Forest ecosystems are highly impacted by several species of invasive non-native shrubs, which develop dense monocultures that exclude both tree regeneration and native biodiversity, and that reduce the ability of forests to supply many ecosystem services. However, little is known of the mechanisms that allow these invasive species to outcompete native shrubs. Most studies of invasive ability focus on above-ground factors, such as competition for light; in contrast, below-ground competition may be a primary mechanism allowing these species to differentially acquire nutrient resources and therefore grow larger and faster than the native species. We will carry out a set of studies to test the general hypothesis that invasive shrub species are able to outcompete native shrubs for below-ground resources through either better acquisition of space (soil volume) or acquisition of nutrient (especially nitrogen) resources. These studies will involve field measurements of root system morphology and root growth rates, and greenhouse studies of competition and nitrogen acquisition from labeled sources. We will also test whether application rates of currently-used herbicides are appropriate for preventing root survival and growth. The results of the research will provide both new fundamental knowledge concerning the mechanisms that allow these species to damage forest resources, and will provide guidance in using herbicides in their management.
|Effective start/end date||9/1/08 → 8/31/11|
- National Institute of Food and Agriculture (National Institute of Food and Agriculture (NIFA))