Journal cover Journal topic
Biogeosciences An interactive open-access journal of the European Geosciences Union
Journal topic
Volume 15, issue 1
Biogeosciences, 15, 369–377, 2018
https://doi.org/10.5194/bg-15-369-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Biogeosciences, 15, 369–377, 2018
https://doi.org/10.5194/bg-15-369-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Research article 17 Jan 2018

Research article | 17 Jan 2018

Nitrogen isotopic composition of plants and soil in an arid mountainous terrain: south slope versus north slope

Chongjuan Chen1, Yufu Jia1, Yuzhen Chen1, Imran Mehmood2, Yunting Fang3, and Guoan Wang1 Chongjuan Chen et al.
  • 1Beijing Key Laboratory of Farmland Soil Pollution Prevention-control and Remediation, Department of Environmental Sciences and Engineering, College of Resources and Environmental Sciences, China Agricultural University, Beijing, 100193, China
  • 2Key Laboratory of Plant-Soil Interactions, MOE, Department of Plant Nutrition, College of Resources and Environmental Sciences, China Agricultural University, Beijing, 100193, China
  • 3CAS Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, 110164, China

Abstract. Nitrogen cycling is tightly associated with environment. The south slope of a given mountain could significantly differ from north slope in environment. Thus, N cycling should also be different between the two slopes. Since leaf δ15N, soil δ15N and Δδ15Nleaf-soilδ15Nleaf-soil =  leaf δ15N − soil δ15N) could reflect the N cycling characteristics, we put forward a hypothesis that leaf δ15N, soil δ15N and Δδ15Nleaf-soil should differ between the two slopes. However, such a comparative study between two slopes has never been conducted. In addition, environmental effects on leaf and soil δ15N derived from studies at global scale were often found to be different from those on a regional scale. This led to our argument that environmental effects on leaf and soil δ15N could depend on local environment. To confirm our hypothesis and argument, we measured leaf and soil δ15N on the south and north slopes of Tian Shan. Remarkable environmental differences between the two slopes provided an ideal opportunity for our test. The study showed that leaf δ15N, soil δ15N and δ15Nleaf-soil on the south slope were greater than those on the north slope, although the difference in soil δ15N was not significant. The result confirmed our hypothesis and suggested that the south slope has higher soil N transformation rates and soil N availability than the north slope. In addition, in this study it was observed that the significant influential factors of leaf δ15N were temperature, precipitation, leaf N, leaf C ∕ N, soil moisture and silt ∕ clay ratio on the north slope, whereas on the south slope only leaf C ∕ N was related to leaf δ15N. The significant influential factors of soil δ15N were temperature, precipitation, soil moisture and silt ∕ clay ratio on the north slope, whereas on the south slope, mean annual precipitation and soil moisture exerted significant effects. Precipitation exerted contrary effects on soil δ15N between the two slopes. Thus, this study supported our argument that the relationships between leaf and soil δ15N and environmental factors are localized.

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The south slope of Tian Shan differs from the north slope in environment. The study showed that leaf δ15N, soil δ15N and △δ15Nleaf-soil on the south slope were greater than those on the north slope. The significant influential factors of leaf and soil δ15N on the south slope were different from those on the north slope. The results suggested that the south slope has higher soil N transformation rates than the north slope and relationships between leaf and soil δ15N and environment are localized.
The south slope of Tian Shan differs from the north slope in environment. The study showed that...
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