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Disaster-mitigation, environment-protection forests
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 In building a disaster-mitigation,environment-protection forest, prior field investigation to grasp the potential natural vegetation of the region is inevitable. Based on the results of ecological investigation, main planted tree species are decided.
Taking the case of Yokohama, Persea thunbergii is main planted tree species in the seaside areas, cuspidata species on slopes, and evergreen oaks in inland areas. They are all evergreen tree species, and function as disaster mitigation and environment protection through the year round.
The combination of planted tree species differs little by little according to planting sites. To select main tree species and other companion species correctly is the most important for reforestation.
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Dense mixed planting of potted seedlings with fully developed root system
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Main tree species from the potential natural vegetation have deep taproots. This leeps them from falling down in a typhoon or a big earthquake, but makes it economically and rhechnically difficult to transplant tall adult trees af them.
Accordingle in ecological reforestation we use 30cm-tall potted seedlings with fully developed root system of as many main and companion tree species as possible. We mix and plant them closely together following the system of natural forests. After seedlings survive the first winter, they grow 1 meter in a year, 3 meters in four years, 6meters in eight years, and 10 meter in twelve years. They from a qusai-natural forest with various ecological functions of disaster mitigation and environment protection.
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Effects of reforestation
Building native forests also contribute to anti global warming. Forests absorb CO2 from the air, and fix it as lignin and carbohydrates such as C6H12O6. Green surface area of a native forest is thirty times larger than that of grass. The function of anti global warming is also thirty times more than that of herbaceous plants.
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*Root system 2 years after plantation
Roots develored 2 meters deep, holding the rocks.
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*Building a disaster-prevention environment-protection forest at the back of Kurihama High School
from the top construction, plantation, 2 years after, 3 years after, 10 years after
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