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.

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 Monitoring the Spatiotemporal Difference in Glacier Elevation on Bogda Mountain from 2000 to 2017

2021 ◽  
Vol 18 (12) ◽  
pp. 6374
Author(s):  
Weibing Du ◽  
Ningke Shi ◽  
Linjuan Xu ◽  
Shiqiong Zhang ◽  
Dandan Ma ◽  
...  
Keyword(s):  
Water Supply ◽  
Radar Data ◽  
Surface Elevation ◽  
North Slope ◽  
The South ◽  
Glacier Surface ◽  
Study Region ◽  
The North ◽  
South Slope ◽  
The Difference

The difference in glacier surface elevation is a sensitive indicator of climate change and is also important for disaster warning and water supply. In this paper, 25 glaciers on Bogda Mountain, in the eastern Tianshan Mountains, are selected as the study object as they are typical of glaciers in arid or semi-arid areas with importance for water supply. The Repeat Orbit Interferometry (ROI) method is used to survey the surface elevation of these glaciers using Sentinel-1A Radar data from 2017. Using data from the Shuttle Radar Topography Mission (SRTM) and a Digital Elevation Model (DEM), the difference in the glacier surface elevation between 2000 and 2017 is obtained. A scheme to evaluate the accuracy of estimated variations in glacier surface elevation is proposed in this article. By considering the surfaces of lakes in the study region as ideal horizontal planes, the average standard deviation (SD) value of the lake elevation is taken as the error caused by the radar sensor and observing conditions. The SD of the lake elevation is used as an index to evaluate the error in the estimated variation of the glacier surface elevation, and the obtained SD values indicate that the result obtained using the ROI method is reliable. Additionally, the glacier surface elevation variation pattern and a Logarithmic Fitting Model (LFM) are used to reduce the error in high-altitude glacial accumulation areas to improve the estimation of the difference in the glacier surface elevation obtained using ROI. The average SD of the elevation of the 12 lakes is ±2.87 m, which shows that the obtained glacier surface elevations are reliable. This article concludes that, between 2000 and 2017, the surface elevation of glaciers on Bogda Mountain decreased by an average of 11.6 ± 1.3 m, corresponding to an average decrease rate of 0.68 m/a, and glaciers volume decreased by an average of 0.504 km3. Meanwhile, the surface elevations of the lakes increased by an average of 8.16 m. The decrease of glacier surface elevation leads to the expansion of glacial lakes. From the north slope clockwise to the south slope, the glacier elevation variation showed a decreasing trend, and the elevation variation gradually increased from the south slope to the north slope. With the increase of glacier altitude, the variation of glacier surface elevation gradually changed from negative to positive. The findings of this article suggest that the rate of glacier retreat on Bogda Mountain increased from 2000 to 2017.

Early seedling establishment of Picea abies in small forest gaps in the Swiss Alps

1998 ◽  
Vol 28 (4) ◽  
pp. 626-639 ◽  
Author(s):  
Peter Brang
Keyword(s):  
Picea Abies ◽  
Swiss Alps ◽  
North Slope ◽  
Organic Layer ◽  
The South ◽  
Direct Sunlight ◽  
The North ◽  
South Slope ◽  
Early Seedling ◽  
Small Forest

Early seedling establishment of Picea abies (L.) Karst. in small forest gaps was studied in drier, subalpine P. abies ecosystems in the Swiss Alps. Study sites were on steep south and north slopes. Average gap size was 15 m x 20 m on the south slope and 15 m x 70 m on the north slope. Sowing trials established on different microsites were observed for 2 or 3 years. Direct sunlight was assessed with hemispherical photography. Emergence was better on the north slope than on the south slope. On the south slope, emergence was higher on the mineral soil than on the organic layer and was negatively associated with direct sunlight, especially during the noon period. On both slopes, drought due to rainfall interception at the gap edge negatively affected emergence. The limiting factor for survival and growth on the south slope was drought (on the organic layer), whereas on the north slope lack of direct radiation and pathogenic fungi developing in the snowpack were limiting. The early regeneration niche on the south slope was narrower than on the north slope.

scholarly journals Regional co-variability of spatial and temporal soil moisture–precipitation coupling in North Africa: an observational perspective

2018 ◽  
Vol 22 (6) ◽  
pp. 3275-3294 ◽  
Author(s):  
Irina Y. Petrova ◽  
Chiel C. van Heerwaarden ◽  
Cathy Hohenegger ◽  
Françoise Guichard
Keyword(s):  
Soil Moisture ◽  
North Africa ◽  
Deep Convection ◽  
Sensible Heat Flux ◽  
Arid Environment ◽  
The South ◽  
Regional Variability ◽  
Convective Systems ◽  
The North ◽  
Temporal Coupling

