Dune Soil Research Articles

Dune soil nitrogen leaching for Chinese-yam cultivation: Impact of microbe-decomposable slow-release fertilizer

Chinese yam production is thriving in Aomori Prefecture, a cold and snowy region in Japan. Recently, there has been an increasing risk of nitrogen leaching in Chinese-yam fields, which consist of sandy soil, due to localized torrential rain. The relationships between the type of fertilizer used for Chinese-yam cultivation, the amount of nitrogen (N) leaching, and the timing of leaching remain unknown. Therefore, this study aimed to fill this knowledge gap by investigating the effects of different fertilizers (fast-acting and/or slow-release fertilizer) and irrigation practices (conventional and/or excessive irrigation) in order to mitigate the detrimental impact of nitrogen leaching on groundwater quality. An enhanced mathematical model and the spatiotemporal dynamics of inorganic nitrogen concentration in soil pore water were evaluated the negative impact of nitrogen leaching on the groundwater environment was evaluated. The results showed that the combined use of slow-release fertilizers could significantly reduce nitrate-nitrogen concentration in soil-water, especially during the harvest season. This study demonstrated that cultivating Chinese yam with a fertilizer application system that includes the use of slow-release fertilizer can diminish the negative impact of nitrogen leaching on the groundwater environment, contributing to our understanding of sustainable agricultural practices in regions facing similar environmental challenges. Therefore, our findings represent an important advancement providing new approaches to maintaining productivity while mitigating the adverse impacts on groundwater environments, as well as offering guidelines for agricultural practices in regions facing similar environmental challenges.

Microstructure and quantitative tracing of carbonate for calcareous root tubes in dune soil from the Tengger Desert of Northwestern China: Implications for its formation age and paleoenvironmental reconstruction

Calcareous root tubes (CRTs), which are formed by the encrustation of roots with pedogenic carbonate, serve as an archive for paleoclimate reconstructions. However, controversies remain regarding the formation age of CRT carbonate and the quantitative tracing of its sources in the hinterland of the desert. In this study, 13 CRT samples were obtained from 11 sites in the Tengger Desert of northwestern China. Samples were described using X-ray micro-tomography Scanning (Micro-CT), and their 14C ages, δ13C, and 87Sr/86Sr values were measured. The results show that more than 99.84 % of pore diameters in the precipitated carbonate layer were less than 1 mm, which was much smaller than the plant roots in this region. Moreover, the root residues from poor cementation CRTs were dated at 151 − 431 cal yr BP, which was significantly younger than the carbonate age of other complete cemented CRT. Thus, most of the root residues found within completely cemented CRTs may invade after the CRTs formation and their 14C ages cannot represent the CRTs formation period, while the carbonate 14C dating results can indicate the CRTs formation period. 87Sr/86Sr values of CRTs occurred at 0.71152 − 0.71189, indicating that the main source of calcium in CRTs was the dissolution of carbonate in rhizosphere soil. δ13C values of CRTs varied between −5.4 ‰ and −3.2 ‰. Using the end-member mixing model, carbon sources from CRTs can be divided into rhizosphere soil respiration CO2 (81 − 82 %) and atmospheric CO2 (18 − 19 %). Hence, δ13C values of CRTs may derive the δ13C signal from soil and record paleoenvironment conditions. This study enhances our understanding of the formation mechanism of pedogenic carbonate and provides an important aspect in assisting paleoenvironmental reconstructions.

Prediction of Soil Bacterial Community Structure and Function in Minqin Desert-oasis Ecotone Artificial Haloxylon ammodendron Forest

