Even when timber extraction is carefully done, with only selected trees being removed, much damage is done to the remaining forest. Roads must be cut, trees dragged out with bulldozers, and “landings” constructed to hold the logs. There is much subsidiary damage; many other nearby trees and vegetation are damaged or killed (uprooted, trunks broken, bark lost). Alper (1993) reports on studies in which it was found that extraction of 10% of trees can destroy up to 50% of the canopy, with skid roads and roads damaging another 10% to 20% of the area. This does not leave much of the forest unscathed. Similar results were found in Malaysia. For the 10% of the trees harvested, 55% of the remaining ones were damaged or destroyed. And in Sarawak, only 21% of the trees remained intact after logging (Jacobs, 1988). After the desired trees are removed, a great deal of debris (“slash”) remains – broken branches, trunks, uprooted underbrush. Because the canopy has been opened, more sunlight strikes the ground, heating it and reducing humidity. These alterations in microclimate lead to changes in the understory vegetation, which is no longer shaded and protected from high temperatures by the canopy. Under these conditions the slash and surrounding forest become highly vulnerable to fire.