Subjects: Agriculture, Forestry,Livestock & Aquatic Products Science >> Soil Science submitted time 2024-05-15 Cooperative journals: 《干旱区科学》
Abstract： It is of great significance to study the effects of desert plants on soil enzyme activities and soil organic carbon (SOC) for maintaining the stability of the desert ecosystem. In this study, we studied the responses of soil enzyme activities and SOC fractions (particulate organic carbon (POC) and mineral-associated organic carbon (MAOC)) to five typical desert plant communities (Convolvulus tragacanthoides, Ephedra rhytidosperma, Stipa breviflora, Stipa tianschanica var. gobica, and Salsola laricifolia communities) in the proluvial fan in the eastern foothills of the Helan Mountain in Ningxia Hui Autonomous Region, China. We recorded the plant community information mainly including the plant coverage and herb and shrub species, and obtained the aboveground biomass and plant species diversity through sample surveys in late July 2023. Soil samples were also collected at depths of 0–10 cm (topsoil) and 10–20 cm (subsoil) to determine the soil physicochemical properties and enzyme activities. The results showed that the plant coverage and aboveground biomass of S. laricifolia community were significantly higher than those of C. tragacanthoides, S. breviflora, and S. tianschanica var. gobica communities (P<0.05). Soil enzyme activities varied among different plant communities. In the topsoil, the enzyme activities of alkaline phosphatase (ALP) and β-1,4-glucosidas (βG) were significantly higher in E. rhytidosperma and S. tianschanica var. gobica communities than in other plant communities (P<0.05). The topsoil had higher POC and MAOC contents than the subsoil. Specifically, the content of POC in the topsoil was 18.17%–42.73% higher than that in the subsoil. The structural equation model (SEM) indicated that plant species diversity, soil pH, and soil water content (SWC) were the main factors influencing POC and MAOC. The soil pH inhibited the formation of POC and promoted the formation of MAOC. Conversely, SWC stimulated POC production and hindered MAOC formation. Our study aimed to gain insight into the effects of desert plant communities on soil enzyme activities and SOC fractions, as well as the drivers of SOC fractions in the proluvial fan in the eastern foothills of the Helan Mountain and other desert ecosystems.
Subjects: Agriculture, Forestry,Livestock & Aquatic Products Science >> Soil Science submitted time 2024-05-15 Cooperative journals: 《干旱区科学》
Abstract： The clay–sand barriers in Minqin desert area, China, represent a pioneering windbreak and sand fixation project with a venerable history of 60 a. However, studies on evaluating the long-term effectiveness of clay–sand barriers against aeolian erosion, particularly from the perspective of surface sediment grain size, are limited and thus insufficient to ascertain the protective impact of these barriers on regional aeolian activities. This study focused on the surface sediments (topsoil of 0–3 cm depth) of clay–sand barriers in Minqin desert area to explain their erosion resistance from the perspective of surface sediment grain size. In March 2023, six clay–sand barrier sampling plots with clay–sand barriers of different deployment durations (1, 5, 10, 20, 40, and 60 a) were selected as experimental plots, and one control sampling plot was set in an adjacent mobile sandy area without sand barriers. Surface sediment samples were collected from the topsoil of each sampling plot in the study area in April 2023 and sediment grain size characteristics were analyzed. Results indicated a predominance of fine and medium sands in the surface sediments of the study area. The deployment of clay–sand barriers cultivated a fine quality in grain size composition of the regional surface sediments, increasing the average contents of very fine sand, silt, and clay by 30.82%, 417.38%, and 381.52%, respectively. This trend became markedly pronounced a decade after the deployment of clay–sand barriers. The effectiveness of clay–sand barriers in erosion resistance was manifested through reduced wind velocity, the interception of sand flow, and the promotion of fine surface sediment particles. Coarser particles such as medium, coarse, and very coarse sands predominantly accumulated on the external side of the barriers, while finer particles such as fine and very fine sands concentrated in the upwind (northwest) region of the barriers. By contrast, the contents of finest particles such as silt and clay were higher in the downwind (southeast) region of the sampling plots. For the study area, the deployment of clay–sand barriers remains one of the most cost-effective engineering solutions for aeolian erosion control, with sediment grain size parameters serving as quantitative indicators for the assessment of these barriers in combating desertification. The results of this study provide a theoretical foundation for the construction of windbreak and sand fixation systems and the optimization of artificial sand control projects in arid desert areas.