Exploring the effects of artificial Haloxylon ammodendron forest planting on the structure and function of a desert soil bacterial community provides data reference for soil micro-ecological restoration and land quality improvement in desert oasis transition zones. Illumina high-throughput sequencing technology and PICRUSt2 functional prediction analysis were used to identify and analyze the structure and function of soil bacterial communities, and the Mantel correlation test and RDA analysis were used to explain the physicochemical factors affecting the structure and function of soil bacterial communities. The results showed that:① the soil bacterial OTU number, Chao1 index, and Shannon index were significantly higher in the H. ammodendron forest than in the mobile dune soil, and the PCoA analysis and Adonis test showed significant differences in the soil bacterial community structure between H. ammodendron and mobile dune soil (P=0.001). ② A total of 34 phyla, 89 classes, 174 orders, 262 families, and 432 genera of bacteria were detected in all samples, and the phyla Proteobacteria, Actinobacteria, Cyanobacteria, and Chloroflexi accounted for 76.05% of the relative abundance of soil bacteria, which belonged to the dominant soil bacteria, among which the relative abundance of Actinobacteria in H. ammodendron forest soil was extremely significantly higher than that in mobile dune soil (P < 0.01). ③PICRUSt2 function prediction revealed that the soil bacterial community of H. ammodendron forest included six categories of primary functions and 28 categories of secondary functions, among which the metabolism of carbohydrates, metabolism of amino acids, and metabolism of cofactors and vitamins were all greater than 10% in relative abundance and were the main metabolic functions of H. ammodendron forest soil bacteria. ④ The planting of H. ammodendron forest significantly improved the nutrient content of soil organic matter and other nutrients. Soil pH, organic matter, total nitrogen, and fast-acting phosphorus were the main physicochemical factors affecting the bacterial community, with soil organic matter significantly affecting the soil bacterial community structure (P < 0.05) and metabolic function (P < 0.05). In conclusion, the artificial H. ammodendron forest helped to increase desert soil microbial diversity, increase the relative abundance of soil bacterial metabolic function genes, and improve the desert soil microenvironment.

Soil Bacterial Community Structure and Physicochemical Influencing Factors of Artificial Haloxylon ammodendron Forest in the Sand Blocking and Fixing Belt of Minqin, China

Microbial activity plays a crucial role in upholding the functional stability of vegetation–soil ecosystems. Nevertheless, there exists a paucity of studies concerning the impact of sand-fixing vegetation (Haloxylon ammodendron) on the structure and functional attributes of soil microbial communities. We employed Illumina high-throughput sequencing and PICRUSt2 functional prediction technology to investigate the characteristics of soil bacterial community structure, diversity, and metabolic functions in an artificial H. ammodendron forest, and RDA analysis and the Mantel test were used to reveal the main environmental factors affecting the structure and ecological functions of soil bacterial communities. The findings revealed a significant increase in the principal nutrient contents (organic matter, total nitrogen, total phosphorus) in the H. ammodendron forest soil compared to the mobile dune soil, while a reduction of 17.17% in the surface soil water content was observed. The H. ammodendron forest exhibited a significant enhancement in the diversity and richness index of soil bacteria. Specifically, Actinobacteria (24.94% ± 11.85%), Proteobacteria (29.99% ± 11.56%), and Chloroflexi (11.14% ± 4.55%) emerged as the dominant bacterial phyla, with Actinobacteria displaying significantly higher abundance compared to the mobile dune soil. PICRUSt2 analyses revealed that the predominant secondary metabolic functions of soil bacteria were carbohydrate metabolism, amino acid metabolism, and the metabolism of cofactors and vitamins. Additionally, the tertiary metabolic pathways exhibited greater activity in relation to enzyme function, nucleotide metabolism, energy metabolism, and antibiotics. The RDA results demonstrated that SOM, AK, and pH collectively accounted for 82.4% of the cumulative contribution, significantly influencing the bacterial community. Moreover, the Mantel test revealed that the metabolic function of soil bacteria primarily relied on five environmental factors, namely SOM, TN, AK, pH, and EC. This study significantly advances our understanding of the structural and functional changes in soil bacterial communities during the reclamation of sandy land through the establishment of artificial H. ammodendron forests.

