Non-native competitive perennial grass impedes the spread of an invasive annual grass.
Davies K. W., A. M. Nafus and R. L. Sheley. 2010. Biological Invasions 12:3187-3194
Abstract
Invasive plants are degrading wildlands
around the globe by displacing native species,
reducing biodiversity, and altering ecological functions.
The current approach of applying herbicides to
invasive plants in wildlands has not been effective at
curtailing their expansion and, in certain circumstances,
may do more harm than good. Preventing the
spread of invasive species has been identified as an
important strategy to protect wildlands. However,
few prevention strategies have actually been tested.
We hypothesized that establishing competitive vegetation
next to infestations would increase the biotic
resistance of the plant community to invasion and
decrease the invasive species propagule pressure
beyond the competitive vegetation. To evaluate this,
we established twelve competitive vegetation barriers
in front of invasive annual grass, Taeniatherum
caput-medusae (L.) Nevski, infestations. The nonnative
perennial grass Agropyron desertorum (Fisch.
ex Link) Schult. was seeded into plant communities
adjacent to the infestations to create the competitive
vegetation barriers. Soil nutrient concentrations and
the spread of T. caput-medusae were compared
between where A. desertorum was seeded and not
seeded (control treatment) 3 years after treatment.
Less T. caput-medusae and lower soil ammonium and
potassium concentrations in the competitive vegetation
barrier than control treatment (P <= 0.01) suggest
that establishing competitive vegetation increased the
biotic resistance of the plant communities to invasion.
Taeniatherum caput-medusae cover and density in the
plant communities protected by the competitive vegetation
barrier (locales across the barriers from the
infestations) were~42- and 47-fold less, respectively,
than unprotected plant communities (P<0.01). This
suggests that invasive plant propagule pressure was
decreased in the plant communities protected by
competitive vegetation barriers. The establishment of
competitive vegetation around infestations may be an
effective strategy to prevent or at least reduce the
spread of invasive plant species.
Key Words
Biotic resistance, Invasibility, Medusahead, Prevention, Propagule pressure
