The forests and grasslands in and around southeastern Vancouver Island harbor dozens of federally-listed rare species, and are of immense aesthetic, cultural, recreational, and economic value to people. The structure, composition, and diversity of these ecosystems in the present day is influenced not only by natural environmental gradients and obvious human disturbances such as suburban and agricultural development, but also by less obvious changes in land use and management practices of native peoples over the past 200 years.
Our research employs a variety of methods and data sources–ranging from land survey records from the 1850s, present-day surveys of plant communities, molecular-genetic analyses of particular species, and geographic information systems–to characterize the influence of past and present, and natural and anthropogenic processes on biodiversity in this region. For example, we have found dense human populations around regional parks impact native plant species detrimentally, while encouraging non-native species. Historical land survey records and geographic analyses have revealed a clear signal of prescribed fire by native peoples maintaining open savannas to a far greater extent, and in a wider variety of environmental conditions, than today. The main traditional food plant of native peoples–camas–shows strong genetic differentiation across space, but no obvious influence of historical bulb trading. Ongoing research addresses the response of butterflies (PDF) to environmental and plant-community changes in this region, and will integrate different sources of historical data to provide a comprehensive picture of how and why plant communities have changes over the past two centuries.