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Stalagmites serve as valuable archives that significantly enhance our understanding of past climate and environmental changes. The trace element records preserved within stalagmites have been used to reconstruct past rainfall patterns at regional scale [1]. However, interpreting these geochemical proxies is challenging, as the functioning of the cave system, within its specific climatological and geological context, must be taken into account. Comparing instrumental climate measurements with these proxies from stalagmites that grew during the 20th century provides an opportunity to investigate how stalagmite geochemistry responds to variations in rainfall.In this study, we present results from a stalagmite collected from cave KNI-51, located in the Kimberley region of northeast Western Australia. Previous uranium–thorium disequilibrium dating of the stalagmite has yielded a high-precision age model (2 sd errors of ±1–2 years over much of the last century) and revealed rapid growth (1–2 mm/yr) [2], allowing for nearly annual resolution of geochemical records. We examined trace element variations related to historical annual rainfall fluctuations, retrieved from five stations near the cave area between 1915 and 2007. Comprehensive statistical analyses, accounting for stationarity and autocorrelation in the time series data, revealed significant correlations when comparing certain trace elements to both total annual rainfall and the rainfall recorded during the monsoon season (December to March). Notably, some trace elements exhibited a stronger response to rainfall occurring during the monsoon period. Furthermore, we applied rolling window correlation to assess the evolution and stability of these correlations over time, identifying intervals where the relationship between the time series appeared weaker or stronger.The multi-annual calibration provided critical insights into how the stalagmite recorded rainfall variability through trace elements fluctuations and represents a key step in defining the response times of the cave and stalagmite recording systems to changes in climate and water balance in the Kimberley region. The disclosed correspondence between the instrumental rainfall record and the trace element signals encoded in the stalagmite demonstrates that rainfall time series can be successfully reconstructed from stalagmites. This marks an important milestone in the development of a calibrated trace element–rainfall transfer function, which can be applied to past stalagmite geochemical records.[1]         S. F. Warken et al., “Reconstruction of late Holocene autumn/winter precipitation variability in SW Romania from a high-resolution speleothem trace element record,” Earth Planet. Sci. Lett., vol. 499, pp. 122–133, 2018, doi: https://doi.org/10.1016/j.epsl.2018.07.027.[2]         R. F. Denniston et al., “Expansion and contraction of the indo-pacific tropical rain belt over the last three millennia,” Sci. Rep., vol. 6, pp. 1–9, 2016, doi: 10.1038/srep34485. 

Molecular biomarkers preserved in lake sediments are increasingly used to develop records of past organism occurrence. When linked with traditional paleoecological methods, analysis of molecular biomarkers can yield new insights into the roles of herbivores and other animals in long-term ecosystem dynamics. We sought to determine whether fecal steroids in lake sediments could be used to reconstruct past ungulate use and dominant taxa in a small catchment in northern Yellowstone National Park. To do so, we characterized the fecal steroid profiles of a selection of North American ungulates historically present in the Yellowstone region (bison, elk, moose, mule deer, and pronghorn) and compared them with those of sediments from a small lake in the Yellowstone Northern Range. Analysis of a set of fecal steroids from herbivore dung (Δ⁵-sterols, 5α-stanols, 5β-stanols, epi5β-stanols, stanones, and bile acids) differentiated moose, pronghorn, and mule deer, whereas bison and elk were partially differentiated. Our results show that bison and/or elk were the primary ungulates in the watershed over the pastc. 2300 years. Fecal steroid influxes reached historically unprecedented levels during the early and middle 20^thcentury, possibly indicating high local use by ungulates. Comparison of fecal steroid influxes with pollen and diatom data suggests that elevated ungulate presence may have contributed to decreased forage taxa (Poaceae,Artemisia, andSalix), relative to long-term averages, and possibly increased lake production. Our results reflect past change within a single watershed, and extending this approach to a network of sites could provide much-needed information on past herbivore communities, use, and environmental influences in Yellowstone National Park and elsewhere.