Chufa management in the middle Rio Grande Valley, New Mexico

Natural wetlands provide food resources for a variety of migratory birds. Although much is known regarding the production of above-ground food resources, little is known about the production of below-ground food resources such as chufa (Cyperus esculentus) tubers. In 1996 and 1997, we compared chufa production among mowing, discing, and sustained flooding treatments in the middle Rio Grande Valley at Bosque del Apache National Wildlife Refuge, New Mexico. Mowing occurred early in the growing season to reduce potential competitors such as cocklebur (Xanthium strumarium), light discing occurred 30 days after wetland drawdown to stimulate tuber production, and periodic sustained flooding occurred during the growing season to drown competing plants. In addition to chufa, we compared mass of total above- and below-ground standing crop, seeds, tubers, and rhizomes among treatments. Mowing and discing treatments had similar below-ground chufa biomass, whereas the sustained flood treatment suppressed chufa growth relative to these treatments. Chufa production was higher during the second year of the study on all treatments, probably due to vegetative cloning over the 2-year study. Although the production of Johnson grass (Sorghum halepense), field bindweed (Convolvulus arvensis), and total underground mass was similar among treatments, seed mass was reduced as a result of discing. From this perspective, mowed and sustained flood treatments were preferred, due to similar total below-ground production among treatments and lower seed mass in the disced treatment. Managers should consider combined above- and below-ground production to provide a diversity of food resources for migratory birds.