Influence of livestock grazing on C sequestration in semi-arid mixed-grass and short-grass rangelands.

We evaluated the effects of livestock grazing on C content of the plant-soil system (to 60 cm) of two semi-arid grasslands: a mixed-grass prairie (grazed 12 years), and a short-grass steppe (grazed 56 years). Grazing treatments included season-long grazing at heavy and light stocking rates, and non-grazed exclosures. Significantly higher soil C (0-30cm) was measured in grazed pastures compared to non-grazed exclosures, although for the short-grass steppe higher soil C was observed with the heavy grazing treatment only. Excluding grazing caused an immobilization of C in excessive aboveground plant litter, and an increase in annual forbs and grasses which lack dense fibrous rooting systems conducive to soil organic matter formation and accumulation. Our data indicate that higher soil C with grazing was in part the result of more rapid annual shoot turnover, and redistribution of C within the plant-soil system as a result of changes in plant species composition.

[1]  W. Lauenroth,et al.  A rapid method for washing roots. , 1971 .

[2]  A. Frank,et al.  Soil carbon and nitrogen of Northern Great Plains grasslands as influenced by long-term grazing. , 1995 .

[3]  David S. Schimel,et al.  Texture, climate, and cultivation effects on soil organic matter content in U.S. grassland soils , 1989 .

[4]  D. Milchunas,et al.  Plant competition, abiotic, and long- and short-term effects of large herbivores on demography of opportunistic species in a semiarid grassland , 1992, Oecologia.

[5]  D. Milchunas,et al.  Effects of grazing, topography, and precipitation on the structure of a semiarid grassland , 1989, Vegetatio.

[6]  J. E. Weaver,et al.  Relation of Root Distribution to Organic Matter in Prairie Soil , 1935, Botanical Gazette.

[7]  Jack A. Morgan,et al.  Carbon exchange rates in grazed and ungrazed pastures of Wyoming. , 2000 .

[8]  A. L. Black,et al.  Soil Property Comparisons in Virgin Grasslands Between Grazed and Nongrazed Management Systems1 , 1987 .

[9]  K. Paustian,et al.  GRASSLAND MANAGEMENT AND CONVERSION INTO GRASSLAND: EFFECTS ON SOIL CARBON , 2001 .

[10]  Richard H. Hart,et al.  IMPACT OF GRAZING MANAGEMENT ON THE CARBON AND NITROGEN BALANCE OF A MIXED-GRASS RANGELAND , 1999 .

[11]  D. W. Nelson,et al.  Total Carbon, Organic Carbon, and Organic Matter , 1983, SSSA Book Series.

[12]  M. Dyer,et al.  PLANT-ANIMAL INTERACTIONS: STUDIES OF THE EFFECTS OF GRASSHOPPER GRAZING ON BLUE GRAMA GRASS' , 1976 .

[13]  J. Hendrickson,et al.  Pasture management influences on soil properties in the Northern Great Plains , 2001 .

[14]  E. Paul,et al.  Soil microbiology and biochemistry. , 1998 .

[15]  Pete Smith.  The potential of US grazing lands to sequester carbon and mitigate the greenhouse effect , 2002 .

[16]  D. Milchunas,et al.  Community attributes along a perturbation gradient in a shortgrass steppe , 1990 .

[17]  James H. Torrie,et al.  Principles and procedures of statistics: a biometrical approach (2nd ed) , 1980 .

[18]  M. Naeth,et al.  Grazing impacts on litter and soil organic matter in mixed prairie and fescue grassland ecosystems of Alberta. , 1991 .

[19]  J. W. Waggoner,et al.  Vegetation, cattle, and economic responses to grazing strategies and pressures , 1997 .

[20]  J. Detling,et al.  Net photosynthesis, root respiration, and regrowth of Bouteloua gracilis following simulated grazing , 1979, Oecologia.

[21]  J. Detling,et al.  Effects of defoliation on net photosynthesis and regrowth of western wheatgrass. , 1981 .

[22]  J. Derner,et al.  Does grazing mediate soil carbon and nitrogen accumulation beneath C4, perennial grasses along an environmental gradient? , 1997, Plant and Soil.

[23]  R. Follett,et al.  Organic Carbon Pools in Grazing Land Soils , 2000 .

[24]  K. Paustian,et al.  Soil Organic Matter in Temperate Agroecosystems , 1997 .

[25]  D. Milchunas,et al.  Root Biomass and Microbial Processes , 2000 .

[26]  J. F. Dormaar,et al.  Long-term grazing effects on fescue grassland soils. , 1971 .

[27]  R. H. Hart,et al.  Plant biodiversity on shortgrass steppe after 55 years of zero, light, moderate, or heavy cattle grazing , 2001, Plant Ecology.

[28]  J. F. Dormaar,et al.  Seasonal variation in chemical characteristics of soil organic matter of grazed and ungrazed mixed prairie and fescue grassland. , 1977 .

[29]  J. F. Dormaar,et al.  Long-term grazing effects on Stripa-Bouteloua prairie soils. , 1972 .

[30]  M. Biondini,et al.  Grazing intensity effects on litter decomposition and soil nitrogen mineralization , 1994 .

[31]  I. Burke,et al.  Livestock Grazing: Animal and Plant Biodiversity of Shortgrass Steppe and the Relationship to Ecosystem Function , 1998 .

[32]  D. Milchunas,et al.  Quantitative Effects of Grazing on Vegetation and Soils Over a Global Range of Environments , 1993 .

[33]  R. H. Hart,et al.  Cattle, vegetation, and economic responses to grazing systems and grazing pressure. , 1988 .

[34]  H. Monger,et al.  Inorganic Carbon Sequestration in Grazing Lands , 2000 .