Nest excavation and agricultural activities of the leaf-cutting ant Atta sexdens create complex belowground heterogeneity in secondary forests of Eastern Amazonia. We examined the effects of this heterogeneity on inorganic-N stocks, net mineralization, and net nitrification to test the hypothesis that the bulk soil of the nests has higher net rates of mineralization and nitrification than soil that was not affected by the influences of ant nests, throughout the profile. This study was conducted in a secondary forest at Fazenda Vitoria, near Paragominas in the Eastern Brazilian Amazon, where a previous study showed that the bulk soil of ant nests had elevated NO3. The results of the inorganic-N measurements were consistent with the previous study, showing elevated NO3 deep in the soil profile of the nests. However, neither net mineralization nor net nitrification were significantly greater at depth in the mineral soil of the nests compared to soil that was not influenced by nests .P . 0:05.; although variability was higher in the nest soil. These results suggest that the NO32 may have diffused into the surrounding mineral from the N-rich organic matter buried by the ants in chambers within the deep soil.
Solute and sediment export from Amazon forest and soybean headwater streams
Solute and sediment export from Amazon forest and soybean headwater streams
Intensive cropland agriculture commonly increases streamwater solute concentrations and export from small watersheds. In recent decades, the lowland tropics have become the world’s largest and most important region of cropland expansion. Although the effects of...