The climate of the SGS is typical of mid-continental semiarid regions in the temperate zone except for the strong influence of the Rocky Mountains approximately 60 km to the west. Mean monthly temperatures range from -4 to 22 degrees C seasonally and have a daily average max-min range of 17 degrees C. Annual precipitation at the CPER averaged 322 mm over the past 51 years and ranged between 107 and 588 mm. Approximately 70% of the mean annual precipitation occurs during the April to September growing season. ( For further information please see Figures Historical Precipitation, Temperature/Precipitation, and Summary Climate Information : SGS climate description and summary tables and charts)
The vegetation of the SGS is dominated by shortgrasses (64%), forbs (7%), succulents (21%), and half-shrubs (8%). The key species of these groups are Bouteloua gracilis and Buchloe dactyloides; Sphaeralcea coccinea; Opuntia polyacantha; and Chrysothamnus nauseosus, Gutierrezia sarothrae, and Eriogonum effusum, respectively. Average above ground net primary production is 125 g/m2 and ranges from 60 to 180 g/m2 depending on available soil water. Major differences in vegetation structure occur in saltgrass meadows dominated by Distichlis stricta and Sporobolus asper, and on floodplains where the shrub Atriplex canescens is an important component.
The main LTER headquarters building (214 m2) has offices, laboratories, a dining/meeting room, and a kitchen. Adjacent to the headquarters is a storage/sample processing building (134 m2) with facilities for washing and drying samples. The dormitory has six rooms; five capable of double occupancy and one with four beds. In addition there are large-animal handling and holding pens and a residence for the site manager. The Shortgrass Steppe LTER Field Station was built to support research as part of the US/IBP Grassland Biome project in the early 1970s.
LTER headquarters building
The LTER Field Station is located 1 km east of State Highway 85 on Weld County Road 114. The station is 8 km north of Nunn, approximately halfway between Greeley, Colorado and Cheyenne, Wyoming, on the Central Plains Experimental Range (CPER). The CPER is a 6200-ha research area maintained by the USDA Agricultural Research Service for applied rangelands research. Field headquarters for the ARS/CPER are located 8 km NE of the LTER Field Station, on County Road 37.
For information on using the LTER Field Station and its facilities, contact Mark Lindquist , LTER Site Manager.