Engineering and Minerological Characteristics of Sand Dunes of Babylon Governorate, Iraq

The engineering and mierological of sand dunes has been investigated in this paper. The engineering characteristics study involved studying the dimensions of the dunes, their slope angles, analyzing the curvature of their surfaces and sieve analysis. The mierological characteristics included XRD, XRF, and Thin section for specimens. The investigated area involved three differnts zones lie in the Babylon Governorate in the cnter of Iraq. The zones are called Ramlet Rashid, Ramlet Albu Faris and Birmana area. It has a desert environment, which is characterized by little rainfall, ranging from 50 to 200 mm annually, and high summer temperatures that can exceed 50°C, with northwest winds dominating. The grain size distribution of the sand was found to be 99% in an engineering study of sand dune soils. According to USCS, the sand is of the type (Sp), which is sandy badly graded. The bulk density of sand dune soils for the study area locations ranged from 1.287 to 1.376 g /cm3, The lowest concentration was 1.287 g/cm3 in the Bermana area (third site), while the highest concentration was 1.376 g/cm3 at the Ramlet Rashid site (first site), with an average of 1.3315 g/cm3. The internal friction angle (Ø) for sand dune soils for the research area sites ranged from 33 to 34 in the direct shear test, with the minimum being 33 in Ramlet Rashid and the maximum being 34 in Albu Faris. Having a 33.5 percent rate The convergence of the internal friction angle (Ø) values for sand dunes reflects the deposition environment as well as the geometric characteristics of the sand dunes, Because the soil is SP without cohesion and clays, the cohesion (C) values for all sites are (0). The petrographic investigation of sand rise soils uncovered that quartz is the most light mineral tracked down in all areas, trailed by rock pieces, which include: sedimentary rocks (calcareous rocks, carbonates, chert, evaporites, and earth rock sections), trailed by feldspar (antacid and plagioclase feldspar), and volcanic stone parts, transformative shakes and mud-covered grains. Concerning its weighty minerals parts, for the most part hazy minerals, the chlorite bunch, the mica bunch, the amphibole bunch, the pyroxene bunch, zircon, termolite, garnet, rhyolite, staurolite, kainite, rutile, and different minerals by 1%. X-Ray diffraction test uncovered the presence of quartz, albite and calcite, and X-Ray fluorescence tests showed the presence of silica (SiO2) and lime (CaO).

Soil origin impacts Acacia longifolia above and belowground development: water and nutrition as players

Context Acacia longifolia is an aggressive invader, disrupting habitats and communities worldwide. Understanding what drives its expansion is of paramount importance. Key functional traits include fast growth and the presence of bacterial symbionts performing nitrogen fixation. Aims To address early plant development of A. longifolia under different soils and growth conditions (water and nutrition availability), establishing the key factors that influence above and belowground responses. Methods Plants were grown in pots with soils collected from forest, agricultural and dune areas in relative proximity, in a controlled experiment designed to study water effect and nutrient availability on early growth. Growth parameters included shoot and root length, nodule number and weight. Bacteria were isolated from nodules for genetic diversity evaluation. Photosynthetic pigments and isotopic nitrogen and carbon analyses were performed to address nitrogen fixation and photosynthesis. Key results Soil origin influenced plant growth and bacterial diversity. Largest plant development was achieved in forest soils with added nutrition and water. Plants from agricultural soil displayed higher aboveground development; however, belowground nodule number and bacterial biodiversity decreased, possibly due to anthropogenic activities. Forest soil promoted belowground development and bacterial diversity. In dune soils overall growth was lower and nitrogen fixation was higher. Conclusion Abiotic factors influenced juvenile acacia development; nutrition acts as a growth enhancer, and soil origin, including its microbial communities, can be considered a development modulator. Bacterial diversity varied according to soil type. Implications Several above and belowground interactions showed the need for an integrative perspective to understand acacias invasive potential.

