Effects of long-term nitrogen deposition on phosphorus leaching dynamics in a mature tropical forest
Elevated anthropogenic nitrogen (N) deposition is suggested to affect ecosystem phosphorus (P) cycling through altered biotic P demand and soil acidification. To date, however, there has been little information on how long-term N deposition regulates P fluxes in tropical forests, where P is often depleted. To address this question, we conducted a long-term N addition experiment in a mature tropical forest in southern China, using the following N treatments: 0, 50, 100, and 150 kg N ha−1 year−1. We hypothesized that (i) tropical forest ecosystems have conservative P cycling with low P output, and (ii) long-term N addition decreases total dissolved phosphorus (TDP) leaching losses due to reduced litter decomposition rates and stimulated P sorption deriving from accelerated soil acidification. As hypothesized, we demonstrated a closed P cycling with low leaching outputs in our forest. Under experimental N addition, TDP flux in throughfall was significantly reduced, suggesting that N addition may result in a less internal P recycling. Contrary to our hypothesis, N addition did not decrease TDP leaching, despite reduced litter decomposition and accelerated soil acidification. We find that N addition might have negative impacts on biological P uptake without affecting TDP leaching, and that the amount of TDP leaching from soil could be lower than a minimum concentration for TDP retention. Overall, we conclude that long-term N deposition does not necessarily decrease P effluxes from tropical forest ecosystems with conservative P cycling.
KeywordsNitrogen deposition Phosphorus cycling Phosphorus leaching Tropical forest
This study was funded by the National Basic Research Program of China (2014CB954400) and National Natural Science Foundation of China (Nos. 41731176, 41473112, 31370498) and Youth Innovation Promotion Association CAS (2015287). We wish to thank Lijie Deng, Shaoming Cai and Quannian Nie for skillful field work. We also thank Xiaoying You and Shaowei Chen for laboratory work. We would like to express our sincere appreciation to the three anonymous reviewers and the editor for their insightful comments, which have greatly aided us in improving the quality of our paper.
- Bol R, Julich D, Brodlin D, Siemens J, Kaiser K, Dippold MA, Spielvogel S, Zilla T, Mewes D, von Blanckenburg F, Puhlmann H, Holzmann S, Weiler M, Amelung W, Lang F, Kuzyakov Y, Feger K-H, Gottselig N, Klumpp E, Missong A, Winkelmann C, Uhlig D, Sohrt J, von Wilpert K, Wu B, Hagedorn F (2016) Dissolved and colloidal phosphorus fluxes in forest ecosystems an almost blind spot in ecosystem research. J Plant Nutr Soil Sci 179(4):425–438CrossRefGoogle Scholar
- Dodd RJ, McDowell RW, Condron LM, Nzga (2012) Using nitrogen fertiliser to decrease phosphorus loss from high phosphorus soils. In: Proceedings of the New Zealand Grassland Association, Vol 74, pp 121–126Google Scholar
- Gehring C, Denich M, Kanashiro M, Vlek PLG (1999) Response of secondary vegetation in Eastern Amazonia to relaxed nutrient availability constraints. Biogeochemistry 45(3):223–241Google Scholar
- Huang Z, Fan Z (1982) The climate of Ding Hu Shan. Trop Subtrop For Ecosyst 1(1):11–23Google Scholar
- Huang Z, Ding M, Zhang Z, Yi W (1994) The hydrological processes and nitrogen dynamics in a monsoon evergreen broad-leafed forest of Dinghu Shan. Acta Phytoecol Sin 18(2):194–199Google Scholar
- Kaspari M, Garcia MN, Harms KE, Santana M, Wright SJ, Yavitt JB (2008) Multiple nutrients limit litterfall and decomposition in a tropical forest. Ecol Lett 11(1):35–43Google Scholar
- Vet R, Artz RS, Carou S, Shaw M, Ro C-U, Aas W, Baker A, Bowersox VC, Dentener F, Galy-Lacaux C, Hou A, Pienaar JJ, Gillett R, Cristina Forti M, Gromov S, Hara H, Khodzher T, Mahowald NM, Nickovic S, Rao PSP, Reid NW (2014) A global assessment of precipitation chemistry and deposition of sulfur, nitrogen, sea salt, base cations, organic acids, acidity and pH, and phosphorus. Atmos Environ 93:3–100CrossRefGoogle Scholar
- Wen D, Wei P, Kong G, Ye W (1999) Production and turnover rate of fine roots in two lower subtropical forest sites at Dinghushan. Acta Phytoecol Sin 23(4):361–369Google Scholar
- Zhang N, Liu X, Li K, Chu G, Yan J (2011) Differential patterns of nutrient elements in rainfall and its redistribution in three typical subtropical forests in South China. Chin J Ecol 30(2):193–200Google Scholar