Abstract
The root system of permanent grasslands is of outstanding importance for resource acquisition. Particularly under semi-arid conditions, the acquisition of water and nutrients is highly variable during the vegetation growth period and between years. Additionally, grazing is repeatedly disturbing the functional equilibrium between the root system and the transpiring leaf canopy. However, very few data is available considering grazing effects on belowground net primary productivity (BNPP) and root-shoot dry mass allocation in natural grassland systems. We hypothesise that grazing significantly reduces BNPP due to carbon reallocation to shoot growth. Root biomass and BNPP were estimated by soil coring in 2004, 2005 and 2006 and from ingrowth cores in 2005 and 2006 at one site which has been protected from grazing since 1979 (UG79), at one winter grazing (WG), and one heavily grazed (HG) site. BNPP was estimated from the summation of significant increments of total and live root biomass and from accumulated root biomass of ingrowth cores. Belowground biomass varied from 1,490–2,670 g m−2 and was significantly lower under heavy grazing than at site UG79. Root turnover varied from 0.23 to 0.33 year−1 and was not significantly different between sites. Heavy grazing significantly decreased live root biomass and BNPP compared to site UG79. Taking BNPP estimates from live root biomass dynamics and ingrowth cores as the most reliable values, the portion of dry mass allocated belowground relative to total net primary productivity (BNPP/NPP) varied between 0.50–0.66 and was reduced under heavy grazing in 2005, but not in 2006. The positive correlation between cumulative root length density of ingrowth cores and leaf dry matter suggests that the ingrowth core method is suitable for studying BNPP in this semi-arid steppe system. Grazing effects on BNPP and BNPP/NPP should be considered in regional carbon models and estimates of belowground nutrient cycling.
Similar content being viewed by others
References
Aerts R, Berendse F, Klerk NM, Bakker C (1989) Root production and root turnover in two dominant species of wet heathlands. Oecologia 81:374–378
Bai YF, Han XG, Wu JG, Chen ZZ, Li LH (2004) Ecosystem stability and compensatory effects in the Inner Mongolia grassland. Nature 431:181–184
Biondini ME, Patton BD, Nyren PE (1998) Grazing intensity and ecosystem processes in a northern mixed-grass prairie, USA. Ecol Appl 8:469–479
Biswell HH, Weaver JE (1933) Effect of frequent clipping on the development of roots and tops of grasses in prairie sod. Ecology 14:368–390
Brouwer H (1983) Functional equilibrium: sense or nonsense? Neth J Agri Sci 31:335–348
Chen ZZ, Wang SP (2000) Typical steppe ecosystems of China. Science Press, Beijing
Chen YX, Lee P, Lee G, Mariko S, Oikawa T (2006) Simulating root responses to grazing of a Mongolian grassland ecosystem. Plant Ecol 183:265–275
Dahlman RC, Kutschera CL (1965) Root productivity and turnover in native prairie. Ecology 46:84–89
Farrar JF, Jones DL (2000) The control of carbon acquisition by roots. New Phytol 147:43–53
Ferraro DO, Oesterheld M (2002) Effect of defoliation on grass growth: a quantitative review. Oikos 98:125–133
Frank DA, Kuns MM, Guido DR (2002) Consumer control of grassland plant production. Ecology 83:602–606
Gill RA, Jackson RB (2000) Global patterns of root turnover for terrestrial ecosystems. New Phytol 147:13–31
Gill RA, Burke IC, Milchunas DG, Lauenroth WK (1999) Relationship between root biomass and soil organic matter pools in the shortgrass steppe of eastern Colorado. Ecosys 2:226–236
Gill RA, Kelly RH, Parton WJ, Day KA, Jackson RB, Morgan JA, Scurlock JMO, Tieszen LL, Castle JV, Ojima DS, Zhang XS (2002) Using simple environmental variables to estimate belowground productivity in grasslands. Global Ecol Biogeogr 11:79–86
Hendricks JJ, Hendrick RL, Wilson CA, Mitchell RJ, Pecot SD, Guo DL (2006) Assessing the patterns and controls of fine root dynamics: an empirical test and methodological review. J Ecol 94:40–57
Higgins PAT, Jackson RB, Rosiers JM, Field CB (2002) Root production and demography in a California annual grassland under elevated atmospheric carbon dioxide. Global Change Biol 8:841–850
Holland EA, Detling JK (1990) Plant responses to herbivory and below-ground nitrogen cycling. Ecology 71:1040–1049
Huang DH, Chen ZZ, Zhang HF (1988) The comparative study on underground biomass of Stipa baicalensis, Stipa krylovii, and Filifolium sibiricum grassland. Res Grassland Ecosys 2:122–131
Hui DF, Jackson RB (2006) Geographic and interannual variability in biomass partitioning in grassland ecosystems: a synthesis of field data. New Phytol 169:85–93
Jackson RB, Canadell J, Ehleringer JR, Mooney HA, Sala OE, Schulze ED (1996) A global analysis of root distributions for terrestrial biomes. Oecologia 108:389–411
Jackson RB, Mooney HA, Schulze ED (1997) A global budget for fine root biomass, surface area, and mineral nutrients. Proc Natl Acad Sci USA 94:7362–7366
Körner C, Renhardt U (1987) Dry matter partitioning and root length/leaf area ratios in herbaceous perennial plants with diverse altitudinal distribution. Oecologia 74:411–418
