• Journal of Korean Society of Forest Science
• /
• v.112 no.3
• /
• pp.331-339
• /
• 2023

This study was conducted to identify seed inflow characteristics according to harvest typeand to provide basic data for developing a regeneration technology for secondary growth forests in Korean red pine (Pinus densiflora) succession forest formation by natural regeneration. Experimental sites were established by applying seed tree (single and group) and clear-cutting methods (10- 20- 30-m strip and 20- 30- 40-m patch). The seed inflow characteristics of the natural regeneration site were analyzed for 6 years from 2014. Most seeds were flowed to the regeneration stand from October to November. In years with good seed fructification, more than 80% were flowed in October. The average annual seed inflow by harvest type was highest in the seed tree area (296,000 seeds/ha/yr), followed by the 20-m patch clear-cutting area (291,000 seeds/ha/yr) and 10-m strip clear-cutting area (281,000 seeds/ha/yr). The distribution uniformity of seed inflow according to treatment was analyzed in the order of the 20-m strip clear-cutting area (52.2), 20-m patch clear-cutting area (52.9), and 10-m strip clear-cutting area (56.1). As a result, the 10-m strip and 20-m patch clear-cutting areas with relatively small harvest areas showed high seed inflow and distribution uniformity.

• Journal of Korean Society of Forest Science
• /
• v.110 no.3
• /
• pp.295-307
• /
• 2021

This study proposed a field-applicable natural regeneration method using natural seeding to afforest a secondary growth forest after felling in Larix kaempferi plantations. In 2016, an experimental site was established usingseed-tree and clear-cutting methods in Gapyeong, Gyeonggi-do, South Korea. Characteristics of seed fructification and inflow in the natural regeneration site were analyzed along with an experimental site in Bonghwa, Gyeongsangbuk-do, which was established in 2014. As a result, the number of seeds per individual tree of V age class L. kaempferi was 690,340 seeds in a good year, with an estimated 13.8 million seeds per ha fruited in natural regeneration sites of L. kaempferi with 25 seed-trees per ha. Seed dispersal began in September and germination rates of seeds dispersed until November were greater than 40%. Reserved seed-tree sites showed the highest amount of seed inflow, followed by the seed-tree site and clear-cut site in descending order. The reserved seed-tree method performed better than other methods for evenly scattering seeds. Therefore, the timing of logging and seedbed generation for natural regeneration of L. kaempferi is estimated to be most effective before September when seeds are purposefully scattered using the reserved seed-tree method as an effective method for uniform seed supply.

• Journal of Korean Society of Forest Science
• /
• v.109 no.4
• /
• pp.400-412
• /
• 2020

We analyzed the growth characteristics of naturally regenerated seedings of Larix kaempferi in order to propose a field-applicable regeneration method. Experimental sites were established at Gapyeong in Gyeonggi-do and at Bonghwa in Gyeongsangbuk-do. We analyzed seed inflow features, occurrence, and growth characteristics of natural seedlings for three years. The reserved seed-tree site producedthe greatest number of inflow seeds and followed by seed-tree site and clear-cut site. In addition, the reserved seed-tree method was found to be more efficient than other methods in evenly scattering seeds. The rate of seedling occurrence at treatment sites (e.g., harvesting and scratching) was 2.4%, which is 8.0 times higher than the seedling occurrence (0.3%) at the non-treatment sites. There were approximately 470,000 seedlings per hectare at the treatment sites in June of the first year after regeneration and approximately 78,000 seedlings per hectare in October of the third year. The average diameter of the root collar of the seedlings in the third year was 6.5 mm, and the average height of the seedlings was 50.4 cm. These results indicate that it is possible to create a secondary forest of L. kaempferi by natural regeneration if harvesting and scraping are implemented during seed fructification. Considering the rapid growth of L. kaempferi shown in this study, the proposed method would be an efficient reforestation technique.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.43 no.3
• /
• pp.223-230
• /
• 2010

