ES_61_1, Spain, Andalucía Monte Porrejón, 1987 WP 9.1 Examples of prescribed burning and its effects

Plot description Town: Jubrique (Málaga) Place: Monte Porrejón Area: 18 ha Slope: % Aspect: N – NW Property: Local Community Use: Timber production and soil protection Objectives: This is an experimental site in which repeated prescribed burnings and other preventive techniques (shrub mastication) have being conducted. Prescribed burnings were carried out in 1987 and The main objective of this study area is to analyze the long-term effects of the use of prescribed burning on tree growth. Other objectives are the effects on fuel complex and understory vegetation biodiversity.

Plot description Vegetation structure: Pinus pinaster stand (30-80 years old; tree density: between trees ha -1 ). Understory formed by needle litter and some Mediterranean shrubs species: Cistus populifolius, Ulex baeticus, Erica scoparia, Arbutus unedo, Daphne gnidium, Rubia peregrina, Pteridium aquilinum. This structure can be associated to a fuel model 9 (Anderson 1981).

Prescription Prescribed burns were carried out in April 1987 and 1991 after a rain to prevent the organic matter burning and to diminish fire severity. The objective of the treatment was to reduce a 70% the available surface fuel, and to renew shrubland vegetation without damaging overstory trees.

Prescription window

Execution Prescribed burning was conducted by strip head fire technique. Ignition was initiated with dip-torches following contour lines and going downslope. Distance between lines was between 1-5 m. Fuel inventory was carried out by two-step sampling techniques in each plot before and after prescribed burns to estimate initial fuel complex characteristics and fuel consumptions by size range classes and stratum. Wind direction and speed, air relative humidity and air temperatures were monitored during the precribed burns, with meteorological stations.

Execution Fire behaviour was monitored during each experimental fire. Ground cameras and video captured fire development and flame characteristics and, along with observers notes, were used to determine the fire spread rate, using a network of posts as references. A grid of thermocouples connected with datologgers was installed inside the plot to provide information on flame, duff and soil temperatures, flame depth, residence time and rate of spread. Maximum temperatures at duff layer: 282 – 485 ºC Maximum temperatures at soil surface: 38 – 228 ºC Maximum temperatures at 2cm soil depth: 15 – 31ºC Rate of spread: 0.4 – 0.8 m/min Flame length: 0.6 – 0.8 m Fireline intensity: 52.2 – Kw/m

Effects A reduction of 67.3% available surface fuels was observed after the first treatment (1987), and of 73.1% after the second treatment (1991), without trees damage. 1995