In the frame of the EU-project Prometheus s.v. the branch station South of the Alps of the Swiss Federal Institute for Forest, Snow and Landscape Research organised a small fire experiment in a sweet chestnut stand in Southern Switzerland (S. Antonino, Canton Ticino). Due to the fire regime conditions in this part of Switzerland (winter forest fire season in the deciduous forest belt, surface fires) the fire experiment took place on 28 March 1998.
Altogether 16 research groups participated in this fire experiment. These groups were mainly from the Swiss Federal Institute for Forest, Snow and Landscape Research (WSL) and his branch station (FNP SdA), the Swiss Federal Institute of Technology in Zurich (ETHZ), the Swiss Federal Laboratories for Materials Testing and Research in Dübendorf (EMPA), the Departments of Geography of the Universities of Basle and Bern and the Fire Ecology Research Group of the Max Planck Institute for Chemistry at the University of Freiburg (Germany).
The different groups of the WSL studied fire propagation and temperature development during the fire, post-fire runoff and soil erosion, effects of the fire to fauna, vegetation and chestnut blight, fine root and mycorrhiza regeneration after the fire and the influence of the fire to soil chemical properties and the soil water. The Institute for Geophysics of the ETHZ took soil samples for rock-magnetic investigations. The EMPA measured the fire temperatures with a mobile IR-camera. The Department of Geography of Bern did splash erosion measurement as well as infiltration and soil aggregate stability measurements and the Department of Geography of the University of Basle did soil respiration and soil microbial biomass measurements. Last but not least the Max Planck Institute for Chemistry took emission samples. The arrangements of all test plots and the location of the point measurements can be seen in the general map (Fig. 1) (149 KB).
Other groups, who participated in the fire experiment were from the Swiss Army and the local fire brigades. The Army took IR-pictures with a video camera from a helicopter and was responsible for setting the fire in a line and the local fire brigades were responsible for making a fire break and to control the fire.
Design of the Fire Experiment
The fire experiment was carried out on a north facing slope with a medium inclination of 30 degrees. The size of the experimental site (inclusive control area) was about 1 ha. The total burnt size was 0.23 ha. One main intentions of the fire experiment was to simulate two different fire intensities ant to study ecological effects of a forest fire in relation to fire intensity. Therefore the upper part of the fire experiment test area was let untreated (fuel load was about 1 kg dry material / m2). and in the lower part we put about one more kilo of chestnut litter per square meter.
Already more than half a year before the fire experiment the first research groups started with taking samples and monitoring the fire experiment test site. Tension lysimeters (ceramic cups) were placed at three different soil levels (20-25 cm; 50-55 cm; 75-80 cm) on the upper and lower part of the fire experiment test site. Every two weeks samples of the soil water were taken and analysed in the laboratory. In every water sample pH, water conductivity and the amount of total organic compounds (TOC) as well as anion and cation concentration were measured. At the same time the first vegetation studies on the fire experiment test site, based on relevés, were conducted as plant sociological surveys over 100 m2 plots using the combined scale after Braun-Blanquet (1964) for estimating frequency. Also pitfall traps, ground eclectors and combination traps (window trap and yellow pan) were installed for collecting insects, spiders and millepedes. The first soil respiration and infiltration measurements were carried out some days before the fire experiment and soil samples for chemical and physical analyses as well as for rock-magnetic investigations and mycorrhiza fungi studies were taken the days before the fire experiment. The day before the fire experiment soil samples with a cylindrical sampler of 1 dm3 (010 cm) were taken to determine the pre-fire soil moisture content. Finally just before setting the fire, fuel samples (0.5 m x 0.5 m) were taken to determine fuel load and fuel moisture content.
Fig.2. and 3. Start of the fire experiment at the lower portion of the slope with relatively high fire intensity (upper) and calming down of fire intensity in the upper portion of the burning plot (lower). Photos: J.G.Goldammer
Three weather stations were installed some days before the fire to monitor the weather conditions during the fire experiment. Every minute a medium value of the air temperature, air humidity, wind direction and wind speed was stored with Skye-Instruments data loggers. Then, in the morning of 28 March, the fire was set at 09:30 by specialists of the Swiss Army.
For monitoring the fire spread 31 N-type thermocouples (fifteen thermocouples in the fuel bed at + 10 cm, eight in a depth of 2.5 cm and eight in a depth of 5 cm) were connected to a Campbell CR10X datalogger with an AM416 multiplexer and distributed to the fire experiment area (see general map). Every two seconds a temperature measurement was made. In addition a mobile IR camera (NEC TH 3101) with a resolution of 256 x 207 pixels was mounted on a tree about 8 m above the ground for monitoring a surface of about 335 m2 and a FLIR 2000 system (Forward Looking Infra Red), mounted on a Alouette III helicopter of the Swiss army, was flying diagonal over the fire experiment and taking online IR-video pictures of the fire spread for about one hour. Last but not least there was a ground crew who noted the passage of the fire and the flame length at certain points and another group as well as the TV were taking video and photo pictures throughout the fire experiment. Also during the fire the group of the Max Planck Institute took emission samples in the control area and the fire experimental test site.
Shortly after the fire experiment the first groups started their investigations. The traps for collecting insects were reinstalled and at the same time another group was already looking for surviving insects. Soil samples for the different investigations were taken, the first infiltration and soil respiration measurements carried out and the runoff and soil erosion testplots, the splash boards as well as an automatically raingauge and five precipitation totalizers installed. The first soil water samples were taken two days after the fire.
Most post-fire investigations were carried on until the end of 1998 and some like runoff and soil erosion measurements, vegetation, fine root and mycorrhiza fungi regeneration and soil water and chestnut blight studies will be carried on also in 1999.
First results are expected for the end of 1999 and will be discussed in the frame of the Prometheus s.v. project.
We wish to express our thanks to the Prometheus coordinator (Algosystems S.A.; Greece) and all Prometheus partners as well as the group landscape inventories of the WSL for creating the general map of the fire experiment. The financial support for the Swiss part of the Prometheus s.v. project of the Swiss Federal Office for Education and Science (BBW-Project No. 97.0058) is gratefully acknowledged.
Braun-Blanquet, J. 1964: Pflanzensoziologie. Wien, Springer. 865 p.
Peter Marxer & Marco Conedera Swiss Federal Institute for Forest, Snow and Landscape Research FNP Sottostazione Sud delle Alpi PO Box 57 CH – 6504 Bellinzona-Ravecchia