Biogeosciences www.biogeosciences.net 1726-4170 1726-4189 5 2 2008 10.5194/bg-5-339-2008 http://www.biogeosciences.net/5/339/2008/ http://www.biogeosciences.net/5/339/2008/bg-5-339-2008.html http://www.biogeosciences.net/5/339/2008/bg-5-339-2008.pdf 339 352 2008-03-07 Input and output of dissolved organic and inorganic nitrogen in subtropical forests of South China under high air pollution Y. T. Fang fangyt@scbg.ac.cn P. Gundersen J. M. Mo W. X. Zhu South China Botanical Garden, the Chinese Academy of Sciences, Guangzhou, 510650, China Forest & Landscape Denmark, Faculty of Life Sciences, University of Copenhagen, Hørsholm Kongevej 11, 2970 Hørsholm, Denmark Department of Biological Sciences, State University of New York – Binghamton, Binghamton, NY 13902, USA The nitrogen (N) emissions to the atmosphere and N deposition to forest ecosystems are increasing rapidly in Southeast Asia, but little is known about the fates and effects of elevated N deposition in forest ecosystems in this warm and humid region. Here we report the concentrations and fluxes of dissolved inorganic (DIN) and organic N (DON) in precipitation, throughfall, surface runoff and soil solution for three subtropical forests in a region of South China under high air pollution over two years (2004 and 2005), to investigate how deposited N is processed, and to examine the importance of DON in the N budget. The precipitation DIN input was 32–34 kg N ha^−1 yr^−1. An additional input of 18 kg N ha^−1 yr^−1 as DON was measured in 2005, which to our knowledge is the highest DON flux ever measured in precipitation. A canopy uptake of DIN was indicated in two young conifer dominated forests (72–85% of DIN input reached the floor in throughfall), whereas no uptake occurred in an old-growth broadleaf forest. The DON fluxes in throughfall were similar to that in precipitation in all forests. In the younger forests, DIN was further retained in the soil, with 41–63% of precipitation DIN leached below the 20-cm soil depth. Additionally, about half of the DON input was retained in these forests. The N retention in two young aggrading forests (21–28 kg N ha^−1 yr^−1) was in accordance with the estimates of N accumulation in biomass and litter accretion. In the old-growth forest, no N retention occurred, but rather a net loss of 8–16 kg N ha^−1 yr^−1 from the soil was estimated. In total up to 60 kg N ha^−1 yr^−1 was leached from the old-growth forest, indicating that this forest was completely N saturated and could not retain additional anthropogenic N inputs. We found that the majority of DIN deposition as well as of DIN leaching occurred in the rainy season (March to August) and that monthly DIN concentrations and fluxes in leaching were positively related to those in throughfall in all three forests, implying that part of the N leaching was hydrologically driven. Our results suggest that long-term high N deposition has caused elevated N leaching in all three forest types although most pronounced in the old-growth forest where wood increment was negligible or even negative. N availability even exceeded the biotic N demand in the young aggrading forests, with intensive rain in the growing season further enhancing N leaching in these forests. Aas, W., Shao, M., Jin, L., Larssen, T., Zhao, D. W., Xiang, R. J., Zhang, J. H., Xiao, J. S., and Duan, L.: Air concentrations and wet deposition of major inorganic ions at five non-urban sites in China, 2001–2003. Atmos. Environ., 41, 1706–1716, 2007. Aber, J. D., Goodale, C. L., Ollinger, S. V., Smith, M. L., Magill, A. H., Martin, M. E., and Stoddard, J. L.: Is nitrogen altering the nitrogen status of northeastern