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Son, Yo-Whan,Lee, Yoon-Young,Kim, Rae-Hyun,Seo, Kyung-Won,Ban, Ji-Yeon,Seo, Kum-Young,Koo, Jin-Woo,Kyung, Ji-Hyun,Noh, Nam-Jin The Ecological Society of Korea 2004 Journal of Ecology and Environment Vol.27 No.6
Photosynthetically active radiation (PAR) beneath the forest canopy, understory species richness and diversity, and biomass were measured in a Larix leptolepis plantation seven years after thinning in Yangpyeong. Four different thinning intensities (control, $10\%,\;20\%\;and\;40\%$ stocking reduction) were applied in 1997. The current PAR values were lower than those measured four years after thinning, and PAR at the heavy thinning plots was significantly higher than that of other thinning intensities. A total of 23 species including 9 tall-trees and 14 shrubs were found for the high layer while a total of 82 species including 10 tall-trees, 29 shrubs, and 43 herbs for the low layer. Species richness and diversity generally increased with thinning intensities, and the trends were more evident for the low layer. Aboveground biomass significantly differed among thinning intensities for both shrubs and herbs. Also there was a negative correlation between biomass and the current number of stems per hectare. The current study suggested that the effects of thinning on light conditions at the forest floor, species richness and diversity and production of understory vegetation continued seven years after the treatment.
Yo Whan Son 한국산림과학회 1994 한국산림과학회지 Vol.83 No.1
Nitrogen and phosphorus cycling was examined for 28-year-old red oak (Quercus rubra L.), European larch (Larix decidua Miller) , white pine (Pinus strobus L.), red pine(Pinus resinosa Ait.) and Norway spruce(Picea abies(L) Karst.) plantations on a similar soil in southwestern Wisconsin. The concentration and content of several soil nutrients differed among the five species but no consistent pattern was observed between deciduous and evergreen species. In .general, total N and P content were greatest in the upper 30cm soil followed by aboveground vegetation and forest floor. Total N and P content with leaf longevity. Annual aboveground N and P requirement (㎏/㏊/yr) totaled 126 and 13 for red oak, 86 and 9 for European larch, 80 and 9 for white pine, 38 and 6 for red pine, and 81 and 13 for Norway spruce, respectively. In three evergreen species, uptake accounted for 72-74% of the annual N requirement whereas retranslocation accounted for 76-77% of the annual N requirement for two deciduous species. Nitrogen and P use efficiency (ANPP/uptake) was more efficient in deciduous species than evergreen species. Annual net N mineralization in the top 20cm of forest floor plus mineral soil differed significantly(p 0.05) among the five species and ranged from 53㎏/㏊/yr for red oak to 117㎏/㏊/yr for European larch. Annual nitrification also differed significantly (p$lt;0.05) among species and comprised from 40% for red oak to 95% for European larch of total annual net N mineralized. Annual leaf litterfall N content(㎏/㏊/yr) over the two years(1988-1989) ranged from 22 for white pine to 53 for Norway spruce but did not explain a significant amount of the observed variation of annual N mineralized among the five species. We speculate that other differences in litter quality may be controlling N mineralization. The results from this common garden experiment demonstrate that differences in N and P cycling among the five species may result from intrinsic characteristics e.g. leaf longevity) rather than environmental conditions.
손요환(Yo Whan Son),이숙희(Sook Hee Lee) 한국산림과학회 2001 한국산림과학회지 Vol.90 No.3
Changes in land-use can affect soil organic matter content and fertility. We compared total soil carbon and nitrogen concentrations, soil respiration, and nitrogen availability under three land-use types in central Korea; conversion of old rice field to natural willow-maple (Salix-Acer) forest, conversion of old field to artificial Korean pine (Pines koraiensis) forest, and indigenous oak (Quercus spp.) forest. After 20 years of fallow the area of rice field conversion to forest had higher soil carbon and nitrogen concentrations in the soil depth of 0-10㎝ and 10-20㎝ than the areas of field conversion to Korean pine forest and indigenous forest. In general, soil carbon and nitrogen concentrations decreased with soil depth. Organic matter accumulation as a balance of input and decomposition seemed to be higher in the soil of previous rice field, and carbon and nitrogen accumulation was largely confined to the topsoil. Soil respiration rates were greatest at the area of rice field conversion to forest, and apeared to be related to soil carbon and soil moisture. Soil nitrogen availability measured by the ion exchange resin bag method differed significantly among land-use types; soil inorganic nitrogen (NH₄^+ + NO₃^-) and ammonium availability were highest in the soil under indigenous oak forest followed by conversion of old field to artificial Korean pine forest and conversion of old field to natural willow-maple forest.
리기다소나무와 낙엽송 인공조림지내 (人工造林地內) 토양발생 이산화탄소에 관한 연구
손요환(Yo WHan Son),김현우(Hyun Woo Kim) 한국산림과학회 1996 한국산림과학회지 Vol.85 No.3
Soil respiration was measured every two weeks from May through November 1995 using the soda lime method in 40-Year-old Pinus rigida and Larix leptolepis plantations on a similar soil in Yangpyeong, Kyonggi Province. Treatments included control and no-roots(plots trenched and root regrowth into plots prevented). Root respiration was evaluated by comparing no-roots sub-plots to control plots. Mean soil respiration showed highly significant species effects(p $lt; 0.01) and was highest at the Pinus rigida control plot(0.38g/㎡/hr) and lowest at the Larix leptolepis no-roots plot(0.31g/㎡/hr). High soil respiration in Pinus rigida may be related to aboveground litter production. The annual CO₂ fluxes ranged from 23 to 27t/ha/yr. We found significant correlations between temperatures(air : R²=0.53, soil : R²=0.55) and soil respiration(p$lt;0.01), but no significant correlations between soil moisture and soil respiration(p$gt;0.1). Root respiration was 3% of total soil respiration. We might underestimate rapt respiration because of shallow trenches and CO₂ measurements right after trenching. Factors controlling soil respiration including belowground litterfall(especially fine roots) inputs, litter quality should be well understood to predict soil carbon fluxes and relative contributions to total soil respiration in forest ecosystems.