Contrasting nitrate leaching from an abandoned Moso bamboo forest and a Japanese cedar plantation: Role of vegetation in mitigating nitrate leaching

Abstract

Abstract Background Nitrate (NO3−) leaching from forest ecosystems can differ depending on the plant species because of differences in nitrogen (N) retention capacities. Abandoned Moso bamboo, which invades adjacent woody forests worldwide, has high nitrate reductase activity and may increase N retention. However, little is known about the effect of bamboo invasion on forest NO3− leaching and its potential factors. Methods We measured NO3− concentrations in soil solutions at a Moso bamboo site (BF) and an adjacent Japanese cedar plantation (CF). We also evaluated soil nitrification and plant N uptake by the in situ depletion method. Results The NO3− concentration in the soil solution below the root zone (50 cm) was lower in BF (48 ± 8 µmol L-1) than in CF (305 ± 16 µmol L− 1). The NO3− concentration in the soil solution was significantly higher for surface soil (0–5 cm) (111 ± 11 µmol L− 1) than for soil below the root zone in BF, but not significantly different between these two layers in CF (357 ± 25 µmol L− 1), indicating high N retention in BF. The net nitrification rates, root NO3− uptake rates, and fine root biomass were higher in BF than in CF, indicating that plant N uptake could be the main contributors to the low NO3− leaching. Conclusions Bamboo invasion has the potential to mitigate forest NO3− leaching due to its high N uptake. Our findings highlight the importance of vegetation with higher N uptake in enhancing N retention under elevated atmospheric N deposition.