Hanford NERP

Hanford NERP


Arid Lands Ecology Reserve

NERP's contain extensive examples of regional ecosystems on protected lands. They often represent sanctuaries and reservoirs for both natural resources and biological diversity.

		The Arid Lands Ecology Reserve in the Hanford Research Park represents the only sizable remaining fragment of shrub-steppe landscape in Washington state. This plant community type, which dominates the landscape at Hanford, has been the subject of basic ecological investigations which have been synthesized in Shrub-Steppe: Balance and Change in a Semi-Arid Terrestrial Ecosystem. This understanding is critical to site remediation and risk assessment.


Global Climate Change

		The shrub-steppe ecosystem at the Hanford NERP includes Rattlesnake Mountain (150-1100 m). This site has been undisturbed since the early 1940's. The mountain supplies a temperature and moisture gradient (e.g. cooler at the top) analog for global climate change.

The soil microorganisms responsible for carbon and nitrogen cycling and plant nutrients are not randomly distributed, but rather form resource islands around plants. Soil microorganisms decreased in concentration as elevation increased. This decrease was less under plants as compared to interplant soil. As the shrub-steppe becomes warmer and drier, a potential outcome of climate change, soil microbial biomass increases more in interplant soil than under plants.


Arid Site Water Balance Using Monolith Lysimeters

Goal		To model an accurate water balance by evaluating evapotranspiration rates for native plant communities in arid landscapes and to select landfill cover systems that minimize groundwater infiltration from precipitation.

		To assess water balances for arid sites, four weighing lysimeters, containing monoliths of undisturbed soil, have been constructed in two native plant communities. The remote facility is accessed by radio-telemetry, requires minimal maintenance, and has generated data continuously since 1987.
		Water loss rates for the first several years were low for all lysimeters and averaged less than 0.33 mm/day. Water balance (use) in the sagebrush community was similar to that in the bunchgrass- dominated community, with evapotranspiration readily accounting for the surface removal of all precipitation through several annual cycles.
		Water use data suggest that shrub-steppe vegetation growing over fine-textured soils, as components of landfill cover systems, is more effective than bare surfaces for limiting percolation of surface water through waste forms to groundwater.