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Site Type: Rangeland Sandy Bottomland MLRA: 67B -Central High Plains, Southern Par[ R067BY031CO Low Plant Density, Excessive Litter Plant Community This plant community occurs when grazing is removed for long periods of time in the absence of fire. Plant composition is similar to the HCPC, however, in time, individual species production and frequency will be lower. Much of the nutrients are tied up in excessive litter. The semiarid environment and the absence of animal traffic to break down litter slows nutrient cycling. Aboveground litter also limits sunlight from reaching plant crowns. Many plants, especially bunchgrasses die off. Thick litter and absence of grazing or fire reduce seed germination and establishment. This plant community will change rapidly with prescribed grazing which allows animal impact and adequate recovery periods between grazing events. Long term non-use/rest (greater than 25 years), will cause plant decadence and mortality to increase and erosion (blowouts, wind scoured areas) may eventually occur as bare ground increases, Once this happens, an ecological threshold has been crossed, and it will require increased energy input in terms of practice cost and management to bring back. Production can vary from 100 to 1000 pounds of air-dry vegetation per acre per year depending on weather conditions and the plants that are present. The following is an estimated growth curve of this plant community expected during a normal year. Vegetative growth begins earlier in the southern reaches (Baca, Bent, Kiowa, Las Animas and Prowers counties) of MLRA-67. Vegetative growth will typically be suppressed during the months of June through August in these counties due to higher evapotranspiration rates. Growth curve number: CO6711 Growth curve name: Warm season dominant, cool season sub-dominant, excess litter; MLRA-676; upland coarse texture soil. JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC 0 0 2 8 20 35 17 10 5 3 0 0 (monthly percentages of total annual growth) Transitions or pathways leading to other plant communities are as follows; • Lono term non-use (rest) if continued can move this plant community across an ecological threshold to the Early Perennials, Annuals and Bare Ground Plant Community. This transition may take greater than 25 years to accomplish. • Prescribed grazino that allows for adequate recovery periods following each grazing event can move this plant community toward the Sand Bluestem, Prairie Sandreed, Switchgrass, Yellow Indiangrass Plant Community (HCPC). Sand Sagebrush Plant Community This plant community is dominated almost entirely with sand sagebrush with little understory species present. Favorable species that remain are few and are protected by the sagebrush. The plant community is created with continuous grazing that does not allow adequate recovery periods between grazing events combined with brush management (spraying) even if it includes one growing season of deferment following spraying. Brush management initially reduces the sagebrush and, unfortunately, eliminates or greatly reduces most if not alt other fortis and shrubs. Continuous grazing then reduces and can eliminate the remaining grass to a point where only reestablishing or established sagebrush remains. Further brush spraying at this point eliminates the sand sagebrush entirely and exposes the soil to wind erosion. Species diversity and production have dropped substantially. Litter levels are low. Watershed function at this point is greatly reduced. Carbon sequestration is greatly reduced. Nutrient cycle and energy flow has been impaired. Bare areas can form or enlarge rather easily leading to possible blowouts or wind scoured areas. Desertification is obvious. Technical Guide USDA NRCS Section IIE 8 Rev. 3/04