scholarly journals The environmental forming and productional functions of the haloxylon aphyllum in the Karnabchul desert

2019 ◽  
pp. 34-38
Author(s):  
E. Z. Shamsutdinova
Keyword(s):  
Soil Moisture ◽  
Outer Part ◽  
Soil Surface ◽  
Hydrothermal Conditions ◽  
Noticeable Effect ◽  
Soil Layers ◽  
Haloxylon Aphyllum ◽  
Aged State ◽  
Ephemeral Vegetation ◽  
Black Saxaul

We have conducted investigation of the environmental function of the desert tree of black saxaul (Haloxylon aphyllum) in the Karnabchul desert. As a result, it was found that different age plants of black saxaul had different effects on the degree of illumination. The greatest influence on the intensity of solar radiation was exerted by the saxaul plant of the black middle-aged state, the least the old generative individuals. Saxaul black had a significant impact on the temperature of the air: in the daytime, especially in the period 13-16 h, reducing the temperature under the crown and on the edge of the crown, and at night increasing it in the same areas. It also had a noticeable effect on the temperature of the soil. The temperature of the soil surface under the crown at night is higher, and during the day the warming was slower than in the outer part of the saxaul crown. Under the influence of black saxaul and soil moisture changed. Under the saxaul crown soil moisture is significantly higher compared to the control (open natural pastures). The highest soil moisture was observed in the upper soil layers at the base of the saxaul trunk. As a result, under the environmental action of black saxaul more favorable hydrothermal conditions for the growth and development of natural wormwood-ephemeral vegetation under the protection of strips and adjacent areas of pastures are formed. The result of production activities chemotaxonomic postbestowal bands consists of two following components: production of fodder mass of the Haloxylon and fodder productivity of wormwood-ephemeral vegetation of natural pastures. By increasing the yield of natural pastures under the protection of pasture protection strips and the harvest of the black saxaul fodder productivity of desert pastures increases more than twice.

scholarly journals Determining the drivers for snow gliding

2018 ◽  
Author(s):  
Reinhard Fromm ◽  
Sonja Baumgärtner ◽  
Georg Leitinger ◽  
Erich Tasser ◽  
Peter Höller
Keyword(s):  
Soil Moisture ◽  
Soil Surface ◽  
Test Site ◽  
Negative Influence ◽  
Important Variable ◽  
High Temporal Resolution ◽  
Soil Layers ◽  
Key Factor ◽  
Avalanche Formation ◽  
Snow Gliding

Abstract. Snow gliding is a key factor for snow glide avalanche formation and soil erosion. This study considers atmospheric and snow variables, vegetation characteristics, and soil properties, and determines their relevance for snow gliding at a test site (Wildkogel, Upper Pinzgau, Austria) during winter 2014/15. The time-dependent data were collected at a high temporal resolution. In addition to conventional sensors a snow melt analyzer was used. The analysis shows that the soil moisture at the soil surface had the largest influence on snow gliding during the first part of the winter (October to January). The soil moisture 1.5 cm below the soil surface was the second important variable in the first part of the winter, and the most important variable in the second part of the winter (February to May). A negative influence on snow gliding had the phytomass of mosses in autumn and spring caused by lower canopy heights at these sites. Furthermore, a higher portion of dwarf shrub phytomass reduces snow gliding, because its rigid structure can transfer forces to the soil. Further investigations may be focused on the freezing and melting processes in the uppermost soil layers, and at the soil surface.

scholarly journals Stem–root flow effect on soil–atmosphere interactions and uncertainty assessments

2016 ◽  
Vol 20 (4) ◽  
pp. 1509-1522
Author(s):  
Tzu-Hsien Kuo ◽  
Jen-Ping Chen ◽  
Yongkang Xue
Keyword(s):  
Heat Flux ◽  
Soil Moisture ◽  
Diffusion Processes ◽  
Sensible Heat Flux ◽  
Soil Layer ◽  
Soil Surface ◽  
Soil Evaporation ◽  
Soil Layers ◽  
Flow Effect ◽  
Top Soil

Abstract. Rainfall that reaches the soil surface can rapidly move into deeper layers in the form of bulk flow through the stem–root flow mechanism. This study developed the stem–root flow parameterization scheme and coupled this scheme with the Simplified Simple Biosphere model (SSiB) to analyze its effects on land–atmospheric interactions. The SSiB model was tested in a single-column mode using the Lien Hua Chih (LHC) measurements conducted in Taiwan and HAPEX–Mobilhy (HAPEX) measurements in France. The results show that stem–root flow generally caused a decrease in soil moisture in the top soil layer and moistened the deeper soil layers. Such soil moisture redistribution results in substantial changes in heat flux exchange between land and atmosphere. In the humid environment at LHC, the stem–root flow effect on transpiration was minimal, and the main influence on energy flux was through reduced soil evaporation that led to higher soil temperature and greater sensible heat flux. In the Mediterranean environment of HAPEX, the stem–root flow substantially affected plant transpiration and soil evaporation, as well as associated changes in canopy and soil temperatures. However, the effect on transpiration could be either positive or negative depending on the relative changes in the soil moisture of the top soil vs. deeper soil layers due to stem–root flow and soil moisture diffusion processes.

