Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Fukuoka, Japan.
Kyushu University Forest, Kyushu University, 394 Tsubakuro, Sasaguri, Fukuoka, 811-2415, Japan.
Sci Rep. 2021 Mar 5;11(1):5335. doi: 10.1038/s41598-021-84753-1.
This study aimed to evaluate nitrogen (N) leaching from Japanese cedar, the main plantation species in Japan, in response to elevated atmospheric N deposition. N leaching and possible factors, including soil nitrification, tree N uptake, and topographic steepness, were evaluated in mature (64-69 year) Japanese cedar trees planted on steep slopes (25°-40°) and neighboring Japanese oak plantations in suburban forests, which served as reference sites. N fertilization (50 kg N ha year as ammonium nitrate) was conducted to evaluate the response of N leaching to an elevated inorganic N pool in the surface soil. The soil water nitrate (NO) concentration below the rooting zone in the Japanese cedar forest (607 ± 59 μmol L) was much higher than that in the Japanese oak plantations (8.7 ± 8.1 μmol L) and increased immediately after fertilization, indicating high N leaching from the Japanese cedar plantations. The relatively low N uptake by Japanese cedar planted on the steep slopes could be an important contributor to the high N leaching. This study highlights the importance of vegetation composition for managing the water quality in headwater streams from forest ecosystems disturbed by atmospheric N deposition.
本研究旨在评估日本主要造林树种日本雪松对大气氮沉降增加的氮淋失响应。在郊区森林中，对种植在陡坡（25°-40°）上的成熟（64-69 年）日本雪松和邻近的日本栎树林（作为对照点）进行了氮淋失和可能的因素（包括土壤硝化、树木氮吸收和地形陡峭程度）评估。进行氮施肥（50 kg N ha 年作为硝酸铵）以评估氮淋失对表层土壤中无机氮库增加的响应。日本雪松林根区以下土壤水中硝酸盐（NO）浓度（607 ± 59 μmol L）远高于日本栎树林（8.7 ± 8.1 μmol L），且施肥后立即升高，表明日本雪松林有大量氮淋失。种植在陡坡上的日本雪松吸收的氮相对较少，这可能是氮淋失较高的一个重要原因。本研究强调了植被组成对于管理受大气氮沉降干扰的森林生态系统集水区水质的重要性。
