Effects of grazing on carbon and nitrogen in plants and soils in a semiarid desert grassland, China
Hui AN, GuoQi LI
Ministry of Education Key Laboratory for Restoration and Reconstruction of Degraded Ecosystem in Northwestern China, United Center for Ecology Research and Bioresource Exploitation in Western China, Ningxia University, Yinchuan 750021, China
Effects of grazing on carbon and nitrogen in plants and soils in a semiarid desert grassland, China
Hui AN, GuoQi LI
Ministry of Education Key Laboratory for Restoration and Reconstruction of Degraded Ecosystem in Northwestern China, United Center for Ecology Research and Bioresource Exploitation in Western China, Ningxia University, Yinchuan 750021, China
摘要 Grazing can modulate the feedback between vegetation and soil nutrient dynamics (carbon and nitrogen), altering the cycles of these elements in grassland ecosystems. For clarifying the impact of grazing on the C and N in plants and soils in the desert grassland of Ningxia, China, we examined the plant biomass, SOC (soil organic carbon), total soil N and stable isotope signatures of plants and soils from both the grazed and ungrazed sites. Significantly lower aboveground biomass, root biomass, litter biomass and vegetation coverage were found in the grazed site compared to the ungrazed site, with decreases of 42.0%, 16.2%, 59.4% and 30.0%, respectively. The effects of grazing on plant carbon, nitrogen, 15N and 13C values were uniform among species. The levels of plant carbon and nitrogen in grasses were greater than those in the forbs (except for the carbon of Cynanchum komarovii and Euphorbia esula). Root 15N and 13C values increased with grazing, while the responses of root carbon and nitrogen to grazing showed no consistent patterns. Root 15N and 13C were increased by 79.0% and 22.4% in the grazed site compared to the ungrazed site, respectively. The values of SOC and total N were significantly lower in the grazed than in the ungrazed sites for all sampling depths (0–10 and 10–20 cm), and values of SOC and total N at the surface (0–10 cm) were lower than those in the deeper soils (10–20 cm). Soil 15N values were not affected by grazing at any sampling depth, whereas soil 13C values were significantly affected by grazing and increased by 19.3% and 8.6% in the soils at 0–10 and 10–20 cm, respectively. The soil 13C values (–8.3‰ to –6.7‰) were higher than those for roots (–20.2‰ to –15.6‰) and plant tissues (–27.9‰ to –13.3‰). Our study suggests that grazing could greatly affect soil organic carbon and nitrogen in contrast to ungrazed grassland and that grazing appears to exert a negative effect on soil carbon and nitrogen in desert grassland.
Abstract: Grazing can modulate the feedback between vegetation and soil nutrient dynamics (carbon and nitrogen), altering the cycles of these elements in grassland ecosystems. For clarifying the impact of grazing on the C and N in plants and soils in the desert grassland of Ningxia, China, we examined the plant biomass, SOC (soil organic carbon), total soil N and stable isotope signatures of plants and soils from both the grazed and ungrazed sites. Significantly lower aboveground biomass, root biomass, litter biomass and vegetation coverage were found in the grazed site compared to the ungrazed site, with decreases of 42.0%, 16.2%, 59.4% and 30.0%, respectively. The effects of grazing on plant carbon, nitrogen, 15N and 13C values were uniform among species. The levels of plant carbon and nitrogen in grasses were greater than those in the forbs (except for the carbon of Cynanchum komarovii and Euphorbia esula). Root 15N and 13C values increased with grazing, while the responses of root carbon and nitrogen to grazing showed no consistent patterns. Root 15N and 13C were increased by 79.0% and 22.4% in the grazed site compared to the ungrazed site, respectively. The values of SOC and total N were significantly lower in the grazed than in the ungrazed sites for all sampling depths (0–10 and 10–20 cm), and values of SOC and total N at the surface (0–10 cm) were lower than those in the deeper soils (10–20 cm). Soil 15N values were not affected by grazing at any sampling depth, whereas soil 13C values were significantly affected by grazing and increased by 19.3% and 8.6% in the soils at 0–10 and 10–20 cm, respectively. The soil 13C values (–8.3‰ to –6.7‰) were higher than those for roots (–20.2‰ to –15.6‰) and plant tissues (–27.9‰ to –13.3‰). Our study suggests that grazing could greatly affect soil organic carbon and nitrogen in contrast to ungrazed grassland and that grazing appears to exert a negative effect on soil carbon and nitrogen in desert grassland.
