Amazing stuff!
"Understanding how fires have shaped ecosystems in the past can help us understand and predict the impacts of fires now and in the future. But to ‘observe’ fires that happened before recorded history, researchers have had to get creative—looking at charcoal in lake sediments or peat, for example. ...
In a new study, they examined bat guano for clues about a region’s fire history. ...
Not only does the fecal matter trap pollen and other indicators of biodiversity, the very atoms it’s composed of can provide intel on climate and the local environment. ... They examined charcoal preserved in bat guano dating back to 1952 in a cave in Tennessee, and compared it to the area’s fire history, which had been recorded in detail since 1985. Sure enough, charcoal deposits in the guano correlated with the timing of known fires as well as with how much of the area burned. The only notable downside was that the record wasn’t good at capturing fires that occurred in winter, likely because bats hibernate during those months.
Intriguingly, the bats’ waste was especially good at recording prescribed burns—fires set purposefully as a form of land management—perhaps because the animals actively seek out the edges of these less-dangerous fires, which flush out their insect prey. “Bat guano's ability to reliably record prescribed fire has important implications for the paleofire field, which has traditionally been unable to distinguish human-caused fire from wildfire,” the authors write."
From the abstract:
"New approaches are needed to resolve persistent geographic gaps and biases in paleofire research. Most sedimentary paleofire research relies on lake and peat sediments. We present an unconventional sedimentary charcoal record preserved in a modern, post-bomb bat guano deposit and compare its accumulation to historical fire data. We find strong correlations between charcoal accumulation rates (CHAR) and non-winter prescribed burns. CHAR in bat guano is more strongly correlated with prescribed fire than wildfire or total area burned, likely due to bats seeking out areas burned by prescribed fire for better foraging opportunities and/or bats avoiding wildfire. We attribute the CHAR in guano being a better recorder of area burned during non-winter months to winter bat hibernation. Our analyses show that charcoal preserved in bat guano is a reliable paleofire proxy system, which has important implications for the paleofire field and encourages future research using bat guano as a viable archive."
Fig. 2
(a) Photo of the Cripps Mill Cave guano core. Depths of radiocarbon samples (Table 1) are noted with asterisks.
(b) Age-depth model of the guano core. The red diamonds note the depth and age of radiocarbon samples. The black line shows the mean of the ensemble of possible age-depth models generated by BACON and the gray shaded region depicts the 95% confidence envelope.
(c) Comparison of Cripps Mill Cave guano charcoal accumulation rates (CHAR; gray) with total annual area burned (black), as well as by wildfire (red) prescribed fire (orange). The bottom plot shows the area burned in total (blue) and by prescribed fire (orange) in non-winter months (e.g., excluding November, December, January, February).
(d) 3 year binned CHAR data share a strong correlation with both total area burned (blue; r = 0.57) and area burned by prescribed fire (orange; r = 0.88, p < 0.01) in non-winter months.
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