forests?, BioScience, 53, 375–390, 2003. Aber, J. D., McDowell, W., Nadelhoffer, K., Magill, A., Berntsen, G., Kamakea, M., McNulty, S., Currie, W., Rustad, L., and Fernandez, I.: Nitrogen saturation in temperate forest ecosystems – hypothesis revisited, BioScience, 48, 921–934, 1998. Aber, J. D., Nadelhoffer, K. J., Steudler, P., and Melillo, J. M.: Nitrogen saturation in northern forest ecosystems – hypotheses and implications. BioScience, 39, 378–386, 1989. Campbell, J. L., Hornbeck, J. W., Mitchell, M. J., Adams, M. B., Castro, M. S., Driscoll, C. T., Kahl, J. S., Kochenderfer, J. N., Likens, G. E., Lynch, J. A., Murdoch, P. S., Nelson, S. J., and Shanley, J. B.: Input-output budgets of inorganic nitrogen for 24 forest watersheds in the northeastern United States: a review, Water Air Soil Pollut., 151, 373–396, 2004. Campell, J. L., Hornbeck, J. W., McDowell, W. H., Buso, D. C., Shanley, J. B., and Likens, G. E.: Dissolved organic nitrogen budgets for upland, forested ecosystems in New England, Biogeochemistry, 49, 123–142, 2000. Chen, B. F., Zhou, G. Y., Zeng, Q. B., Li, Y. D., and Wu, Z. M.: Study on hydrochemical cycling in tropical mountain rain forest ecosystem, Forest Res., 10, 111–117, 1997. Chen, X. Y. and Mulder, J.: Atmospheric deposition of nitrogen at five subtropical forested sites in South China, Sci. Total Environ., 378, 317–330, 2007a. Chen, X. Y. and Mulder, J.: Indicators for nitrogen status and leaching in subtropical forest ecosystems, South China, Biogeochemistry, 82, 165–180, 2007b. Cornell S. E., Jickell, T. D., Cape, J. N., Rowland, A. P., and Duce, R. A.: Organic nitrogen deposition on land and coastal environments: a review of methods and data, Atmos. Environ., 37, 2173–2191, 2003. Dise, N. B., Matzner, E., and Forsius, M.: Evaluation of organic horizon C:N ratio as an indicator of nitrate leaching in conifer forests across Europe, Environ. Pollut., 102, 453–456, 1998. Fan, H. B. and Hong, W.: Estimation of dry deposition and canopy exchange in Chinese fir plantation, Forest Ecol. Manag., 147, 99–107, 2001. Fang, Y. T., Yoh, M., Mo, J. M., Gundersen, P., and Zhou, G. Y.: Response of nitrogen leaching to simulated nitrogen deposition in a disturbed and a mature forest in southern China, Pedosphere, accepted, 2008. Fang, Y. T., Zhu, W. X., Mo, J. M., Zhou, G. Y., and Gundersen, P.: Dynamics of soil inorganic nitrogen and their responses to nitrogen additions in three subtropical forests, south China, J. Environ. Sci.-China, 18, 752–759, 2006. Fenn, M. E., Poth, M. A., Aber, J. D., Baron, J. S., Bormann, B. T., Johnson, D. W., Lemly, A. D., McNulty, S. G., Ryan, D. F., and Stottlemyer, R.: Nitrogen excess in North American ecosystems: Predisposing factors, ecosystem responses, and management strategies, Ecol. Appl. 8, 706–733, 1998. Galloway, J., Cowling, E., and Kessler, E.: Reactive nitrogen, Ambio, 31, 59, 2002. Gan, J. M., Xue, J. Y., and Zhao, H. K.: A preliminary study on changes of nutrient import and export in the process of rainfall in the Ailao Mountains region of Yunnan Province, J. Natural Res., 10, 43–50, 1995. Guan, L. L., Zhou, G. Y., Zhang, D. Q., Liu, J. X., and Zhang, Q. M.: Twenty years of litterfall dynamics in subtropical evergreen broad-leaved forests at the Dinghushan forest ecosystem research station, Acta Phytoecol. Sin., 28, 449–456, 2004. Gundersen, P., Emmett, B. A., Kjønaas, O. J., Koopmans, C., and Tietema, A.: Impact of nitrogen deposition on nitrogen cycling in forest:a synthesis of NITREX data, Forest Ecol. Manag., 101, 37–55, 1998. Gundersen, P., Schmidt, I. K., and Raulund-Rasmussen, K.: Leaching of nitrate from temperate forests – effects of air pollution