Krümmelbein J, Wang ZH, Zhao Y, Peth S, Horn R (2006) Influence of various grazing intensities on soil stability, soil structure and water balance of grassland soils in Inner Mongolia, P. R. China. Adv Geo Ecol 38:93–101
Liu ZL, Li ZH (1987) Primary productivity of Leymus chinense and Stipa grandis steppe in Inner Mongolia. J Arid Land Res Environ 1:13–33
McNaughton SJ, Banyikwa FF, McNaughton MM (1998) Root biomass and productivity in a grazing ecosystem: the Serengeti. Ecology 79:587–592
Milchunas DG, Lauenroth WK (1992) Carbon dynamics and estimates of primary production by 14C dilution and 14C turnover. Ecology 73:593–607
Milchunas DG, Lauenroth WK (1993) Quantitative effects of grazing on vegetation and soils over a global range of environments. Ecol Monogr 63:327–366
Milchunas DG, Lauenroth WK (2001) Belowground primary production by carbon isotope decay and long-term root biomass dynamics. Ecosystems 4:139–150
Milchunas DG, Mosier AR, Morgan JA, LeCain DR, King JY, Nelson JA (2005) Root production and tissue quality in a shortgrass steppe exposed to elevated CO2: using a new ingrowth method. Plant Soil 268:111–122
Neill C (1992) Comparison of soil coring and ingrowth methods for measuring belowground production. Ecology 73:1918–1921
Ni J (2004) Estimating net primary productivity of grassland from field biomass measurements in temperate northern China. Plant Ecol 174:217–234
Olson BE, Wallander RT (1997) Biomass and carbohydrates of spotted knapweed and Idaho fescue after repeated grazing. J Range Manag 50:409–412
Pandey CB, Singh JS (1992) Rainfall and grazing effects on net primary productivity in a tropical savanna, India. Ecology 73:2007–2021
Pucheta E, Bonamici I, Cabido M, Díaz S (2004) Below-ground biomass and productivity of a grazed site and a neighbouring ungrazed exclosure in a grassland in central Argentina. Aust Ecol 29:201–208
Schimel DS (1995) Terrestrial ecosystems and the carbon cycle. Global Change Biol 1:77–91
Schwinning S, Ehleringer JR (2001) Water use trade-offs and optimal adaptations to pulse-driven arid ecosystems. J Ecol 89:464–480
Scurlock JMO, Cramer W, Olson RJ, Parton WJ, Prince SD (1999) Terrestrial NPP: towards a consistent data set for global model evaluation. Ecol Appl 9:913–919
Scurlock JMO, Johnson K, Olson RJ (2002) Estimating net primary productivity from grassland biomass dynamics measurements. Global Change Biol 8:736–753
Sims PL, Singh JS (1978) The structure and function of ten western North American grasslands. III. Net primary production, turnover, and efficiencies of energy capture and water use. J Ecol 66:573–597
Singh JS, Lauenroth WK, Steinhorst RK (1975) Review and assessment of various techniques for estimating net aerial primary production in grassland from harvest data. Bot Rev 41:181–232
Steffens M, Kölbl A, Totsche KU, Kögel-Knabner I (2008) Grazing effects on soil chemical and physical properties in a semiarid steppe of Inner Mongolia (P.R. China). Geoderma 143:63–72
Steingrobe B, Schmid H, Claassen N (2000) The use of the ingrowth core method for measuring root production of arable crops—influence of soil conditions inside the ingrowth core on root growth. J Plant Nutr Soil Sci 163:617–622
Tennant D (1975) A test of a modified line intersect method of estimating root length. J Ecol 11:995–1001
Tong C, Wu J, Yong S, Yang J, Yong W (2004) A landscape-scale assessment of steppe degradation in the Xilin River Basin, Inner Mongolia, China. J Arid Environ 59:133–149
Van der Maarel E, Titlyanova A (1989) Above-ground and below-ground biomass relations in steppes under different grazing conditions. Oikos 56:364–370
Wang YF, Wang SP (1999) Influence of different stocking rates on belowground biomass in Inner Mongolia steppe. Acta Agr Sin 7:198–203
Xiao XM, Wang YF, Jiang S, Ojima DS, Bonham CD (1995) Interannual variation in the climate and above-ground biomass of Leymus chinense steppe and Stipa grandis steppe in the Xilin river basin, Inner Mongolia, China. J Arid Environ 31:283–299
Zhou ZY, Sun OJ, Huang JH, Li LH, Liu P, Han XG (2007) Soil carbon and nitrogen stores and storage potential as affected by land-use in an agro-pastoral ecotone of northern China. Biogeochemistry 82:127–138
Acknowledgments
This work was supported by the Deutsche Forschungsgemeinschaft (DFG, SA 359/30–1) embedded into the joint-research project FG 536, MAGIM, and the National Nature Science Foundation of China (NSFC, 40471077). We would like to thank IMGERS meteorological station for providing climatic data and Mrs. Qing Chen for her help in field work and Dr. Zhiyong Zhou for encouraging discussion. We also thank Dr. Daniel Milchunas for his constructive suggestions on earlier drafts of this manuscript.
Author information
Authors and Affiliations
Corresponding author
Additional information
Responsible Editor: Tibor Kalapos, Ph.D.
Prof. B. Sattelmacher, the mentor of this project, died in November 2005.
Rights and permissions
About this article
Cite this article
Gao, Y.Z., Giese, M., Lin, S. et al. Belowground net primary productivity and biomass allocation of a grassland in Inner Mongolia is affected by grazing intensity. Plant Soil 307, 41–50 (2008). https://doi.org/10.1007/s11104-008-9579-3
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s11104-008-9579-3