Figure 4

Relationship between fire occurrence and reconstructed temperature and precipitation in the Blue Mountains of the Malheur National Forest, Oregon, USA. Top left panel shows each annual precipitation and temperature reconstruction between 1706 and 1900 as small hash marks on the y-axis and x-axis, respectively (fire histories were reconstructed to 1650, but precipitation reconstructions only extend to 1706). The position of hollow blue circles (no fire year) and solid red circles (fire year) on the y− and x-axes correspond to the reconstructed precipitation and temperature value for that year. The size of red circles corresponds to the number of sites recording fire. The remaining panels show: the density of years in which no fire was recorded (upper right), density of years in which fire was recorded at less than 3 sites (lower left), and density of years in which fire was recorded at more than 3 sites (lower right).