No impact of nitrogen fertilization on carbon sequestration in a temperate Pinus densiflora forest

Carbon (C) sequestration capacity in forest ecosystems is generally constrained by soil nitrogen (N) availability. Consequently, N fertilization is seen as a promising tool for enhancing ecosystem-level C sequestration in N-limited forests. We examined the responses of ecosystem C (vegetation and soil) and soil N dynamics to 3 years of annual nitrogen-phosphorus-potassium (N3P4K1 = 11.3 g N, 15.0 g P, 3.7 g K m−2 year−1) or PK fertilization (P4K1), observed over 4 years in a 40-year-old Pinus densiflora forest with poor N nutrition in South Korea. PK fertilization without N was performed to test for PK limitation other than N. Neither tree growth nor soil C fluxes responded to annual NPK or PK fertilization despite an increase in soil mineral N fluxes following NPK fertilization. NPK fertilization increased the rate of N immobilization and 80% of the added N was recovered from mineral soil in the 0–5 cm layer, suggesting that relatively little of the added N was available to trees. These results indicate that N fertilization does not always enhance C sequestration even in forests with poor N nutrition and should therefore be applied with caution

Soil properties of cultivation sites for mountain-cultivated ginseng at local level

AbstractBackgroundIdentifying suitable site for growing mountain-cultivated ginseng is a concern for ginseng producers. This study was conducted to evaluate the soil properties of cultivation sites for mountain-cultivated ginseng in Hamyang-gun, which is one of the most well-known areas for mountain-cultivated ginseng in Korea.MethodsThe sampling plots from 30 sites were randomly selected on or near the center of the ginseng growing sites in July and August 2009. Soil samples for the soil properties analysis were collected from the top 20 cm at five randomly selected points.ResultsMountain-cultivated ginseng was grown in soils that varied greatly in soil properties on coniferous, mixed, and deciduous broad-leaved stand sites of elevations between > 200 m and < 1,000 m. The soil bulk density was higher in Pinus densiflora than in Larix leptolepis stand sites and higher in the < 700-m sites than in > 700-m sites. Soil pH was unaffected by the type of stand sites (pH 4.35–4.55), whereas the high-elevation sites of > 700 m were strongly acidified, with pH 4.19. The organic carbon and total nitrogen content were lower in the P. densiflora stand sites than in the deciduous broad-leaved stand sites. Available phosphorus was low in all of the stand sites. The exchangeable cation was generally higher in the mixed and low-elevation sites than in the P. densiflora and high-elevation sites, respectively.ConclusionThese results indicate that mountain-cultivated ginseng in Korea is able to grow in very acidic, nutrient-depleted forest soils

Carbon and nitrogen accumulation and decomposition from coarse woody debris in a naturally regenerated Korean red pine (pinus densiflora S. et Z.) forest

The contribution of coarse woody debris (CWD) to forest carbon (C) and nitrogen (N) dynamics is poorly quantified. This study quantified total C and N content in CWD and estimated the decomposition rates of CWD at different decay stages in a 70-year-old naturally regenerated Korean red pine forest (Pinus densiflora S. et Z.). The N concentration in CWD varied among species and decay classes (from 0.15% to 0.82%), and exhibited a decreasing pattern in C:N ratios with increasing decay class. Total CWD amounts of 4.84 Mg C ha−1, dominated by pine logs (45.4%) and decay class III (40.0%), contained total N of 20.48 kg N ha−1, which was approximately nine times the N input from annual tree mortality. In addition, this study demonstrated that the decay constant rate k was 0.2497 for needle litter, whereas k values were 0.0438, 0.0693, 0.1054, and 0.1947 for red pine CWD of decay class I, II, III, and IV, respectively. The decay rates were significantly related to wood density, N concentration, and C:N ratio across the decay classes of CWD. The results suggest that the C:N ratio of CWD is a key factor affecting its decomposition

Carbon and nitrogen status of decomposing roots in three adjacent coniferous plantations