The research was financially supported by the National Natural Science Foundation of China (31260125, 31000214).
通讯作者:
Hui AN
E-mail: anhui81@gmail.com
引用本文:
Hui AN, GuoQi LI. Effects of grazing on carbon and nitrogen in plants and soils in a semiarid desert grassland, China[J]. 干旱区科学, 2015, 7(3): 341-349.
Hui AN, GuoQi LI. Effects of grazing on carbon and nitrogen in plants and soils in a semiarid desert grassland, China. Journal of Arid Land, 2015, 7(3): 341-349.
Baron V S, Mapfumo E, Dick A C, et al. 2002. Grazing intensity impacts on pasture carbon and nitrogen flow. Journal of Range Management, 55: 535–541.Cheng J, Wu G, Zhao L, et al. 2011. Cumulative effects of 20-year exclusion of livestock grazing on above- and belowground biomass of typical steppe communities in arid areas of the Loess Plateau, China. Plant, Soil and Environment, 57: 40–44.Cheng W X, Chen Q S, Xu Y Q, et al. 2009. Climate and ecosystem 15N natural abundance along a transect of Inner Mongolian grasslands: Contrasting regional patterns and global patterns. Global Biogeochemical Cycles, 23: GB2005.Conant R T, Paustian K, Elliott E T. 2001. Grassland management and conversion into grassland: effects on soil carbon. Ecological Applications, 11: 343–355.Cui X Y, Wang Y F, Niu H S, et al. 2005. Effect of long-term grazing on soil organic carbon content in semiarid steppes in Inner Mongolia. Ecological Research, 20: 519–527.Deines P. 1980. The isotopic composition of reduced organic carbon. In: Fritz P, Fontes J C. Handbook of Environmental Isotope Geochemistry I, the Terrestrial Environment. Amsterdam: Elsevier, 329–345.Derner J D, Boutton T W, Briske D D. 2006. Grazing and ecosystem carbon storage in the North American Great Plains. Plant and Soil, 280: 77–90.Dixon E R, Blackwell M S A, Dhanoa M S, et al. 2010. Measurement at the field scale of soil δ13C and δ15N under improved grassland. Rapid Communications in Mass Spectrometry, 24: 511–518.Ehleringer J R, Buchmann N, Flanagan L B. 2000. Carbon isotope ratios in belowground carbon cycle processes. Ecological Applications, 10: 412–422.Evans R D, Ehleringer J R. 1994. Water and nitrogen dynamics in an arid woodland. Oecologia, 99: 233–242.Evans R D, Bloom A J, Sukrapanna S S, et al. 1996. Nitrogen isotope composition of tomato (Lycopersicon esculentum Mill. cv. T-5) grown under ammonium or nitrate nutrition. Plant, Cell and Environment, 19: 1317–1323.Feigin A, Kohl D H, Shearer G, et al. 1974. Variation in the natural nitrogen-15 abundance in nitrate mineralized during incubation of several Illinois soils. Soil Science Society of America Journal, 38: 90–95.Frank D A, Evans R D. 1997. Effects of native grazers on grassland N cycling in Yellowstone National Park. Ecology, 78: 2238–2248.Frank D A, Groffman P M, Evans R D, et al. 2000. Ungulate stimulation of nitrogen cycling and retention in Yellowstone Park grasslands. Oecologia, 123: 116–121.Frank D A, Evans R D, Tracy B F. 2004. The role of ammonia volatilization in controlling the natural 15N abundance of a grazed grassland. Biogeochemistry, 68: 169–178.Gao Y H, Luo P, Wu N, et al. 2007. Biomass and nitrogen responses to grazing intensity in an alpine meadow on the eastern Tibetan Plateau. Polish Journal of Ecology, 55: 469–479. Gillson L, Hoffman M T. 2007. Rangeland ecology in a changing world. Science, 315: 53–54.Golluscio R A, Austin A T, García M G C, et al. 2009. Sheep grazing decreases organic carbon and nitrogen pools in the Patagonian Steppe: combination of direct and indirect effects. Ecosystems, 12: 686–697.Han G D, Hao X Y, Zhao M L, et al. 2008. Effect of grazing intensity on carbon and nitrogen in soil and vegetation in a meadow steppe in Inner Mongolia. Agriculture, Ecosystems & Environment, 125: 21–32.Harris W N, Moretto A S, Distel R A, et al. 2007. Fire and grazing in grasslands of the Argentine Caldenal: effects on plant and soil carbon and nitrogen. Acta Oecologica, 32: 207–214.Högberg P, Högbom L, Schinkel H, et al. 1996. 