The Effect of Prosopis juliflora (Fabaceae) on the Physical and Chemical Properties of Coastal Dune Soil in Western Mexico

Vargas-Lomelín, J.G.; Macías-Rodríguez, M.Á.; Zarazúa-Villaseñor, P.; Rodríguez-Zaragoza, F.A.; Neri-Luna, C., and Albuquerque, F., 2023. The effect of Prosopis juliflora (Fabaceae) on the physical and chemical properties of coastal dune soil in western Mexico. Journal of Coastal Research, 39(1), 63–72. Charlotte (North Carolina), ISSN 0749-0208. Prosopis juliflora (Fabaceae) is a dominant legume and potential ecosystem engineer in the dunes of Jalisco, western Mexico. The objective of the present study was to evaluate how P. juliflora modifies soil physical and chemical properties in three coastal dunes that belong to different watersheds. To determine the physical properties of the three sites, soil samples were taken inside the canopy of five P. juliflora trees and five soil samples were taken outside their canopies. The same trees and soil positions regarding the canopy of P. juliflora were considered to determine the chemical properties, but the samples were taken at two different depths. A multidimensional and permutational analysis of variance (PERMANOVA) was performed to evaluate differences in the physical properties among the sites and between the sampling positions relative to the canopy of P. juliflora. This PERMANOVA also evaluated differences among sites, sample depths, and the positions of the samples relative to the P. juliflora canopy. A test of homogeneity of dispersions was performed to determine the data dispersion type, whereas a similarity percentage analysis identified which variables contributed most to the observed differences. A principal coordinate analysis was performed to visualize the differences in the model. The results demonstrated that P. juliflora modified the soil physical properties, specifically the real density, total porosity percentage, and percentages of silt and clay. The soil physical properties also varied significantly among the three sites. In addition, P. juliflora modified the soil chemical properties, increasing the electrical conductivity, pH, and total nitrogen, iron, and available phosphorus content. The results show significant differences between the two soil depths, as well as among sites. Ultimately, this study contributes to understanding of the implications of soil property modifications by plants in coastal dunes, which will give guidelines for managing and conserving these ecosystems.

Topsoil Carbon Stocks in Urban Greenspaces of The Hague, the Netherlands

Urbanization influences soil carbon (C) stocks and flows, which, in turn, affect soil-derived ecosystem services. This paper explores soil C storage in urban greenspaces in the Dutch city of The Hague along a transect from the suburban seaside towards the city centre, reflecting a toposequence from dune to peaty inland soils. C storage and C mineralisation potential were evaluated in relation to soil type and greenspace categories. Several soil-quality characteristics were measured, including dissolved organic C, pH, electrical conductivity, nitrogen, phosphorus, sulphur, calcium carbonate, and the water-holding capacity of the soil to evaluate what drives soil C storage in the urban context. The total SOC storage of the upper 30 cm of the greenspaces in The Hague (20.8 km2 with 37% greenspace) was estimated at 78.4 kt, which was significantly higher than assumed given their soil types. Degradability of soil organic matter in laboratory batch tests varied between 0.2 and 3 mg C gSOC−1 day−1. Degradability was highest in the seaside dune soils; however, extrapolated to the topsoil using the bulk density, topsoil C mineralization was higher in the urban forest. Soils beneath shrubs appeared to be hotspots for C storage, accounting for only 13% of the aerial cover but reflecting 24% of the total C storage. Land ownership, land use, greenspaces size, litter management and soil type did not result in significantly different C stocks, suggesting that processes driving urban soil C storage are controlled by different factors, namely land cover and the urbanization extent.

Carbonate cementing minerals in rhizoliths from Badain Jaran Desert: Implication for pedo-diagenesis and environment of dune soil