<p>This study evaluated the carbon (C) and nitrogen (N) status of decomposing roots in three adjacent plantations consisting of one deciduous (larch: Larix leptolepis) and two evergreen (red pine: Pinus densiflora; rigitaeda pine: P. rigitaeda) species planted in the same year (1963) under similar site conditions. The mass loss rates and C and N status of three diameter classes of roots (UF &lt; 2 mm, F 2-5 mm, CF 5-10 mm in diameter) were examined in the upper 15 cm of the mineral soil using in situ buried root bags for 496 days.The remaining mass of decomposing roots was significantly higher for larch (69.0%) than for red pine (59.6%) or rigitaeda pine (59.1%) over 496 days. The mass loss rates of decomposing roots did not differ significantly among the three root diameter classes, but the C and N status of decomposing roots was affected by the tree species. The larch roots showed low C concentrations but high N concentrations, C and N remaining compared to the pine roots over the study period. The results indicate that the substrate quality indicators of roots were not attributed to the mass loss rates, C and N status of decomposing roots in three coniferous tree species grown under similar environmental conditions.</p

Heterotrophic Soil Respiration Affected by Compound Fertilizer Types in Red Pine (Pinus densiflora S. et Z.) Stands of Korea

This study was conducted to evaluate the effects of fertilizer application on heterotrophic soil respiration (Rh) in soil respiration (Rs) components in red pine stands. Two types of fertilizer (N3P4K1 = 113:150:37 kg·ha−1·year−1; P4K1 = 150:37 kg·ha−1·year−1) were applied manually on the forest floor for two years. Rs and Rh rates were monitored from April 2011 to March 2013. Mean Rs and Rh rates were not significantly affected by fertilizer applications. However, Rh in the second year following fertilizer application fell to 27% for N3P4K1 and 17% in P4K1 treatments, while there was an increase of 5% in the control treatments compared with the first fertilization year. The exponential relationships between Rs or Rh rates and the corresponding soil temperature were significant (Rh: R2 = 0.86–0.90; p &lt; 0.05; Rs: R2 = 0.86–0.91; p &lt; 0.05) in the fertilizer and control treatments. Q10 values (Rs increase per 10 °C increase in temperature) in Rs rates were lowest for the N3P4K1 treatment (3.47), followed by 3.62 for the P4K1 treatment and 3.60 in the control treatments, while Rh rates were similar among the treatments (3.59–3.64). The results demonstrate the importance of separating Rh rates from Rs rates following a compound fertilizer application

Carbon and nitrogen status by decay class in fallen dead wood of three pine species in southern Korea

AbstractThe importance of a quantitative assessment of C and N contents of dead wood is increasing in forest ecosystems. This study aimed to determine the density and carbon (C) and nitrogen (N) status of dead wood with decay class for three pine species (Pinus densiflora, Pinus rigida, and Pinus koraiensis) in southern Korea. The C concentration in dead wood was significantly different among species (P. densiflora, 50.31%; P. koraiensis, 47.22%; P. rigida, 44.96%), whereas decay class did not affect the C concentration (p > 0.05). The density and C content of dead wood in all species decreased with increasing decay class. The N concentrations of dead wood increased more rapidly in P. rigida and P. koraiensis than in P. densiflora, with an increasing decay class. Thus, the N content of dead wood was unchanged or increased in P. rigida and P. koraiensis, whereas that of P. densiflora decreased because of density reduction with increasing decay class. Our results indicate that the unchanged, increased, or decreased status of C and N in dead wood depends on the species and decay class

Canopy cover effects on nitrogen and phosphorus status in understory vegetation in oak and pine stands

The rate of change of leaf mass, N and P levels in understory vegetation at various levels of canopy cover were measured for 2 years following canopy cover manipulations in northern red oak (Quercus rubra L.) and red pine (Pinus resinosa Ait.) stands in northern Lower Michigan, USA. Canopy cover treatments consisted of clearcut, 25% (50% during first sampling year), 75%, and uncut. Leaf mass, and N and P contents were significantly higher in the clearcut treatment than in other canopy cover treatments, except for the 25% treatment in red pine stands. Leaf N concentrations in understory vegetation were also significantly higher in the clearcut (1991, 20.8 mg g−1; 1992, 22.4 mg g−1) than in the uncut treatment (1991, 16.5 mg g−1; 1992, 16.9 mg g−1). Canopy type (northern red oak and red pine) had little influence on understory nutrient status and leaf mass. In addition, fronds of bracken ferns in all canopy cover treatments in both northern red oak and pine stands were a major sink of nutrients in the understory. The results of this study showed that partial canopy removal generally had only a minor impact on understory leaf production and nutrient status compared with clearcuts during the 2-year period following canopy removal

Carbon and Nitrogen Responses in Litterfall and Litter Decomposition in Red Pine (Pinus densiflora S. et Z.) Stands Disturbed by Pine Wilt Disease

