Research about Santa Fe Lake

USGS2026

Cultural pollen delivery is not needed to account for consistent, trace abundances of Zea mays pollen in the sediments of Santa Fe Lake

Roos (2026) proposes an intriguing cultural mechanism to account for the rare (<1.5% of terrestrial pollen), but consistent (28/34 samples spanning 450 years), presence of Zea mays (maize) pollen in the sediments of Santa Fe Lake from 800 to 350 cal yr BP (1150 – 1600 cal yr CE; Henne et al., 2026a, 2026b). Whereas the importance of maize agriculture to Ancestral Puebloans is well established, Roos argues that the near-absence of maize pollen from soils proximate to historical maize cultivation and in peat or lake-sediment records in the Southwestern USA indicates that natural pollen delivery was not sufficient to account for the trace abundances of maize pollen we counted at Santa Fe Lake. Roos concludes that ceremonial practices provide an alternative mechanism that should be considered in the interpretation of lake-sediment archives like Santa Fe Lake. We agree that the cultural practices described by Roos are a credible source of pollen delivery and understand the significance of sacred lakes to Indigenous communities (Bodine, 1988). However, we conclude that natural delivery to the Santa Fe catchment is sufficient to account for the trace abundances of maize pollen in our record. We first place our consistent finding of maize pollen in a context beyond the Southwestern USA that includes other mountain regions, discuss why it is unlikely to find consistent maize pollen in the records presented by Roos, and expand on what makes Santa Fe Lake a superior archive for maize pollen than previous records. Based on this discussion, we conclude that natural pollen deposition is the most parsimonious explanation for consistent maize pollen over a period of 450 years.

New Mexico↗

USGS2024

Climatic variability as a principal driver of primary production in the southernmost subalpine Rocky Mountain lake

Mountain lakes are sensitive indicators of anthropogenically driven global change, with lake sediment records documenting increased primary production during the twentieth century. Atmospheric nutrient deposition and warming have been attributed to changes in other Western mountain lakes, however, the intensity of these drivers varies. We analyzed a sediment core representing a 270-year record from Santa Fe Lake, New Mexico, to constrain the southern margin of Rocky Mountain lakes and quantify patterns of change in lake biogeochemistry, production, and diatoms since 1750. Lake sediments were dated using 210 Pb and analyzed for carbon (C), nitrogen (N), stable isotopes (δ 13 C, δ 15 N), diatoms, and phototrophic pigments. The abundance of cyanobacteria, purple sulfur-reducing bacteria, and diatom pigments were elevated during the stable conditions of the Little Ice Age; these phototrophic groups declined in the late 1800s and reached a minimum by 1950. From 1950 to 2020, sediments recorded an increased abundance of cryptophyte, diatom, and chlorophyte groups. The C and N (percentage dry mass) increased after 1950, whereas δ 15 N and δ 13 C values declined. Changes since the mid-twentieth century are contemporaneous with warming trends in the Southwest and modest deposition of atmospheric N. Our findings highlight the geographic variability of mountain lake responses to changing environmental conditions.

New Mexico↗