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VERHOEFF PIT # 2 <br />Site Type: Rangeland vel Breaks <br />MLRA: 69 -Upper Arkansas Valley Rolling Plains EXH1131T: ~" -XY064C0 <br />Plant Communities <br />Ecological Dynamics of the Site: <br />Continuous grazing that does not allow for adequate recovery opportunities between grazing events <br />causes this site to deteriorate. Grasses such as little bluestem, sideoats grama, prairie sandreed, <br />switchgrass and big bluestem decrease in both frequency and production. If proper recovery periods <br />between grazing events are not allowed during the growing season, blue grama will dominate the site <br />and eventually develop into a patchy sodbound condition. Mid and tall grasses will eventually be <br />removed from the plant community. Cushion plants such as mat loco and sessile nailwort in addition <br />to red threeawn, wormwood, fringed sagebrush, small soapweed and cheatgrass will increase or <br />invade the site. In time, continuous use in combination with high stock densities or long term non-use <br />(rest) and lack of fire will result in large amounts of bare ground. <br />Tillage is not recommended on this site due to steep shallow soils and associated low production <br />potential. <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-69. 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 />Plant Communities and Transitional Pathways <br />greased Blue Grama with <br />Decreased Mid/Tall <br />--- '__ <br />PG I I CG <br />Sideoats Grama <br />LittleBluestern LTNi <br />Blue Grama <br />(HCPC) ~ NF <br />Blue Grama <br />Sod <br />LTPG <br />LTPG HCG <br />Bare;°Grownd, <br />Cryptogams, <br />Annuals <br />CG -continuous grazing without adequate recovery opportunity, HCG -heavy <br />continuous grazing, HCPC -Historic Climax Plant Community, LTNU -long <br />term non-use (>40 years), LTPG -long-term prescribed grazing (>40 years), <br />NF - no fire, PG -prescribed grazing with adequate recovery opportunity <br />Technical Guide <br />Section IIE <br />USDA NRCS <br />Rev. 3/04 <br />~9 <br />