DendrochronologyDendrochronology

Dendroecology• Dendroecology uses dated tree rings to study

ecological events such as fire and insect outbreaks

• Was developed by Theodor Hartig and Robert Hartig in late 1800s Germany

• In the US, dendroecology did not develop until the 1970s with the work of Hal Fritts

• Since the 1970s, dendroecology has come to include fire history, insects, masting, stand-age structure, pathogen outbreaks, and endogenous disturbance history

Dendropyrochronology

• Reconstruction of fire histories is one of the major applications of dendrochronology for use in management of forests and the reestablishment of fire as a disturbance agent

• The goal of the dendrochronologists is to determine the natural range of variability for fire on a particular site, which describes …

Fire Regimes

• A natural fire regime is a general classification of the role fire would play across a landscape in the absence of modern human intervention, but including the influence of aboriginal burning.

• In the southeastern US, there have been 4 different fire regimes

Southeastern Fire Regimes

• The first fire regime existed prior to Euro-American settlement

• Fire-tolerant species – species that are able to survive fire events– Examples – most pines (excluding white pine) and

several species of oak

• Fire-intolerant species – species that are not able to survive fire events– Examples – maples, tulip poplars, sycamores,

gums

Southeastern Fire Regimes

• The second type of fire regime began when Euro-American settlers arrived and adopted Native American burning techniques to manage vegetation.

Southeastern Fire Regimes

• The third type of fire regime began with the Industrial Revolution when widespread timber harvesting used steam-driven locomotives that also provided the ignition source for an era of high-severity fires

Southeastern Fire Regimes

• Finally, the fourth type of fire regime is marked by fire suppression during the 20th century, which allowed forests to recover, but also allowed fire-intolerant species to increase in dominance and hinder regeneration of yellow pines and xeric oaks

Southeastern Fire Regimes

Fire exclusion – the most successful ad campaign ever…

• The current period in fire history is one of fire management, where the historic role of fire is increasingly studied and integrated into forest management, mainly through the use of prescribed burns

Southeastern Fire Regimes

The Problem

• The urban-wildland interface can be defined as an elevated human population living in a natural setting adjacent to population centers

Types of fires:Surface fire -Stand replacing fire -Ground fire -

Low severity wildfires … stays on the ground. Kills Low severity wildfires … stays on the ground. Kills grass, shrubs, seedlings, saplings, dead and decayed grass, shrubs, seedlings, saplings, dead and decayed trees, and diseased trees.trees, and diseased trees.

… versus high severity wildfires… kills everything

Fire regimes:

• Fire frequency: how often

• Fire seasonality: when fires occur throughout the year

• Fire severity: effects on forests – not a measure of fire temperature

• Fire intensity: a measure of fire temperature

• Fire extent: spatial aspects

• Patchy fires versus landscape level fires

• Fire variability: changes in fire over time and space

• Climatic or human-driven?

The fire-scar record from tree rings.

Catface on Table Mountain pine log, Reddish Knob, Virginia

Fire scars

The fire-scar record from tree rings.

Fire scars on ponderosa pine, El Malpais National Monument, New Mexico

Notice how the tree tries to compartmentalize the fire scar wound by growing succeeding years around the wound.

Detail of fire scar on ponderosa pine, El Malpais National Monument, New Mexico