We measured the ¹⁵N natural abundance values of 320 individuals belonging to 45 different plant species of the Brazilian cerrado. We also determined δ¹⁵N of soil nitrogen as a function of soil depth. Our purpose was to test the hypothesis that N‐limited cerrado would have a large range of plant δ¹⁵N values, similar to patterns seen in northern high‐latitude ecosystems. Foliar δ¹⁵N values did demonstrate the large range found in some other N‐limited ecosystems, varying from −5‰ to +7.9‰. Significant variability within individual species was also seen across cerrado community types. Several factors contributed to this variability, including the presence of N‐fixing legumes, associations with mycorrhizal fungi, δ¹⁵N variability of soil organic matter with depth, fire events, and the seasonality of N‐immobilization and mineralization processes in cerrado soils.

In this paper we explore a speleothem δ¹⁸O record from Palestina cave, northwestern Peru, at a site on the eastern side of the Andes cordillera, in the upper Amazon Basin. The δ¹⁸O record is interpreted as a proxy for South American Summer Monsoon (SASM) intensity and allows the reconstruction of its variability during the last 1600 years. Two periods of anomalous changes in the climate mean state corresponding to the Medieval Climate Anomaly (MCA) and the Little Ice Age (LIA) periods identified in the Northern Hemisphere are recognized in the record, in which decreased and increased SASM activity, respectively, have been documented. Variations in SASM activity between the MCA and the LIA seem to be larger over the northern part of the continent, suggesting a latitudinal dependence of the MCA footprint. Our results, based on time series, composite and wavelet analyses, suggest that the Atlantic Multidecadal Oscillation (AMO) plays an relevant role for SASM modulation on multidecadal scales (∼65 years), especially during dry periods such as the MCA. Composite analyses, applied to evaluate the influence of the AMO on the Palestina cave δ¹⁸O and other δ¹⁸O-derived SASM reconstructions, allow insight into the spatial footprints of the AMO over tropical South America and highlight differences between records during key studied periods. This work also reveals that replicating regional climate signals from different sites, and using different proxies is absolutely essential for a comprehensive understanding of past changes in SASM activity.