scholarly journals Nitrogen isotopic composition of plants and soil in an arid mountainous terrain: sunny slope versus shady slope

2017 ◽  
Author(s):  
Chongjuan Chen ◽  
Yufu Jia ◽  
Yuzhen Chen ◽  
Imran Mehmood ◽  
Yunting Fang ◽  
...  
Keyword(s):  
Environmental Effects ◽  
Regional Scale ◽  
Local Environment ◽  
Global Scale ◽  
Influential Factors ◽  
N Cycling ◽  
N Availability ◽  
Soil N ◽  
The Difference ◽  
Soil Δ15n

Abstract. Nitrogen cycling is tightly associated with environment. Sunny slope of a given mountain could significantly differ from shady slope in environment. Thus, N cycling should also be different between the two slopes. Since leaf δ15N, soil δ15N and △δ15Nleaf-soil (△δ15Nleaf-soil = leaf δ15N − soil δ15N) could reflect the N cycling characteristics, we put forward a hypothesis that leaf δ15N, soil δ15N and △δ15Nleaf-soil should differ across the two slopes. However, such a comparative study between two slopes has never been conducted yet. In addition, environmental effects on leaf and soil δ15N derived from studies at global scale were often found to be different from that at 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 sunny and shady slopes of Mount Tianshan. Remarkable environment 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 sunny slope were greater than that on the shady slope although the difference in soil δ15N was not significant. The result confirmed our hypothesis and suggested that the sunny slope has higher soil N transformation rates and soil N availability than the shady slope. Besides, this study observed that the significant influential factors of leaf δ15N were temperature, precipitation, leaf N, leaf C / N and silt / clay ratio on the shady slope, whereas on the sunny slope only leaf C / N was related to leaf δ15N. The significant influential factors of soil δ15N were temperature, precipitation and silt / clay ratio on the shady slope, whereas on the sunny slope MAP 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 local-dependent.

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

2018 ◽  
Vol 15 (1) ◽  
pp. 369-377 ◽  
Author(s):  
Chongjuan Chen ◽  
Yufu Jia ◽  
Yuzhen Chen ◽  
Imran Mehmood ◽  
Yunting Fang ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Environmental Effects ◽  
Influential Factors ◽  
N Cycling ◽  
North Slope ◽  
Soil N ◽  
The South ◽  
The North ◽  
South Slope ◽  
Soil Δ15n

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-soil (Δδ15Nleaf-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.

Empirical relationships between temperature and nitrogen availability across North American forests

1992 ◽  
Vol 22 (5) ◽  
pp. 707-712 ◽  
Author(s):  
Xiwei Yin
Keyword(s):  
N Mineralization ◽  
Regional Scale ◽  
Mineral Soil ◽  
Published Data ◽  
N Availability ◽  
Net N Mineralization ◽  
Soil N ◽  
Litter Fall ◽  
Available N ◽  
N Pool

Published data were analyzed to examine whether nitrogen (N) availability varies along macroclimatic gradients in North America. Extractable N produced during 8-week aerobic laboratory incubation was used as an index of potential net N mineralization. Mean extractable N during the growing season in the forest floor plus top mineral soil was used as an index of the available N pool. Using multiple regression, potential net N mineralization was shown to increase with available N and with litter-fall N (R2 = 0.722). Available N increased with increasing total soil N and with decreasing mean January and July air temperatures (R2 = 0.770). These relationships appeared to hold also for deciduous and coniferous forests separately across regions. Results suggest that net N mineralization output under uniform temperature and moisture conditions can be generally expressed by variations of N input (litter fall) and the available soil N pool, and that the available soil N pool is predictable along a temperature gradient at a regional scale.

scholarly journals Introduction of Dalbergia odorifera enhances nitrogen absorption on Eucalyptus through stimulating microbially mediated soil nitrogen-cycling

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Xianyu Yao ◽  
Qianchun Zhang ◽  
Haiju Zhou ◽  
Zhi Nong ◽  
Shaoming Ye ◽  
...  
Keyword(s):  
Microbial Biomass ◽  
Soil Ph ◽  
N Cycling ◽  
N Availability ◽  
Soil N ◽  
Total N ◽  
Available N ◽  
Soil C ◽  
Hot Season ◽  
Dalbergia Odorifera

