Effects of chronic nitrogen application on the growth and nutrient status of a Japanese cedar (Cryptomeria japonica) stand
Authors: Nagakura, Junko; Akama, Akio; Mizoguchi, Takeo; Okabe, Hiroaki; Shigenaga, Hidetoshi; Yamanaka, Takashi
Source: Journal of Forest Research, Volume 11, Number 5, October 2006 , pp. 299-304(6)
Abstract:To investigate the potential effects of nitrogen (N) deposition on Japanese forests, a chronic N-addition experiment that included three treatments (HNO3, NH4NO3, and control) was carried out in a 20-year-old Japanese cedar (Cryptomeria japonica D. Don) stand in eastern Japan over 7 years. The amount of N applied was 168 kg N ha−1 year−1 on the HNO3 plots and 336 kg N ha−1 year−1 on the NH4NO3 plots. Tree growth, current needle N concentration, and soil solution chemistry were measured. Nitrogen application decreased the pH and increased NO3 −, Ca2+, Mg2+, and Al concentrations in the soil solution. The needle N concentration increased in both of the N plots during the first 3 years. Nevertheless, the annual increments in height and in the diameter at breast height of the Japanese cedars were not affected by N application, and no visible signs of stress were detected in the crowns. Our results suggest that young Japanese cedar trees are not deleteriously affected by an excess N load.
Document Type: Research article
Publication date: 2006-10-01