Subjects: Agriculture, Forestry,Livestock & Aquatic Products Science >> Soil Science submitted time 2024-04-15 Cooperative journals: 《干旱区科学》
Abstract： The unique geomorphological features and farming methods in the Mollisol region of Northeast China increase water catchment flow and aggravate the erosion of ephemeral gully (EG). Vegetation suffers from rain erosion and damage during the growth stage, which brings serious problems to the restoration of grass in the early stage. Therefore, effects of coir geotextile and geocell on EG erosion under four confluence intensities were researched in this study. Results of the simulated water discharge erosion test showed that when the confluence strength was less than 30 L/min, geocell and coir geotextile had a good effect on controlling EG erosion, and sediment yield of geocell and coir geotextile was reduced by 25.95%–37.82% and 73.73%–88.96%, respectively. However, when confluence intensity increased to 40 L/min, protective effect of coir geotextile decreased, and sediment yield rate increased sharply by 189.03%. When confluence intensity increased to 50 L/min, the protective effect of coir geotextile was lost. On the other hand, geocell showed that the greater the flow rate, the better the protective effect. In addition, with the increase in confluence intensity, erosion pattern of coir geotextile developed from sheet erosion to intermittent fall and then to completion of main rill, and the protective effect was gradually weakened. In contrast, the protective effect of EG under geocell was gradually enhanced from the continuous rill to the intermittent rill and finally to the intermittent fall. This study shows that coir geotextile and geocell can prevent EG erosion, and the effect of geocell is better than that of coir geotextile on the surface of EG.
Subjects: Agriculture, Forestry,Livestock & Aquatic Products Science >> Soil Science submitted time 2024-03-13 Cooperative journals: 《干旱区科学》
Abstract： One of the goals of grazing management in the desert steppe is to improve its ecosystem. However, relatively little is known about soil microbe communities in the desert steppe ecosystem under grazing management. In this study, we investigated the diversity and aboveground biomass of Caragana korshinskii Kom. shrub communities in long-term fencing and grazing areas, combined with an analysis of soil physical-chemical properties and genomics, with the aim of understanding how fence management affects plant-soil-microbial inter-relationships in the desert steppe, China. The results showed that fence management (exclosure) increased plant diversity and aboveground biomass in C. korshinskii shrub area and effectively enhanced soil organic carbon (233.94%), available nitrogen (87.77%), and available phosphorus (53.67%) contents. As well, the Shannon indices of soil bacteria and fungi were greater in the fenced plot. Plant-soil changes profoundly affected the alpha- and beta-diversity of soil bacteria. Fence management also altered the soil microbial community structure, significantly increasing the relative abundances of Acidobacteriota (5.31%–8.99%), Chloroflexi (3.99%–5.58%), and Glomeromycota (1.37%–3.28%). The soil bacterial-fungal co-occurrence networks under fence management had higher complexity and connectivity. Based on functional predictions, fence management significantly increased the relative abundance of bacteria with nitrification and nitrate reduction functions and decreased the relative abundance of bacteria with nitrate and nitrite respiration functions. The relative abundances of ecologically functional fungi with arbuscular mycorrhizal fungi, ectomycorrhizal fungi, and saprotrophs also significantly increased under fence management. In addition, the differential functional groups of bacteria and fungi were closely related to plant-soil changes. The results of this study have significant positive implications for the ecological restoration and reconstruction of dry desert steppe and similar areas.