To compare seed collection and the growth of Anadara subcrenata in Suncheon and Boseong Bays, environmental factors and the growth of larvae and spats were investigated from August 2008 to July 2009 in commercial farming sites in both bays. The variation in water temperature in both bays was similar, but the salinity was lower in Suncheon Bay than in Boseong Bay. The chlorophyll-a content was higher in Suncheon Bay due to the large inflow of freshwater. The density and shell length of A. subcrenata larvae did not differ significantly between the two bays. However, the relative growth of shell height to shell length was significantly higher in Suncheon Bay (P<0.05). The growth of A. subcrenata spats attached to a collector was significantly faster in Suncheon Bay (P<0.05). The spats in Suncheon and Boseong Bays grew to 24.3 and 21.0 mm in shell length, respectively, within 1 year after spawning, and the shell length reached 35.6 and 34.8 mm, respectively, within 2 years of spawning. The initial spats density was higher in Boseong Bay, but the growth of spats was better in Suncheon Bay. The faster growth of A. subcrenata in Suncheon Bay can be explained by the high chlorophyll-a content in this bay. Based on the low survival (%) and slower growth rate of spats in Boseong Bay, the commercial culture density of A. subcrenata in Boseong Bay should be reduced to the optimum level of the carrying capacity.

• Journal of Korean Society of Environmental Engineers
• /
• v.34 no.1
• /
• pp.42-48
• /
• 2012

In this study, experiment on phosphorus removal was performed by using microbubble liquid film flotation tank with microbubble module. After dissolving gas and liquid in dissolving tank, microbubble liquid film system created microbubbles in equal size under fixed low pressure. After being passed through $A_2O$ and m-$O_3$ process, secondary treatment wastewater was used as influent in phosphorus removal process. When the T-P concentration of influent was 2.89 mg/L, alum(8%, 30 mg/L) was injected into a microbubble flotation tank, the treatment resulted 94% of T-P removal rate. Remaining T-P concentration was less than 0.2 mg/L, which is in accord with the effluent quality standard. Seasonal variations in water temperature showed no differences in T-P removal property. When the inflow concentration of SS was 1.0 mg/L or more, it served as coagulation nuclei in the coagulation process. In that condition, average T-P removal rate was higher than 97%. When 50% of floated scum was returned, coagulator Al included in scum assisted the injected coagulator and maximized the coagulation efficiency of pollutant. In such treatment, the T-P concentration was measured as 0.18 mg/L and satisfied the outflow water quality standard, which is 0.2 mg/L or less.

• Korean Journal of Environmental Biology
• /
• v.34 no.2
• /
• pp.63-72
• /
• 2016

The objective of this study was to identify the life form characteristics, naturalized degree and introduction period of naturalized plants on upland fields in South Korea. The survey sites were selected in 222 upland fields over 9 provinces where are relatively dry soil conditions and are disturbed continuously by farming practices. It seemed that these uplands maintain good condition for the invasion and settlement of alien plants. Field surveys were carried out twice from May to June and from August to September in 2013. The vascular plants of the upland fields were listed into 539 taxa which contain 103 families, 320 genera, 448 species, 2 subspecies, 74 varieties and 15 forms. Ninety nine taxa were naturalized plants composed of 23 families, 64 genera, 91 species and 8 varieties. The urbanization index and naturalized index is 30.65% and 18.37%, respectively. Among total 99 naturalized plants, Compositae (30 taxa) was the most dominant family, and followed by Gramineae (14 taxa). On the basis of dormancy form, 78 taxa were belong to Th (Therophyte). In radicoid form, $R_5$ plants (86 taxa) and $R_3$ plants (14 taxa) were dominantly distributed. In disseminule form, $D_4$ including 63 taxa and $D_2$ containing 26 taxa were dominant. On the basis of growth form, erect form (e) containing 26 taxa was dominant. In conclusion, life form spectrum was $Th-R_5-D_4-e$ type. According to life form analysis, naturalized degree and introduction period, alien plants with unique characteristics may have high ability to settle and spread nationwide after inflow into South Korea. It needs further to observe some plant species with or without ecological features such as widely disseminated seeds by wind or water, high seed productivity, long life-span seeds, high germination rate of seeds, or non-dormant germinable seed.