Lab.of Forest Engineering at Kochi University Logging in Japan Forest is the Sustainable Resource

How to harvest forests in Japan

[Production of rough timber | Opening up forest by roads]
[Improvement of logging in Japan | Research and Development for logging]


Japan extends a long distance north to south. Southern areas of the country are in the subtropical zone, middle areas in the temperate zone and northern areas in the subarctic zone. These include mountainous areas, so there are large differences in climate in the country. For example, Sapporo has 50 or more midwinter days, while Naha has about 3 months of midsummer days each year. Because of the rainy season except Hokkaldo during from June to July and the some typhoons during from August to October, northern and middle areas have nearly 1500mm of annual precipitation, particularly southern and by the side of Pacific Ocean areas have more than 2500mm of annual precipitation. As the meteorological records quoting from "Chronological Scientific Tables 1992", the maximum daily precipitation is 806 mm in Mie prefecture(1968) and the maximum hourly precipitation is 150mm in Kochl prefecture(1944).

In Japan, forest area accounts for 67% of total national land area(1). The total forest area(2) is 25,212,000 ha, 14,651,000 ha in privately owned forest, 2,700,000 ha in public forest and 7,861,000 ha in national forest. The man-made forest area is 10,327,000 ha, the natural forest area is 13,523,000 ha, and the others area(includes non-planted area and bamboo stand etc.)is 1,361,000 ha. The 98.9% of growing stock in man-made forests are coniferous trees and on the natural forests the 71.1% of growing stock are broad leaved trees. The component of growing stock by coniferous forests to the total is 64.5%. The total growing stock in forest is increasing by 76 million m3 every year, but since most of the trees planted during the reconstruction after World War II are still young, the growing stock per ha of man-made forests is 154.7 m3 and its of natural forests is only 113.7 m3 because of the consisting of low quality broad leaved trees. So the resources are still immature. The total growth volume(2) is 3,138 million m3, 1,967 million m3 in privately owned forest, 313 million m3 in public forest and 858 mllllon m3 in national forest. The growth volume of man-made forest is 1,598 million m3 and 1,538 million m3 in natural forest.

The number of forestry households(3) is 2,509,000 households, 1,595,000 are in agriculture and forestry, 913,000 are in non-agriculture and forestry. The number of households in agriculture and forestry is decreasing same as the decreasing the number of farm households, it was 2,279,000 households in 1970 and 1,981,000 in 1980. Most of forestry households join in owners' association as the member(4). Forestry population(5) is 110,000 persons in 1990, but it was 210,000 persons in 1970. The average age of forestry population(6) was reported to be more than 55 years old in 1982. The tendency of ageing is the result of the lack of new population. The shrinking size and ageing of the forestry population are problems in forest management. In Japan, the environment of forest operations must be improved rapidly. The lack of forestry population is the most serious problem.

Total final cutting area(7) is 243,787 ha in 1990, the component of it's volume in national forest is 36%. Total cutting volume(8) is 37,613,000 m3, the component of volume in national forest is 25%. The final cutting area continues to fall (290,900 ha in 1985) because of the keeping away from the expensive afforestation cost by clear cutting in non-national forest production. Furthermore, the cutting volume continues to fall (42,067,000 m3 in 1985) because of the shrinking production of national forest saddled with its deficit finance.

Amount of forestry product(9) is 977,144 million yen in 1990, the component of forestry product to Gross Domestic Product (400 598,900 million yen) is only 0.24%. On the other hand, Lumber imports account for about 5% of Japan's total imports. Because of the lumbering countries' policy to promote the export of processed products(10), 60% of imports are processed and 40 % are logs. Domestic production is stagnant because production, distribution and processing systems have not been developed. The self-sufficiency rate continues to fall (86.7% in 1960, 45% in 1970, 31.7% in 1980, 26.4% in 1990).

