*3.1. Burn Characteristics*

Temperatures at the soil surface during the low intensity fires (F1) averaged 228 ◦C. The highest temperature recorded was 400 ◦C. Mean burn time >100 ◦C was 0.79 min (Figure 4). Weight of ash averaged 11 g (*n* = 3 for all values). Due to the infrared thermometer's maximum temperature threshold of 420 ◦C, a true average of the soil surface temperature could not be calculated for the medium and high intensity fires. For this reason, we measured the percentage of time >420 ◦C. This resulted an average of 43% of the total burn time for medium intensity fires (F2). Highest temperature recorded was ≥420 ◦C. Mean burn time >100 ◦C was 15.98 min (Figure 4). Weight of ash averaged 36 g (*n* = 3 for all values). Temperatures at the soil surface during the high intensity fires (F3) averaged >420 ◦C for 85% of the total burn time. Highest temperature recorded was ≥420 ◦C. Mean burn time >100 ◦C was 190.67 min (Figure 4). Weight of ash averaged 200.6 g (*n* = 3 for all values).

**Figure 4.** The burn time and soil surface temperatures of each subplot for F1, F2 and F3 treatments.

### *3.2. Fire Intensity Treatment E*ff*ects on Haplic Luvisol Properties*

### 3.2.1. Soil and Ash pH

Results obtained for the pH of soil showed a slight decrease for F1 (low intensity fire treatment; Figure 5). This was followed by an increase in pH after F2 and F3 (medium and high fire treatment, respectively). F3 was significantly increased at *p* > 0.05 compared with the F0 measured pH (Table 1), F1 and F2 were not significantly different. This shows that immediately after the burn, medium and high intensity fires can change the Haplic Luvisol pH from slightly acidic to neutral. The pH of ash increased by ca. 1.0 for each treatment: F1 8.42, F2 9.79, F3 10.33. This is a dramatic change as the pH scale is logarithmic (Table 3). The coefficient of variation for F1 and F2 was 5%, whereas it was 14% for F3.

**Table 3.** Mean values of pH (soil and ash), soil organic matter (OM), carbon (C), calcium (Ca), potassium (K), magnesium (Mg) and phosphorus (P) in low (F1), medium (F2) and high (F3) fire intensity treatments, and pre-fire (F0). *n* = 9 samples for F0 and *n* = 3 samples for F1, F2 and F3.


3.2.2. Organic Matter and Carbon

Results obtained for organic matter (OM) content varied greatly among the plots (Table 3). F1 and F3 lowered the OM% by a small amount (0.53% and 0.82% respectively), though not significantly (Table 1), whereas, F2 increased the amount of OM by only 0.14%. The coefficient of variation for all treatments was around 20% (Table 3). These results show that organic matter in Haplic Luvisol is not significantly affected by fire.

The carbon content of the soil samples (Table 3) remained at similar levels for F1 and F2 treatments compared to F0, 33 mg/kg. For F3, the amount of carbon decreased by 13%, from 33.00 to 29 mg/kg (Table 3). Carbon levels in the soil samples did not significantly change after any of the treatments (Table 1). Coefficient of variation was 30% for all treatments. Carbon levels in Haplic Luvisol after a fire event of any intensity are not affected.

**Figure 5.** Ratio of pre-fire to post-fire change for pH (soil and ash), organic matter, carbon, calcium, magnesium, potassium and phosphorus. >1 = positive change, 1 = no change, <1 = negative change. Note the different scales on each graph.
