Figure 3: Trends in basal area (m2/ha) of snags in northern Arizona mixed-conifer and ponderosa pine forest, 1997 to 2007. Boxes indicate the interquartile range (25th to 75th percentile), the line within the box indicates the median, and the external lines show the range in the data excluding outliers (circles, defined as observations more than 1.5 box lengths outside the box).