Subjects: Agriculture, Forestry,Livestock & Aquatic Products Science >> Soil Science submitted time 2024-03-13 Cooperative journals: 《干旱区科学》
Abstract： In the Loess Plateau of China, land-use pattern is a major factor in controlling underlying biological processes. Additionally, the process of land-use pattern was accompanied by abandoned lands, potentially impacting soil microbe. However, limited researches were conducted to study the impacts of land-use patterns on the diversity and community of soil microorganisms in this area. The study aimed to investigate soil microbial community diversity and composition using high-throughput deoxyribonucleic acid (DNA) sequencing under different land-use patterns (apricot tree land, apple tree land, peach tree land, corn land, and abandoned land). The results showed a substantial difference (P<0.050) in bacterial alpha-diversity and beta-diversity between abandoned land and other land-use patterns, with the exception of Shannon index. While fungal beta-diversity was not considerably impacted by land-use patterns, fungal alpha-diversity indices varied significantly. The relative abundance of Actinobacteriota (34.90%), Proteobacteria (20.65%), and Ascomycota (77.42%) varied in soils with different land-use patterns. Soil pH exerted a dominant impact on the soil bacterial communities' composition, whereas soil available phosphorus was the main factor shaping the soil fungal communities' composition. These findings suggest that variations in land-use pattern had resulted in changes to soil properties, subsequently impacting diversity and structure of microbial community in the Loess Plateau. Given the strong interdependence between soil and its microbiota, it is imperative to reclaim abandoned lands to maintain soil fertility and sustain its function, which will have significant ecological service implications, particularly with regards to soil conservation in ecologically vulnerable areas.
Subjects: Agriculture, Forestry,Livestock & Aquatic Products Science >> Soil Science submitted time 2024-01-12 Cooperative journals: 《干旱区科学》
Abstract： Vegetation restoration through artificial plantation is an effective method to combat desertification, especially in arid and semi-arid areas. This study aimed to explore the ecological effect of the plantation of Sabina vulgaris on soil physical and chemical properties on the southeastern fringe of the Mu Us Sandy Land, China. We collected soil samples from five depth layers (0–20, 20–40, 40–60, 60–80, and 80–100 cm) in the S. vulgaris plantation plots across four plantation ages (4, 7, 10, and 16 years) in November 2019, and assessed soil physical (soil bulk density, soil porosity, and soil particle size) and chemical (soil organic carbon (SOC), total nitrogen (TN), available nitrogen (AN), available phosphorus (AP), available potassium (AK), cation-exchange capacity (CEC), salinity, pH, and C/N ratio) properties. The results indicated that the soil predominantly consisted of sand particles (94.27%–99.67%), with the remainder being silt and clay. As plantation age increased, silt and very fine sand contents progressively rose. After 16 years of planting, there was a marked reduction in the mean soil particle size. The initial soil fertility was low and declined from 4 to 10 years of planting before witnessing an improvement. Significant positive correlations were observed for the clay, silt, and very fine sand (mean diameter of 0.000–0.100 mm) with SOC, AK, and pH. In contrast, fine sand and medium sand (mean diameter of 0.100–0.500 mm) showed significant negative correlations with these indicators. Our findings ascertain that the plantation of S. vulgaris requires 10 years to effectively act as a windbreak and contribute to sand fixation, and needs 16 years to improve soil physical and chemical properties. Importantly, these improvements were found to be highly beneficial for vegetation restoration in arid and semi-arid areas. This research can offer valuable insights for the protection and restoration of the vegetation ecosystem in the sandy lands in China.
