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Other Research at Kachana

Fire experiment 2004

This experiment was performed in the year 2004 by Andr Annen, Laura Parolini and Chris Henggeler. The original documentation (in German) was written by Laura Parolini and Andr Annen and can be found here. Translation by Philipp Nauer.

The aim of the experiment was to examine two sites with different treatment in their reaction to fire. Site A has been previously treated with high density cattle for several hours. Site B experienced no treatment.

1 Preparation

Vegetation coverage of the two areas was estimated by assigning the dominant species of Spinifex (Triodia sp. and Plectrachne sp.) to three different height classes. The coverage of Spinifex could then be calculated by counting the plants and measuring the average diameter of each height class. Assuming a similar coverage for dry Spinifex the total ground cover was estimated. Other plant species were not relevant for total coverage and could be neglected.

Photo 1. Treated area (site A)
Photo 2. Untreated area (site B)
Site A Site B
Area 4.90 m x 5.80 m
= 28.42 m2
4.90 m x 5.80 m
= 28.42 m2
Spinifex Class 1: Height 0 20 cm
0.02 m2 / plant
47 plants
0.94 m2
4 plants
0.08 m2
Spinifex Class 2: Height 20 40 cm
0.06 m2 / plant
59 plants
3.54 m2
39 plants
2.34 m2
Spinifex Class 3: Height > 40 cm
0.12 m2 / plant
16 plants
1.92 m2
85 plants
10.2 m2
Total coverage Spinifex 6.4 m2 12.62 m2
Total coverage dry Spinifex
(factor 1 to Spinifex)
6.4 m2 12.62 m2
Vegetation coverage 12.8 m2 25.24 m2
Termite mounds 0.06 m2 0.25 m2
Total "living" cover 12.86 m2
≈ 45.3 %
12.62 m2
≈ 89.7 %
Total coverage ratio 0.5 0.8
Bare ground (rocks and sand) 15.56 m2
≈ 54.7 %
2.93 m2
≈ 10.3 %

There is remarkable variation in both vegetation coverage and distribution to different classes of the two sites. On site A the small plants in class 1 and 2 dominate whether site B is manly covered by bigger plants (class 3). More above ground biomass is therefore found on site B while on site A most of the biomass has been eaten or crushed into the soil.

Measurements

1.1 Temperature

Besides the vegetation analysis the differences in temperature between Spinifex and bare ground has been measured, at 8 o'clock in the morning, at 11.30 am when the sun reached its highest point and at 3 o'clock in the afternoon. At noon there is a remarkable difference of 12C on site B and 10C on site A between vegetation and rock. There is very little variation between the two sites.

Site A Site B
1. Measurement: 8 am
Air temperature: 28C
Spinifex
28C
Rock
33.5C
Spinifex
28C
Rock
33.5C
2. Measurement: 11.30 am
Air temperature: 34C
Spinifex
36C
Rock
48C
Spinifex
36C
Rock
46C
3. Measurement: 3 pm
Air temperature: 35C
Spinifex
35C
Rock
45C
Spinifex
36C
Rock
46C
Date of measurement: September 11th 2004
1.2 Evaporation

Furthermore evaporation rate was calculated for the two dominating ground characters (Spinifex and rock). A container with a certain amount of water was left for 5 days on the site, then the loss of water was measured and the evaporation rate could be calculated. The temperatures in these 5 days were more or less the same as above.

Spinifex 8 mm/d
Rock 12 mm/d
Date of measurement: September 11th - September 15th 2004

It will be interesting to see these rates in the next few years, if the measurement continues.

2 Experiment and Observation

At 4.30 am on the 23th of September 2004 the two sites were lit. A petroleum lighter was used to light up a 5 cm wide plastic strip along the diagonal of each site. Observations were focussed on spreading speed of the fire. The borders of the site had been wetted.

On site B flames up to 2 m high formed very quickly due to high numbers of "class 3"-plants. The fire spread constantly and after 10 minutes all above ground biomass was completely burnt.

Photo 3. High flames
Photo 4. Spreading to the border

Spreading of the fire on site A was not constant. As high flames were building on the few "class 3"-plants the rest of the fire burnt relatively low and spread slowly. After 15 minutes the fire died by itself. Only a narroe stripe along the diagonal (about 1-2 m wide) was burnt.

Photo 5. Slow spreading
Photo 6. Fire extinguished by itself
Photo 7. Different results on each site

On the broad scale landscape the fire would probably spread in a similar way. Fire lit by lightning for example would spread less quickly on treated areas and the chances that it goes out by itself would be relatively high.

Of future interest would be the behaviour of the sites if treatment with cattle continues.

Written by Andr Annen, 2004. Translation by Philipp Nauer, 2005


Fire experiment 2005

Additional photos were taken in October 2005 to highlight the difference in regeneration ability after a fire. Both sites experienced no fires prior to the experiment for the last 14 years and had one year without treatment to regenerate.

Differences after one year of regeneration

As one can clearly see the untreated site B has almost no plant cover, its just a square of bare rock within the vegetation. Site A has a good cover of Spinifex, its already difficult to make out the borders of the site.