Regeneration and Colonization of an Invasive Macrophyte Grass in Response to Desiccation

Abstract

The emergent macrophyte Urochloa subquadripara, an exotic and invasive species, causes extensive damage to aquatic plant assemblages. Regeneration and colonization by fragments of U. subquadripara may be affected by desiccation and may differ according to the fragment portion (apical, intermediate or basal). We tested the hypotheses that the ability of U. subquadripara fragments to regenerate and colonize declines with increasing time of exposure to desiccation, and that apical portions regenerate and colonize more quickly than intermediate and basal ones. Apical, intermediate and basal portions were exposed to different desiccation periods and left to grow in a greenhouse. Sprout and root growth were negatively and significantly affected by the desiccation period; fragments exposed to intermediate levels of desiccation regenerated and colonized the sediment at rates similar to those of the control. In addition, apical fragments showed greater development and sediment colonization than intermediate and basal fragments. Thus, the data supported our two hypotheses. Our results show that U. subquadripara has a high regeneration potential, indicating that the use of water drawdown to control its spread may be ineffective, and new strategies are required.

Native Macrophyte Density and Richness Affect the Invasiveness of a Tropical Poaceae Species

“…In addition, natural and anthropogenically induced droughts are common disturbances in several types of freshwater ecosystems. Urochloa arrecta is highly resilient to drought, and it can regenerate, even after 26 days of desiccation [23]. Therefore, U. arrecta may invade sites subjected to disturbances more successfully, especially those caused by droughts.…”

“…ex T. Durand & Schinz) Morrone & Zuloaga is known to have invaded several natural and artificial aquatic ecosystems in South America [20], resulting in a negative impact on native aquatic communities [21]–[22]. This member of the Poaceae family (described as Urochloa subquadripara by Thomaz et al [15], Michelan et al [22] and Michelan et al [23]) is highly invasive because it regenerates readily from both fragments [23] and seeds [24] and exhibits an efficient dispersion strategy, high relative growth rates and rapid recovery rates after disturbances [15], [23].…”

Effects of an Invasive Alien Poaceae on Aquatic Macrophytes and Fish Communities in a Neotropical Reservoir

“…ex T. Durand & Schinz) Morrone and Zuloaga; identified in previous studies by Michelan et al . ,b as Urochloa subquadripara ) is an aquatic grass that is a subject of concern because it is invading several Neotropical waterbodies (Reinert et al . , Michelan et al .…”

Aquatic macrophyte mats as dispersers of one invasive plant species

“…ex T. Durand & Schinz) Morrone & Zuloaga (in previous investigations identified as Urochloa subquadripara; e.g., Thomaz et al, 2009) is a highly invasive Poaceae native to Africa that reduces diversity and changes the composition of macrophytes and fish assemblages in Neotropical regions (Carniatto et al, 2013;Amorim et al, 2015). This species grows quickly from fragments (Michelan et al, 2010a), it roots in the shores and its stems extend toward limnetic regions, thus exhibiting a typical "rooted with floating stems" life form. The impacts caused by this species and its rapid regeneration are causes of concern and thus, knowing the potential vectors of this species has a practical interest.…”