A-Ram Yang

Influence of thinning on carbon storage in a Japanese larch (Larix kaempferi) plantation in Yangpyeong, central Korea.

This study was conducted to determine the carbon (C) contents in a Japanese larch (Larix kaempferi) plantation with four different thinning intensities over 12 years in Yangpyeong, central Korea. Thinning was applied in April of 1997 [control, no thinning (2250 trees/ha)], light thinning (T10, 10% thinning, 2000 trees/ha after thinning), moderate thinning (T20, 20%thinning, 1750 trees/ha after thinning), and heavy thinning (T40, 40% thinning, 1200 trees/ha after thinning)]. We measured individual tree DBH (cm) in November, 2009 and calculated biomass using the allometric regression equation. Forest floor (litter and coarse woody debris (CWD)) and soils, litter and soils up to 30 cm were collected and analyzed. Even though tree survival rate during 12 years was highest in the heavy thinning plot (T40), vegetation C content (Mg C/ha) was significantly higher in the light thinning plot (T10) than the other plots: 58.5 for control, 64.9 for T10, 60.4 for T20, and 55.8 for T40, respectively. Moreover, total soil C content (Mg C/ha) was higher in the moderate thinning plot (T20), however, there was no significant difference among the other plots; 56.2 for control, 57.8 for T10, 63.7 for T20, and 62.3 for T40. C contents of forest floor (litter plus CWD) were largest in the control plot, which might be influenced by the individual tree species competition; 11.9 for control, 10.2 for T10, 10.1 for T20, and 6.6 for T40, respectively. Total ecosystem C content was higher in the moderate thinning plot (T20) than those in other thinned and unthinned plots: 125.2 for control, 131.2 for T10, 132.4 for T20, and 125.9 for T40, respectively. Moderate thinning treatment (T20) seemed more effective to conserve total ecosystem C content while the individual tree growth (mean DBH and height) was higher in the heavy thinning plot (T40).

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.

Effect of thinning on carbon storage in soil, forest floor and coarse woody debris of Pinus densiflora stands with different stand ages in Gangwon-do, central Korea

This study was conducted to investigate effects of thinning on carbon (C) storage of soil, forest floor and coarse woody debris (CWD) in Pinus densiflora stands, central Korea. Two study stands (25- and 55-year-old stands) were located in P. densiflora forests of Gangwon-do and thinned in 2008. Each stand was divided into three plots by different thinning intensities based on stand density: no thinning (control, 0%), moderate thinning (M, 30%), and heavy thinning (H, 50%) in the 25-year-old stand and no thinning (control, 0%), light thinning (L, 20%), and moderate thinning (M, 30%) in the 55-year-old stand. We measured C storage of 0–30 cm depth soil, forest floor and CWD in 2009. Total C storage (t C ha−1) of soil, forest floor and CWD in two thinned plots was significantly higher than that in the control plot only in the 55-year-old stand: 66.4 for control, <84.2 for L, <117.9 for M. On the other hand, total C storage in the 25-year-old stand did not show a consistent tendency among thinning intensities. We speculated that 1 year was too short to detect any consistent changes in total C storage of soil, forest floor and CWD by thinning, and long-term observation would be needed.

Influence of forest tending (Soopkakkugi) works on litterfall and nutrient inputs in a Pinus densiflora stand

This study was conducted to examine litterfall and nutrient inputs following forest tending works (FTW) which are one of the most important forest management activities in Korea. We measured litterfall and nutrient (C, N, P, K, Ca, Mg) inputs from needle litter in FTW and non-FTW (control) stands of approximately 40-year-old red pine (Pinus densiflora S. et Z.) forests in the Hwangmaesan Soopkakkugi model forest in Sancheonggun Gyeongsangnam-do, Korea. Seasonal inputs of litterfall components such as needle, broadleaf, branch, bark and total litter inputs followed a similar pattern between the FTW and control stands. Annual average needle and total litterfall were significantly lower in the FTW (2483 kg ha−1 yr−1; 4038 kg ha−1 yr−1) than in the control stands (3377 kg ha−1 yr−1; 5589 kg ha−1 yr−1) during the study period. Nitrogen concentration of needle litter was significantly affected by FTW (P < 0.05), while other nutrient (C, P, K, Ca, Mg) concentrations were not significantly different between the FTW and control stands. There was a significant difference (P < 0.05) in the organic C, N, P and Ca inputs by needle litter following FTW, whereas K and Mg inputs were not significantly different between the FTW and control stands. The results indicate that the reduction of litterfall and nutrient inputs following FTW can be attributed to reduced needle litterfall and vary considerably nutrient cycle in FTW stands.

