In forest ecosystems, understanding the relationship between the vertical distribution of fine roots and residual soil nitrogen is essential for clarifying the diversity–productivity–water purification relationship. Vertical distributions of fine-root biomass (FRB) and concentrations of nitrate-nitrogen (NO3-N) in soil water were investigated in a conifer plantation with three thinning intensities (Control, Weak and Intensive), in which hardwood abundance and diversity were low, moderate and high, respectively. Intensive thinning led to the lowest NO3-N concentration in soil water at all depths (0–100 cm) and highest FRB at shallow depths (0–50 cm). The NO3-N concentration at a given depth was negatively correlated with total FRB from the surface to the depth at which NO3-N concentration was measured, especially at shallow depths, indicating that more abundant fine roots led to lower levels of downward NO3-N leaching. FRB contributed positively to nitrogen content of hardwood leaves. These findings demonstrate that a hardwood mixture in conifer plantations resulted in sufficient uptake of NO3-N from soil by well developed fine-root systems, and translocation to canopy foliage. This study suggests that productivity and water purification can be achieved through a hardwood mixture in conifer plantations.
|出版ステータス||Published - 2022 8月|
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