TITLE:
Reduction of Native Diversity by Invasive Plants Depends on Habitat Conditions
AUTHORS:
Yvonne Künzi, Daniel Prati, Markus Fischer, Steffen Boch
KEYWORDS:
Diversity Impact of Neophytes, Indicator Values, Plant Species Richness
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.6 No.17,
October
30,
2015
ABSTRACT: Invasions by exotic plant species and their impacts on invaded communities are a highly topical
field of research because it provides a basis for the management of neophyte populations. However,
for many invasive neophyte species in Central Europe little is known about their impacts on
invaded plant communities. Moreover, it has hardly been considered whether effects vary among
habitat conditions. Here, we selected each ten sites with different habitat conditions invaded by
Erigeron annuus, Fallopia japonica, Impatiens glandulifera and Solidago canadensis which were
listed as invasive in Switzerland. At each site, we established four 4 m × 1 m subplots covering a
gradient from very low to very high cover of the particular neophyte species to investigate the effect
of increasing neophyte cover on the species richness, Shannon diversity and evenness of the
invaded plant communities. Moreover, we measured soil pH and characterized habitat conditions
using Ellenberg indicator values to light and soil fertility. Whereas increasing cover of I. glandulifera
had no effect on the diversity of invaded plant communities, an increasing cover of E. annuus
negatively affected Shannon diversity. An increasing cover of F. japonica combined with a decreasing
soil pH negatively affected the Shannon diversity of invaded plant communities. Similarly, an
increasing cover of S. canadensis in combination with decreasing soil fertility negatively affected
the Shannon diversity and evenness of invaded communities. Our results indicate that significant
effects of increasing neophyte cover are mostly coupled to particular habitat conditions and then
rather suppress than eliminate native plant species in invaded communities. We therefore suggest
including abiotic variables in further impact studies on biotic invasions. Furthermore, adapting
measures to the respective environmental context can be a useful tool in priority setting for the
management of invasive neophyte populations and the restoration of invaded habitats.