Pedogenic carbonates are a good proxy of soil formation and functioning because the morphology of minerals is directly related with the processes of dissolution–precipitation. Carbonate rhizolith is one type of pedogenetic carbonate forming in modern soils of dunes and loess. The calcite micro-morphology with the sedimentary hydrogeochemical conditions prevailing during their formation remains open. Electron microscopy with an X-ray energy dispersive spectrometer and X-ray diffraction were used to investigate in detail the micro-morphology of carbonate cements of the rhizoliths and obtain paleoenvironmental information in the dune soil of Badain Jaran Desert in Northwest China. Two types of carbonates rhizoliths, primary rhizoliths (PR) and reworked rhizoliths (RR), were found. The PRs are present in situ within dune soils. The RRs are being eroded out from soil, potentially dislocated or transferred, and weathered at the soil surface. PRs displayed homogeneous micritic mass of calcite crystals, with pores, cavities and voids among the mass. RRs displayed various morphologies of calcite crystals (polyhedral, euhedral rhombic, tooth-like, prismatic and pillar), rosettes, short rods, and calcified fungal hyphae. The diagenesis differences at soil depth and surface affected the crystal morphologies. The homogeneous micritic mass of calcite crystals of the PRs were formed during the early diagenesis, preferentially in wet soils with semi-closed and semi-redox conditions. In contrast, the cementing minerals of the RRs became bigger and clearer in the late diagenesis than during early diagenesis due to recrystallization in open, dry and oxidative conditions at the soil surface. Therefore, the cement crystal morphologies of the rhizoliths can reflect the local environmental and climatic conditions. These objects can be used as environmental and pedo-diagenesis proxies in dune soil or sediments, recording the associated conditions of moisture, temperature, wind, erosion, weathering, solar radiation at the soil surface or at depth. Therefore, assessing the micromorphology of pedogenic carbonates has important implications for soil ecology and evolution as well as plant root physiology in deserts.

Dry-Season Soil and Co-Cultivated Host Plants Enhanced Propagation of Arbuscular Mycorrhizal Fungal Spores from Sand Dune Vegetation in Trap Culture.

The use of arbuscular mycorrhizal fungi (AMF) as biofertilizer in agriculture is a sustainable approach to fertilization. The first step in the production of AMF biofertilizer is inoculation of mycotrophic plants with a composite of soil and native plant roots, containing potentially viable AMF spores from natural habitats, to a trap culture. A single host plant or a consortium of host plants can be used to propagate AMF spores. However, the difference in the comparative efficiency of mono- and co-cultivated host plants used for the production of AMF spores and the maintenance of original AMF community composition has not been well elucidated. Here, we prepared trap culture with nutrient-poor soil from coastal sand dune vegetation collected during the dry season when the AMF spore density and relative abundance of Glomeromycota ITS2 sequences were significantly higher (p = <0.05) than in the wet season. The AMF communities in the soil were mainly composed of Glomus spp. Maize (Zea mays L.) and/or Sorghum (Sorghum bicolor (L.). Moench) were grown in trap cultures in the greenhouse. Our results demonstrated that co-cultivation of the host plants increased the production of AMF spores but, compared to mono-cultivation of host plants, did not better sustain the native AMF community compositions in the coastal sand dune soil. We propose that the co-cultivation of host plants in a trap culture broadens AMF-host plant compatibilities and thus sustains the symbiotic association of the natively diverse AMF. Therefore, the results of this study suggest that further research is needed to confirm whether the co-culturing of more than one host plant is as efficient a strategy as using a monoculture of a single host plant.

Blowout dynamics in lime‐rich and lime‐poor coastal dunes in the Netherlands

AbstractBlowouts can mitigate the negative effects of acidification in the topsoil, especially in industrialized countries with high atmospheric nitrogen (N) deposition. However, blowout activity may differ between lime‐rich and lime‐poor dunes, which creates different regional responses and interactions between processes and patterns.To further explore this, five Dutch dune sites were selected over the gradient from lime‐rich and lime‐poor dunes. We mapped blowout activity in 5 years between 1996 and 2017 with aerial photographs, and used transport potential, atmospheric N‐deposition and rabbit density as explanatory variables. We also studied soil and plant parameters in the field in different stages of succession.All sites showed fluctuations, but blowout activity net increased in the lime‐rich sites, and decreased in the lime‐poor sites. Differences in blowout activity could not be explained by sand transport potential, which differed between years, but not sites. Differences in blowout activity could to some extent be explained by rabbit density and exceedance of the critical N load, although the transition site between lime‐rich and lime‐poor dunes showed high blowout activity despite low rabbit density.Differences in blowout activity between lime‐rich and lime‐poor dunes were also related to differences in topsoil chemistry, especially with respect to lime content, Fe content and different forms of phosphorus (P). High pH was a key factor, which reduced sensitivity to high N deposition through reduced P‐availability to the vegetation, higher proportion of arbuscular mycorrhizal plants, which may improve food quality for rabbits, and lower root biomass, which may increase erodibility of the dune soil. High pH and low P availability may even occur in lime‐poor dunes with a little lime, as long as blowouts stay active and counteract acidification. However, when pH values drop below 6.5, P availability to the vegetation will increase and start feedback processes leading to blowout stabilization.

