ARS | Publication request: Plant community responses following the periodic selective removal of giant reed (Arundo donax) in Webb County Laredo, TX

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: April 1, 2010
Publication Date: N/A

Technical Abstract: Exotic plants often produce detrimental ecological effects in the habitats they invade. The invasive grass, Arundo donax, is found throughout most of the Rio Grande watershed and is gaining bi-national attention due to evidence of high water usage, increased erosion, alteration of river flow and drastic changes to riparian plant communities. Recently, various agencies have begun implementing removal strategies for the possible management of Arundo donax. To date, little is known regarding the potential recruitment and re-emergence of other native vegetation and changes that may occur in plant community structure after treatment. Four sites were chosen along a 35 mile stretch of the Rio Grande in Webb County near Laredo, TX. In each site one to four 25m2 were established. All experimental plots were initially treated by removing all above ground biomass of Arundo donax. Measurements of shoot length and diameter were taken to estimate total initial biomass. Each plot was revisited on a monthly basis or as needed to remove all Arundo donax greater than one meter in length. Additionally, we measured and recorded any emergent transitional vegetation. Initial diversity indices (Shannon) across all four sites were nil. After two years of selective removal of Arundo donax, the species diversity within all four sites increased from zero to 1.33, 1.36, 1.54, and 2.04. Collectively 35 non-Arundo species were identified throughout the two year study, including the forbs (15 species), grasses (2 species), and trees (6 species). Such plants include little mallow (Malva parviflora), mock vervain (Glandularia quadrangulata), deer pea vetch (Vicia ludoviciana), granjeno (Celtis pallida), palo blanco (Celtis laevigata) and plains bristle grass (Cetaria leucopila). These results suggest that over time, selective removal or periodic disturbance to Arundo donax populations increases species richness, illustrating the potential for ecological restoration.