Technical methods for artificially promoting seed production in Korean pine plantations

For Korean pine, a tree species with a long rotation period, tapping the economic potential of its seeds, shortening the capital payback period and securing near-term income are very important issues in addition to considering timber revenue. The Fengcheng area currently has 800 hectares of Korean pine plantations, of which 3600 hectares have entered the seed-bearing stage; in a good year, the average yield is 350 kg of seeds per hectare, with a total output value of up to 13 million yuan. Further increasing the seed production of these stands can effectively boost the development of the forestry economy in mountainous areas.

In February 1998, before sap flow began, we applied the top-cutting technique to existing Korean pine plantations that had entered the seed-bearing stage, greatly increasing seed production. During the operation, trees in the stand that had already forked and trees in the lower layer were not topped. Workers climbed the trees manually, fastened safety belts, and used pole pruners to cut the treetops of the differently treated trees within a radius of several meters. Each worker could complete 2 mu of forest land per day, with a labor cost of 30-50 yuan. This is a one-time investment, and no further top-cutting is needed afterward. For stands with a density of about 1000 trees per hectare, cut the top between the 3rd and 4th whorls of branches counting from the top of the tree; for stands with a density of about 6 trees per hectare, cut the top between the 1st and 2nd whorls of branches counting from the top of the tree.

Practice has shown that for Korean pine plantations about 30 years old, the top-cutting technique can effectively increase seed production, with an average yield increase of 75.47%. Adopting seed-production promotion techniques is an important means of effectively increasing the economic potential of Korean pine plantations. It can increase output value by more than 1100 yuan per hectare. A one-time low-cost investment can bring long-term benefits.

Stands that have not yet entered the seed-bearing stage should not be topped for the time being. The purpose of top-cutting is to increase seed yield, but timber yield and log-making requirements must also be considered. It is best to choose stands more than 30 years old, where the trunk below the cutting point is at least 10 m high, which can meet the log-making needs for 8 m, 6 m and 4 m lengths.

For stands with excessively high density that are intended for seed-production promotion, thinning should be carried out first. The thinning intensity should follow the "Technical Regulations for the Establishment of Korean Pine Fruit and Timber Dual-Purpose Forests in Liaoning Province", and then top-cutting treatment should be carried out.

Control the seed collection period. The start of seed collection should be controlled to after September 15. At this time, the nutrient indicators of the seed kernel reach their maximum, the cones turn yellow, and they fall off very easily during collection, making it unlikely to damage the trees during collection. If seeds are collected too early, the cones are greener and the fruit stalks are firmly attached to the tips of the treetops; excessive beating can easily break the treetops, causing artificial secondary top-cutting and resulting in low yields for many years afterward. In addition, if seeds are collected too early, seed quality is poor, the thousand-kernel weight and kernel yield are lower, and nutrient content is low, which cannot meet the requirements for export commodities. Buyers can easily identify this, leading to @#@136@#@ price declines, a bumper harvest without a bumper income, and serious damage to the region's seed brand image.