Abstract Background There is substantial evidence that Eucalyptus for nitrogen (N) absorption and increasing the growth benefit from the introduction of N-fixing species, but the underlying mechanisms for microbially mediated soil N cycling remains unclear. Methods We investigated the changes of soil pH, soil water content (SWC), soil organic carbon (SOC), total N (TN), inorganic N (NH4+-N and NO3−-N), microbial biomass and three N-degrading enzyme activities as well as the biomass and N productivity of Eucalyptus between a pure Eucalyptus urophylla × grandis plantation (PP) and a mixed Dalbergia odorifera and Eucalyptus plantation (MP) in Guangxi Zhuang Autonomous Region, China. Results Compared with the PP site, soil pH, SWC, SOC and TN in both seasons were significantly higher at the MP site, which in turn enhanced microbial biomass and the activities of soil N-degrading enzymes. The stimulated microbial activity at the MP site likely accelerate soil N mineralization, providing more available N (NH4+-N in both seasons and NO3−-N in the wet-hot season) for Eucalyptus absorption. Overall, the N productivity of Eucalyptus at the MP site was increased by 19.7% and 21.9%, promoting the biomass increases of 15.1% and 19.2% in the dry-cold season and wet-hot season, respectively. Conclusion Our results reveal the importance of microbially mediated soil N cycling in the N absorption on Eucalyptus. Introduction of D. odorifera enhances Eucalyptus biomass and N productivity, improve soil N availability and increased soil C and N concentration, which hence can be considered to be an effective sustainable management option of Eucalyptus plantations.

scholarly journals Stable isotope signatures of soil nitrogen on an environmental-geomorphic gradient within the Congo Basin

2020 ◽  
Author(s):  
Simon Baumgartner ◽  
Marijn Bauters ◽  
Matti Barthel ◽  
Travis William Drake ◽  
Landry Cizungu Ntaboba ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Montane Forest ◽  
Local Scale ◽  
N Cycling ◽  
Congo Basin ◽  
N Availability ◽  
Miombo Woodland ◽  
Lowland Forest ◽  
Stable Isotope Signatures ◽  
Soil Δ15n

Abstract. Nitrogen (N) availability can be highly variable in tropical forests on a regional and on a local scale. While environmental gradients influence N cycling on a regional scale, topography is known to affect N availability on a local scale. We compared stable isotope signatures (δ15N) of soil profiles in tropical lowland forest, tropical montane forest, and subtropical Miombo woodland within the Congo Basin as a proxy to assess ecosystem-level differences in N cycling. Furthermore, we examined the effect of surface slope angles on δ15N in the same forests to quantify local differences induced by topography. Soil δ15N profiles indicated that the N cycling in in the montane forest is more closed and dominated by organic N turnover, whereas the lowland forest and Miombo woodland experienced a more open N cycle dominated by inorganic N. Furthermore, our results show that slope angles only affects the soil δ15N signature in the Miombo forest, which is prone to erosion due to the lower vegetation cover and intense rainfalls at the onset of the wet season. Lowland forest, on the other hand, with a flat topography and protective vegetation cover, showed no influence of topography on soil N cycling. Values from the montane forest showed high variability in stable isotope signatures, but they were not constrained by topography. A pan-tropical analysis of soil δ15N values (i.e. from our study and the literature) reveals that soil δ15N is best explained by factors controlling erosion, namely mean annual precipitation, leaf area index, and slope angles. The erosive forces vary immensely between different tropical forest ecosystems and our results highlight the need of more spatial coverage of N-cycling studies in tropical forests, to further elucidate the local impact of topography on N cycling in this biome.

Soil-N cycling in temperate alley cropping agroforestry and monoculture croplands

2021 ◽  
Author(s):  
Xenia Bischel ◽  
Marife D. Corre ◽  
Marcus Schmidt ◽  
Edzo Veldkamp
Keyword(s):  
Environmental Effects ◽  
Western Europe ◽  
Management Practices ◽  
Alley Cropping ◽  
Pore Space ◽  
Agroforestry Systems ◽  
N Cycling ◽  
Soil N ◽  
Soil C ◽  
Gene Abundance

