Fire serves an important function in maintaining the health of certain ecosystems, but as a result of changes in climate and in human use (and misuse) of fire, fires are now a threat to many forests and their biodiversity.

Fire is a vital and natural part of the functioning of numerous forest ecosystems. Humans have used fire for thousands of years as a land management tool. Fire is one of the natural forces that has influenced plant communities over time and as a natural process it serves an important function in maintaining the health of certain ecosystems. However, in the latter part of the twentieth century, changes in the human-fire dynamic and an increase in El Niño frequency have led to a situation where fires are now a major threat to many forests and the biodiversity therein. Tropical rain forests and cloud forests, which typically do not burn on a large scale, were devastated by wildfires during the 1980s and 1990s (FAO, 2001).

Although the ecological impact of fires on forest ecosystems has been investigated across boreal, temperate and tropical biomes, comparatively little attention has been paid to the impact of fires on forest biodiversity, especially for the tropics. For example, of the 36 donor-assisted fire projects carried out or ongoing in Indonesia, a mega diversity country, between 1983 and 1998, only one specifically addressed the impact on biodiversity.

ECOSYSTEM EFFECTS OF FIRE:

Forest fires have many implications for biological diversity. At the global scale, they are a significant source of emitted carbon, contributing to global warming which could lead to biodiversity changes. At the regional and local level, they lead to change in biomass stocks, alter the hydrological cycle with subsequent effects for marine systems such as coral reefs, and impact plant and animal species' functioning. Smoke from fires can significantly reduce photosynthetic activity (Davies and Unam, 1999) and can be detrimental to health of humans and animals.

IMPACTS OF HUMAN-INDUCED OR SEVERE NATURAL WILDFIRE ON PLANT DIVERSITY

Wildfire is unusual in most undisturbed, tall, closed-canopy, tropical rain forests because of the moist microclimate, moist fuels, low wind speeds and high rainfall. However, rain forests may become more susceptible to fire during severe droughts, as experienced during El Niño years. In these forests which are not adapted to fire, fire can kill virtually all seedlings, sprouts, lianas and young trees because they are not protected by thick bark. Damage to the seed bank, seedlings and saplings hinders recovery of the original species (Woods, 1989). The degree of recovery and need for rehabilitation interventions depends on the intensity of burning (Schindele, Thoma and Panzer, 1989).

EFFECTS OF FIRE ON FOREST FAUNA

In forests where fire is not a natural disturbance, it can have devastating impacts on forest vertebrates and invertebrates - not only killing them directly, but also leading to longer-term indirect effects such as stress and loss of habitat, territories, shelter and food. The loss of key organisms in forest ecosystems, such as invertebrates, pollinators and decomposers, can significantly slow the recovery rate of the forest (Boer, 1989).

Estimates from the 1998 fires in the Russian Federation suggest that mammals and fish were badly affected. Mortality of squirrels and weasels, estimated immediately after the fires, reached 70 to 80 percent; boar 15 to 25 percent; and rodents 90 percent (Shvidenko and Goldammer, 2001).

Loss of habitat, territories and shelter

Fire serves an important function in maintaining the health of certain ecosystems, but as a result of changes in climate and in human use (and misuse) of fire, fires are now a threat to many forests and their biodiversity.

Fire is a vital and natural part of the functioning of numerous forest ecosystems. Humans have used fire for thousands of years as a land management tool. Fire is one of the natural forces that has influenced plant communities over time and as a natural process it serves an important function in maintaining the health of certain ecosystems. However, in the latter part of the twentieth century, changes in the human-fire dynamic and an increase in El Niño frequency have led to a situation where fires are now a major threat to many forests and the biodiversity therein. Tropical rain forests and cloud forests, which typically do not burn on a large scale, were devastated by wildfires during the 1980s and 1990s (FAO, 2001).

Although the ecological impact of fires on forest ecosystems has been investigated across boreal, temperate and tropical biomes, comparatively little attention has been paid to the impact of fires on forest biodiversity, especially for the tropics. For example, of the 36 donor-assisted fire projects carried out or ongoing in Indonesia, a mega diversity country, between 1983 and 1998, only one specifically addressed the impact on biodiversity.

ECOSYSTEM EFFECTS OF FIRE:

Forest fires have many implications for biological diversity. At the global scale, they are a significant source of emitted carbon, contributing to global warming which could lead to biodiversity changes. At the regional and local level, they lead to change in biomass stocks, alter the hydrological cycle with subsequent effects for marine systems such as coral reefs, and impact plant and animal species' functioning. Smoke from fires can significantly reduce photosynthetic activity (Davies and Unam, 1999) and can be detrimental to health of humans and animals.

IMPACTS OF HUMAN-INDUCED OR SEVERE NATURAL WILDFIRE ON PLANT DIVERSITY

Wildfire is unusual in most undisturbed, tall, closed-canopy, tropical rain forests because of the moist microclimate, moist fuels, low wind speeds and high rainfall. However, rain forests may become more susceptible to fire during severe droughts, as experienced during El Niño years. In these forests which are not adapted to fire, fire can kill virtually all seedlings, sprouts, lianas and young trees because they are not protected by thick bark. Damage to the seed bank, seedlings and saplings hinders recovery of the original species (Woods, 1989). The degree of recovery and need for rehabilitation interventions depends on the intensity of burning (Schindele, Thoma and Panzer, 1989).

EFFECTS OF FIRE ON FOREST FAUNA

In forests where fire is not a natural disturbance, it can have devastating impacts on forest vertebrates and invertebrates - not only killing them directly, but also leading to longer-term indirect effects such as stress and loss of habitat, territories, shelter and food. The loss of key organisms in forest ecosystems, such as invertebrates, pollinators and decomposers, can significantly slow the recovery rate of the forest (Boer, 1989).

Estimates from the 1998 fires in the Russian Federation suggest that mammals and fish were badly affected. Mortality of squirrels and weasels, estimated immediately after the fires, reached 70 to 80 percent; boar 15 to 25 percent; and rodents 90 percent (Shvidenko and Goldammer, 2001).

Loss of habitat, territories and shelter

Loss of food

Fire-adapted fauna

 

EFFECTS OF SUPPRESSION OF THE NATURAL FIRE REGIME

Temperate forests in the United States and Australia in which fire was deliberately suppressed are now experiencing devastating wildfires because of an unnatural accumulation of fuel. Deliberate human suppression of fire can also have direct negative impacts on species. In forests where fire is a natural part of the system, plant and animal species are adapted to a natural fire regime and benefit from the aftermath of a fire.

In boreal forests, exclusion of fire induces the build-up of organic layers that prevents melting of the upper soil during spring and summer and rise of the permafrost layer, resulting in impoverishment of forests, decrease in productivity and conversion of forests to marshes.

Loss of food

Fire-adapted fauna

 

EFFECTS OF SUPPRESSION OF THE NATURAL FIRE REGIME

Temperate forests in the United States and Australia in which fire was deliberately suppressed are now experiencing devastating wildfires because of an unnatural accumulation of fuel. Deliberate human suppression of fire can also have direct negative impacts on species. In forests where fire is a natural part of the system, plant and animal species are adapted to a natural fire regime and benefit from the aftermath of a fire.

In boreal forests, exclusion of fire induces the build-up of organic layers that prevents melting of the upper soil during spring and summer and rise of the permafrost layer, resulting in impoverishment of forests, decrease in productivity and conversion of forests to marshes.