Figure 1: Sampling locations within the study watersheds
affected by the 2002 Hayman Fire, Colorado, USA. Water chemistry samples
(n=71) were collected in June 2018 and the symbol size at each sampling
point increases with stream NO3-concentration.
Our nine study watersheds ranged in size from 3.2 to 35.4
km2, slope from 17-38%, and elevation from 2284-2694
m (Table 1). At the time of our sampling, 16 years after the fire, mean
normalized differenced moisture index (NDMI) was the lowest in Brush
(-0.13) and highest in Gunbarrel (-0.02) where burn extents were 71 and
18% respectively (Tables 1-2). Burn extent varied from 1-90% across
the watersheds, but seven of them had more than half of their
contributing area burned and 36-64% of that burned at high severity
(Table 2). Patch density was high which is consistent with a mixture of
fire severity classes. High severity patches, defined by complete canopy
consumption, generally had the largest patch size and radius (Table 2),
suggesting that post-fire pine reestablishment may be limited in high
severity areas (Chambers et al., 2016).
Table 1: Physical characteristics and solute concentrations of
each study watershed for samples collected in June 2018.