Research Highlight: Forest disturbance by insects or disease can have a significant influence on nutrient return by litterfall and decomposition, but information regarding disturbance gradients is scarce. This study demonstrated that the disturbance intensity caused by pine wilt disease greatly altered the quality and quantity of carbon (C) and nitrogen (N) in litterfall components and decomposition processes. Background and Objectives: This study was conducted to evaluate the C and N status of litterfall and litter decomposition processes in a natural red pine (Pinus densiflora S. et Z.) stand disturbed by pine wilt disease in southern Korea. Nine red pine plots with varying degrees of disturbance caused by pine wilt disease were established based on differences in the stand basal area. Litterfall and the decomposition of needle litter and branches under different degrees of disturbance were measured for three years. Results: There was a significant correlation (p &lt; 0.05) between disturbance intensity and the C and N concentration of litterfall components depending on the time of sampling. The annual C and N inputs through litterfall components decreased linearly with decreasing disturbance intensities. The decomposition rates of branches were higher in slightly disturbed plots compared with severely disturbed plots for the late stage of branch decomposition, whereas the decomposition rates of needle litter were not affected by the disturbance intensity of pine wilt disease. Carbon and N concentrations from needle litter and branches were not linearly related to the intensities of disturbance, except for the initial stage (one year) of needle litter decomposition. Conclusions: The results indicated that the incidence of pine wilt disease was a major cause of C and N loss through litterfall and decomposition processes in pine wilt disease disturbed stands, but the magnitude of loss depended on the severity of the disease disturbance

Canopy cover effects on mass loss, and nitrogen and phosphorus dynamics from decomposing litter in oak and pine stands in northern Lower Michigan

Patterns of litter decomposition and nitrogen (N) and phosphorus (P) release in relation to various levels of canopy cover were examined using litterbags placed on the forest floor of northern red oak (Quercus rubra L.) and red pine (Pinus resinosa Ait.) stands in northern Lower Michigan, USA. A series of experimental plots consisted of four levels of canopy cover treatments, i.e. clearcut, 25% (50% during first sampling year), 75%, and uncut. Mass loss from decomposing leaves was higher for oak leaves in red oak stands (approximately 60% loss of the original mass) than for pine needles in red pine stands (approximately 40% loss of the original mass) during the 2 year study period. Leaf mass loss in the clearcut red oak treatment was significantly higher than in the uncut red oak treatment. In contrast, no canopy cover effects on litter mass loss were found in red pine stands. Nitrogen concentrations in decomposing litter increased during the 2 year period in all canopy cover treatments in both stand types, but they did not differ significantly among canopy cover treatments. These results indicate that various levels of red oak and red pine canopy removal generally have a minor impact on litter decomposition and nutrient (N and P) release during the first 2 years following canopy manipulation, except in red oak clearcuts. © 1996 Elsevier Science B.V. All rights reserved

Canopy cover effects on soil nitrogen mineralization in northern red oak (Quercus rubra) stands in northern Lower Michigan

It has been shown in many studies of nutrient cycling in forest ecosystems that clearcutting creates increased nitrogen (N) mineralization in the soils. However, little is known about the direction and rate of change of N mineralization following various levels of canopy removal in northern red oak (Quercus rubra L.) stands, despite the fact that an understanding of these processes may have important implications for self-replacement in such stands. Accordingly, a series of experimental plots was manipulated to produce various levels of canopy cover, i.e. clearcut, 25% (50% during first sampling year), 75%, and uncut in northern red oak stands in northern Lower Michigan. Net N mineralization and nitrification in the top 15 cm of mineral soil were examined during the first two growing seasons (1991–1992) following the treatments, using an in situ buried bag technique. Net N mineralization over the course of both growing seasons (May–October) ranged from 79 kg ha−1 per growing season in the clearcut treatment to 22 kg ha−1 per growing season in the uncut stand. The highest net N mineralization was observed in the clearcut with the highest increase of soil temperature. Net N mineralization was significantly higher in the partial canopy cover treatments compared to the uncut stand during the second growing season, but not in the first growing season. Nitrification was unaffected by factors such as increased soil pH, elevated NH4+ availability, and soil temperature after canopy removal. The results indicated that even small amounts of canopy removal (leaving 75% canopy cover) are sufficient to cause substantial increases in the amount of N available for the establishment and growth of understory oaks