Abstract. The magnitude and sign of soil moisture–precipitation coupling (SMPC) is investigated using a probability-based approach and 10 years of daily microwave satellite data across North Africa at a 1∘ horizontal scale. Specifically, the co-existence and co-variability of spatial (i.e. using soil moisture gradients) and temporal (i.e. using soil moisture anomaly) soil moisture effects on afternoon rainfall is explored. The analysis shows that in the semi-arid environment of the Sahel, the negative spatial and the negative temporal coupling relationships do not only co-exist, but are also dependent on one another. Hence, if afternoon rain falls over temporally drier soils, it is likely to be surrounded by a wetter environment. Two regions are identified as SMPC “hot spots”. These are the south-western part of the domain (7–15∘ N, 10∘ W–7∘ E), with the most robust negative SMPC signal, and the South Sudanese region (5–13∘ N, 24–34∘ E). The sign and significance of the coupling in the latter region is found to be largely modulated by the presence of wetlands and is susceptible to the number of long-lived propagating convective systems. The presence of wetlands and an irrigated land area is found to account for about 30 % of strong and significant spatial SMPC in the North African domain. This study provides the first insight into regional variability of SMPC in North Africa, and supports the potential relevance of mechanisms associated with enhanced sensible heat flux and mesoscale variability in surface soil moisture for deep convection development.

scholarly journals Assessment of the SMAP-Derived Soil Water Deficit Index (SWDI-SMAP) as an Agricultural Drought Index in China

2018 ◽  
Vol 10 (8) ◽  
pp. 1302 ◽  
Author(s):  
Jueying Bai ◽  
Qian Cui ◽  
Deqing Chen ◽  
Haiwei Yu ◽  
Xudong Mao ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Soil Water ◽  
Water Deficit ◽  
Microwave Remote Sensing ◽  
Agricultural Drought ◽  
Drought Monitoring ◽  
In Situ Observation ◽  
Soil Water Deficit ◽  
The South ◽  
The North

China is frequently subjected to local and regional drought disasters, and thus, drought monitoring is vital. Drought assessments based on available surface soil moisture (SM) can account for soil water deficit directly. Microwave remote sensing techniques enable the estimation of global SM with a high temporal resolution. At present, the evaluation of Soil Moisture Active Passive (SMAP) SM products is inadequate, and L-band microwave data have not been applied to agricultural drought monitoring throughout China. In this study, first, we provide a pivotal evaluation of the SMAP L3 radiometer-derived SM product using in situ observation data throughout China, to assist in subsequent drought assessment, and then the SMAP-Derived Soil Water Deficit Index (SWDI-SMAP) is compared with the atmospheric water deficit (AWD) and vegetation health index (VHI). It is found that the SMAP can obtain SM with relatively high accuracy and the SWDI-SMAP has a good overall performance on drought monitoring. Relatively good performance of SWDI-SMAP is shown, except in some mountain regions; the SWDI-SMAP generally performs better in the north than in the south for less dry bias, although better performance of SMAP SM based on the R is shown in the south than in the north; differences between the SWDI-SMAP and VHI are mainly shown in areas without vegetation or those containing drought-resistant plants. In summary, the SWDI-SMAP shows great application potential in drought monitoring.

The effect of soil moisture and thaw depth on CH4 flux from wet coastal tundra ecosystems on the north slope of Alaska

Chemosphere ◽  
1993 ◽  
Vol 26 (1-4) ◽  
pp. 329-337 ◽  
Author(s):  
G.L. Vourlitis ◽  
W.C. Oechel ◽  
S.J. Hastings ◽  
M.A. Jenkins
Keyword(s):  
Soil Moisture ◽  
North Slope ◽  
Ch4 Flux ◽  
The North ◽  
North Slope Of Alaska ◽  
Thaw Depth ◽  
Tundra Ecosystems

scholarly journals Snowmelt Hydrology of Two Subarctic Slopes, Southern Yukon, Canada

1998 ◽  
Vol 29 (4-5) ◽  
pp. 331-346 ◽  
Author(s):  
Sean K. Carey ◽  
Ming-ko Woo
Keyword(s):  
Organic Soil ◽  
Organic Layer ◽  
Runoff Generation ◽  
The South ◽  
The North ◽  
Local Topography ◽  
South Slope ◽  
Mineral Soils ◽  
Aspen Forest ◽  
North And South

Large quantities of water are discharged from subarctic basins during snowmelt season. Runoff contributing areas as well as timing and magnitude of meltwater generation from different slopes are highly variable. Two slopes in the lower Wolf Creek basin, southern Yukon, were studied in 1997. The south-facing slope has a dense aspen forest that is leafless in the melt period (April – May) and is underlain by seasonal frost. The north-facing slope has open stands of spruce and an organic layer that rests on mineral soils with permafrost. In 1997, snowmelt is advanced by over 10 days on the south slope, which receives more solar radiation than the north aspect. All meltwater on the south slope infiltrates the frozen silt without generating runoff. By the time significant melt events occur on the north slope the frost and snow are gone from the south. Meltwater is able to infiltrate the frozen organic soil but deep percolation is prevented by the ice-rich substrate. Lateral flow begins after the organic layer is saturated, with much runoff along intermittent rills fed by diffuse and pipe flows. Rills and pipes are interconnected but the drainage network and runoff contributing area change depending on the disposition of the snow as well as water and frost table positions relative to local topography. Contrasts between the north and south slopes have important implications on direct runoff generation during the melt period. Situations similar to the study site can be found elsewhere in subarctic North America and the observed processes have a bearing upon hydrological modelling for the subarctic environment.

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>

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