Nitrogen flux patterns through Oxisols and Ultisols in tropical forests of Cameroon, Central Africa

ABSTRACTWe lack an understanding of nitrogen (N) cycles in tropical forests of Africa, although the environmental conditions in this region, such as soil type, vegetation, and climate, are distinct when compared with other tropical forests. Herein, we simultaneously quantified N fluxes through precipitation, throughfall, and 0-, 15-, and 30-cm soil solutions, as well as litterfall, in two forests with different soil acidity (Ultisols at the MV village (exchangeable Al3+ in 0–30 cm, 126 kmolc ha–1) and Oxisols at the AD village (exchangeable Al3+ in 0–30 cm, 59.8 kmolc ha–1)) over 2 years in Cameroon. The N fluxes to the O horizon via litterfall plus throughfall were similar for both sites (MV and AD, 243 and 273 kg N ha–1 yr–1, respectively). Those values were remarkably large relative to other tropical forests, reflecting the dominance of legumes in this region. The total dissolved N flux from the O horizon at the MV was 28 kg N ha–1 yr–1, while it was 127 kg N ha–1 yr–1 mainly as NO3–-N (~80%) at the AD...