PSLA Lecture Series: Dr. Carla D'Antonio
Figure 1. The invasive weed Grose covering the landscape in New Zealand
On Thursday April 20, 2017 Dr. Carla D’Antonio visited the University of Maryland to share her stories about invasive species, and how things might not always be as you would expect. Her research is very important in understanding how invasives will affect the environment they invade. The invasive species Gorse, Ulex europeaus, was taking over abandoned fields in New Zealand, and it was expected to remain the dominant species if left unmanaged. However, several years later this was not the case, as native species began growing and reclaiming the abandoned fields. Gorse thrived only after grazing changed the habitat, but when grazing stopped, the native species returned.
Dr. D’Antonio also shared her thoughts of what an invasive plant needs to create a new “steady state” condition different from what the natural state would be, or for succession to occur. Along dammed rivers, a tree species, ended up creating a new steady state, not because it was very competitive, but because of an altered environmental state due to a dam. She showed that management strategies such as removing the thatch of an invasive weed Bromus tectorum increased the ability of native wildflowers to germinate in the invaded area, meaning that even annual invasives can become persistant. Some of Dr. D’Antonio’s other work showed that removal of one non-native grass improved the invasion of another invasive plant, a nitrogen-fixing tree in Hawaii. This was likely due to the grass shading out the soil surface and preventing seed germination1.
Dr. D’Antonio provided all who attended her seminar with a new view on invasives and how things may not always turn out as you would expect them to based on existing conditions. Her final suggestion to everyone in the room was to set up long term transects in our study areas, so you would be able to see changes that we might miss on the short research cycle of 2-3 years.
1D’Antonio, C.M., and M. Mack. 2001. Exotic grasses potentially slow invasion of an N-fixing tree into a Hawaiian woodland. Biological Invasions. 3:69-73.
