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Figure 11.Plant community growth curve(percent production by month). <br /> CO6710,Warm-season dominant;MLRA-6713;upland coarse-textured soils.. <br /> Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec <br /> 0 0 0 5 20 40 20 10 5 0 0 0 <br /> State 4 <br /> Tilled State <br /> The Tilled State is the result of mechanical farming operations. An ecological threshold has been crossed due to <br /> complete removal of vegetation and years of soil tillage. Physical, chemical, and biological soil properties have been <br /> dramatically altered. <br /> Community 4.1 <br /> Go-Back Plant Community <br /> Go-back land is created when the soil is tilled or farmed (sodbusted)and abandoned.All of the native plants are <br /> destroyed, soil organic matter is reduced, soil structure is changed and a plowpan or compacted layer is formed. <br /> Residual synthetic chemicals often remain from past farming operations and erosion processes may be active. Go- <br /> back land evolves through several plant communities beginning with an early annual plant community,which <br /> initiates the revegetation process. Plants such as Russian thistle, kochia and other annuals begin to establish. <br /> These plants give some protection from erosion and start to build minor levels of soil organic matter. This early <br /> annual plant community lasts for two to several years. Fendler threeawn, sand dropseed and several other early <br /> perennials can dominate the plant community for several years. Eventually other native species become <br /> reestablished. In much of the MLRA go-back land has eroded where tillage or farming and severe erosion has <br /> occurred. If the parent material that the original soil developed from is lost, then another ecosite will evolve. If the <br /> same parent material is present,then re-seeding or the slow process of developing soil and vegetation will start by <br /> similar processes as mentioned above. This is a very slow process (100 years or more). <br /> Community 4.2 <br /> Seeded Plant Community <br /> This plant community can vary considerably depending on how eroded the soil was, the species seeded,the quality <br /> of the stand that was established and how long ago the stand was established. The management of the stand since <br /> establishment will significantly affect the species composition and annual production. <br /> Transition 1.2 to 2 <br /> State 1 to 2 <br /> Continuous grazing without adequate recovery periods between grazing events shifts this plant community across <br /> an ecological threshold toward the Warm-Season Shortgrass Plant Community. <br /> Transition 1 to 3 <br /> State 1 to 3 <br /> Long-term heavy continuous grazing, or excessive defoliation, without adequate recovery periods following each <br /> grazing event will cause a shift across an ecological threshold to the Increased Bare Ground Plant Community. <br /> Erosion and loss of organic matter/carbon reserves are concerns. <br /> Transition 1 to 4 <br /> State 1 to 4 <br /> Mechanical tillage of this ecological site will cause an immediate transition across an ecological threshold to the <br /> Tilled State. This transition can occur from any plant community and it is irreversible. <br /> Transition 2 to 3 <br />