Effects of an Experimental Flood on Litter Dynamics in the Middle Rio Grande Riparian Ecosystem

The objectives of the study were to measure the effects of an experimental flood on : (1) leaf litter production by the riparian forest; (2) leaf decomposition; and (3) the amount of forest floot organic matter. The study area is located at Bosque del Apache National Wildlife Refuge, approximately 160 km south of Albuquerque, New Mexico. Experimental and reference study sites of about 3·1 ha were both located in cottonwood (Popu/usfremontii) riparian forests that had not been flooded for approximately 50 years. The experimental and control study sites were sampled for two years before flooding the experimental site. The experimental flood peaked on about 31 May, the average date of peak flow in the I 00 year hydro graph for the USGS gauging station on the Rio Grande at Embudo, New Mexico. Litter fall was lower at the flood site than at the control site, whereas the rate of leaf decomposition was higher at the flood site during the period of inundation. However, the flood did not produce a measurable response in standing stock of forest floor litter. This pool of carbon may require the cumulative effects of several years of flooding to show a measurable response.