干旱区生态环境知识资源中心

We investigated the utility of subfossil bat guano as a paleoenvironmental archive by comparing elemental ratios and delta C-13, delta N-15, and delta D values of various simple extracts from bulk material. Solvent-extracted guano yielded consistent C:N and N:H ratios, and delta C-13 values of solvent-extracted guano exhibited strong covariation with delta D values, as well as with the delta C-13 values of other simple extracts (bulk guano, bulk lipid). The results suggest that reliable records are easily recovered for delta C-13, and also indicate that delta N-15 values may have utility as a paleoenvironmental archive. Despite coeval delta C-13 values of bulk guano and solvent-extracted guano, C-14 ages of the different fractions did not always yield similar ages, indicating that future refinement of a suitable extraction protocol is required. Applying these protocols to an ancient bat guano deposit allowed us to infer that climate at the Grand Canyon during the late Pleistocene was more variable and generally cooler and wetter, relative to Holocene climate. We conclude that guano deposits are an underutilized, yet powerful continental paleoenvironmental archive of climate change for semi-arid and tropical regions.