Contamination of Japan 11 – Remobilsation of Cesium. Forest Fire Situation in Japan

Forest Fire Situation in Japan

http://www.fire.uni-freiburg.de/iffn/country/jap/jap_1.htm
Forest Fire Situation in Japan
(IFFN No. 26 – January 2002, p. 54-60)

By
Tobias Zorn, Global Fire Monitoring Center (GFMC), Fire Ecology Research Group, Max Planck Institute for Chemistry c/o Freiburg University P.O. Box 79085 Freiburg GERMANY and
Kouji Nakayama and Osamu Hashiramoto Forestry Agency Japan 1-2-1 Kasumigaseki Chiyoda-ku Tokyo, 100-8952 JAPAN

Introduction

Forests are deeply embedded in Japanese culture. This is not only represented by abundant traditional wooden buildings. Many tree reserves around temples and shrines indicate the high value of trees and forests. With 25 million ha of forests, corresponding to a forest cover rate of 67 percent, Japan is one of the most densely forested countries in the world (Japan FAO Association 1997).
The territory of Japan extends from 20° N to 46° N with climatic features ranging from subtropical to boreal conditions. The overall climatic conditions are characterized by high precipitation and a generally mild climate. During the winter, the continental high-pressure weather system is dominant, replaced in summer by the Pacific high-pressure system. The onset of monsoons in June-July and at the end of September coincide with this change of high-pressure areas. Annual rainfall is between 1 000 and 4 000 mm (Forestry Agency Japan 1990).
Stretching over 3 000 km, the archipelago of Japan consists of four major islands, Hokkaido, Honshu, Shikoku and Kyushu. Mountainous and hilly areas cover about 75 percent of the land area. Mountain slopes are generally very steep and dissected by short rivers of all sizes. Forestry is concentrated in mountainous regions with steep terrain, which makes forest firefighting countermeasures difficult and complex. Because of the scarcity of flat land, these areas are suitable for farming and settlement (Forestry Agency Japan 1990, Japan FAO Association 1997, Ota 1993; The National Land Afforestation Promotion Organization 1991).
The climax vegetation is forest, reflecting the warm monsoon climate with high precipitation. However, the species composition and the distribution of forest types differ from region to region because of marked climatic differences in Japan’s long, narrow land area and also because of complex differences in topography, geology and soil. These forests are classified into four types or zones: (1) sub-frigid (including sub-alpine), (2) cool temperate, (3) warm temperate, and (4) subtropical (Japan FAO Association 1997).
The sub-frigid forest zone (also called sub-alpine forest where its occurrence is governed by height above sea level) is located in the mountains of central Honshu and in central Hokkaido. In northeastern Hokkaido it occurs even close to sea level. The dominant tree species are white fir (Abies mariana), yezo spruce (Picea jezoensis), Glehn’s spruce (Picea glehnii) and, in Honshu, Veitch fir (Abies veitchii), northern Japanese hemlock (Tsuga diversifolia), and hondo spruce (Picea jezoensis var. hondoensis).
The cool temperate forest zone is characterized by the beech belt (Fagus crenata; in Japanese, buna). This type of forest occurs at elevations higher than 1 000 m above sea level in Kyushu, at 600 m around the Kanto district (greater Tokyo and Yokohama) and at sea level from the central part of Honshu north to western Hokkaido. Other tree species are Japanese lime tree (Tilia japonica), Japanese horse chestnut (Aesculus turbinala), katsura tree (Cercidiphyllum japonicum), and Japanese walnut (Juglans ailanthifolia).
The warm temperate forest zone itself is characterized by laurel (Machilus thunbergii), live oak (Quercus phylliraeoides), and camphor tree (Cinnamomum camphora).
In addition to these three main zones, a subtropical forest zone is found in Okinawa and in the southwestern part of Kyushu Island.

The forest fire situation in Japan

Influenced by its climatic and topographic conditions, it is a widely accepted perception that natural disasters such as floods and landslides are common in Japan (Forestry Agency Japan 1994). Despite the humid climate, the annual number of forest fires often exceeds 4 000, affecting an average area of more than 4 000 ha in the 1980s and 2 300 ha in the 1990s (Tab.1 and 2).


Source: Forestry Agency Japan (2000)


Source: Forestry Agency Japan (2000)


Figure 1. Number of forest fires by causes in Japan in the period 1976 to 1988. Source: Forestry Agency (2000)

Figure 2. Number of forest fires by causes in the period 1989 to 1998 in Japan. Source: Forestry Agency Japan (2000).

Figure 3 shows that 99 percent of the wildland fires are human-caused (Nakagoshi et al. 1987), such as from the misuse of fire during afforestation and cultivation, bonfires, campfires, playing with fire, burning of rubbish, cigarettes, matches and fire works.

Figure 3. Causes of forest fires in Japan related to the number of fire incidents.

