Abstract
ABSTRACTInorganic 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.
Highlights
Throughfall is the part of the incident rainfall that either falls to the soil surface directly through gaps in the canopy or drips from branches and foliage (Crockford and Khanna 1997; Bhat et al 2011)
Fluxes, and electrical conductivity (EC) during the 2 year study period were generally lower in the rainfall than in the throughfall (Figure 2), whereas those values in the throughfall were not significantly affected (P > 0.05) by fertilizer application (Figure 2)
The inorganic nitrogen concentration and EC in the throughfall showed clear monthly peaks (October 2011, June 2012) in which the concentration increased during the lowest rainfall month; those values of the rainfall were not related to monthly rainfall patterns
Summary
Throughfall is the part of the incident rainfall that either falls to the soil surface directly through gaps in the canopy or drips from branches and foliage (Crockford and Khanna 1997; Bhat et al 2011). The nutrient content of throughfall may either decrease or increase through the canopy. Decreases reflect nutrient absorption by foliage, whereas increases result from nutrient leaching from foliage (Fan and Hong 2001). NO3¡ concentrations can be reduced in throughfall compared with rainfall because tree foliage absorbs nutrients from rainfall (Crockford and Khanna 1997). The absorption and release processes occurring in the canopy affect elemental concentrations in throughfall
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