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Site Type: Rangeland MLRA: 67B -Central High Plains, Southern Part Transitions or pathways leading to other plant communities are as follows: Sandy Bottomland R067BY031CO • Continuous orazino without adequate rest periods between grazing events will move this plant community toward the Blue grama, Sand Sagebrush Plant Community. Reduced production and erosion are a concern. • Non-use (rest) and lack of fire will shift this plant community to the Low Plant Density, Excessive Litter Plant Community. • Prescribed orazino that allows for adequate recovery opportunity following each grazing event and proper stocking will maintain the Sand Bluestem, Prairie Sandreed, Switchgrass, Yellow Indiangrass Plant Community (HCPC). Blue Grama, Sand Sagebrush Plant Community This plant community evolves with continuous grazing without adequate recovery periods between grazing events during the growing season. Sand Bluestem, prairie sandreed, yellow Indiangrass, Switchgrass, western sandcherry and leadplant have decreased in frequency and production. Blue grama and sand sagebrush has increased and dominates the community. Sand dropseed, red threeawn, slimflower scurfpea, hairy goldaster, Croton, western ragweed, stickleaf, lupine, loco, and milkvetch have also increased. This plant community is relatively stable but at risk of losing some of the tall grass species, palatable forbs and shrubs. The reduction of tall grass species, nitrogen-fixing (orbs, key shrub component and increased warm season shortgrass has altered the biotic integrity of this plant community. Nutrient cycle, water cycle and energy flow may be impaired. This is an early stage of desertification. The production varies from 500 to 1300 pounds of air-dry vegetation per acre per year depending on the weather conditions and amount of mid and tall grass species still present. Production will average 950 pounds of air-dry vegetation per acre per year. 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-676. Vegetative growth will typically be suppressed during the months of June through August in these counties due to higher evapotranspiration rates. Growth curve number: CO6710 Growth curve name: Warm season dominant; MLRA-67B; upland coarse textured soils. JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC 0 0 0 5 20 40 20 10 5 0 0 0 (monthly percentages of total annual growth) Transitions or pathways leading to other plant communities are as follows: • Continuous orazino and especially continuous grazing with brush manaoement (spravinq) will eliminate tall grasses, palatable forbs and shrubs and move this plant community across an ecological threshold to the Sand Sagebrush Plant Community. If continued long enough it will move to the Early Perennials, Annuals and Bare Ground Plant Community. • Brush Manaoement (spraving) and prescribed orazing will move this plant community across an ecological threshold toward the Grass Dominant Plant Community. Loss of palatable forbs, native legumes and shrubs is a concern. • Prescribed orazino that allows adequate recovery periods between each grazing event and proper stocking will move this plant community back to the Sand Bluestem, Prairie Sandreed, Switchgrass, Yellow Indiangrass Plant Community (HCPC). Tectuucal Guide USDA NRCS Section IIE 7 Rev. 3/04