On the scaling and standardization of charcoal data in paleofire reconstructions

McMichael, Crystal N.H.; Heijink, Britte M.; Bush, Mark B.; Gosling, William D.

doi:10.21425/f5fbg49431

Cited by 13 publications

(9 citation statements)

References 29 publications

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“…Without such a protocol a standardization method is necessary to account for differences in laboratory procedure, catchment size, and sediment properties when comparing charcoal amounts across sites (44). We performed proportional relative scaling to standardize the charcoal abundance data from each lake record (45), and report it as the Charcoal Index Value.…”

Section: Analysis Of Lake Sedimentsmentioning

confidence: 99%

“…The scaled measurements are then multiplied by the proportion of samples within the record containing charcoal (f/N). Proportional relative scaling is particularly robust in assessing fire in systems where fire is infrequent or rare, because is used as the true absence value, and samples containing small or infrequent amounts of charcoal are down-weighted (45). The scaled data are reported as the Charcoal Index value.…”

Section: ℎ = ( * 100) * /mentioning

confidence: 99%

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Widespread reforestation before European influence on Amazonia

Bush

Nascimento

Åkesson

et al. 2021

Science

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An estimated 90 to 95% of Indigenous people in Amazonia died after European contact. This population collapse is postulated to have caused decreases in atmospheric carbon dioxide concentrations at around 1610 CE, as a result of a wave of land abandonment in the wake of disease, slavery, and warfare, whereby the attendant reversion to forest substantially increased terrestrial carbon sequestration. On the basis of 39 Amazonian fossil pollen records, we show that there was no synchronous reforestation event associated with such an atmospheric carbon dioxide response after European arrival in Amazonia. Instead, we find that, at most sites, land abandonment and forest regrowth began about 300 to 600 years before European arrival. Pre-European pandemics, social strife, or environmental change may have contributed to these early site abandonments and ecological shifts.

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Section: Analysis Of Lake Sedimentsmentioning

confidence: 99%

Section: ℎ = ( * 100) * /mentioning

confidence: 99%

Widespread reforestation before European influence on Amazonia

Bush

Nascimento

Åkesson

et al. 2021

Science

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“…For charcoal data, we performed proportional relative scaling to standardize the measurements of each lake record from 0 to 100, to account for differences in quantification methods (e.g. particle counts, surface area), laboratory procedure, catchment size and sediment properties [62].…”

Section: Methodsmentioning

confidence: 99%

Early to mid-Holocene human activity exerted gradual influences on Amazonian forest vegetation

Nascimento

Heijink

Bush

et al. 2022

Phil. Trans. R. Soc. B

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Humans have been present in Amazonia throughout the Holocene, with the earliest archaeological sites dating to 12 000 years ago. The earliest inhabitants began managing landscapes through fire and plant domestication, but the total extent of vegetation modification remains relatively unknown. Here, we compile palaeoecological records from lake sediments containing charcoal and from pollen analyses to understand how human land-use affected vegetation during the early to mid-Holocene, and place our results in the context of previous archaeological work. We identified gradual, rather than abrupt changes in forest openness, disturbance and enrichment, with useful species at almost all sites. Early human occupations occurred in peripheral sites of Amazonia, where natural fires are part of the vegetation dynamics, so human-made fires did not exert a novel form of disturbance. Synchronicity between evidence of the onset of human occupation in lake records and archaeological sites was found for eastern Amazonia. For southwestern and western Amazonia and the Guiana Shield, the timing of the onset of human occupation differed by thousands of years between lake records and archaeological sites. Plant cultivation showed a different spatio-temporal pattern, appearing ca 2000 years earlier in western Amazonia than in other regions. Our findings highlight the spatial–temporal heterogeneity of Amazonia and indicate that the region cannot be treated as one entity when assessing ecological or cultural history. This article is part of the theme issue ‘Tropical forests in the deep human past’.

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“…We therefore standardized the charcoal data in two ways. First, we used the approach proposed by McMichael et al (2021), using their “proportional relative scaling” within each site, that is, as

(c_{normali} - c_{\min}) / (c_{\max} - c_{\min})

, where c i is the charcoal in the sample, c min is the minimum charcoal count in the record, and c max is the maximum charcoal count in the record. This value was then multiplied by the proportion of samples in the record with charcoal.…”

Section: Methodsmentioning

confidence: 99%

Warming, drought, and disturbances lead to shifts in functional composition: A millennial‐scale analysis for Amazonian and Andean sites

van der Sande,

Bush,

Åkesson

et al. 2023

Global Change Biology

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Tropical forests are changing in composition and productivity, probably in response to changes in climate and disturbances. The responses to these multiple environmental drivers, and the mechanisms underlying the changes, remain largely unknown. Here, we use a functional trait approach on timescales of 10,000 years to assess how climate and disturbances influence the community-mean adult height, leaf area, seed mass, and wood density for eight lowland and highland forest landscapes. To do so, we combine data of eight fossil pollen records with functional traits and proxies for climate (temperature, precipitation, and El Niño frequency) and disturbances (fire and general disturbances). We found that temperature and disturbances were the most important drivers of changes in functional composition. Increased water availability (high precipitation and low El Niño frequency) generally led to more acquisitive trait composition (large leaves and soft wood). In lowland forests, warmer climates decreased community-mean height probably because of increased water stress, whereas in highland forests warmer climates increased height probably because of upslope migration of taller species. Disturbance increased the abundance of

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On the scaling and standardization of charcoal data in paleofire reconstructions

Cited by 13 publications

References 29 publications

Widespread reforestation before European influence on Amazonia

Widespread reforestation before European influence on Amazonia

Early to mid-Holocene human activity exerted gradual influences on Amazonian forest vegetation

Warming, drought, and disturbances lead to shifts in functional composition: A millennial‐scale analysis for Amazonian and Andean sites

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