Subjects: Agriculture, Forestry,Livestock & Aquatic Products Science >> Soil Science submitted time 2024-01-12 Cooperative journals: 《干旱区科学》
Abstract： Proposed agroforestry options should begin with the species that farmers are most familiar with, which would be the native multipurpose trees that have evolved under smallholder farms and socioeconomic conditions. The African birch (Anogeissus leiocarpa (DC.) Guill. & Perr.) and pink jacaranda (Stereospermum kunthianum Cham.) trees are the dominant species in the agroforestry parkland system in the drylands of Tigray, Ethiopia. Smallholder farmers highly value these trees for their multifunctional uses including timber, firewood, charcoal, medicine, etc. These trees also could improve soil fertility. However, the amount of soil physical and chemical properties enhanced by the two species must be determined to maintain the sustainable conservation of the species in the parklands and to scale up to similar agro- ecological systems. Hence, we selected twelve isolated trees, six from each species that had similar dendrometric characteristics and were growing in similar environmental conditions. We divided the canopy cover of each tree into three radial distances: mid-canopy, canopy edge, and canopy gap (control). At each distance, we took soil samples from three different depths. We collected 216 soil samples (half disturbed and the other half undisturbed) from each canopy position and soil depth. Bulk density (BD), soil moisture content (SMC), soil organic carbon (SOC), total nitrogen (TN), available phosphorus (AP), available potassium (AK), pH, electrical conductivity (EC), and cation exchange capacity (CEC) were analysed. Results revealed that soil physical and chemical properties significantly improved except for soil texture and EC under both species, CEC under A. leiocarpus, and soil pH under S. kunthianum, all the studied soils were improved under both species canopy as compared with canopy gap. SMC, TN, AP, and AK under canopy of these trees were respectively 24.1%, 11.1%, 55.0%, and 9.3% higher than those soils under control. The two parkland agroforestry species significantly enhanced soil fertility near the canopy of topsoil through improving soil physical and chemical properties. These two species were recommended in the drylands with similar agro-ecological systems.
Subjects: Agriculture, Forestry,Livestock & Aquatic Products Science >> Soil Science submitted time 2023-10-17 Cooperative journals: 《干旱区科学》
Abstract：Leguminosae are an important part of terrestrial ecosystems and play a key role in promoting soil nutrient cycling and improving soil properties. However, plant composition and species diversity change rapidly during the process of succession, the effect of leguminosae on soil physical-chemical and biological properties is still unclear. This study investigated the changes in the composition of plant community, vegetation characteristics, soil physical-chemical properties, and soil biological properties on five former farmlands in China, which had been abandoned for 0, 5, 10, 18, and 30 a. Results showed that, with successional time, plant community developed from annual plants to perennial plants, the importance of Leguminosae and Asteraceae significantly increased and decreased, respectively, and the importance of grass increased and then decreased, having a maximum value after 5 a of abandonment. Plant diversity indices increased with successional time, and vegetation coverage and above- and below-ground biomass increased significantly with successional time after 5 a of abandonment. Compared with farmland, 30 a of abandonment significantly increased soil nutrient content, but total and available phosphorus decreased with successional time. Changes in plant community composition and vegetation characteristics not only change soil properties and improve soil physical-chemical properties, but also regulate soil biological activity, thus affecting soil nutrient cycling. Among these, Leguminosae have the greatest influence on soil properties, and their importance values and community composition are significantly correlated with soil properties. Therefore, this research provides more scientific guidance for selecting plant species to stabilize soil ecosystem of farmland to grassland in the Loess Plateau, China.
Subjects: Agriculture, Forestry,Livestock & Aquatic Products Science >> Soil Science submitted time 2023-10-17 Cooperative journals: 《干旱区科学》
Abstract：Restoration of mining soils is important to the vegetation and environment. This study aimed to explore the variations in soil nutrient contents, microbial abundance, and biomass under different gradients of substrate amendments in mining soils to select effective measures. Soil samples were collected from the Bayan Obo mining region in Inner Mongolia Autonomous Region, China. Contents of soil organic matter (SOM), available nitrogen (AN), available phosphorus (AP), available potassium (AK), microbial biomass carbon/microbial biomass nitrogen (MBC/MBN) ratio, biomass, and bacteria, fungi, and actinomycetes abundance were assessed in Agropyron cristatum L. Gaertn., Elymus dahuricus Turcz., and Medicago sativa L. soils with artificial zeolite (AZ) and microbial fertilizer (MF) applied at T0 (0 g/kg), T1 (5 g/kg), T2 (10 g/kg), and T3 (20 g/kg). Redundancy analysis (RDA) and technique for order preference by similarity to ideal solution (TOPSIS) were used to identify the main factors controlling the variation of biomass. Results showed that chemical indices and microbial content of restored soils were far greater than those of control. The application of AZ significantly increases SOM, AN, and AP by 20.27%, 23.61%, and 40.43%, respectively. AZ significantly increased bacteria, fungi, and actinomycetes abundance by 0.63, 3.12, and 1.93 times of control, respectively. RDA indicated that AN, MBC/MBN ratio, and SOM were dominant predictors for biomass across samples with AZ application, explaining 87.6% of the biomass variance. SOM, MBC/MBN ratio, and AK were dominant predictors with MF application, explaining 82.9% of the biomass variance. TOPSIS indicated that T2 was the best dosage and the three plant species could all be used to repair mining soils. AZ and MF application at T2 concentration in the mining soils with M. sativa was found to be the most appropriate measure.