THE SILTING UP OF VEGETABLE CROP AREA IN GANDIOLAIS (NORTHERN COAST OF SENEGAL)

The Gandiolais is part of the large "Niayes" ecosystem in the Saint Louis region. It is bordered by active dunes from the recent Quaternary delimiting interdune depressions in which the sub-surface water table has favored the practice of vegetable crops. These vegetable cropping areas are production systems that are now facing silting up.&#x0D; Our results show that this silting is due to deflation and/or mass movement of dune soils. These two phenomena are generated by the sensitivity of dune soils to deflation by trade winds and drought. The resulting negative consequences include, among others, the abandonment of vegetable cropping activities by farmers.&#x0D; Solutions to reduce trade wind speeds and improve the cohesion and structuring of dune soils are proposed. In particular, we recommend the creation of windbreaks and the reconstitution of sufficient plant cover.

Morphology and mineralogical composition of sandblasting dust particles from the Taklimakan Desert

The physicochemical characteristics of dust particles from the Taklimakan Desert are the fundamental basis for the assessment of particle variation during their long-distance transport and the subsequent environmental effects. In this study, 43,222 individual sandblasting dust particles, which were mobilised using a chamber with surface soils of sand dunes and Gobi (the two types of surfaces constituting the desert) were analysed to statistically quantify the shape and mineralogical composition of dust particles from the desert. The mode of the number-size distribution of particles from the sand dunes was 0.5–0.7 μm and that of particles from Gobi soils was approximately 1.0 μm. In contrast, the distributions of particle number fractions versus shape factors such as aspect ratio and roundness were similar, despite the irregular shape of the particles. Clay mineral particles were most frequently composed of chlorite and kaolinite, accounting for 66.74 ± 12.08% of the particles from both types of soils. Quartz and feldspar particles accounted for 9.57 ± 4.52% and 2.84 ± 1.28%, respectively. The mineralogical composition of particles smaller than 1.0 μm, in both soil types, was dominated by chlorite (Al-Si-O-Mg), kaolinite (Ai-Si-O), and quartz (SiO). Gypsum (CaS) and halite (NaCl) were the major salt components in particles from both soil types. Gypsum-containing particles existed in a wide size range and occupied 3.42%–8.98% of the particles from Gobi soils and 0.27%–2.18% of the particles from sand dunes. Most gypsum-containing particles were mixed with Si-containing minerals in the form of silicate or aluminosilicate; the remaining gypsum-containing particles were gypsum crystals or mixtures of gypsum and Ca-containing minerals. These results provide a comprehensive statistical profile of dust particles released by the sandblasting process from the Taklimakan Desert to the atmosphere.

Surrogate atmospheric dust particles generated from dune soils in laboratory: Comparison with field measurement

Desert dust strongly influences the climate and the environment by altering the radiation budget, participating in atmospheric chemical reactions, and engaging the biogeochemical cycle. Studying its impacts requires knowledge of the physical and chemical properties of the original particles from the source origin. Unfortunately, the field collection of atmospheric samples in the desert is impractical. Fine surface soil is thus considered an alternative material from which to obtain the information applicable to dust particles from the desert soil. In this study, a laboratory system was set up to generate dust particles with simulated natural wind erosion processes from surface soils or directly from desert surfaces. Surface soils and field dust were simultaneously collected during a local blowing dust event. The comparison between the laboratory-generated dust and the field dust showed a consistent trend in particle size distribution and chemical composition. The chemical compositions were found to have explainable differences with the Certified Reference Materials for Asian dust (CJ-2). The laboratory-generated dust particles with the system could be applied as surrogates for soil-emitted dust in desert areas.

