Carbon and nitrogen allocation shifts in plants and soils along aridity and fertility gradients in grasslands of China

Abstract

Plant carbon (C) and nitrogen (N) stoichiometry play an important role in the maintenance of ecosystem structure and function. To decipher the influence of changing environment on plant C and N stoichiometry at the subcontinental scale, we studied the shoot and root C and N stoichiometry in two widely distributed and dominant genera along a 2,200-km climatic gradient in China's grasslands. Relationships between C and N concentrations and soil climatic variables factors were studied. In contrast to previous theory, plant C concentration and C:N ratios in both shoots and roots increased with increasing soil fertility and decreased with increasing aridity. Relative N allocation shifted from soils to plants and from roots to shoots with increasing aridity. Changes in the C:N ratio were associated with changes in N concentration. Dynamics of plant C concentration and C:N ratios were mainly caused by biomass reallocation and a nutrient dilution effect in the plant-soil system. Our results suggest that the shifted allocation of C and N to different ecosystem compartments under a changing environment may change the overall use of these elements by the plant-soil system.

REFERENCES Aerts, R., & Chapin, F. S. III (2000). The mineral nutrition of wild plants revisited: A re-evaluation of processes and patterns. Advances in Ecological Research, 30, 1–67. Alam, R., Iqbal, A., Khan, I., Ali, I., Munir, I., Tahir, M., … Swati, A. (2013). Carbon and nitrogen stoichiometry in Brassica napus L. seedlings after supplementation with Ca²⁺ and K⁺ under irrigated and drought stress conditions. African Journal of Biotechnology, 10, 18418–18424. An, Y. A., Wan, S. Q., Zhou, X. H., Subedar, A. A., Wallace, L. L., & Luo, Y. Q. (2005). Plant nitrogen concentration, use efficiency, and contents in a tallgrass prairie ecosystem under experimental warming. Global Change Biology, 11, 1733–1744. Castle, S. C., & Neff, J. C. (2009). Plant response to nutrient availability across variable bedrock geologies. Ecosystems, 12, 101–113. Chen, D., Wang, S., Xiong, B., Cao, B., & Deng, X. (2015). Carbon/Nitrogen imbalance associated with drought-induced leaf senescence in Sorghum bicolor. PLoS ONE, 10, e0137026. Drenovsky, R. E., James, J. J., & Richards, J. H. (2010). Variation in nutrient resorption by desert shrubs. Journal of Arid Environments, 74, 1564–1568. Elser, J. J., Fagan, W. F., Kerkhoff, A. J., Swenson, N. G., & Enquist, B. J. (2010). Biological stoichiometry of plant production: Metabolism, scaling and ecological response to global change. New Phytologist, 186, 593–608. Finzi, A. C., Austin, A. T., Cleland, E. E., Frey, S. D., Houlton, B. Z., & Wallenstein, M. D. (2011). Responses and feedbacks of coupled biogeochemical cycles to climate change: Examples from terrestrial ecosystems. Frontiers in Ecology and the Environment, 9, 61–67. Fox, J., Nie, Z., & Byrnes, J. Sem: Structural Equation Models. 2013. Guo, Q., Hu, Z., Li, S., Li, X., Sun, X., & Yu, G. (2012). Spatial variations in aboveground net primary productivity along a climate gradient in Eurasian temperate grassland: Effects of mean annual precipitation and its seasonal distribution. Global Change Biology, 18, 3624–3631. Harris, D., Horwáth, W. R., & van Kessel, C. (2001). Acid fumigation of soils to remove carbonates prior to total organic carbon or carbon-13 isotopic analysis. Soil Science Society of America Journal, 65, 1853–1856. He, J. S., Fang, J., Wang, Z., Guo, D., Flynn, D. F., & Geng, Z. (2006). Stoichiometry and large-scale patterns of leaf carbon and nitrogen in the grassland biomes of China. Oecologia, 149, 115–122. Hijmans, R. J., Cameron, S. E., Parra, J. L., Jones, P. G., & Jarvis, A. (2005). Very high resolution interpolated climate surfaces for global land areas. International Journal of Climatology, 25, 1965–1978. Huxman, T. E., Cable, J. M., Ignace, D. D., Eilts, J. A., English, N. B., Weltzin, J., & Williams, D. G. (2004). Response of net ecosystem gas exchange to a simulated precipitation pulse in a semi-arid grassland: The role of native versus non-native grasses and soil texture. Oecologia, 141, 295–305. IPCC. (2013). Climate Change: The Physical Science Basis Working Group I Contribution to the IPCC 5th Assessment Report-Changes to the underlying Scientific/Technical Assessment IPCC. Cambridge, UK and New York, NY, USA: Cambridge University Press. Kang, L., Han, X., Zhang, Z., & Sun, O. J. (2007). Grassland ecosystems in China: Review of current knowledge and research advancement. Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences, 362, 997–1008. Li, H., Li, J., He, Y., Li, S., Liang, Z., Peng, C., … Luo, Z. B. (2013). Changes in carbon, nutrients and stoichiometric relations under different soil depths, plant tissues and ages in black locust plantations. Acta Physiologiae Plantarum, 35, 2951–2964. Li, M. H., & Yang, J. (2004). Effects of microsite on growth of Pinus cembra in the subalpine zone of the Austrian Alps. Annals of Forest Science, 61, 319–325. Lu, X., Yan, Y., Fan, J., Cao, Y., & Wang, X. (2011). Dynamics of above-and below-ground biomass and C, N, P accumulation in the alpine steppe of Northern Tibet. Journal of Mountain Science, 8, 838–844. Luo, W., Elser, J. J., Lü, X. T., Wang, Z., Bai, E., Yan, C., … Han, X. (2015). Plant nutrients do not covary with soil nutrients under changing climatic conditions. Global Biogeochemical Cycle, 29, 1298–1308. Luo, Y., Hui, D., & Zhang, D. (2006). Elevated CO₂ stimulates net accumulations of carbon and nitrogen in land ecosystems: A meta-analysis. Ecology, 87, 53–63. Luo, W., Jiang, Y., Lü, X., Wang, X., Li, M.-H., Bai, E., … Xu, Z. (2013). Patterns of plant biomass allocation in temperate grasslands across a 2500-km transect in northern China. PLoS ONE, 8, e71749. Marba, N., Duarte, C. M., & Agusti, S. (2007). Allometric scaling of plant life history. Proceedings of the National Academy of Sciences of the United States of America, 104, 15777–15780. Meehl, G. A., & Tebaldi, C. (2004). More intense, more frequent, and longer lasting heat waves in the 21st century. Science, 305, 994–997. Oleksyn, J., Reich, P. B., Zytkowiak, R., Karolewski, P., & Tjoelker, M. G. (2003). Nutrient conservation increases with latitude of origin in European Pinus sylvestris populations. Oecologia, 136, 220–235. Ordoñez, J. C., van Bodegom, P. M., Witte, J. P. M., Wright, I. J., Reich, P. B., & Aerts, R. (2009). A global study of relationships between leaf traits, climate and soil measures of nutrient fertility. Global Ecology and Biogeography, 18, 137–149. Peng, S., Piao, S., Shen, Z., Ciais, P., Sun, Z., Chen, S., … Chen, A. (2013). Precipitation amount, seasonality and frequency regulate carbon cycling of a semi-arid grassland ecosystem in Inner Mongolia, China: A modeling analysis. Agricultural and Forest Meteorology, 178, 46–55. Peñuelas, J., Sardans, J., Rivas-ubach, A., & Janssens, I. A. (2012). The human-induced imbalance between C, N and P in Earth's life system. Global Change Biology, 18, 3–6. Reich, P. B., & Oleksyn, J. (2004). Global patterns of plant leaf N and P in relation to temperature and latitude. Proceedings of the National Academy of Sciences of the United States of America, 101, 11001–11006. Sardans, J., Penuelas, J., & Ogaya, R. (2008). Drought-induced changes in C and N stoichiometry in a Quercus ilex Mediterranean forest. Forest Sciences, 54, 513–522. Sardans, J., Rivas-Ubach, A., & Peñuelas, J. (2012). The C:N: P stoichiometry of organisms and ecosystems in a changing world: A review and perspectives. Perspectives in Plant Ecology, Evolution and Systematics, 14, 33–47. Schlesinger, W. H., Cole, J. J., Finzi, A. C., & Holland, E. A. (2011). Introduction to coupled biogeochemical cycles. Frontiers in Ecology and the Environment, 9, 5–8. Sterner, R. W., & Elser, J. J. (2002). Ecological stoichiometry: The biology of elements from molecules to the biosphere. Princeton, News Jersey, USA: Princeton University Press. Wang, C., Wang, X., Liu, D., Wu, H., Lu, X., Fang, Y., … Bai, E. (2014). Aridity threshold in controlling ecosystem nitrogen cycling in arid and semi-arid grasslands. Nature Communications, 5, 4799. Yang, Y., Fang, J., Ma, W., Guo, D., & Mohammat, A. (2010). Large-scale pattern of biomass partitioning across China's grasslands. Global Ecology and Biogeography, 19, 268–277. Yang, Y., & Luo, Y. (2011). Carbon: Nitrogen stoichiometry in forest ecosystems during stand development. Global Ecology and Biogeography, 20, 354–361. Yang, Y., Luo, Y., Lu, M., Schädel, C., & Han, W. (2011). Terrestrial C: N stoichiometry in response to elevated CO₂ and N addition: A synthesis of two meta-analyses. Plant and Soil, 343, 393–400. Yuan, Z. Y., & Chen, H. Y. H. (2015). Decoupling of nitrogen and phosphorus in terrestrial plants associated with global changes. Nature Climate Change, 5, 465–469. Yuan, Z. Y., Chen, H. Y., & Reich, P. B. (2011). Global-scale latitudinal patterns of plant fine-root nitrogen and phosphorus. Nature Communications, 2, 344. Zhang, L., Guo, H. D., Jia, G. S., Wylie, B., Gilmanov, T., Howard, D., … Kato, T. (2014). Net ecosystem productivity of temperate grasslands in northern China: An upscaling study. Agricultural and Forest Meteorology, 184, 71–81.