and forest management, Environ. Rev., 14, 1–57, 2006. Hall, S. J. and Matson, P. A.: Nutrient status of tropical rain forests influences soil N dynamics after N additions, Ecol. Monogr., 73, 107–129, 2003. Ham, Y. S., Tamiya, S., and Choi, I. S.: Contribution of dissolved organic nitrogen deposition to nitrogen saturation in a forested mountainous watershed in Tsukui, Central Japan, Water Air Soil Pollut., 178, 113–120, 2006. Ham, Y. S. and Tamiya, S.: Contribution of dissolved organic nitrogen deposition to total dissolved nitrogen deposition under intensive agricultural activities, Water Air Soil Pollut., 178, 5–13, 2006. He, J. H., Chen, Z. Q., and Liang, Y. A.: The soil of Ding Hu Shan, Trop. Subtrop. For. Ecosys., 1, 25–38, 1982. Huang, Z. F. and Fan, Z. G.: The climate of Ding Hu Shan, Trop. Subtrop. For. Ecosys., 1, 11–23, 1982. Huang, Z. L., Ding, M. M., Zhang, Z. P., and Yi, W. M.: The hydrological processes and nitrogen dynamics in a monsoon evergreen broad-leafed forest of Dinghu shan, Acta Phytoecol. Sinic., 18, 194–199, 1994. Kristensen, H. L., Gundersen, P., Callesen, I., and Reinds, G.: Throughfall nitrogen deposition has different impacts on soil solution nitrate concentration in European coniferous and deciduous forests, Ecosystems, 7, 180–192, 2004. Liu, G. S., Jiang, N. H., and Zhang, L. D.: Soil physical and chemical analysis and description of soil profiles, Standards Press of China, Beijing, 1996. Lohse, A. L. and Matson, P.: Consequences of nitrogen additions for soil processes and solution losses from wet tropical forests, Ecol. Appl., 15, 1629–1648, 2005. Lovett, G. M., Weather, K. C., and Arthur, M. A.: Control of nitrogen loss from forested watersheds by soil carbon: nitrogen ratio and tree species composition, Ecosystems, 5, 712–718, 2002. Luo, L. C., Qin, B. Q., Song, Y. Z., and Yang, L. Y.: Seasonal and regional variations in precipitation chemistry in the Lake Taihu Basin, China, Atmos. Environ., 41, 2674–2679, 2007. MacDonald, J. A., Dise, N. B., Matzner, E., Armbruster, M., Gundersen, P., and Forsius, M.: Nitrogen input together with ecosystem nitrogen enrichment predict nitrate leaching from European forests, Global Change Biol., 8, 1028–1033, 2002. Magill, A. H., Aber, J. D., Currie, W. S., Nadelhoffer, K. J., Martin, M. E., McDowell, W. H., Melillo, J. M., and Steudler, P.: Ecosystem response to 15 years of chronic nitrogen additions at the Harvard Forest LTER, Massachusetts, USA, Forest Ecol. Manag., 196, 7–28, 2004. Matson, P. A., McDowell, W. H., Townsend, A. R., and Vitousek, P. M.: The globalization of N deposition: ecosystem consequences in tropical environments, Biogeochemistry, 46, 67–83, 1999. McDowell, W. H., Magill, A. H., Aitkenhead-Peterson, J. A., Aber, J. D., Merriam, J. L., and Kaushal, S. S.: Effects of chronic nitrogen amendment on dissolved organic matter and inorganic nitrogen in soil solution, Forest Ecol. Manag., 196, 29–41, 2004. Michalzik, B., Kalbitz, K., Park, J. H., Solinger, S., and Matzner, E.: Fluxes and concentrations of dissolved organic carbon and nitrogen – a synthesis for temperate forests, Biogeochemistry, 52, 173–205, 2001. Mo, J. M., Brown, S., Peng, S. L., and Kong, G. H.: Nitrogen availability in disturbed, rehabilitated and mature forests of tropical China, Forest Ecol. Manag., 175, 573–583, 2003. Mo, J. M., Brown, S., Xue, J. H., Fang, Y. T., Li, Z. A., Li, D. J., and Dong, S. F.: Response of nutrient dynamics of decomposing pine (\textitPinus massoniana) needles to simulated N deposition in a disturbed and a rehabilitated forest in tropical China, Ecol. Res., 22, 649–658, 2007. Mo, J. M., Brown, S., Xue, J. H, Fang, Y. T., and Li, Z. A.: