- October 27, 2020 at 4:25 pm #1777Xavier BenitoKeymaster
Questions and comments for the oral communications presented at the Synthesizing paleorecords session, including the keynote talk by Yoshi Maezumi “Exploring Amazonian Legacies: Integrating Paleoecological, Archaeological, and Paleoclimatological Archives“November 10, 2020 at 1:14 pm #2077CaroleAParticipant
I have got a question regarding Geoffrey’s fire calibration talk today: Geoffrey, are you considering comparing your charcoal influx to additional metrics other than the loading index? And could you share some literature regarding this loading index? I am just wondering if this index might be introducing additional uncertainty to your analyses and it is not very intuitive to me to understand what it actually stands for. Thanks for any clarifications!November 10, 2020 at 1:43 pm #2078elizabeth.leclerc1Participant
I also have a couple of thoughts/questions for Geoffrey’s fire calibration talk. I might have missed this, but is the charcoal loading index at/near zero in the early part of the 20th century because there were no/few fires? Or were fires generally too small or far away to contribute? If the latter, it seems it is still challenging to identify small, cultural fires and to distinguish these from larger, natural fires. I am curious if eastern Maine might be a good place for extending this research, given the long history of small agricultural fires that extends to present (i.e. burning of blueberry barrens, first by Indigenous peoples and continued by modern farmers) and also numerous water bodies for coring. Thanks.November 10, 2020 at 1:54 pm #2079dhsandweissParticipant
On Orijemie Emuobosa’s great talk: How does one recognize bat guano in excavations? Is it easy? Also, can you id the insects from the guano and use them as environmental signals?November 11, 2020 at 3:11 pm #2082geoffreymjohnsonParticipant
Carole, thank you yes, I am considering other measurements of fire activity and it’s spatial relationships to the core sites. I particularly like the idea of using remotely sensed fire products, however I have been cautioned to use these in conjunction with other mapped fire products because fire history maps often have a longer temporal component, which as you saw from my work was quite important in the low fire area of my study! However, remotely sensed products certainly have advantages for larger spatial scales because of the standardized data across spaces which most other forms of spatial fire history to not have.
To your question about the index: I calculated this as the area of the fire divided by the distance to the coring site squared (I=A/D^2). To my knowledge this has not been calculated this exact way before, but it is based on the theoretical model of deposited particles decreasing exponentially with distance.
I hope that this does not introduce error because the margins are quite small for the fire area and distance which can be measured quite accurately. I am quite absorbed now with carefully modifying how I represent the sedimentary data however. The data I presented had not been smoothed or adjusted with time lags, and it is possible that this is going to be a crucial to model past fire size distributions.November 12, 2020 at 1:03 am #2084geoffreymjohnsonParticipant
To partially answer Elizabeth’s question, yes, the small amount of fire in the recent past in my study area, particularly prior to ~2000 CE, is one of the interesting issues. However, I do believe that in some ways this is helpful because I am quite interested in the signal of each fire event. I am also very enthusiastic about expanding the spatial scope of this, and I hope to include several more sites along the Pacific coast. The quality of the age models is crucial for this kind of exercise and in particular 210Pb and/or 137Cs dates are extremely important to understand the age-depth relationship in the upper portion of each core. I think that regions likely need to evaluated separately as huge differences in vegetation could otherwise become the primary factor determining influx of charcoal, but I do think that similar analyses an and should be attempted in other regions like the the NE. Thanks for the comments!
- You must be logged in to reply to this topic.