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,.,~f <br />f <br />r <br />y <br />Site Type: Rangeland <br />MLRA: 67B -Central High Plains, Southern Part <br />• Lonq term non-use (rest) and no fire will move this plant community a~ <br />toward the Bare Ground, Annuals, Cryptogams Plant Community. Thi <br />years or more to achieve. <br />Gravel Breaks <br />R067BY063C0 <br />ass an ecological threshold <br />transition may take 40 <br />• Prescribed grazinq that allows for adequate recovery opportunity follo~ing each grazing event and <br />proper stocking will maintain the Little Bluestem, Sideoats Grama Pla t Community (HCPC). <br />Blue Grama with Decreased Mid and Tall Grass Plant Commun ty <br />This plant community developed with continuous grazing without adequat recovery periods during <br />the growing season. The dominant grass is blue grama. Little bluestem nd sideoats grama are still <br />present as secondary grasses in the community. Big bluestem, Indiangra s, switchgrass, prairie <br />sandreed, needleandthread, western wheatgrass, purple prairie clover an winterfat have been <br />significantly reduced. Hairy grama, sand dropseed, red threeawn as well s Hoods phlox, hairy <br />goldaster, western ragweed and slimflower scurfpea have increased. Wo dy plants include small <br />soapweed and skunkbush sumac. <br />JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC <br />0 0 2 7 25 35 15 10 5 1 0 0 <br />Plant frequency and vigor have decreased. Reduction of tall, mid and rhi omatous wheatgrass, <br />nitrogen fixing fortis, shrub component and increased warm season short rass has begun to alter the <br />biotic integrity of this community. Water and nutrient cycles are becoming impaired. Litter levels have <br />been reduced. Flow paths and rills are more apparent. Pedestalled plant are common. <br />Desertification is in an early stage. <br />Total annual production, during an average year, ranges from 300 to 800 ounds of air-dry weight and <br />will average 500 pounds. <br />The following is an. estimated growth curve of this plant community expect d during a normal year. <br />Vegetative growth begins earlier in the southern reaches (Baca, Bent, Kio a, Las Animas and <br />Prowers counties) of MLRA-67B. Vegetative growth will typically be supp essed during the months of <br />June through August in these counties due to higher evapotranspiration r tes. <br />Growth curve number: C06709 <br />Growth curve name: Warm season dominant, cool season sub-dominant; MLRA-67B; upland coarse <br />textured soils. <br />~montniy percentages of total annual growth) <br />Transitions or pathways leading to other plant communities are as follows <br />• Continuous grazinq without adequate recovery opportunities between razing events will shift this <br />plant community across an ecological threshold toward the Blue Gram Sod, Threadleaf Sedge <br />Plant Community. Weedy species are starting to invade and almost al mid grasses are removed. <br />• Prescribed grazinq which allows for adequate recovery periods followi g each grazing event and <br />proper stocking will move this plant community toward the Little Bluest m, Sideoats Grama, Plant <br />Community (HCPC). <br />• Lonq term non-use (rest) and no fire will shift this plant community acr <br />toward the Bare Ground, Annuals, Cryptogams Plant Community. Thi <br />years or more to achieve. <br />Technical Guide <br />Section IIE <br />ss an ecological threshold <br />transition may take 40 <br />USDA NRCS <br />Rev. 3/04 <br />