Production of rough timber

About 78% of total cutting volume, amounting to about 29,300,000 m3 is produced as rough timber(11) about 67% is in private forests. In national forests managed by Forestry Agency, the production of rough timber is decreasing to 7,417,000 m3 in 1990(as of 1985: 9,742,000 m3).

In Japan there were 11,120 of logging contractors(12-1) (12-2) in 1985. Of which 1,120 contractors were forest owners assoclations 84% of the total cutting volume was produced in final cutting . As regards the logging in 1989 by forestry owners' associations(13-1) (13-2), the component of the logged volume by them to the total cutting volume was 10% and the component of final cutting volume to the logged volume by them was 51 %.

Handy forest machines of which engine are built-in are diffused with conquering the vibration syndrome. But earth-augers are not diffused because of the vibration occurred by soil mixed with pebbles. Logging machines used in Japan are mainly yarders and skidders. The variation of those numbers are slight.

Mini-forwarders, monorails, monocables, and radio-controlled self-propelled carriages are used in thinning operations. Particularly, in the private forest areas constructed forest road network including more than 2 m width of spur road, mini-forwarders are well diffused and the number is continuously increasing. The price of mini-forwarders powered less than 10PS is less than 1 millon yen and this type vehicle is used in forest owners by themselves. The price of it powered about 50PS equipped with grapple loader is 4 million yen and this type is used in logging contractors in the private forest areas of which slope is mainly more than 30degrees ,radio-controlled self-propelled carriages are well diffused the price of this machine is about 2.5 million yen.

In Japan there are many volcanoes, particularly in the foot of volcanoes,for examples Mt.Fuji in Shizuoka, Mt.Taisetsu in Hokkaldo and Mt.Aso in the Kyusyu region(14-1) (14-2), the terrain of forest is characterized with moderate slopes, then most of timbers are logged by skidders. On the non-volcamc mountain range near the rural communities for example in Tohoku, Cyugoku and North Kyusyu regions, its terrain is characterized with short slopes. Because of the cheap construction cost of forest roads and spur roads thinned timbers are often logged by mini forwarders by forestry households themselves or owners' associations. In hardly fold mountain range, for example in South Kinki and Shikoku regions, its terrain is characterized with steep and long slopes and underlying hard rock near the surface. On these regions, the most of timbers are logged by more than 500m span of cable system. Generally speaking, forests where range near the mountain village are on the low mountains of which slopes are short and owned by forestry households. The higher and remoter areas from the village, forests are on the longer slopes and have the tendency on belng owned by companies or Forestry Agency.

On logging system, skidders are used in moderate areas of which slopes are less than 20degrees and cable systems are used in other areas. The span of yarding cable system is depend on the distance between ridges, that is on the length of slope. Naturally, the kind of logging machine diffused in a region depend on the characteristics of its terrain. Most of contractors don't have both skidders and yarders because of their lacking capital and experience.

Since 1987 in Japan behind Austha, Northern Europe and Northern America the highly mechanized machines such as processor, forwarder and harvester have been introduced in logging. Some logging contractors in Hokkaido began to use imported forwarders and harvesters. Processor made in Austria was begun to use by a logging contractor in Tochigi. Since 1975, Japan's forestry machine manufacturing companies have produced proto-type machines of mobile yarder equipped with spar. Since 1989 those machines have been sailed on. In 1990 mobile yarders were imported from Austria. In 1991, forests in Kyushu region were hardly damaged by typhoon then in order to log the windfall trees rapidly, those highly mechanized machines and mobile yarders were introduced there. In Japan processors are rapidly diffused in many logging contractors using yarders too, but mobile yarders are introduced in only forest owners' associations with the national and prefectural subsidies and a few forestry companies because of its too expensive price comparing to its productivity . Imported machines are sailed on about twice of its domestic price.

So, considering the shrinking size and ageing of the population some of its reasons are the low wage (15) and intensive and frequent industrial accidents(16-1) (16-2) in logging, we should advance the mechanization in logging by decreasing operations in steep slopes such as limbling, bucking and prehauling.

