Waterfowl of a subtropical African floodplain

摘要: The Pongolo River floodplain supports large populations of waterfowl which feed on the vegetative structures submerged plant Potamogeton crispus. Maintenance a stable grazing system is contingent upon plants having specific life history characteristics to counter effects grazing. Feeding uproot P. crispus and remove approximately 90% attached turions, but only 15–25% annual turion production consumed. A hypothesis was developed from exclosure laboratory experiments account for this anomaly: while birds preferentially select uprooted rapidly produce many small turions are energetically unrewarding still have high viability. Thus, depletes available food supply, it stimulates an unavailable reserve growth potential that maintains standing crop. Waterfowl consume too few fruits affect size seed bank ensures persistence species over periodic droughts. stimulation net by less than 10%, more important, uprooting can be crucial factor in determining timing inputs detrital web highly seasonal floods. comparison with theoretical models demonstrates traits other rate responsible maintaining stability system, changes environmental conditions (e.g., water depth) must accounted any model stability.