In the last 30 years large parts of Thailand’s forests have been cleared for agriculture. Fire played an important role in this since it had been an agricultural tool for many centuries in Southeast Asia, either to clear harvesting debris or to clear new land. At the same time, legally or illegally, large tracts of forest land were logged. Selective felling altered the forest structure letting herbaceous ground vegetation invade the forest ground. Furthermore, the ethnic minorities in the mountains of the North practice slash-and-burn agriculture which is resulting in the spread of large areas of grasslands.
The prolonged and hotter dry seasons and the reduced rainfall are attributed to forest destruction. The drought and heat, combined with the more open forest structure and the availability of readily combustible herbaceous fuels cause a “fire friendly” environment and thus accelerate and close the destructive cycle of forest fires.
Forest fires in Thailand occur annually during the dry season in the deciduous forests of drier environments but now also moist and evergreen forests are affected, and double burning (burning twice per year) on dry sites has become a regular feature.
The amount and distribution of rainfall strongly affect forest fire occurrence. The monsoon rainfalls in Thailand are strongly seasonal, lasting from about May to October. The dry season can last up to 7 months during which day-time temperature extremes can exceed 40° C. On the Malaya Peninsula the climate is moister and less extreme. In Thailand, annual rainfall varies between 700 mm in inland areas and the North-Eastern plateau to about 4000 mm in coastal areas.
The distribution of forest types closely follows the rainfall distribution pattern. Natural forest vegetation can be grouped into dry, hill and moist evergreen forests types of the moister areas (totaling about 43%) and mixed and dry dipterocarp forest in drier areas, representing 22% and 31% of the forest respectively. The remaining 4% include primarily mangroves and pine forests (RFD, 1992/2).
Fig.1. Freshly burned monsoon forest – a typical scene foundthroughout continental Southeast Asia during the dry season (Photo: J.G.Goldammer) (will be added later)
Forest Fires and Forest Destruction in Thailand
Forest cover has been halved during the last 30 years, from 53.33% in 1961 to 26.64% (13.67 million ha) in 1991 (RFD, 1992/3; Tab.1). Non-governmental organizations claim that half of the remaining forests are severely degraded and should not be classed forest anymore.
Forest destruction reached a peak between 1976 and 1978 when 2.26% of forest was destroyed annually. It tapered off to an all-time low in 1989 (0.08%) when a logging ban was introduced in response to a series of floods and landslides. Despite the ban, forest destruction has picked up again at an average annual rate of 0.655%. The only exception was the already heavily degraded NE of the country.
On the basis of this information the national forest cover will have reached 25.33% by the end of this year and about 20% in the year 2000. Especially affected will be the central, western and southern areas of the country.
In the past concession forestry was assumed as being the main reason for forest destruction. Today, non-concessioned (i.e. illegal) timber harvest, forest fire and encroachment are considered the main reasons of forest destruction. However, encroachment and conversion to agriculture is merely the final result of repeated attack on the forest through timber cutting and burning. Only after removal of the forest vegetation can the land be converted to other uses.
Regarding timber harvesting, in 1991 the country consumed about 3.46 million m3 of which nearly all was imported. Only 0.23 million m3 were locally produced and sold. Of this 0.14 million m3 derived from illegal logging, i.e. 2/3 of all domestic production.
In terms of forest fires, data collected between 1984 and 1986 showed that about 21% of the forest land was affected by fire annually. In 1992 it was about 15%. This corresponds to an area of ca. 1.9 million ha (Tab.3). The majority of the fires occurred in the North. Forest plantations that constitute about 5% of the forest area are twice as prone to fires as natural forests (RFD 1992/1).
In 1990 alone, fires caused losses in timber revenue of 1.2 billion US$. Compared to unaffected areas, an threefold increase in surface runoff and a 3 to 30 fold increase in soil erosion caused losses estimated between 16 to 32 billion US$. Further effects listed include affected scenery and its impact on tourism, greenhouse effects, and effects on wildlife and biodiversity (Kasetsart University, 1991)
Tab.1. Development of forest cover in Thailand, 1961-1991. The figure 26.67 % in 1991 corresponds to ca. 85.4 million rai (=13.67 million ha). Source: Royal Forest Department (1992/3).
