ES_21_2 Spain, Canary Islands, Gran Canaria, Osorio (Teror) 2002

W.P. 9.1. Examples of prescribed burning and its effects

UL-UFF

Plot Description

Town: Teror. Gran CanariaPlace: OsorioArea: 13,02 haGeneral slope: 5-15%Use: This zone is reforested

stand of laurel forest and is visited by school estudents and other visitors. The Osorio Farm constitutes Gran Canaria’s most exquisite natural setting.

Objectives:

1. Wildfire prevention (diminishing the fuel load and change the forest structure).

2. Accelerate the forest dynamics.3. Trainning the firefighters service (2002 is the first year of prescribed

burning in Gran Canaria)

Plot Description

Vegetation structure: laurel forest reforested stands (Laurus novocanariensis, Myrica faya,...) and vigorous understorey by ferms (Pteridium aquilinum). In winter the dead ferms are very inflamable fuel.

MOTIVATION

In the 90s repopulations were realized by species of laurel forest in the hillside of Osorio’s mountain. During these years it has been growing other plants (ferms, blackberry,... principally) that are competing for the light, the nutrients and dthe water against the planted vegetation. In many zones the forest has stagnated. Also, these news fuel structures are very vulnerable to the wildfires. The prescribed fire accelerates the natural dynamics of the laurel forest and makes it more resistant to the fire.

Prescription: Weather and fuel conditions in the burning day to have the wished effects

The plot have to be burned bearing the proximity with the infrastructures (Osorio’s Farm) and the management of the smoke.

Variable Low Wished High

Temperature (ºC) 5 15 26

Air Relative Humidity (%) 35 45 65

Mid flame Wind speed (km/h) 2 15 25

Soil moisture 0 50 100

1-h fuel moisture (%) 5 7 10

10 and 100 h, Live herbaceous, Live woody and humus moisture 7 10 15

Rate of spread (km/h) 0,1 0,5 2,0

Flame length (m) 0,1 0,5 1,5

Fire type (1 = heat, 2 = rear, 3 = flank, 4 = circle) 2-3

PRESCRIPTION WINDOW (summary)

Prescription

Plot preparation: Preparation of the plot is not done. One anchors the prescribed burning in the existing ways.

Limitations: The plot has the peculiarity to inhabits of Osorio’s shrew (Crocidura Osorio) a endemic species. In this moment not wise the relation between the shrew and the fire.

2002 is the first year that ejecutes the prescribed burning as fuel management tool. The fire is not accepted even. There appear many problems: social, permissions, conservacionist’s groups,...

Way

Execution

The accomplishment of prescribed burning under laurel forest species is complicated enough. These species are very sensitive to the fire for what it is necessary to fit the flame length not to damage them.

This is done by the ignition pattern, using the fire torch as scalpel from firemen. With it we will look for low flame lenghts, low times of fire residence and the suctions.

Also de firemen uses the water ant the hand tools for lowering the flame lenght.

The seventeen parcels were burned in diferent days, beggining with the highest.

Way

In the opened zones of the plot the ignition pattern has been for points or for strips. In these cases the flame lenght has been a bit higher. Even this way the diferents reforested species have been protected in the plot.

Execution

Effects

The prescribed burning has diminished the fuel load and modified the forest structure. In the zones of many plants, the canopy have been closed preventing the entry of light. This has provoked the decrease of species as the ferms.

In the most oppened zones the ferm vegetation has grown very much. In the first analysis it can seem that the burning has not served. But it is a green ferm stand without dead load fuel below.

The majority of plants have supervived. Some of them have lost leaves for convection but they have not died. In the spring they return to appear.

01 week later autumn

17 months later spring

13 months later winter

Effects in the time