<p>Monoculture croplands are commonly associated with deleterious environmental effects due to high fertilization rates. Agroforestry (alternate alleys of trees and crops or alley cropping) has the potential to mitigate the negative environmental effects from agriculture. Understanding the soil-N cycling aids in assessing how the soil function of nutrient cycling is impacted when monoculture system is converted into agroforestry. Currently, there is no systematic comparison in soil-N cycling rates between monoculture and agroforestry croplands in Western Europe. Our study aimed to investigate gross rates of soil-N cycling between agroforestry and monoculture croplands. We measured gross rates of soil-N cycling, using 15N isotopic pool dilution in May-June 2017, at three sites in Germany (Wendhausen, Dornburg, and Forst with Vertic Cambisol, Calcaric Phaeozem, Gleyic Cambisol soils, respectively); each site has paired monoculture and agroforestry systems (established in 2008, 2007, and 2010 at the respective sites). In each management system at each site, we had four replicate plots; for agroforestry system, we conducted measurements in the tree row and within the crop row at 1 m, 4 m, and 7 m from the tree row. The crop management practices in agroforestry crop row and monoculture were the same at each site.</p><p>For gross rates of ammonium cycling, differences were observed between agroforestry tree row, crop row and monoculture at the site with Vertic Cambisol soil. Higher gross N mineralization rates were observed in monoculture than agroforestry tree row whilst agroforestry tree row exhibited higher gross NH<sub>4</sub><sup>+</sup> immobilization rates than agroforestry crop row (P < 0.02). This was correlated to higher soil C/N ratio and higher water-filled pore space in the tree row. Tree rows also tend to have higher microbial biomass at all sites. Gross rates of nitrate cycling were higher in the tree row than in the crop row and monoculture at the site with Calcaric Phaeozem soil. This showed a similar pattern with the gene abundance of ammonium oxidizing archeae (AOA), supporting a niche differentiation of AOA by utilizing ammonium mineralized from soil organic matter rather than from fertilizer source. At the site with Vertic Cambisol soil, dissimilatory nitrate reduction to ammonium was very high in the tree row. These changes in soil-N cycling and AOA gene abundance in the tree rows suggest that trees in sites with older agroforestry systems had enhanced the cycling of N in the soil.</p>

scholarly journals Introduction of Dalbergia Odorifera Enhances Nitrogen Absorption on Eucalyputs Through Stimulating Microbially Mediated Soil Nitrogen-cycling

2021 ◽  
Author(s):  
Xianyu Yao ◽  
Qianchun Zhang ◽  
Haiju Zhou ◽  
Zhi Nong ◽  
Shaoming Ye ◽  
...  
Keyword(s):  
Microbial Biomass ◽  
Soil Ph ◽  
N Cycling ◽  
N Availability ◽  
Soil N ◽  
N Accumulation ◽  
Total N ◽  
Available N ◽  
Hot Season ◽  
Dalbergia Odorifera

Abstract Background: There is the substantial evidence that Eucalyptus for nitrogen (N) absorption and increasing the growth benefit from the introduction of N-fixing species, but the underlying mechanisms for microbially mediated soil N cycling remains unclear. Methods: We investigated the changes of soil pH, soil water content (SWC), soil organic carbon (SOC), total N (TN), inorganic N (NH4+-N and NO3--N), microbial biomass and three N-degrading enzyme activities as well as the biomass and N accumulation of Eucalyptus between a pure Eucalyptus urophylla × grandis plantation (PP) and a mixed Dalbergia odorifera and Eucalyptus plantation (MP) in Guangxi Zhuang Autonomous Region, China. Results: Compared with the PP site, soil pH, SWC, SOC and TN in both seasons were significantly higher at the MP site, which in turn enhanced microbial biomass and the activities of soil N-degrading enzymes. The stimulated microbial activity at the MP site likely accelerated soil N mineralization, providing more available N (NH4+-N in both seasons and NO3--N in the wet-hot season) for Eucalyptus absorption. Overall, the N accumulation of Eucalyptus at the MP site was increased by 19.7% and 21.9%, promoting the biomass increases of 15.1% and 19.2% in the dry-cold season and wet-hot season, respectively.Conclusion: Our results reveal the importance of microbially mediated soil N cycling in the N absorption on Eucalyputs. Introduction of D. odorifera can enhance N absorption and growth on Eucalyputs, improve soil N availability and increased soil C sequestration, which hence can be considered to be an effective sustainable management option of Eucalyptus plantations.

scholarly journals Stable isotope signatures of soil nitrogen on an environmental–geomorphic gradient within the Congo Basin

SOIL ◽  
2021 ◽  
Vol 7 (1) ◽  
pp. 83-94
Author(s):  
Simon Baumgartner ◽  
Marijn Bauters ◽  
Matti Barthel ◽  
Travis W. Drake ◽  
Landry C. Ntaboba ◽  
...  
Keyword(s):  
Tropical Forests ◽  
Montane Forest ◽  
N Cycling ◽  
Congo Basin ◽  
N Availability ◽  
Slope Gradient ◽  
Miombo Woodland ◽  
Lowland Forest ◽  
Stable Isotope Signatures ◽  
Soil Δ15n

