerable as other species that are not as proficient or adapted to selfing or clonal replication; this means other species may be in greater peril. This concept holds for most organisms, especially plants and animals (as opposed to protozoans, for example).

I do have an extensive list of papers that describe similar situations (albeit couched in more scientific than management language). I list these at the end of this letter; I have copies of all of them and we could arrange to get you copies as well.

I probably can drop by at some point to take a look at your site and also could see if one of my students would be interested in helping you with whatever you may need (e.g. you seem to indicate species surveys and micro-climatological studies are needed). I have a graduate student who is doing similar work in York Region and I'll see if she would like to come by as well. We could explore these possibilities further in a couple of weeks (once my field research season tapers off for awhile).

Please do not hesitate to contact me by phone, fax, or e-mail in the coming weeks if you think our assistance can be of use. I am usually in the office Tuesday and Wednesday afternoons and occasionally Thursdays during the summer (during the rest of the year, I'm usually there every day except Fridays).

A (relatively) short list of relevant papers (the first # is the accession # from my electronic database):

2857.     Palik, B. J., and P. G. Murphy. 1990.
                Disturbance versus edge effects in sugar-maplelbeech forest
                fragments. Forest Ecology and Management 32: 187-202.

2907.     Matlack, G. R. 1993.
                Microenviroriment variation within and among forest edge sites in
                the eastern United States. Biological Conservation 66: 185-194.

2908.     Matlack, G. R. 1993.
                Sociological edge effects: Spatial distribution of human impact in
                suburban forest fragments. Environmental Management
                17: 829-839.

3045.     Brothers, T. S., and A. Spingam. 1992.
                Forest fragmentation and alien plant invasion of central Indiana
                old-growth forests, Conservation Biology 6: 91 -100.

3048.     Laurence, W. F., and E. Yensen. 1991.
                Predicting the impacts of edge effects in fragmented habitats.
                Biological Conservation 55: 77-92.

3049.     Weaver, M., and M. Kellman. 1981.
                The effects of forest fragmentation on woodland tree biotas in
                southern Ontario. Journal of Biogeography 8: 199-210.

3050.     Harris, L. D. 1988.
                Edge effects and conservation of biotic diversity. Conservation
                Biology 2: 330-332,

3051.     Yalmer, R. H. 1988.
                Changes in wildlife communities near edges. Conservation Biology
                2: 333-339.

3054.     Whitney, G. G., and J. R. Runkle. 1981.
                Edge versus age effects in the development of a beech-maple
                forest. Oikos 37: 377-381.

3123.     Knappen, J. P., M. Scheffer, and B. Hanns. 1992.
                Estimating habitat isolation in landscape planning. Landscape and
                Urban Planning 23: 1-16.

3130.     Taylor, P. D., L. Fahrig, K. Henein, and G. Merriam. 1993.
                Connectivity is a vital element of landscape structure. Oikos 68:
                571-573.

3141.     VIhitney, G. G., and W, J. Someriot. 1985.
                A case study of woodland continuity and change in the American
                midwest. Biological Conservation 31: 265-287.

3312.     Riley, J. L., and P. Mohr. 1994.
                The natural heritage of southern Ontaria's settled landscapes. A
                review of conservation and restoration ecology for land-use and
                landscape planning. Technical Report TR-00 I (Southern Region,
                Aurora, Science and Technology Transfer), Ontario Ministry of
                Natural Resources Information Centre, Toronto, Ontario 78 pp.

3540.     Matlack, G. R. 1994.
                Vegetation dynamics of the forest edge - trends in space and
                successional time. Journal of Ecology 82: 113-123.

4025.     Murcia, C. 1995.
                Edge-effects in-fraginented forests: implications for conservation.
                Trends In Ecology and Evolution 10: 58-62.

4029.     Murphy, S. D., and C. J. Swanton. 1995.
                Agroecosystem health: Is plant diversity a useful indicator?
                Agroecosystem Health Project, Miscellaneous Publications.
                Discussion Paper #16. 25 pp.

4682.     Murphy, S. D., and L. Vasseur. 1995.
                Pollen limitation in a northern population of Hepatica acutiloba.
                Canadian Journal of Botany 73:1234-1241.

5624.     Poser, S. F., W. J. Crins, and T. J. Beechey. 1993.
                Integrity standards for Natural Heritage Areas in Ontario. Ontario
                Ministry of  Natural Resources, Huntsville, ON. 144 pp.

6006.     Riley, J.L. (ed.). 1989.
                Distribution and status of the vascular plants of central region,
                Ontario Ministry of Natural Resources. OMNR, Parks and
                Recreational Areas Section, Central Region, Richmond Hill
                (Toronto ON) 110 pp.

With best wishes. Stephen D. Murphy, B.Sc. (Hons.), Ph.D. Assistant Professor phone extension: 5616;  e-mail: sd2murph@fes.uwaterloo.ca

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