Soil moisture profile estimation from surface measurements at multiple frequencies

Soil Research ◽  
1999 ◽  
Vol 37 (6) ◽  
pp. 1107
Author(s):  
R. B. Keam ◽  
J. R. Holdem ◽  
J. A. Schoonees
Keyword(s):  
Soil Moisture ◽  
Radio Wave ◽  
Soil Surface ◽  
Dielectric Materials ◽  
Time Domain Reflectometry ◽  
Moisture Profile ◽  
Soil Layers ◽  
Surface Measurements ◽  
Layered Dielectric ◽  
Profile Estimation

It is possible to obtain estimates in situ of volumetric soil moisture content (SMC) as a function of depth using measurements of radio wave reflection at the soil surface at several discrete frequencies. The feasibility of the method was demonstrated through computer simulation by deriving empirical relationships between the number of frequencies, the frequency range, and the number of soil layers for which the SMC is estimated. The SMC profile was obtained to a depth of 1.5 m by inverting, through function minimisation, a simulation of the reflection coefficient from layered dielectric materials. The number of soil layers in which SMC could be resolved was found to be twice the number of frequencies used. The required bandwidth increased with the number of soil layers from 20 MHz for 6 layers to 140 MHz for 16 layers. Within some assumptions about the nature of the radio wave propagation, the theoretical accuracy of the estimate depended only on the quantisation error introduced by having to consider discrete layers of uniform soil with finite thicknesses. The method may have potential for enabling sensitive measurements of SMC profiles at lower cost and lower complexity than methods which use analysis of steps or pulses, such as time-domain reflectometry, and should be well suited for routine use by horticulturists and soil researchers.

Seasonal activity and estivation of lumbricid earthworms in the midlands of Tasmania

Soil Research ◽  
1994 ◽  
Vol 32 (6) ◽  
pp. 1355 ◽  
Author(s):  
RB Garnsey
Keyword(s):  
Soil Moisture ◽  
Adult Development ◽  
Survival Rates ◽  
Soil Surface ◽  
Early Spring ◽  
Lumbricus Rubellus ◽  
Late Winter ◽  
Cocoon Production ◽  
Density And Biomass ◽  
Earthworm Activity

Earthworms have the ability to alleviate many soil degradational problems in Australia. An attempt to optimize this resource requires fundamental understanding of earthworm ecology. This study reports the seasonal changes in earthworm populations in the Midlands of Tasmania (<600 mm rainfall p.a.), and examines, for the first time in Australia, the behaviour and survival rates of aestivating earthworms. Earthworms were sampled from 14 permanent pastures in the Midlands from May 1992 to February 1994. Earthworm activity was significantly correlated with soil moisture; maximum earthworm activity in the surface soil was evident during the wetter months of winter and early spring, followed by aestivation in the surface and subsoils during the drier summer months. The two most abundant earthworm species found in the Midlands were Aporrectodea caliginosa (maximum of 174.8 m-2 or 55.06 g m-2) and A. trapezoides (86 m-2 or 52.03 g m-2), with low numbers of Octolasion cyaneum, Lumbricus rubellus and A. rosea. The phenology of A. caliginosa relating to rainfall contrasted with that of A. trapezoides in this study. A caliginosa was particularly dependent upon rainfall in the Midlands: population density, cocoon production and adult development of A. caliginosa were reduced as rainfall reduced from 600 to 425 mm p.a. In contrast, the density and biomass of A. trapezoides were unaffected by rainfall over the same range: cocoon production and adult development continued regardless of rainfall. The depth of earthworm aestivation during the summers of 1992-94 was similar in each year. Most individuals were in aestivation at a depth of 150-200 mm, regardless of species, soil moisture or texture. Smaller aestivating individuals were located nearer the soil surface, as was shown by an increase in mean mass of aestivating individuals with depth. There was a high mortality associated with summer aestivation of up to 60% for juvenile, and 63% for adult earthworms in 1993 in the Midlands. Cocoons did not survive during the summers of 1992 or 1994, but were recovered in 1993, possibly due to the influence of rainfall during late winter and early spring.

scholarly journals Variations of deep soil moisture under different vegetation types and influencing factors in a watershed of the Loess Plateau, China

