Impacts of Arundo donax in southern California (USA)
Arundo donax (Poaceae) is a perennial grass species native to Southern and Central Asia and has been cultivated for hundreds of years. The species is expanding rapidly along riparian habitats in Mediterranean-climate habitats where it can have negative impacts on native plants and associated invertebrate species. In southern California (USA), riparian habitats are extremely endangered and are prone to invasion by A. donax. As A. donax can grow rapidly and form mono-specific stands, it can alter the habitat structure which can have implications on all trophic levels including carnivores on which little research has been carried out. A study was conducted along a 27 km stretch of the Santa Clara River in California. Three sites were selected, and three habitat types were selected within each study site: native (< 30 % A. donax), mixed (30-70 % A. donax) and dominated (> 70 % A. donax). Camera traps were placed in each site and were active during three periods: August to November 2016 (dry season); March-June 2017 (wet season) and March to June 2018 (wet season). In total, 8 carnivores were captured on the camera traps throughout the whole study and included coyotes (Canis latrans), bobcats (Lynx rufus), striped skunks (Mephitis mephitis), Virginia opossums (Didelphis virginiana), raccoons (Procyon lotor), long-tailed weasels (Mustela frenata), grey foxes (Urocyon cinereoargenteus), and mountain lions (Puma concolor). Small prey mammals were also trapped during the study. Detections of all large mammals were significantly lower in the dominated habitat type compared to the other two, which suggests a decreased preference for A. donax habitats. Small mammal abundance was similar if not higher in A. donax habitats, suggesting the possibility of the grass acting as a refuge for prey species.
Sources
Hardesty-Moore M, Orr D, McCauley DJ (2020) Invasive plant Arundo donax alters habitat use by carnivores, Biological Invasions 22, 1983-1995.