Saplings of good species of trees are grown at the Thaechon County Forestry Management Station in North Phyongan Province.
“Mountains make up 70 percent of our county. Our station takes the lion’s share of turning all the mountains in the county into ‘gold and treasure mountains’,” said Kim Jong Nam, manager of the Thaechon County Forestry Management Station in North Phyongan Province.
What is distinctive in its sapling cultivation is that it turns out Changsong larch saplings without using agrochemicals and sun screens.
In general, the production of the saplings requires much labour as they should be kept in the shade and for other reasons. In particular, they are easily susceptible to grubs and other harmful insects.
To reduce such damage, the station took a variety of measures in the past, including the making and using of biological pesticide, but to no avail. In the course of seeking an efficient method, it found out a mixed cultivation method which is to plant rows of Changsong larch and black walnut or chestnut saplings alternately.
According to chief engineer Sonu Yong Sam, proper selection of tree species in creating mixed forests could diminish blight damage owing to antagonism. Secretions from some species restrain or irritate harmful insects to prevent blight.
As black walnut and chestnut saplings are insusceptible to harmful insects, so are those of Changsong larch without the use of agrochemicals.
The station produces Changsong larch saplings 1.2 times more than previously by applying the labour- and cost-saving mixed cultivation method.
It also conducts research into the production of big fruit tree saplings through direct sowing in order to increase the output of wild fruit tree saplings. This method is to sow the seeds of trees directly on mountains, not at tree nursery, thus saving large areas of land and much labour.
Based on a successful trial test last year, the station intends to apply the method to a wide area this year.
Meanwhile, it properly selects the mixing ratio of substrates in accordance with the peculiarities of saplings to raise them in greenhouses in the current year.
It produces the saplings of dozens of kinds of wild fruit trees and other good tree species annually to make greener the mountains in the county.