Forest cover (%)
North (N) 169,644
Northeast (NE) 168,854
East (E) 36,503
Central & West (CW) 67,399
South (S) 70,715
Tab.2. Average annual forest destruction (%) in Thailand in theperiods 1985-89 and 1989-91. Source: Royal Forest Department (1992/3).
1985 – 1989
1989 – 1991
Tab.3. Regional and total forest burned over in Thailand in 1992. The extrapolated value is based on the surveyed forest area (compiled by Fire Ecology Research Group on the base of forest inventory data).
RegionTotal land area (km2)Forested area (km2)Area sampled during 1992 inventory (ha)Burned areas within sampled areas (%)Extrapolated area burned per year (km2) North
* including Central
People’s Attitude to Forest Fires
There is a widespread belief among scientists as well as rural people that Southeast Asia’s forests are adapted to regular fires. The long time-span that is involved before changes in the forest structure are visible, getting accustomed to large areas on fire during the dry season and the fact that most fires remain ground fires of low to moderate fire intensity contribute to this belief. However, recent studies have shown that seedlings and undergrowth are usually completely destroyed by fire, sapling growth is reduced by 20-25%, with 40% dying. One to five year old trees have mortality rates of about 20%, as do 80% of the roots near the surface (Kasetsart University, 1991). My own investigations showed seedling survival rates after fires as low as 10%, supporting the above-mentioned findings.
Studies conducted by the Royal Forest Department show that gathering of fuel and non-timber products and burning of agricultural debris are the reasons for about half of all forest fires (25% and 20% respectively). Arson, primarily for speculative reasons is responsible for 19% of fires. Hunting, carelessness and unidentified causes are responsible each for 12% of the fires. No naturally caused forest fires were recorded during 12 years of observation.
Forest fire Control in Thailand
The control of forest fires is the responsibility of the Royal Forest Department, carried out by the Forest Fire Control and Rescue Bureau which is split into 4 administrative sections. The bureau maintains 4 upcountry Forest Fire Control Centres as its working units. These centres maintain 34 sub-units, 14 Forest Fire Control Stations, and 20 Forest Fire Control Projects that were initiated by his Majesty the King.
The strategies applied in forest fire control include forest fire promotion campaigns (mobile campaign units, mass-media, school programmes, exhibitions, billboards etc.) and forest fire suppression. Of the total forested areas about 12% (20.000 km2) are covered by forest fire control, concentrated in the North of the country. The biggest stations control 1.500 km2 the smallest less than 5 km2. Of the areas under control only about 0.5% (100 km2) are affected by fire annually, compared to about 15% nationwide, indicating the success of the fire prevention and control efforts. They include training of staff and local volunteers in fuel management, fire detection and reporting, fire suppression and law enforcement and rescue operations.
A Look into the Future
In the light of continued and accelerating forest destruction and the inability to reforest these areas (less than 25% of the annually destroyed areas can be replanted) fire control has shown to be a successful means to reduce or halt the process. A successful control of fires would remove one of the conditions necessary to convert forest land to other uses. If this can be combined with more effective law enforcement and the development of alternative wood and fuel resources for the local population, the Thai forests have a chance of recovering and surviving.
However, to achieve this the forest fire control measures have to be made a priority and applied nationwide. Fire control efforts have to be coordinated among different institutions and scientifically adjusted to prevailing local conditions. The legal framework has to be adjusted so as to be able to apply forest fire legislation in and outside forested areas. Furthermore, legal adjustments regarding land ownership and user rights outside the forest are necessary to change current short-term oriented land use attitudes towards a long-term oriented and sustainable management.
Kasetsart University 1991. Forest fire and its effect on the forest ecosystems in Thailand. Bangkok (in Thai).
Royal Forest Department 1992/1. Forest fire control in Thailand. Bureau of Forest Fire Control and Rescue, Bangkok.
Royal Forest Department 1992/2. Forest statistics of Thailand 1991. Planning Division, Royal Forest Department, Bangkok.
Royal Forest Department 1992/3. Analysis of the forest situation in Thailand from Landsat imagery. Office of Remote Sensing Survey and Mapping, Royal Forest Department, Bangkok (in Thai).
Royal Forest Department 1992/4. Forest fire control. Draft, prepared as a part of the Thai Forest Sector Master Plan, Royal Forest Department, Bangkok.
From:Clemens Fehr Address: Royal Forest Department P.O.Box 55 T-Bang Khen 10900