Common Reed Phragmites australis: Control and Effects Upon Biodiversity in Freshwater Nontidal Wetlands

Abstract

Phragmites australis (common reed) has expanded in many wetland habitats. Its ability to exclude other plant species has led to both control and eradication programs. This study examined two control methods-herbicide application or a herbicide-burning combinationfor their efficacy and ability to restore plant biodiversity in non-tidal wetlands. Two Phragmites -dominated sites received the herbicide glyphosate. One of these sites was burned following herbicide application. Plant and soil macroinvertebrate abundance and diversity were evaluated pre-treatment and every year for four years post-treatment using belt transects. The growth of Phragmites propagules-seeds, rhizomes, and rooted shoots-was examined in the greenhouse and under bare, burned, or vegetated soil conditions. Both control programs greatly reduced Phragmites abundance and increased plant biodiversity. Plant re-growth was quicker on the herbicide-burn site, with presumably a more rapid return to wetland function. Re-growth at both sites depended upon a pre-existing, diverse soil seed bank. There were no directed changes in soil macroinvertebrate abundance or diversity and they appeared unaffected by changes in the plant community. Phrag-mites seeds survived only on bare soils, while buried rhizomes survived under all soil conditions. This suggests natural seeding of disturbed soils and inadvertent human planting of rhizomes as likely avenues for Phragmites colonization. Herbicide control, with or without burning, can reduce Phragmites abundance and increase plant biodiversity temporarily. These changes do not necessarily lead to a more diverse animal community. Moreover, unless Phragmites is eradicated and further human disturbance is prohibited, it will likely eventually re-establish dominance.

Long-term effects of a Phragmites australis invasion on birds in a Lake Erie coastal marsh

“…As noted previously, P. australis is able to colonize wetlands quickly and produce large patches, which can displace resident wetland plants (Ailstock et al, 2001;Trebitz and Taylor, 2007;Tulbure and Johnston, 2010;Whyte et al, 2008). The wide range of disturbances and environmental variables that P. australis can tolerate, coupled with its morphological characteristics, contribute to P. australis having a competitive advantage over many resident wetland plant species.…”

“…Supporting this hypothesis, Gagnon Lupien et al (2015) attribute their finding that P. australis had no severe effect on bird use in southwestern Quebec marshes to the early stage of invasion in their study system. As P. australis expands, replacing meadow marsh and cattail marsh, it smooths and elevates substrate, filling in small holes and open-water pools through litter accumulation (Weinstein and Balletro, 1999;Windham and Lathrop, 1999), reducing floral diversity, and creating dense stands of stiff stems (Ailstock et al, 2001;Schummer et al, 2012;Windham, 2001). These changes alter marsh habitat making it less heterogeneous.…”

Ecology of freshwater shore zones

“…Aquatic and terrestrial plants support animal communities that differ from those of unvegetated sediments, and often differ across plant species (e.g., Moon 1934;Brodersen 1995;Radomski and Goeman 2001;Romanuk and Levings 2003;Salovius and Kraufvelin 2004;Kraufvelin and Salovius 2004). Consequently, invasions of alien plants frequently not only push out native plants but also change associated animal communities (e.g., Ailstock et al 2001;Strayer et al 2003). Predation by terrestrial predators (birds and mammals) may be so intense that it reduces the density of aquatic prey near the water's edge by direct consumption or intimidation (Power 1984;Power et al 1989;Burlakova and Karatayev 2007).…”

Genetics, novel weapons and rhizospheric microcosmal signaling in the invasion ofPhragmites australis

“…7 Plant community studies in the P. australis dominated ecosystems have shown that Phragmites are not conducive to the establishment of other plant species and that colonization of disturbed wetland areas by this plant usually ensures the development of dense stands. [8][9][10][11] The present review is mainly focused on the discussion of the various mechanisms by which P. australis exerts its invasive behavior to successfully colonize and replace the native biodiversity.…”