15N abundance of surface soils, roots and mycorrhizas in profiles of European forest soils. Oecologia, 108: 207–214.Holland E A, Detling J K. 1990. Plant response to herbivory and belowground nitrogen cycling. Ecology, 71: 1040–1049.Kang L, Han X, Zhang Z, et al. 2007. Grassland ecosystems in China: review of current knowledge and research advancement. Philosophical Transactions of the Royal Society B: Biological Sciences, 362: 997–1008.Ma H B, Xie Y Z. 2008. Plant compensatory growth under different grazing intensities in desert steppe. Scientia Agricultura Sinica, 41: 3645–3650. (in Chinese)Milchunas D G, Lauenroth W K. 1993. Quantitative effects of grazing on vegetation and soils over a global range of environments. Ecological Monographs, 63: 327–366.Nadelhoffer K J, Fry B. 1994. Nitrogen isotope studies in forest ecosystems. In: Michener R, Lajtha K. Stable Isotopes in Ecology and Environmental Science. Oxford: Blackwell Scientific, 22–44. Natelhoffer K, Fry B. 1988. Controls on natural nitrogen-15 and carbon-13 abundances in forest soil organic matter. Soil Science Society of America Journal, 52: 1633–1640.Neff J C, Reynolds R L, Belnap J, et al. 2005. Multi-decadal impacts of grazing on soil physical and biogeochemical properties in southeast Utah. Ecological Applications, 15: 87–95.Olofsson J, Kitti H, Rautiainen P, et al. 2001. Effects of summer grazing by reindeer on composition of vegetation, productivity and nitrogen cycling. Ecography, 24: 13–24.Piñeiro G, Paruelo J M, Oesterheld M. 2006. Potential long-term impacts of livestock introduction on carbon and nitrogen cycling in grasslands of Southern South America. Global Change Biology, 12: 1267–1284.Rossignol N, Bonis A, Bouzillé J B. 2006. Consequence of grazing pattern and vegetation structure on the spatial variations of net N mineralisation in a wet grassland. Applied Soil Ecology, 31: 62–72.Savadogo P, Sawadogo L, Tiveau D. 2007. Effects of grazing intensity and prescribed fire on soil physical and hydrological properties and pasture yield in the savanna woodlands of Burkina Faso. Agriculture, Ecosystems & Environment, 118: 80–92.Schlesinger W H. 1997. Biogeochemistry: an Analysis of Global Change. New York: Academic Press.Scurlock J M O, Hall D O. 1998. The global carbon sink: a grassland perspective. Global Change Biology, 4: 229–233.Stark S, Grellmann D. 2002. Soil microbial responses to herbivory in an arctic tundra heath at two levels of nutrient availability. Ecology, 83: 2736–2744.Su Y Z, Li Y L, Cui J Y, et al. 2005. Influences of continuous grazing and livestock exclusion on soil properties in a degraded sandy grassland, Inner Mongolia, northern China. Catena, 59: 267–278.Templer P H, Arthur M A, Lovett G M, et al. 2007. Plant and soil natural abundance δ15N: indicators of relative rates of nitrogen cycling in temperate forest ecosystems. Oecologia, 153: 399–406.Tracy B F, Frank D A. 1998. Herbivore influence on soil microbial biomass and nitrogen mineralization in a northern grassland ecosystem: Yellowstone National Park. Oecologia, 114: 556–562.Van Wijnen H J, Van Der Wal R, Bakker J P. 1999. The impact of herbivores on nitrogen mineralization rate: consequences for salt-marsh succession. Oecologia, 118: 225–231.Wu G L, Liu Z H, Zhang L, et al. 2010. Long-term fencing improved soil properties and soil organic carbon storage in an alpine swamp meadow of western China. Plant and Soil, 332: 331–337.Zacheis A, Ruess R W, Hupp J W. 2002. Nitrogen dynamics in an Alaskan salt marsh following spring use by geese. Oecologia, 130: 600–608.Zhang K B, Li R, Hou R P, et al. 2004. Study on plant diversity of different control measures of desertification in Yanchi county, Ningxia. Science of Soil and Water Conservation, 2: 66–72. (in Chinese) Zhou Z Y, Li F R, Chen S K, et al. 2011. Dynamics of vegetation and soil carbon and nitrogen accumulation over 26 years under controlled grazing in a desert shrubland. Plant and Soil, 341: 257–268.
2015, Vol. 7 
