Chapter 3
Protection from Fire

3.3 Grass pressing and other fire pre-suppression work

Greenbreaks and other fuelbreaks are strips of land prepared in advance to help keep fires from spreading past them. Fuel reduction and fuel treatments are ways to make a whole area difficult to burn by removing or compacting the fuel. Each of these techniques must be used in combination with other methods. Pressing Imperata is an especially useful technique for fire protection in both agroforestry and Assisted Natural Regeneration.

Pre-suppression requires labor but it is more effective and efficient than suppression. The work may be done individually or collectively by the people protect their individual or collective high-value areas such as farms and reforestation projects.

3.3.1 Fuel reduction and treatment

There are different approaches to reducing and treating fuel, each with its limitations.

Intercropping. To protect newly planted trees and shrubs, and to make full use of the land, the grass between the trees may be cleared and the area planted to other crops that will not easily burn (Section 4.4). To keep grass out, the area must be intercropped and weeded throughout the year. Limitation: After a few years, the trees will be large enough to shade out many annual crops, but may not prevent grass from growing. This will be a dangerous period of time until the trees can completely suppress the grass, so other methods (like slashing or fuelbreaks) have to be used.

Slashing. Slashing (cutting) and removing Imperata effectively reduces the fire hazard. One person can slash about 200-400 m² in a day. Even if cut grass is left on the ground, it is less flammable since air does not circulate well in the piled grass. Flames are usually twice as high as the fuel. Cut grass is shorter than standing grass, so the flames will be shorter and easier to put out. While the regrowth is still green, it will not burn readily. Limitation: Imperata grows back quickly after slashing, so slashing must be repeated frequently.

Grazing. Cattle and water buffalo graze young Imperata and prevent it from accumulating. Limitation: Constant grazing on young Imperata exhausts and compacts the soil. Livestock doesn't graze old, unpalatable Imperata; it is left as a fire hazard.

Pressing. Pressing is also called "lodging" or "rolling." The grass is pressed low to the ground by trampling or by rolling a weight over it. Pressing bends the base of an Imperata culm (stem) like folding a plastic water hose. The weight of the grass helps keep it bent down. Grass in the lower layers dies. Limitation: Fire can still burn in pressed Imperata. However, it burns more slowly and the flames are shorter. If the grass is pressed to a 25 cm layer, the flames will only be about 50 cm high, making them much easier to put out.

Benefits of pressing:

1. Pressed Imperata is much less flammable, since the air does not circulate well in the compacted grass.

2. Imperata regrowth after pressing is only 20-60% as fast as regrowth after slashing. Therefore, pressing does not have to be repeated as often as slashing.

3. Pressing is easier than slashing. One strong, experienced person can press about 900 m2 in a day. Women and children can press Imperata.

4. Pressing helps keep Imperata from shading other plants.

5. People can easily move around in areas where the grass has been pressed.

6. Pressed grass mulches the soil. Dead Imperata on the bottom begins to decompose within a few weeks. Weeds are suppressed.

When to press:

1. Press when Imperata is 1 m tall. If the Imperata is young and shorter than 1 m, pressing is less effective; the grass will spring up again.

2. Press when the grass is wet. The water on the leaves helps them stick together so that the grass does not spring up again.

3. Press at the beginning of the dry season to reduce the fuel hazard.

4. Press at the beginning of the rainy season to keep Imperata from shading young tree seedlings, and to help vines grow over and suppress it.

In what direction to press:

1. If grass is already naturally lodged, press it in the same direction, all the way to the ground.

2. Pressing downhill is easier and more effective than pressing uphill.

3. Press all the grass in the same direction. If the pressing "weaves" the grass like a basket, it won't lie as flat.

Tools for pressing on irregular or steep slopes with obstacles

On regular slopes with few obstacles

3.3.2 Fuelbreaks

Fuelbreaks are strips of land with a low fire hazard: they have little grass and other flammable fuel. If a fire spreads into a fuelbreak from one side, the fire's spread will slow down, giving people a chance to put it out before it spreads through the fuelbreak to the other side.

Fuelbreak width

It is hard to say how wide a fuelbreak should be. Recommendations range from 6 m to more than 30 m. Even very wide fuelbreaks may be crossed by fires, but it is difficult to maintain many wide fuelbreaks. It is important to use existing and natural fuelbreaks when possible, and to make "green" fuelbreaks (next page) multi-purpose and productive. Fuelbreaks running across the slope (on the contour) should be wider than fuelbreaks running up and down the slope (vertically), because fire can easily jump uphill.

Fuelbreak types

Natural fuelbreaks include streams, rivers, rocky outcrops, and gullies. Existing man-made fuelbreaks include roads, trails, and rice paddies.

• Use existing natural or man-made fuelbreaks and widen them where necessary.

Existing greenbreaks include forest and agricultural areas, especially moist gallery forests (Section 2.4).

• Remove dead plant material and flammable plants (such as Chromolaena, grasses and ferns) along the edge of existing forests and shrublands, to make them more effective fuelbreaks.

Grazed fuelbreaks. Grazing can be used to help maintain a fuelbreak by removing new grass as it grows.

• Control grazing animals to keep them from damaging nearby trees and crops.

Live fuelbreaks or greenbreaks. These are wide strips where Imperata has been replaced with less flammable vegetation.

• Choose species for greenbreaks that:

• are easy to establish

• can quickly shade or outcompete Imperata

• survive or re-sprout if burned

• do not drop flammable leaves

• retain succulent green foliage throughout the year

• Plant trees at a close spacing (such as 1m x 1m) to achieve rapid crown closure and early suppression of the Imperata.

• Tree species that have been used as live fuelbreaks in tropical timber plantations include Acacia auriculiformis, A. mangium, Calliandra calothyrsus, Gmelina arborea, Leucaena leucocephala, Macadamia hildebrandii, Schima wallichii, Syzygium ctimini, and Vitex pubescens.

Multipurpose fuelbreaks. People will have more interest in establishing and maintaining multipurpose greenbreaks, even if they require more work than simple fuelbreaks.

• Incorporate food or wood production in fuelbreaks where possible (see example next page).

Clean firebreaks are areas where vegetation has been completely removed by slashing or cultivation. This approach is not recommended for permanent fuelbreaks because it requires much labor, does not produce anything, and causes erosion if cultivated.

• Slash or cultivate Imperata again before the regrowth begins to dry or turn brown (before it becomes flammable).

"Black" firebreaks are burned areas. Burning for firebreaks is not recommended, because it is unproductive, temporary (the grass grows right back), causes soil erosion, and may cause wildfires. It is dangerous unless an expert supervises the burning.

Example of a multipurpose greenbreak

Fuelbreak placement

The most obvious place for a fuelbreak is around the borders of high-value areas, to protect them from adjacent grasslands. A land owner or village might place fuelbreaks around their boundaries. In addition to boundary fuelbreaks, a large plantation or ANR project should be broken up by internal fuelbreaks every 50 m, so that if a fire gets into one part of the project, it may be possible to keep it from spreading to another.

Fuelbreaks should also be placed near the boundaries of high risk areas (like grazing areas), where fires are likely to start. Instead of putting the fuelbreak on the exact boundary, it may be more practical to put the fuelbreak beside a nearby natural or manmade fuelbreak, such as a stream or road.

Spreading fires slow down and lose intensity at the tops of ridges, so fuelbreaks may be located along the ridge-top. A 10-20 m fuelbreak of young grass can be effective at the top of a ridge if it is frequently slashed.