Land management explains major trends in forest structure and composition over the last millennium in California's Klamath Mountains.

SignificanceWe provide the first assessment of aboveground live tree biomass in a mixed conifer forest over the late Holocene. The biomass record, coupled with local Native oral history and fire scar records, shows that Native burning practices, along with a natural lightning-based fire regime, promoted long-term stability of the forest structure and composition for at least 1 millennium in a California forest. This record demonstrates that climate alone cannot account for observed forest conditions. Instead, forests were also shaped by a regime of frequent fire, including intentional ignitions by Native people. This work suggests a large-scale intervention could be required to achieve the historical conditions that supported forest resiliency and reflected Indigenous influence.

Palaeoenvironmental, epigraphic and archaeological evidence of total warfare among the Classic Maya.

Despite over a century of archaeological research, the nature and broader consequences of Maya warfare remain poorly understood. Classic period (250-950 CE) Maya warfare has largely been viewed as ritualized and limited in scope1-6. Evidence of violent warfare in the Terminal Classic period (800-950 CE) is interpreted as an escalation of military tactics that played a role in the socio-economic collapse of the Classic Maya civilization7,8. The implications of specific textual references to war events (war statements) remain unknown, however, and the paucity of field data precludes our ability to test collapse theories tied to warfare. Here we connect a massive fire event to an attack described with a Classic period war statement. Multiple lines of evidence show that a large fire occurred across the ancient city of Witzna, coincident with an epigraphic account describing an attack and burning of Witzna in 697 CE. Following this event, evidence shows a dramatic decline in human activity, indicating extensive negative impacts on the local population. These findings provide insight into strategies and broader societal impacts of Classic period warfare, clarify the war statement's meaning and show that the Maya engaged in tactics akin to total warfare earlier and more frequently than previously thought.