Relationship between the distribution of vegetation and the environment in the coastal embryo dunes of Jalisco, México.

BackgroundThe poorly developed soils of the embryo dunes imply little capacity for plant support, however, the adaptation mechanisms of plants respond sensitively to environmental variations, even when these variations are small, which results in a set of specialized habitats and flora that are rarely shared with other terrestrial ecosystems. The coastal dunes of the Mexican Pacific remain vaguely studied, this is why this research explored the relationship between environmental properties and the presence of plant species in the embryo dunes of the coast of Jalisco, Mexico.MethodsTwenty-nine sites were sampled, one or two sites per embryo dune, with a random stratified design. Geomorphological and vegetation data were collected at site. Laboratory determinations included soil color, particle size, organic matter, pH, electrical conductivity, magnetite content, and moisture retention. Statistical analysis included correlation analysis to identify relationships between environmental variables; principal component analysis (PCA) and cluster analysis to group dune sites by environmental properties; canonical correspondence analysis (CCA) to determine a possible significant relationship between the presence of plant species and environmental variables; cluster analysis to group dune sites by presence/absence of plant species and correlate both clusters to validate the relationship between them, the salient aspects of this relationship were described and the spatial distribution of the groups was mapped.ResultsEleven plant species were identified, six of them exclusive to the embryo dunes and the rest ubiquitous. The incipient development of these soils is reflected in a low content of organic matter, silt, clay, and moisture retention, with scattered data on granulometry, electrical conductivity, organic matter, and magnetite. Some significant correlations were found between some environmental properties, and the CCA showed a significant relationship between the presence of plant species and environmental variables (p-value of the Monte Carlo test = 0.026). The cluster analysis of dune sites according to environmental variables and the cluster analysis by presence/absence of plant species produces the formation of five groups of sites with significant environmental differences and five groups of sites with significant floristic differences. A significant connection (r = 0.471, p = 0.01) between the two clustering schemes also evidences the meaningful relationship between the presence of plant species and the environmental characteristics of the embryo dunes of Jalisco, Mexico. Differences in habitat preferences were observed among plant species exclusive to the embryo dunes; thus, Abronia maritima, Uniola pittieri, and Pectis arenaria showed a preference for embryo dunes with poor edaphic conditions, in contrast to Okenia hypogaea, Canavalia rosea, and Scaevola plumieri, which were mostly found in embryo dunes with higher fertility.

Carbonate Cementing Minerals in Rhizoliths from Badain Jaran Desert: Implication for Pedo-Diagenesis and Environment of Dune Soil

Carbonate Cementing Minerals in Rhizoliths from Badain Jaran Desert: Implication for Pedo-Diagenesis and Environment of Dune Soil

Optimal Use of Natural Resources in Al-Muthanna Desert (Soil as A model)

Soil is one of the important natural resources in Al-Muthanna desert, and the climate has played an important role in its formation. The soil in the study area is classified into several types that vary in their quality for agriculture. I concluded that the soil of the depressions and the plains alluvial soils are among the best types of those soils, followed by the sandy desert soil, which is characterized by its large area and can be exploited when providing water for it. As for the gypsum desert soils, they are of medium quality for cultivation, due to the presence of gypsum in them in high quantities and the lack of water retention. While the sandy and rocky dune soils are unsuitable for agriculture due to their high permeability. Wind and water erosion works to expose rocky soil rocks and transfer sand dune soil particles, but they constitute an important resource in the manufacture of building materials and glass if they are used properly.

The Effect of Natural Factors on the Cultivation and Production of Sesame Crop in Al-Qadisiyah Governorate