2016 ◽  
Vol 20 (8) ◽  
pp. 3309-3323 ◽  
Author(s):  
Xuening Fang ◽  
Wenwu Zhao ◽  
Lixin Wang ◽  
Qiang Feng ◽  
Jingyi Ding ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Influencing Factors ◽  
Loess Plateau ◽  
Vegetation Restoration ◽  
Native Vegetation ◽  
Watershed Scale ◽  
Vegetation Types ◽  
Deep Soil ◽  
Soil Layers ◽  
Management Measures

Abstract. Soil moisture in deep soil layers is a relatively stable water resource for vegetation growth in the semi-arid Loess Plateau of China. Characterizing the variations in deep soil moisture and its influencing factors at a moderate watershed scale is important to ensure the sustainability of vegetation restoration efforts. In this study, we focus on analyzing the variations and factors that influence the deep soil moisture (DSM) in 80–500 cm soil layers based on a soil moisture survey of the Ansai watershed in Yan'an in Shanxi Province. Our results can be divided into four main findings. (1) At the watershed scale, higher variations in the DSM occurred at 120–140 and 480–500 cm in the vertical direction. At the comparable depths, the variation in the DSM under native vegetation was much lower than that in human-managed vegetation and introduced vegetation. (2) The DSM in native vegetation and human-managed vegetation was significantly higher than that in introduced vegetation, and different degrees of soil desiccation occurred under all the introduced vegetation types. Caragana korshinskii and black locust caused the most serious desiccation. (3) Taking the DSM conditions of native vegetation as a reference, the DSM in this watershed could be divided into three layers: (i) a rainfall transpiration layer (80–220 cm); (ii) a transition layer (220–400 cm); and (iii) a stable layer (400–500 cm). (4) The factors influencing DSM at the watershed scale varied with vegetation types. The main local controls of the DSM variations were the soil particle composition and mean annual rainfall; human agricultural management measures can alter the soil bulk density, which contributes to higher DSM in farmland and apple orchards. The plant growth conditions, planting density, and litter water holding capacity of introduced vegetation showed significant relationships with the DSM. The results of this study are of practical significance for vegetation restoration strategies, especially for the choice of vegetation types, planting zones, and proper human management measures.

scholarly journals Potential Applications of GNSS-R Observations over Agricultural Areas: Results from the GLORI Airborne Campaign

2018 ◽  
Vol 10 (8) ◽  
pp. 1245 ◽  
Author(s):  
Mehrez Zribi ◽  
Erwan Motte ◽  
Nicolas Baghdadi ◽  
Frédéric Baup ◽  
Sylvia Dayau ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Signal To Noise Ratio ◽  
Soil Surface ◽  
Satellite System ◽  
Area Index ◽  
Vegetation Height ◽  
Study Sites ◽  
Global Navigation Satellite ◽  
Vegetation Characteristic ◽  
Agricultural Areas

The aim of this study is to analyze the sensitivity of airborne Global Navigation Satellite System Reflectometry (GNSS-R) on soil surface and vegetation cover characteristics in agricultural areas. Airborne polarimetric GNSS-R data were acquired in the context of the GLORI’2015 campaign over two study sites in Southwest France in June and July of 2015. Ground measurements of soil surface parameters (moisture content) and vegetation characteristics (leaf area index (LAI), and vegetation height) were recorded for different types of crops (corn, sunflower, wheat, soybean, vegetable) simultaneously with the airborne GNSS-R measurements. Three GNSS-R observables (apparent reflectivity, the reflected signal-to-noise-ratio (SNR), and the polarimetric ratio (PR)) were found to be well correlated with soil moisture and a major vegetation characteristic (LAI). A tau-omega model was used to explain the dependence of the GNSS-R reflectivity on both the soil moisture and vegetation parameters.

scholarly journals Spreading of chemical substance after its accidental spillage onto the soil surface under unsaturated conditions and variable porosity

2019 ◽  
pp. 41-44
Author(s):  
Olena Kozhushko ◽  
Petro Martyniuk
Keyword(s):  
Mathematical Model ◽  
Soil Moisture ◽  
Soil Profile ◽  
Moisture Transport ◽  
Soil Surface ◽  
Chemical Substance ◽  
High Concentration ◽  
Solute Transfer ◽  
Variable Porosity ◽  
The One

In this paper we study a mathematical model of soil moisture transport with variable porosity. The problem is set for the case of highly concentrated solute spilled onto soil surface. We investigate the way solute transfer, adsorption of contaminant by soil particles and variable porosity influence infiltration of solute into the soil profile. For that purpose, two models are used: a classical one and the one with consideration of mentioned factors. By comparing the results of both models, we established that high concentration of solute causes moisture transport to transpire more slowly, and the pollutant to remain on the soil surface for longer time. Numerical results indicate that porosity can vary considerably under the conditions of intensive contamination with salts.

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