Effects of long-term nitrogen deposition on phosphorus leaching dynamics in a mature tropical forest

• Published in: Biogeochemistry Vol. 138; no. 2; pp. 215 - 224
• Main Authors: Zhou, Kaijun, Lu, Xiankai, Mori, Taiki, Mao, Qinggong, Wang, Cong, Zheng, Mianhai, Mo, Hui, Hou, Enqing, Mo, Jiangming
• Format: Journal Article
• Language: English
• Published: Cham Springer Science + Business Media 01.04.2018; Springer International Publishing; Springer Nature B.V
• Subjects: Acidic soils; Acidification; Anthropogenic factors; Biogeosciences; Cycles; Decomposition; Deposition; Dynamics; Earth and Environmental Science; Earth Sciences; Ecosystems; Environmental Chemistry; Fluxes; Forest management; Forests; Human influences; Leaching; Life Sciences; Litter; Nitrogen; ORIGINAL PAPERS; Phosphorus; Soil; Soil acidification; Terrestrial ecosystems; Throughfall; Tropical climate; Tropical forests; Uptake; Tropical forest; Phosphorus leaching; Nitrogen deposition; Phosphorus cycling
• ISSN: 0168-2563; 1573-515X
• DOI: 10.1007/s10533-018-0442-1

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.