Sesame crop, one of the very important oily, industrial, and summer crops that is economically important, has been investigated. The plantation and production of this crop has been studied in Al-Qadisiyah governorate during 2003-218. This is because this governorate is well-known by sesame plantation. Such a study helps to know the geographical distribution of sesame agricultural season in 2017-2018, and explore the most important natural factors that affect its plantation. Different research approaches have been adopted based on that facts that need to be met. A field study approach has been used in studying sesame crop descriptively and conceptually, shedding light on its nutritional and economic importance. Moreover, a descriptive comparative approach has been adopted when studying the geographical factors to know about the factors that affect its plantation and production in the area in question. Results have shown that climatic conditions of the area is suitable for its plantation and production. However, the soils of Al-Qadisiyah are of various categories. The best category is the riverbank soil, then comes river basin soil, and the depression soil of poor drainage. The latter has been invested after reclaiming it through planting the rice crop. Another type of soil is the sand dune soil which is unsuitable for agricultural production. Another type is the gypsum desert soil, which is agriculturally poor. Results have further revealed that rivers are considered the main surface water resource in the irrigation process as represented by the Euphrates Riverand its branches within the governorate. This is due to the lack of rain and its fluctuation.

Soil microbes weaken the positive effect of an aquatic–terrestrial subsidy on plant performance

AbstractAimsLinkages formed through aquatic–terrestrial subsidies can play an important role in structuring communities and mediating ecosystem functions. Aquatic–terrestrial subsidies may be especially important in nutrient-poor ecosystems, such as the freshwater sand dunes surrounding Lake Michigan. Adult midges emerge from Lake Michigan in the spring, swarm to mate and die. Their carcasses form mounds at the base of plants, where they may increase plant productivity through their nutrient inputs. However, the effect of aquatic–terrestrial subsidies on plant productivity could depend on other biotic interactions. In particular, soil microbes might play a key role in facilitating the conversion of nutrients to plant-available forms or competing for the nutrients with plants.MethodsIn a greenhouse experiment, we tested how carcasses from lake emergent midges (Chironomidae) and soil microbes independently and interactively influenced the performance of a common dune grass, Calamovilfa longifolia. To determine whether midges influenced abiotic soil properties, we measured how midge additions influenced soil nutrients and soil moisture.Important FindingsMidges greatly increased plant biomass, while soil microbes influenced the magnitude of this effect. In the absence of soil microbes plant biomass was seven times greater with midges than without midges. However, in the presence of soil microbes, plant biomass was only three times greater. The effect of midges might be driven by their nutrient inputs into the soil, as midges contained 100 times more N, 10 times more P and 150 times more K than dune soils did. Our results suggest that soil microbes may be competing with plants for these nutrients. In sum, we found that midges can be an important aquatic–terrestrial subsidy that produces strong, positive effects on plant productivity along the shorelines of Lake Michigan, but that the impact of aquatic–terrestrial subsidies must be considered within the context of the complex interactions that take place within ecological communities.

Outcrop distribution and formation of carbonate rhizoliths in Badain Jaran Desert, NW China

Carbonate rhizoliths and related features are environmental and ecological indicators of not only palaeosols, but also modern soils. They designate subaerial vadose and pedogenic diagenesis environments. Rhizoliths are commonly used as a tool for paleoenvironmental reconstructions, but uncertainty remains regarding their formation mechanisms. Field characteristics of the dune rhizoliths in the Badain Jaran Desert, NW China were analyzed to investigate formation mechanisms and interpret paleoenvironmental significance. Systematic field sampling and intensive examination showed that the tube-like rhizoliths without morphological structures of plant roots have been placed at the dune soil surface following erosion and weathering but the underground rhizoliths are still connected to the dead Artemisia roots. Rhizoliths occurred only along the windward, long gentle slopes of mega-dunes. Their distribution patterns of both types in connection with plant distribution and landscapes have been studied. Their petrological and mineralogical characters were performed in detail using microscopic and spectroscopic techniques (cathodoluminescence, scanning electronic microscopy and energy dispersive X-ray spectroscopy) in laboratory. Altogether, field and laboratory analyses showed that rhizolith cement is calcium carbonate and despite the high porosity of soil and high aridness of climate, soil moisture plays an important role in sustaining Artemisia growth and rhizolith formation. Desert rhizoliths can therefore be used as a proxy to infer local soil moisture and plant communities. Moreover, as soil moisture content is related to climate and landscape position, rhizoliths could indirectly be indicators of aboveground environmental conditions, e.g. annual precipitation or humidity.