Biotic survey of Los Alamos radioactive liquid-effluent receiving areas

A preliminary study was completed of the vegetation and small mammal communities and associated climatology in three canyon liquid waste receiving areas at the Los Alamos Scientific Laboratory. Data were gathered on plant and animal composition, distribution, and biomass, along with air temperature, humidity, and precipitation, as a function of elevation and where data were available with season. Initial studies of the understory vegetation in the spring of 1974 indicate grass species to be dominant at higher elevations, with forb species becoming dominant at lower elevations. Generally, the highest total mass estimates for standing green vegetation were obtained in the study sites located in the upper portions of the canyons where precipitation is greatest, and where the terrain and intermittent stream flow result in a wetter habitat. Fourteen species of small mammals were trapped or observed in canyon study areas during two trapping sessions of May--June 1974 and December 1974--February 1975. A greater number of species and the highest rodent biomass estimates in the spring were generally associated with the ponderosa pine/pinion--juniper woodland in the upper reaches of the canyons, and were lowest in the pinion--juniper woodland at the lower portions of the canyons. This trend was observed in only one of the canyons during the winter season. Climatological data gathered in the three canyons since 1973 are also presented to serve as a data base for future reference