Opening up forest by roads

We have the Forest Road Regulation, it has been issued in order to regulate the constructing forest road easily damaged by disasters(17). The road construction cost on steep slopes and underlying hard rock near the surface amounts to more than 50,OOO yen/m. Most of cost is spent to construct concrete retaining walls and bridges. If the unconformable forest road to the regulation is damaged by disaster such as skidding road and spur road, it must be restored without subsidies. Since 1955, the log transportation in national forests was begun to change from by forest railways to trucks the construction of forest road have been promoted with some Forestry Structure Improvement Projects. Now, the forest road density in Japan is reached to only 4.9m/ha without public road or other lower quality roads. Including all roads in forests, the road density in forest is estimated at about 12.2m/ha. Yet, forest roads are not enough to innovate our forestry.

By some diligent foresters who have more than 500ha of forests have opened up their forests, since Prof.Dr.Hanz Hafner at University of Agriculture and Forestry in Vienna visited in Japan and gave them meamningful guidance in 1962. Now there are more than 50m/ha of forest road density in their forests. On the other hand small sized forest owners who have less than 50ha have opened up their forests by 1.5m width of spur roads in order to log thinned timbers with mini-forwarders. Their goal of forest road density is more than 400m/ha and the distance between roads is less than 30m. They want to fell trees onto the roads, then they can log only a tree accordlng to demand economically. On those cases, there are significant back grounds that forest owners manage their forests very intensively in order to produce the more than 25,000 yen/m3 of high quality timbers and the burden sharing of road construction cost is less than 200yen/m.

But in most of forests less than 15,000 yen/m3 of building lumbers are produced and wider width of roads is necessary for them to log many trees economically. Therefore the burden-sharing investment for road construction is very expensive for their managements. Even if those case, forest owners have invested for silviculture works such as planting, weeding in every summers until growing up to 1.5m height and a few times improvement cutting until 20 years of stand age. They need incomes recovering these investments estimated at more than 1,500,000 yen/ha, but they are subsidized at approximately 1,000,000yen/ha.

Improvement of logging in Japan

Now, there are three ways to improve the logging in Japan. One of them is the construction of roads in forest including narrow width of road in order to reduce the investment for silviculture works and to catch the chance of high selling timber price.

Second way is the construction of forest road which has the strong structure against disasters in the forests where it is difficult to construct the high density of road network. On this way, forest owners are obliged to carry out the extensive management, furthermore they must take measures against the problems of forestry population. So, the highly mechanization is necessary on all forest operations.

Third way is the diffusion of fully mechanized machines such as harvester, forwarder and machines for silviculture works in forest of which slopes are very gentle.

Research and Development for logging

We have the following problems in forestry, but the total growing stock in Japan is rapidly increasing.

1. Expensive investment for silviculture
2. Expensive road construction cost against much precipitation
3. Hish quality product by intensive forest management
4. Hardly fold mountain range with much ridge and valley
5. Shrinking size and ageing of the forestry population

Wood as a renewable resource will be used in future, if the productivity of forestry will be sustained. In order to achieve this goal, we have the following subject of the research and development for logging in Japan.

On the first way of improvement, the highly mechanization will be not significant, but it is very necessary to develop the reasonable priced machines including very small sized mobile yarder with the well planned work system.

On the second way, the highly mechanized cable system including of large sized mobile yarder and processor wlll be applied to logging in the forests of which slopes are long and steep. But the very difficult technical problem on the development of silvicultural machines such as the robot will remain.

On the third way, the diffusion of fully mechanized vehicle on gentle slopes under considehng of the impact to forests such as the soil compaction by vehicle.

In planning opening up forest by roads in detail, we should get every data in the field even if it is the construction of narrow road. DTM based on contour map or aerial photograph is used in outline planning of road, but these data are not satisfying in detail practical planning in Japan, because of the low accuracy of elevation and the complexity of terrain. Now we are standing at the turning point to develop the method of surveying data in forests economically or to bear the theoretical studies.

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