fire

Forest Fire

Fire is the most important factor encouraging pest attack. Fire puts the tree under stress and weakens its natural resistance against pests, if the tree survives. Thus the injured and fire-damaged tree becomes susceptible to pest attack. There is a number of insect pests attacking fire-damaged trees. Interestingly, these insects would not be able to cause any harm if the tree was not affected by fire. Some of these pest insects are Xylothrips religiosus and other powderpost beetles, Vanapa oberthuri, Illacuris laticollis, Aesiotes spp. and Sympiezoscelus spp. and other Curculionidae wood-borers, pin- and shot-hole borers (Scolytidae and Platypodidae), and termites. An infestation with pin- and shot-hole borers takes place already a few hours after the respective tree has been damaged by fire. Other secondary pests take advantage of the thus even more weakened tree and join the 'dinner party'. Apart from of the above mentioned insects fungi are commonly encountered secondary pests.

Damaged Hoop Pine plantation during the drought in 1997 (left); pin- and shot-holes in a fire-damaged Hoop Pine (second from left); fungal growth at the base of a fire-damaged Hoop Pine (second from right); agroforesty garden in newly established plantation (right)

Due to the fact that fires are mainly man-made, awareness campaigns with the aim to change the attitude of the people who set fires are the only reasonable means of tackling this problem. The strict enforcement of the respective laws would be also desirable in order to deter people from arson. Otherwise little can be done in order to prevent fires. It is certainly helpful to propagate a ground cover of the legume Desmodium uncinatum preventing or at least slowing down the spread of fires in newly established plantations. Furthermore, it might be worthwhile to allow gardening in newly established plantations so that local people might learn to appreciate the value of forestry and thus possibly become more cautious with fire. Apart from that, fire resistant Pinus sp. can be planted in notorious areas, even though these species might not survive fires.

Ground cover with Desmodium uncinatum (Leguminosae) in newly established plantations slows down the spread of fire and acts as a natural fertiliser (left); a plot of apparently fire-resistant Pinus sp. fell prey to man-made fire (right)

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