Explanation: “Setting a brush fire” (Japanese: hiire) may include setting a prescribed fire (NTT 1999). Open-air fires include fires set at the occasion of Obon (Festival of the Dead), a Buddhist ritual that is celebrated annually in July (Western Julian calendar) or August (Chinese lunar calendar), depending on the location. For several consecutive evenings, in the cemetery next to the temple, family members hang lit paper lanterns or deposit lighted candles. Wind and animals (often crows) are some of the reasons for the spread of fire into the open landscape.
In the early spring season (due to the longitudinal range of the chain of the islands the spring season stretches over two and a half to three months, from February in Kyushu to May in Hokkaido), a lot of dry litter is accumulated on the forest floor and the forest floor itself is also dry. Since rainfall or downpours usually accompany thunderstorms, lightning is rarely a fire cause in Japan. The occurrence of fires is highly correlated to human activities in this densely populated country. Propagation of forest fire is highly influenced by weather, human activity and forest conditions. As Figure 4 shows, the frequency, the distribution over the year and the number of forest fires is high during the season with the lowest precipitation and relative humidity and during the months when outdoor activities are high.
Most of the broadleaved forests do not burn easily. Because of the generally cool and wet weather conditions, only a few forest fires occur in the sub-alpine conifer forests. Forest fires are more common in western Japan, where secondary forests of Pinus densiflora are widely distributed. Pine forests (P. densiflora, P. thunbergii and P. lutchuensis) tend to burn easily.

Fire control organization

In Japan, the fire services of cities, towns and villages are responsible for wildland fire suppression. For large fire situations support systems are available (Tab. 3 and 4), such as dispatch of the fire services of neighbouring cities, towns and villages and the Japan Self-Defence Forces.

Table 3. Fire services of cities, towns and villages in 1998.
Municipal Agencies Number
Fire prevention headquarters 920
Fire departments 1 662
Fire houses 3 232
Fire brigades 3 643
Fire squads 25 393

Source: White Book on Fire Service in Japan (1998).

Figure 4. Distribution of the number of fire incidents over the year
(5-year average between 1994-1998). Source: NTT (1999).

Table 4. Forest fire protection facilities subsidized by the Government of Japan

Water tanks 3 694
Natural water supply facilities 21
Aerial fire–fighting supply bases 12
Forest fire-fighting equipment
Fire defence radios 1 743
Receivers 1 340
Chainsaws 290
Portable sprayers 24 150
Portable water dischargers 297
Light portable pumps 96
Utility vehicles 118
Water trucks with small water pumps 23
Brush Cutters 1

To ensure that adequate fire-fighting capability can be deployed to forest fires, the Agency has developed fire defence support systems for large areas, is promoting the use of helicopters for information collection and aerial fire-fighting and provides guidance to prefectures and municipalities on timely requests for wide-area assistance. Helicopters are increasingly used for detection and communication in addition to being used in aerial fire suppression, including the use of fire retardants (White Book on Fire Service in Japan 1998).

Fire defence program for special forest fire regions

Since 1970 the Fire and Disaster Management Agency has been promoting a special forest fire defence programme in high risk areas in cooperation with the Forestry Agency. In municipalities bordering large areas of forest where there is a high risk of fire, the fire defence program includes the following measures:

Forest fire prevention through public education, patrols and monitoring;

Forest management with regard to fire prevention, such as the establishment and maintenance of firebreak belts;

Establishment of communication systems;

Development and improvement of fire fighting facilities;

Restriction of fire use during the fire season; and
Fire fighting training.

By 1997, this programme had been implemented successfully in 226 areas involving 940 municipalities in 38 prefectures (White Book on Fire Service in Japan 1998).
The early deployment of helicopters for reconnaissance and fire-fighting is an important concept in Japan. Further use of this strategy, in which helicopters work in close cooperation with ground firefighting operations, will require the development of additional bases for helicopter operations. In addition, water tanks and other water supplies are required for use during forest fires, especially in regions where residential areas are adjacent to forests and homes are at risk. There is a need to establish and continually update forest fire defence plans covering essential items about forest fire characteristics and firefighting operations. These plans allow firefighters to accurately grasp the state of a forest fire, determine firefighting tactics, deploy firefighting resources effectively and ensure reliable communications and a sufficient supply of water in the affected area. The effective use of simulation systems based on these forest fire defence plans has to be ensured.

Forest fire prevention campaign

A joint initiative by Fire and Disaster Management Agency and the Forest Agency, the national forest fire prevention campaign is held in conjunction with the spring national fire prevention campaign to raise public awareness and increase the effectiveness of fire prevention. This yearly educational campaign focuses on spreading the forest fire prevention message through educational activities aimed primarily at hikers, local residents and primary and junior high school students; banners and posters placed in stations, municipal offices and at the entrances to mountain routes; advertisements in the various media services, fire prevention training and study meetings.

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One wonders how much cesium and other fission and fuel product will be re-entered into the atmosphere from forest fires in Japan given the above forest fire statistics.

See also:

https://nuclearhistory.wordpress.com/2013/10/20/contaminated-forests-management-after-chernobyl-and-fukushima/

https://nuclearhistory.wordpress.com/2013/10/20/forests-around-chernobyl-have-been-absorbing-radioactive-elements-a-fire-would-send-them-skyward-again/

https://nuclearhistory.wordpress.com/2013/10/20/main-investigation-results-on-the-forest-radioecology-in-the-kyshtym-and-chernobyl-accident-zones/

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