Grasslands are one of the world's most extensive terrestrial biomes and are central to the survival of herders, their livestock and diverse communities of large wild mammals. In Africa, tropical soils are predominantly nutrient-limited but productive grassy patches in wooded grassland savannah ecosystems grow on fertile soils created by geologic and edaphic factors, megafauna, fire and termites. Mobile pastoralists also create soil-fertility hotspots by penning their herds at night, which concentrates excrement-and thus nutrients-from grazing of the surrounding savannahs. Historical anthropogenic hotspots produce high-quality forage, attract wildlife and increase spatial heterogeneity in African savannahs. Archaeological research suggests this effect extends back at least 1,000 years but little is known about nutrient persistence at millennial scales. Here we use chemical, isotopic and sedimentary analyses to show high nutrient and N enrichment in on-site degraded dung deposits relative to off-site soils at five Pastoral Neolithic sites (radiocarbon dated to between 3,700 and 1,550 calibrated years before present (cal. BP)). This study demonstrates the longevity of nutrient hotspots and the long-term legacy of ancient herders, whose settlements enriched and diversified African savannah landscapes over three millennia.

The distribution of mounds, plazas, and defensive palisades associated with Cahokia Mounds State Historic Site (CMSHS) defines the core urban environment of Eastern North America’s first American Indian city. The large mounds surrounding Cahokia’s centrally located Grand Plaza, including the palisades that enclose them, are referred to as Downtown Cahokia. In this portion of the site, archaeologists have identified material culture (e.g., ceramics), earthen fills to level the plaza, and several earthen mound constructions. These findings suggest an occupational history for the area that occurred over the 9th–14th centuries CE, with the emergence of plaza delineation and earthwork construction beginning in the early 11th century CE. In sum, Downtown Cahokia and its Grand Plaza are considered by archaeologists to be a vibrant space characterized by ongoing American Indian transformations to an early metropolitan landscape. We conducted magnetometer and electromagnetic induction surveys at the western edge of the Grand Plaza. When compared with the LiDAR-derived visualizations we generated from this portion of the site, our aerial and terrestrial remote sensing data offered new information on the nature and sequence of monument construction in Downtown Cahokia, as well as architectural changes in domestic and special-use structures. These multi-scalar and complementary remote sensing datasets allowed us, without excavating, to trace important sequences of change in Downtown Cahokia’s history.

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