Abstract. Nitrogen (N) availability can be highly variable in tropical forests on regional and local scales. While environmental gradients influence N cycling on a regional scale, topography is known to affect N availability on a local scale. We compared natural abundance of 15N isotopes of soil profiles in tropical lowland forest, tropical montane forest, and subtropical Miombo woodland within the Congo Basin as a proxy to assess ecosystem-level differences in N cycling. Soil δ15N profiles indicated that N cycling in the montane forest is relatively more closed and dominated by organic N turnover, whereas the lowland forest and Miombo woodland experienced a more open N cycle dominated by inorganic N. Furthermore, we examined the effect of slope gradient on soil δ15N within forest types to quantify local differences induced by topography. Our results show that slope gradient only affects the soil δ15N in the Miombo forest, which is prone to erosion due to a lower vegetation cover and intense rainfall at the onset of the wet season. Lowland forest, on the other hand, with a flat topography and protective vegetation cover, showed no influence of topography on soil δ15N in our study site. Despite the steep topography, slope angles do not affect soil δ15N in the montane forest, although stable isotope signatures exhibited higher variability within this ecosystem. A pan-tropical analysis of soil δ15N values (i.e., from our study and literature) reveals that soil δ15N in tropical forests is best explained by factors controlling erosion, namely mean annual precipitation, leaf area index, and slope gradient. Erosive forces vary immensely between different tropical forest ecosystems, and our results highlight the need for more spatial coverage of N cycling studies in tropical forests, to further elucidate the local impact of topography on N cycling in this biome.

Global maps of current and future nitrogen mineralization

2020 ◽  
Author(s):  
Julia Maschler ◽  
Daniel S. Maynard ◽  
Devin Routh ◽  
Johan van den Hoogen ◽  
Zhaolei Li ◽  
...  
Keyword(s):  
Nitrogen Mineralization ◽  
Climate Models ◽  
Net Primary Productivity ◽  
Plant Biomass ◽  
Global Scale ◽  
N Availability ◽  
Soil N ◽  
Climate Conditions ◽  
Tropical Regions ◽  
Terrestrial Carbon Sequestration

<p>Soil nitrogen is a prominent determinant of plant growth, with nitrogen (N) availability being a key driver of terrestrial carbon sequestration. The local availability of soil N is thus crucial to our understanding of broad-scale trends in soil fertility, productivity, and carbon dynamics. Here, we provide global, high-resolution maps of current and future (2050) potential net nitrogen mineralization (N-min), revealing global patterns in soil N availability. Highest mineralization rates are found in warm and moist tropical regions, leading to a strong latitudinal gradient in N-min. We observed a positive correlation of N-min rates with human population density and net primary productivity. Projected climate conditions for 2050 suggest that N availability will further decrease in areas of low N availability and increase in areas of high N availability, thereby intensifying current global trends. These results shed light on the core processes governing productivity at a global scale, providing an opportunity to improve the accuracy of plant biomass and climate models.</p>

scholarly journals Soil <i>δ</i><sup>15</sup>N is a better indicator of ecosystem nitrogen cycling than plant <i>δ</i><sup>15</sup>N: A global meta-analysis

SOIL ◽  
2021 ◽  
Vol 7 (2) ◽  
pp. 733-742
Author(s):  
Kaihua Liao ◽  
Xiaoming Lai ◽  
Qing Zhu
Keyword(s):  
Meta Analysis ◽  
Global Scale ◽  
N Cycling ◽  
Mean Annual Temperature ◽  
Experimental Warming ◽  
Analysis Method ◽  
Higher Temperature ◽  
The Mean ◽  
Increasing Temperature ◽  
Soil Δ15n

Abstract. The nitrogen-15 (15N) natural abundance composition (δ15N) in soils or plants is a useful tool to indicate the openness of ecosystem N cycling. This study aimed to evaluate the influence of the experimental warming on soil and plant δ15N. We applied a global meta-analysis method to synthesize 79 and 76 paired observations of soil and plant δ15N from 20 published studies, respectively. Results showed that the mean effect sizes of the soil and plant δ15N under experimental warming were −0.524 (95 % CI (confidence interval): −0.987 to −0.162) and 0.189 (95 % CI: −0.210 to 0.569), respectively. This indicated that soil δ15N had negative response to warming at the global scale, where warming had no significant effect on plant δ15N. Experimental warming significantly (p<0.05) decreased soil δ15N in Alkali and medium-textured soils, in grassland/meadow, under air warming, for a 4–10-year warming period and for an increase of >3 ∘C in temperature, whereas it significantly (p<0.05) increased soil δ15N in neutral and fine-textured soils and for an increase of 1.5–3 ∘C in temperature. Plant δ15N significantly (p<0.05) increased with increasing temperature in neutral and fine-textured soils and significantly (p<0.05) decreased in alkali soil. Latitude did not affect the warming effects on both soil and plant δ15N. However, the warming effect on soil δ15N was positively controlled by the mean annual temperature, which is related to the fact that the higher temperature can strengthen the activity of soil microbes. The effect of warming on plant δ15N had weaker relationships with environmental variables compared with that on soil δ15N. This implied that soil δ15N was more effective than plant δ15N in indicating the openness of global ecosystem N cycling.

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