Seongjun Kim

Initial effects of thinning on soil carbon storage and base cations in a naturally regenerated Quercus spp. forest in Hongcheon, Korea

Thinning can affect soil carbon (C) and base cation balances by reducing tree density and altering microclimate and organic matter budget; however, the subsequent changes in soil C and base cation contents after thinning are not well elucidated. Thus, this study investigated the effects of thinning on C storages in soil (at 0–10 cm, 10–20 cm, and 20–30 cm depths) and forest floor and concentrations of soil exchangeable base cations (Ca2+, Mg2+, K+, and Na+). Thinning treatments of different intensities based on the removed basal area (no thinning: control, 15% thinning: T15, and 30% thinning: T30) were applied to a naturally regenerated 31 to 40-year-old Quercus spp. forest. Soil C concentrations at 10–20 cm and 20–30 cm depths were significantly higher in T15 and T30 than in the control after 39 months, but not after 4 months. T15 and T30 treatments seemed to increase soil C storage at 0–30 cm after 39 months, but did not significantly change forest floor C storage after 4 and 39 months. Concentrations of exchangeable K+ of T15 and exchangeable base cations except for Ca2+ of T30 depth were significantly lower than those of the control at 0–10 cm after 4 months, but not after 39 months. This study shows that thinning treatments on a naturally regenerated Quercus spp. forest could increase soil C concentration after a few years but temporally decrease concentrations of soil exchangeable base cations.

Short-Term Effects of Experimental Warming and Precipitation Manipulation on Soil Microbial Biomass C and N, Community Substrate Utilization Patterns and Community Composition

Abstract Soil microorganisms are major drivers of soil carbon (C) cycling; however, the response of these microorganisms to climate change remains unclear. In the present study, we investigated how 18 months of multifactor climate treatments (warmed air temperature by 3 °C and decreased or increased precipitation manipulation by 30%) affected soil microbial biomass C and nitrogen (N), community substrate utilization patterns, and community composition. Decreased and increased precipitation significantly reduced microbial biomass C by 13.5% and 24.9% and microbial biomass N by 22.9% and 17.6% in unwarmed plots, respectively (P

Effects of thinning intensity on understory vegetation in Chamaecyparis obtusa stands in South Korea

ABSTRACT The study was conducted to analyze the effects of thinning intensity on understory vegetation in Chamaecyparis obtusa stands. The site was located on Mt Moonsu in Gochang-gun, South Korea and consisted of five treatment plots: 5 m × 5 m quadrats were installed in each plot. The total flora of the C. obtusa stand included 47 families, 60 genera, and 70 species. Three classes of floristic regional indicator plants were verified: six taxa in class I, one taxon in class II, and one taxon in class III. Also, Phytolacca americana and Robinia poseudoacacia appeared as naturalized plants in heavy thinning and control plots, respectively. Their Naturalized Index and Urbanization Index were shown as 1.00% and 0.74%, respectively. Within the treatment plots, the greatest number of species appeared in the heavily thinned plots (31 species). Chamaecyparis obtusa showed the highest dominance index of 4.67. Regarding species richness of understory vegetation, there was a very distinct difference between the thinned and non-thinned plots, whereas there was no significant differences among the treatment plots such as light thinning, normal thinning, heavy thinning, and super heavy thinning plots. Thus, understory vegetation was influenced by the presence of thinning, but not influenced by thinning intensity in this study.

Inorganic nitrogen dynamics of throughfall following fertilization in a red pine stand

ABSTRACT Inorganic nitrogen fluxes caused by rainfall and throughfall following fertilizer applications were measured in a red pine stand located in the Wola National Experimental Forest in Jinju, Korea. Fertilizer (N3P4K1 = 113:150:37 kg ha−1 yr−1) was applied for 2 years, and inorganic nitrogen fluxes were monitored from April 2011 to March 2013. Monthly variations in inorganic nitrogen concentrations were generally higher in the throughfall than in the rainfall, whereas monthly variations in concentrations were similar between the fertilized and control treatments. The mean NH4+ and NO3− concentrations during the study period were 0.39 and 0.21 mg L−1 for the rainfall, 1.06 and 1.06 mg L−1 for the control, and 1.01 and 0.89 mg L−1 for the fertilizer treatments, respectively. Inorganic nitrogen fluxes were generally higher during the growing season (May–October) than during the dormant season (November–April). Inorganic nitrogen fluxes were higher in the throughfall (17.03 kg ha−1 yr−1 in the control treatments and 14.93 kg ha−1 yr−1 in the fertilizer treatments) than in the rainfall (10.66 kg ha−1 yr−1). This result indicates that inorganic nitrogen concentrations and fluxes of throughfall are affected by the amount of throughfall rather than by fertilizer application in a red pine stand.