Divergent Responses of Soil Buffering Capacity to Long-Term N Deposition in Three Typical Tropical Forests with Different Land-Use History

• Published in: Environmental science & technology Vol. 49; no. 7; pp. 4072 - 4080
• Main Authors: Lu, Xiankai, Mao, Qinggong, Mo, Jiangming, Gilliam, Frank S, Zhou, Guoyi, Luo, Yiqi, Zhang, Wei, Huang, Juan
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 07.04.2015
• Subjects: Acidification; Buffers; Cations - chemistry; China; Ecosystem; Ecosystems; Environmental science; Forests; Hydrogen-Ion Concentration; Land use; Nitrogen; Nitrogen - chemistry; Plants; Soil - chemistry; Tropical Climate; China; China, People's Rep
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es5047233

Elevated anthropogenic nitrogen (N) deposition has become an important driver of soil acidification at both regional and global scales. It remains unclear, however, how long-term N deposition affects soil buffering capacity in tropical forest ecosystems and in ecosystems of contrasting land-use history. Here, we expand on a long-term N deposition experiment in three tropical forests that vary in land-use history (primary, secondary, and planted forests) in Southern China, with N addition as NH4NO3 of 0, 50, 100, and 150 kg N ha–1 yr–1, respectively. Results showed that all three forests were acid-sensitive ecosystems with poor soil buffering capacity, while the primary forest had higher base saturation and cation exchange capacity than others. However, long-term N addition significantly accelerated soil acidification and decreased soil buffering capacity in the primary forest, but not in the degraded secondary and planted forests. We suggest that ecosystem N status, influenced by different land-use history, is primarily responsible for these divergent responses. N-rich primary forests may be more sensitive to external N inputs than others with low N status, and should be given more attention under global changes in the future, because lack of nutrient cations is irreversible.