Characterization and quantitative assessment of interspecific and intraspecific penetration of below‐ground vegetation by cogongrass (Imperata cylindrica (L.) Beauv.) rhizomes

Abstract

Cogongrass ( Imperata cylindrica (L.) Beauv.), an invasive C4 perennial grass, negatively influences native plant communities by forming dense monotypic stands that alter ecosystem properties and lower local species diversity. A hypothesized mechanism by which cogongrass achieves competitive dominance is a novel use of below-ground vegetative disturbance of neighboring vegetation (i.e. puncturing). However, very little empirical evidence is found in the peer-reviewed literature to quantify this phenomenon, much less establish it as a true form of competitive interaction. The present field study was conducted to quantify the occurrence of rhizome-mediated, below-ground vegetative penetration, both interspecifically and intraspecifically, document how this phenomenon is influenced by spatial location relative to the cogongrass stand, and determine the role that above-ground and below-ground biomass might have in the process. Analyses of 100 sod samples indicated that rhizome-mediated, below-ground vegetative penetration is a much larger intraspecific phenomenon than an interspecific one. The data also strongly suggested spatial location as a significant factor, with most penetrations occurring in the interior of a cogongrass stand as opposed to the advancing border. Significant correlations between rhizome-mediated, below-ground vegetative penetration and above-ground cogongrass biomass were found in the overall plot analysis and most strongly in the advancing border of the cogongrass stands.

Mechanisms of dominance by the invasive hybrid cattail Typha × glauca

“…We expected Typha treatments to lower light penetration and temperature at the soil surface (Angeloni et al 2006;Hager 2004) and to decrease native plant Herman et al (2001) and P values calculated using two-tailed t tests species' abundances (Frieswyk et al 2007;Tuchman et al 2009;Zedler and Kercher 2004). We anticipated negative, intraspecific effects of Typha density and Typha litter on the biomass of individual Typha plants and overall Typha biomass (Gurevitch et al 1992;Holly and Ervin 2006) and hypothesized that waterlevel treatments would have species-specific effects on native plant biomass (Fraser and Miletti 2008;Weiher and Keddy 1995).…”

“…Dominance is enhanced when the inter-specific effects of invasion on co-occurring plant species are high relative to intra-specific effects on other individuals of the same species (Holly and Ervin 2006;Perry et al 2005).…”

Conservation Value of Cacao Agroforestry Systems for Terrestrial Herbaceous Species in Central Sulawesi, Indonesia

“…Weedy herbs can reduce the capability of regeneration for local natural species (Wong et al 2010). The grass Imperata cilindrica (L.) Beauv., were presented in eight (15%) of our plots, seem to be an aggressive invasive that it often tends to reach 100 percent cover in disturbed sites (Holly & Ervin 2006). A second weedy Poaceae in our study system is Paspalum conjugatum P.J.…”

Biophysical criteria used by farmers for fallow selection in West and Central Africa

“…In the savannah transition zone of West Africa, it is considered by farmers to be the most serious weed of cropped fields (Chikoye et al, 2000). Elsewhere, it has been shown to be highly effective at competing for nitrogen (Brewer and Cralle, 2003) and also inter-specific penetration of its rhizomes cause injury to neighbouring plants, accentuating its competitiveness (Holly and Ervin, 2006).…”