PARENT SESSION
Symposium 11: Digging Deeper or Scratching the Surface? Exploring Ecological Theories in Urban Soils.
Organized by: M Pavao-Zuckerman and L Byrne
Wednesday, August 4, 8:00 AM to 10:30 AM, Oregon Ballroom 203.
Do soils modified by invasive species necessitate new ecological management responses?
Heneghan, Liam*,1, Umek, Lauren1, 1 Environmental Science Program, Chicago, Illinois, USA
ABSTRACT- Invasive species are implicated as major stressors of the ecosystems that they invade. Generally, they are regarded as second only to habitat loss as a factor involved in modern human-caused extinctions. Of necessity, much research has focused on the impacts of individual species on the invaded ecological communities. However, there is a growing appreciation of a need to investigate synergy between invaders (where one species facilitates the spread another, typically unrelated, species), and furthermore to explore the impact of these species on important ecosystem processes (such as decomposition, nutrient cycling). I report here on work being undertaken in urban woodland fragments in the Chicago area on the interaction between a major plant pest, Rhamnus cathartica, (European buckthorn) and Eurasian earthworms. The preliminary results of these studies indicate that invasive earthworms achieve their highest abundance and greatest biomass in woodland patches dominated by European buckthorn. Furthermore, an investigation of the impact of invasive shrubs and earthworm populations revealed that they are responsible for a very rapid incorporation of forest floor material into the soil, and in lasting changes in the fertility of woodland soils. When these studies are combined with those showing that loss of forest litter results in the collapse of invertebrate populations that reside there, the potential for broad mischief is great. Management approaches that do not incorporate knowledge on modified soil foodwebs are ecosystem processes are unlikely to be effective.
Key words: invasive species, Rhamnus cathartica, ecosystem management, exotic earthworms