Divergent responses of soil buffering capacity to long-term N deposition in three typical tropical forests with different land-use history.
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.
Lu X, Q Mao, J Mo, FS Gilliam, G Zhou, Y Luo, W Zhang, and J Huang. 2015. Divergent responses of soil buffering capacity to long-term N deposition in three typical tropical forests with different land-use history. Environmental Science & Technology 49:4072-4080.