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Site Type: Rangeland <br />MLRA: 69 -Upper Arkansas Valley Rolling Plains <br />Plant Communities <br />Sandy <br />R069XY026CO <br />Ecological Dynamics of the Site: <br />Continuous grazing without adequate recovery opportunities following each grazing event during the <br />growing season will cause blue grams to increase and eventually form a sodbound condition. Major <br />warm season grasses such as sand bluestem, yellow Indiangrass and switchgrass will decrease in <br />frequency and production. Needleandthread will initially increase, then decrease. Key fortis and <br />shrubs such as American vetch, purple prairie clover, scarlet globemallow, western sandcherry and <br />fourwing saltbush will decrease also. Red threeawn, annuals and bare ground will increase with long <br />term continuous grazing, heavy continuous grazing or excessive defoliation. Years of non-use (rest) <br />or lack of fire will cause litter to accumulate and reduce plant density. <br />Drier and warmer climatic conditions exist in the central portion of MLRA-69. This area includes the <br />eastern half of Pueblo county, northern Otero, extreme northwestern Bent, western edge of Kiowa, <br />southern edge of Lincoln and all of Crowley County. These conditions are primarily caused by a rain <br />shadow effect from the southern Rocky Mountains. Evapotranspiration rates (atmospheric demand) <br />will be higher in this area of MLRA-1i9. Total annual production will typically be lower. <br />The historic climax plant community (description follows the plant community diagram) has been <br />determined by study of rangeland relic areas, areas protected from excessive disturbance, seasonal <br />use pastures, short duration)/time controlled grazing and historical accounts. <br />The following is a diagram that illustrates the common plant communities that can occur on the site <br />and the transition pathways (arrows) among communities. Bold lines surrounding each plant <br />community or communities represent ecological thresholds. The ecological processes will be <br />discussed in more detail in the plant community descriptions following the diagram. <br />Technical Guide USDA NRCS <br />Section IIE 4 Rev. 3/04 <br />