Fertilizers are commonly applied to improve the productivity and quality of bamboo. However, the nutrient responses of bamboo components after regular fertilization are not fully understood. This study was carried out to determine the effects of regular fertilization on the nutrient distribution of biomass components (i.e., culms, branches, leaves, roots, rhizomes) in a Moso bamboo stand in southern Korea. The study site was fertilized regularly for approximately 30 years to produce edible bamboo shoots. A total of 20 bamboo plants (10 fertilized and 10 unfertilized) were cut to measure the nutrient (C, N, P, K, Ca, Mg) concentrations of each bamboo component. Belowground roots and rhizomes were sampled at a 30-cm soil depth. The N, P, and K concentrations and stocks of aboveground biomass components were increased by regular fertilization, whereas the C, Ca, and Mg stocks were attributed to culm densities. The nutrient stocks of belowground roots were significantly lower in the fertilized plots than those in the unfertilized plots, except for the P stocks. The results indicate that regular fertilization could be a key factor to maintaining bamboo shoot productivity because of the increased responses of the nutrient concentration and stocks of bamboo components.

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 < 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.

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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 (N 3 P 4 K 1 , P 4 K 1) 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 N 3 P 4 K 1 than in the P 4 K 1 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.

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 (N 3 P 4 K 1 = 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 NH 4 + and NO 3 ¡ 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.