tree covered hill with a rough grass road

"In the next 25 to 50 years, the majority of the world's population will live in cities. It is critical that we learn to predict the impacts of urban development on biological diversity if we hope to maintain a semblance of ecological integrity in that urbanized landscape. Jokers Hill — an island in a sea of development — is a place where we can test ideas about disturbance, deforestation and atmospheric change, a place where we can learn how to maintain ecological integrity on a rapidly urbanizing planet."

Ann Zimmerman, Director of the Koffler Scientific Reserve at Jokers Hill

At the intersection of Highway 9 and Bathurst north of Toronto, among the rich tills and ruggedly undulating glacial deposits that compose the western reaches of the Oak Ridges Moraine, one comes upon a curious spectacle: against a backdrop of row housing is a small pasture with grazing cows and an old farmhouse — white sheets flapping from the clothesline like streamers in the wind. The flags of surrender or the banners of resistance? To one side are the sprawling horse farms of King Township, their grounds neatly manicured. To the other, the nearly treeless housing tracts of Newmarket. In between, an old growth forest of oak, aspen, maple, pine and hemlock. This is where the drama of urban encroachment on the natural environment is being played out.

Between the houses and the horse farms, in fact, are 348 hectares of diverse forest, old field, pasture, conifer plantation and wetland communities, collectively called Jokers Hill. Straddling a watershed divide, the site's groundwater resources feed both the Humber River to the south and the Holland River to the north. In recognition of the site's outstanding geologic features, the Ontario Ministry of Natural Resources designated Jokers Hill an Earth Sciences Area of Natural and Scientific Interest (ANSI). Its biological features have gained it a nomination for a Life Sciences ANSI.

Until 1995 the site was a sprawling estate of impressive historico-architectural pedigree, where Canada's first international Three-Day Equestrian Event was held, where you could hobnob with royalty and watch Jimmy Elder, a U of T grad and Canada's first (and six-time) Olympic equestrian medalist, ride. Then the owners of Jokers Hill, Drs. Murray and Marvelle Koffler, set their estate apart from the other estate homes and horse farms of King Township. In the largest-ever land grant in Canadian university history, they donated Jokers Hill to the University of Toronto.

Now this large tract of relatively undisturbed land serves as a locus for university-level teaching and research. With membership in the Organization of Biological Field Stations, the Koffler Scientific Reserve at Jokers Hill joins a network of North American biological research centres. Its paddocks and riding trails have been transformed into a living laboratory for anthropologists, biologists, geographers, geologists, foresters, architects and designers from the University of Toronto and the nearby institutions of York and Guelph universities and the Royal Ontario Museum who are conducting research into the impact of urban encroachment on natural environments. Its crop fields and upland forests now serve as classrooms for students who are learning the art of scientific observation and how to formulate and test hypotheses about the ecology of human-altered landscapes.

All natural habitats are subject to a regime of global stresses, from climate change to increases in UV-B exposure. Because of its proximity to a major urban centre, Jokers Hill has the added pressures of smog and habitat fragmentation with which to contend. Comparing findings from Joker's Hill with those at more remote field stations will help scientists to understand how different combinations of factors impact the environment in distinct ways, and to design more effective intervention and ecosystem management strategies.

Much of the value of Jokers Hill lies in its providing a site to undertake long-term ecological research on ecosystem function and species interactions. James Thomson of zoology, for example, is studying bumblebees and other wild pollinators to better understand their role, especially with respect to native plants, and the ecological challenges they face from diseases and other stresses in a rapidly urbanizing environment. Says Thomson, "There is a lot of concern about widespread declines of pollinating insects in this part of the world. Much of the talk is speculative, however, rather than evidence-based. To document decline in an iron-clad way takes a real commitment to working in one place over decades to generate the necessary long-term datasets. Jokers Hill, where such extended monitoring can be set up, is well suited to answer this kind of question. Moreover, if, as predicted, development in the GTA increases, Jokers Hill will become an island of natural habitats surrounded by more human-impacted areas, which will in all probability further impact the local plants and animals; the mutual relationship between plants and pollinators is one place where that stress may reach the breaking point."

A hallmark of research at the site is the emphasis on identifying the underlying mechanisms that determine biological community structure, species and genetic diversity, and the response of plants and insects to human-caused global environmental change. Marc Johnson, a doctoral candidate in botany, is studying genetic variability in evening-primrose, and how patches of evening-primrose plants with varying degrees of genetic diversity affect the community of insects that feed on this plant. Working in collaboration with Anurag Agrawal, now an adjunct member of the botany department, Johnson has found that genetic variation affects the number and abundance of insects equally or in some cases more strongly than environmental variation. He is testing how the plant's herbivore community affects evening-primrose survival and reproduction, and whether these insects can drive the evolution of this plant's defenses against herbivorous insects. The results of these experiments have important implications for increasing crop yields of a plant that is fast becoming a multimillion dollar biopharmaceutical wonder.

Agrawal and Peter Kotanen, a botanist at the University of Toronto at Mississauga, have been testing the enemy release hypothesis of plant invasions at Jokers Hill — i.e., the idea that non-native plants may be such successful invaders because they have left their own enemies behind. The two have done some of the most comprehensive tests ever undertaken on the enemy release hypothesis, working with multiple plant species and pathogen and herbivore groups over several years. Jokers Hill has served as an ideal testing ground for these experiments because it has preserved a high level of native species richness. In addition there are numerous old fields containing a mix of native and alien species that reflect the history of human use of the site.

The global scientific community also has a direct stake in what Jokers Hill can reveal. Kotanen is studying ragweed, a native Canadian plant which has reversed the usual pattern by invading Europe. Ragweed is a notorious weed in urban and agricultural areas, with a history of association with humans that goes back to the earliest days of North American aboriginal agriculture. Now it is found throughout Central France, Western Russia and Central Europe. Kotanen is the North American point person in an international collaborative project to trace the pedigree and ecological and evolutionary consequences of its trans-Atlantic crossing.

Maintaining ecological integrity at Jokers Hill is good not just for science, but for the broader community as well. The Reserve's Scientific Oversight Committee is drafting a scientific master plan for Jokers Hill. That plan includes public access to hiking trails on the site, delivery of public lectures and other outreach activities that will be coordinated by a stewardship body, the Friends of Jokers Hill.

A fusion of field- and lab-based science is taking place north of Toronto. Forty years ago, the Kofflers began to amass small portions of the Oak Ridges Moraine into a property that now constitutes the sixth largest landholding on that sensitive landscape. Their stewardship of that property and their resolve to see it contribute to environmental research and teaching have morphed into the Koffler Scientific Reserve at Jokers Hill — a place of ongoing scientific investigations into threatened biodiversity, the genetic stresses on populations imposed by urbanization, the stability of communities in the face of invasive species, the consequences of global change for ecosystems and the management of urban ecosystems.