Response of litter decomposition to simulated N deposition in disturbed, rehabilitated and mature forests in subtropical China, Plant Soil, 282, 135–151, 2006. Mo, J. M., Fang, Y. T., Zhang, D. Q., Kong, G. H., and Fen, Z. N.: Effects of rainfall reallocation on nutrient dynamic of a pine forest in Dinghushan, Guihaia, 22, 529–533, 2002. Mo, J. M., Peng, S. L., Brown, S., Kong, G. H., and Fang, Y. T.: Nutrient dynamics in response to harvesting practices in a pine forest of subtropical China, Acta Phytoecol. Sin., 28, 810–822, 2004. Möller, A., Kaiser, K., and Guggenberger, G.: Dissolved organic carbon and nitrogen in precipitation, throughfall, soil solution, and stream water of the tropical highlands in northern Thailand, J Plant Nutr. Soil Sci., 168, 649–659, 2005. Nadelhoffer, K. J., Colman, B. P., Currie, W. S., Magill, A., and Aber, J. D.: Decadal-scale fates of $^15$N tracers added to oak and pine stands under ambient and elevated N inputs at the Harvard Forest (USA), Forest Ecol. Manag., 196, 89–107, 2004. Neff, J. C., Holland, E. A., Dentener, F. J., Mcdowell, W. H., and Russell, K. M.: The origin, composition and rates of organic nitrogen deposition: A missing piece of the nitrogen cycle?, Biogeochemistry, 57/58, 99–136, 2002. Ohte, N., Mitchell, M. J., Shibata, H., Tokuchi, N., Toda, H., and Iwatsubo, G.: Comparative evaluation on nitrogen saturation of forest catchements in Japan and Northeastern United States, Water Air Soil Pollut., 130, 649–654, 2001. Perakis, S. S. and Hedin, L. O.: Nitrogen loss from unpolluted South American forests mainly via dissolved organic compounds, Nature, 415, 416–419, 2002. Richter, A., Burrows, J. P., Nub, H., Granier, C., and Niemeier, U.: Increase in tropospheric nitrogen dioxide over China observed from space, Nature, 437, 129–132, 2005. Sha, L. Q., Zheng, Z., Feng, Z. L., Liu, Y. H., Liu, W. J., Meng, Y., and Li, M. R.: Biogeochemical cycling of nitrogen at a tropical seasonal rain forest in Xishuanbanna, SW China, Acta Phytoecl. Sin., 26, 689–694, 2002. Stoddard, J. L.: Long-term changes in watershed retention of nitrogen-its causes and aquatic consequences, Environ. Chem. Lakes Reservoirs, 237, 223–284, 1994. Tang, X. L., Liu, S. G., Zhou, G. Y., Zhang, D. Q., and Zhou, C. Y.: Soil-atmospheric exchange of CO₂, CH₄, and N₂O in three subtropical forest ecosystems in southern China, Global Change Biol., 12, 546–560, 2006. Wang, Z., He, D., Song, S., Chen, S., Chen, D., and Tu, M.: The vegetation of Dinghushan Biosphere Reserve, Trop. Subtrop. For. Ecosys., 1, 77–141, 1982. Wen, D. Z., We, I. P., Kong, G. H., and Ye, W. H.: Production and turnover rate of fine roots in two lower subtropical forest sites at Dinghushan, Acta Phytoecol. Sin., 23, 361–369, 1999. Xiao, J.: The formation and harm of N wet N deposition in Zhuangzhou city, Energy Environ., 59–61, 2005. Zhang, X. F.: Atmospheric nitrogen wet deposition and its effects on wetland water environment of Shanghai area, Chinese J. Appl. Ecol., 17, 1099–1102, 2006. Zhang, Y. M., Zhou, G. Y., Wen, D. Z., Zhang, D. Q., and Zhang, Q. M.: Biomass dynamics of the \textitCastanopsis chinensis-Schima superba-Cryptocarya concinna community of monsoon evergreen broad-leaved forest in Dinghushan Reserve, Trop. Subtrop. For. Ecosys., 9, 10–17, 2002. Zheng, X. H., Fu, C. B., Xu, X. K., Yan, X. D., Huang, Y., Han, S. H., Hu, F., and Chen, G. X.: The Asian nitrogen cycle case study, Ambio, 31, 79–87, 2002. Zhou, G. Y. and Yan, J. H.: The influence of region atmospheric precipitation characteristics and its element inputs on the existence and development of Dinghushan forest ecosystems, Acta Ecol. Sin., 21, 2002–2012, 2001.