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Summary

Indigenous settlement has coincided with fire-adapted oak-dominated forests for millennia in southern New England.

Abstract 

The relative influence of climate and Indigenous cultural burning on past forest composition in southern New England, US, remains debated. Employing varied analyses, this study compared data on Indigenous settlements from over 5000 years before present (YBP) with relative tree abundances estimated from pollen and land survey records. Results suggested that fire-tolerant vegetation, mainly oak (Quercus spp.), was more abundant near Indigenous settlements from 4955 to 205 YBP (i.e., 86–91% fire-tolerant trees), and significantly (p < 0.05) higher from 3205 to 205 YBP; fire-tolerant vegetation was less abundant away from settlements, where it also experienced greater fluctuations. Correlative models showed that warmer temperatures and distance to Indigenous settlement, which are both indicators of fire, were important predictors in the 17th–18th centuries of fire-tolerant tree abundance; soil variables were less important and their relationships with vegetation were unclear. A marked increase in oak abundance occurred above 8 °C mean annual temperature and within 16 km of major Indigenous settlements. Pyrophilic vegetation was most correlated with distance to Indigenous villages in areas with 7–9 °C mean annual temperature, typical of higher latitudes and elevations that usually supported northern hardwoods. Widespread burning in warmer areas potentially weakened relationships between distance and pyrophilic abundance. Indigenous land use imprinted upon warmer areas conducive to burning created patterns in fire-tolerant vegetation in southern New England, plausibly affecting most low-elevation areas. Results imply that restoration of fire-dependent species and of barrens, savannas, and woodlands of oak in southern New England benefit from cultural burning.

Main research questions

1. Were Indigenous archaeological sites associated with oak forests over millennia in southern New England?
2. Does the presence of archaeological sites predict the distribution of oak forests over millennia in southern New England?

What the research builds on

Associations between Indigenous settlement and fire-adapted oak-dominated forests were observed around the time of European or European-American arrival, but spatial associations between the two have not been fully explored extending back for millennia.

What the research add to the discussion

Indigenous archaeological sites in southern New England have long been located in or near fire-adapted oak-dominated forests.

Novel methodology 

Radiocarbon-dated archaeological sites were compared with estimates of tree species abundance produced from pollen fossils in lake sediments; results show that the abundance of oak was always higher near archaeological sites. Correlative models were trained to associate the abundance of certain tree species (obtained from historical land survey records) with Native American settlement variables; climate along with distance to settlement were routinely most important in predicting oak abundance.

How the finding may affect future research

It suggests that Indigenous presence and associated cultural burning was responsible for the maintenance and enhancement of oak in southern New England forests for millennia.

Implications for policy 

To maintain or boost oak forests, cultural burning should be applied.