Changes in soil properties of Abies holophylla and Quercus-dominated stands 4 years after trenching

Abstract Few studies tried to isolate the influence of plant roots on the soil characteristics including soil carbon (C) and nitrogen (N) storage. We evaluated the impact of root trenching on soil characteristics of coniferous (Abies holophylla) and deciduous (Quercus spp.) stands 4 years after trenching. Trenching treatment significantly increased the soil water content and nitrate concentration in both stand types. Soil pH, cation exchange capacity, soil C and N pools and isotopic compositions of C and N were significantly different between two stands, but trenching was not found to have significant impact on these soil properties. Our results indicated that root trenching in coniferous and broad-leaved deciduous forests of temperate region could significantly alter soil moisture regime and inorganic N levels, but not C and N stabilization in soils.

Litter decomposition and nutrient dynamics following forest tending (Soopkakkugi) works in a Pinus densiflora stand

This study was conducted to determine mass loss rates and nutrient dynamics from decomposing litter following forest-tending (Soopkakkugi) works (FTW) which are one of the most important forest management activities in Korea. We measured litter decomposition rates for 2 years in FTW and non-FTW (control) stands of approximately 40-year-old red pine (Pinus densiflora S. et Z.) forests in the Hwangmaesan Soopkakkugi model forest in Sancheonggun Gyeongsangnam-do, Korea. Mass loss rates from decomposing needle litter were significantly lower (P < 0.05) in the FTW than in the control stands for three of the six sampling dates during the study period. Nutrient concentrations and nutrients remaining such as carbon, nitrogen, phosphorus, potassium, and magnesium from decomposing litter were significantly different (P < 0.05) between the FTW and control stands because of decreased mass loss rates by increased gaps following FTW. The results indicate that FTW clearly influence litter decomposition and nutrient dynamics from decomposing needle litter because of the change of environmental factors caused by partial canopy removal such as FTW.

Short-term effect of thinning on carbon storage in soil, forest floor and coarse woody debris of Quercus spp. stand in Hoengseong, Gangwon-do, Korea

This study was conducted to investigate the short-term effect of thinning on the carbon (C) storage of soil, forest floor and coarse woody debris (CWD) in a Quercus spp. stand in Hoengseong, Gangwon-do, Korea. Thinning was conducted in March 2010 with different thinning intensities based on the removed volume in each plot: no thinning (control, 0%), light thinning (L, 15%), moderate thinning (M, 20%), and heavy thinning (H, 35%). We measured the C storage at four different depths ranging from 0–50 cm, on the forest floor and in CWD four months after thinning in July 2010. The total C storage (Mg C ha−1) in soil, forest floor and CWD of L was significantly lower than that of the three other plots at an early stage of thinning: 38.5 for control, 31.1 for L, 40.6 for M and 45.8 for H. Further long-term monitoring will be needed to observe the total C storage in soil, forest floor and CWD in this study stand because the total C storage with different thinning intensities might vary temporally.

Carbon and Nitrogen Resorption of Needles As Affected by Compound Fertilizer in a Red Pine Stand

Abstract This study aimed to examine carbon (C) and nitrogen (N) resorption efficiency between green needles and needle litter in response to compound fertilizer types in a red pine stand. Green needles and needle litter were collected during the growing season (July, September) and during the heavy litterfall season (November) from two compound fertilizer (N3P4K1, P4K1) and control treatments. The C concentration of green needles and needle litter was not significantly (P > 0.05) affected by compound fertilizer, whereas the N concentration in green needles was significantly higher in the N3P4K1 than in the P4K1 and control treatments. C and N resorption efficiency was not significantly affected by compound fertilizer, but N resorption efficiency was significantly affected by sampling month (P < 0.05). N resorption efficiency was significantly higher in November, followed by September and July. In addition, N resorption efficiency was lower in the current-year needles than in the 1- or 2-year-old needles. These results demonstrate a lack of clear relation between C or N resorption efficiency and N availability in response to the compound fertilizer.