TY - JOUR
T1 - Factors contributing to soil nitrogen mineralization and nitrification rates of forest soils in the Japanese archipelago
AU - Urakawa, Rieko
AU - Ohte, Nobuhito
AU - Shibata, Hideaki
AU - Isobe, Kazuo
AU - Tateno, Ryunosuke
AU - Oda, Tomoki
AU - Hishi, Takuo
AU - Fukushima, Keitaro
AU - Inagaki, Yoshiyuki
AU - Hirai, Keizo
AU - Oyanagi, Nobuhiro
AU - Nakata, Makoto
AU - Toda, Hiroto
AU - Kenta, Tanaka
AU - Kuroiwa, Megumi
AU - Watanabe, Tsunehiro
AU - Fukuzawa, Karibu
AU - Tokuchi, Naoko
AU - Ugawa, Shin
AU - Enoki, Tsutomu
AU - Nakanishi, Asami
AU - Saigusa, Nobuko
AU - Yamao, Yukio
AU - Kotani, Ayumi
N1 - Funding Information:
This study was conducted as part of the GRENE (Green Network of Excellence) environmental information project (PI: Motomi Itoh, University of Tokyo) from the Ministry of Education, Culture, Sports, Science and Technology, Japan. This work was also supported by the ReSIN-III (Regional and comparative Soil Incubation study on Nitrogen dynamics in forest ecosystems-III) project and Grant-in-Aid for Scientific Research funded by the Japan Society for the Promotion of Science ( 25252026 , 26660127 and 15K14756 ). We would like to thank the technical staff of the experimental forests and centers where the samples were collected for their support and cooperation. We appreciate the valuable comments from two anonymous reviewers.
Publisher Copyright:
© 2015 Elsevier B.V.
PY - 2016/2/1
Y1 - 2016/2/1
N2 - Nitrogen (N) is the primary limiting nutrient for forest production. Therefore, understanding how environmental factors affect N transformation rates is essential for the provision of sustainable ecosystem services. Because these factors are interlinked, it is important to consider direct and indirect structural relationships to better understand the factors contributing to N transformations. In this study, we analyzed the structural cause-effect relationships surrounding N transformations by structural equation modeling using a database containing net and gross N transformation rates and related soil chemical properties from 38 sites across the Japanese archipelago. The average net N mineralization and nitrification rates in the Japanese forest soils were 0.62±0.68 and 0.59±0.65mgNkg-1d-1, respectively, and gross N mineralization and nitrification rates were 4.22±3.59 and 0.98±0.68mgNkg-1d-1, respectively. Compared with previous large scale studies, net and gross N transformation rates in Japanese forest soils were considerably diverse despite their relatively small land area and were representative of temperate forest ecosystems. Structural equation modeling analysis showed that net N transformations were directly affected by gross N transformations, which in turn were significantly and directly affected by soil organic matter contents. Soil organic matter was significantly affected by organic layer amount, tree species and soil group. The effect of soil group was the greatest among these factors, suggesting that soil organic matter contents in Japanese forest soils were mainly influenced by soil parent materials. This was especially evident for Andosols, which are derived from volcanic sediments and contain large amounts of soil organic matter leading to high N transformation rates in the Japanese forest soils. Among the factors related to organic layers and mineral soil layers, soil organic matter content and organic layer amount, which represent substrate availability, had significant effects on gross and net N transformation rates. However, by refining the scale of the dataset using soil groups/soil parent materials, the influence of substrate quality and soil chemical properties on N transformations was suggested. From the current dataset, it was indicated that soil parent materials were the most important factor controlling the pattern of N transformations in the soil of Japanese forest ecosystems. This conclusion should be repeatedly refined considering the spatial distribution of factors such as climatic conditions and forest types with additional site datasets obtained from future surveys.
AB - Nitrogen (N) is the primary limiting nutrient for forest production. Therefore, understanding how environmental factors affect N transformation rates is essential for the provision of sustainable ecosystem services. Because these factors are interlinked, it is important to consider direct and indirect structural relationships to better understand the factors contributing to N transformations. In this study, we analyzed the structural cause-effect relationships surrounding N transformations by structural equation modeling using a database containing net and gross N transformation rates and related soil chemical properties from 38 sites across the Japanese archipelago. The average net N mineralization and nitrification rates in the Japanese forest soils were 0.62±0.68 and 0.59±0.65mgNkg-1d-1, respectively, and gross N mineralization and nitrification rates were 4.22±3.59 and 0.98±0.68mgNkg-1d-1, respectively. Compared with previous large scale studies, net and gross N transformation rates in Japanese forest soils were considerably diverse despite their relatively small land area and were representative of temperate forest ecosystems. Structural equation modeling analysis showed that net N transformations were directly affected by gross N transformations, which in turn were significantly and directly affected by soil organic matter contents. Soil organic matter was significantly affected by organic layer amount, tree species and soil group. The effect of soil group was the greatest among these factors, suggesting that soil organic matter contents in Japanese forest soils were mainly influenced by soil parent materials. This was especially evident for Andosols, which are derived from volcanic sediments and contain large amounts of soil organic matter leading to high N transformation rates in the Japanese forest soils. Among the factors related to organic layers and mineral soil layers, soil organic matter content and organic layer amount, which represent substrate availability, had significant effects on gross and net N transformation rates. However, by refining the scale of the dataset using soil groups/soil parent materials, the influence of substrate quality and soil chemical properties on N transformations was suggested. From the current dataset, it was indicated that soil parent materials were the most important factor controlling the pattern of N transformations in the soil of Japanese forest ecosystems. This conclusion should be repeatedly refined considering the spatial distribution of factors such as climatic conditions and forest types with additional site datasets obtained from future surveys.
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U2 - 10.1016/j.foreco.2015.11.033
DO - 10.1016/j.foreco.2015.11.033
M3 - Article
AN - SCOPUS:84949294814
VL - 361
SP - 382
EP - 396
JO - Forest Ecology and Management
JF - Forest Ecology and Management
SN - 0378-1127
ER -