2 Rhizomes respond quickly after fire, sending up new sprouts and quickly outgrowing any native species which might have otherwise taken root in a burned-over site. Fire events thus tend to help push riparian stands in the direction of pure Arundo donax. This usually results in significant stands of giant reed with little additional plant species diversity. Establishment and success of giant reed within a riparian corridor thus results in a decline in the diversity of native riparian plant species - reed supplants native habitat. All evidence indicates that giant reed does not provide either food or habitat for native species of wildlife.
Areas largely taken over by giant reed are therefore depauperate of wildlife.
This also means that native flora and fauna do not offer any significant control mechanisms for giant reed. It is uncertain what the natural controlling mechanisms for this species are in the Old World. As a result, riverine areas dominated by giant reed tend to have warmer water temperatures and lower diversity of aquatic animals, including fishes. Other studies have indicated that in addition to higher water temperatures, this lack of stream-side canopy structure may result in increased pH in the shallower sections of the river due to high algal photosynthetic activity. In turn, high pH facilitates the conversion of total ammonia to the toxic unionized ammonia form which further degrades water quality for aquatic species and for downstream users.