Replication Data for: nitrous oxide and methane fluxes from rainforest and cacao agroforest on highly weathered soils in the Congo Basin, including repeated field monthly measurements of trace stem and soil nitrous oxide and methane fluxes, one-time measurements of soil biochemical characteristics in the top 50 cm of soil at three study sites in Cameroon, and stem flux measurements at different tree heights in forest and cacao agroforestry