Subjects: Agriculture, Forestry,Livestock & Aquatic Products Science >> Soil Science submitted time 2023-08-26 Cooperative journals: 《干旱区研究》
Abstract： As an effective agricultural management method for improving ecological and environmental benefits,the farmland shelterbelt system is crucial in improving soil physical and chemical properties, the ecologicalenvironment, and crop yield. This study clarifies the effects of this system on ecosystem functions and provides aguide for the ecological restoration of fragile ecosystems. In the Hetao Irrigation District, three typical farmlandshelterbelts (four-, five-, and eight-line patterns) were selected to measure soil properties at a 0-100 cm depth andvegetation properties of shelterbelts and farmland at different distances (0.3 H, 0.7 H, 1 H, 2 H, 3 H, and 4 H)from the shelterbelts during the growing seasons from 2019 to 2021. Soil moisture storage (SMS) and soilnutrient storage [soil carbon storage (SCS), soil nitrogen storage (SNS), and soil phosphorus storage (SPS)] weremeasured. The results showed that (1) the soil bulk density and clay content of different shelterbelts differedsignificantly in the horizontal direction, while the soil properties differed significantly in the vertical direction. (2)The shelterbelts had enhanced water retention and nutrient supply functions, and the soil water and nutrientreserves of the four-line pattern were higher than those of the five- and eight-line patterns (SMS = 237.44 mm;SCS = 544.93 g·m− 2; SNS = 953.72 g·m− 2; SPS = 859.04 g·m− 2). (3) The average tree height and DBH of thefour- row shelterbelt were 30.06 m and 0.41 m, respectively. Additionally, the four- row shelterbelt had themaximum crop yield of 15.75 t·hm−2. (4) Redundancy analysis showed that a close relationship existed betweenenvironmental factors and ecosystem functions in the different shelterbelts, soil characteristics were closelyrelated to soil water and nutrient reserves, and vegetation attributes were negatively correlated with SNS andSPS. In conclusion, the four-line pattern demonstrated the strongest capacity for water and nutrient supply. Theresults of this study provide a sufficient theoretical basis for shelterbelt construction and ecological restoration inecologically fragile areas.
Subjects: Agriculture, Forestry,Livestock & Aquatic Products Science >> Soil Science submitted time 2023-08-26 Cooperative journals: 《干旱区研究》
Abstract： Soil salinization caused by natural and anthropogenic factors is an environmental hazard that isespecially important in arid and semi-arid regions of the world. The accumulation of salts in soil is a major threatto crop production and global agriculture. Therefore, the rapid and precise detection of salt- affected lands ishighly critical for sustaining soil productivity. This paper aims to analyze the performance of the random forestalgorithm in mapping soil salinity in the Yinchuan Plain using Landsat-8 OLI, Sentinel-2A satellite images, andground-based soil salt content (SSC) measurements with the aid of the Google Earth Engine (GEE) platform. Weestimated SSC by establishing the relationship between spectral index characteristics and ground-measured soilsalt content. The results show that GEE can provide reliable data support for soil salinity prediction. The randomforest model established with Sentinel-2A as the data source performed better (R2 = 0.789, RMSE = 1.487) thanand can therefore be used for the estimation of soil salinity using high- resolution remote sensing, which canprovide theoretical support for large-scale soil salinity monitoring.
Subjects: Agriculture, Forestry,Livestock & Aquatic Products Science >> Soil Science submitted time 2023-08-26 Cooperative journals: 《干旱区研究》
Abstract： The ecological water transport of the Tarim River increases flood intensity on both sides of the basin,which has an important effect on the carbon cycle of the riparian Populus euphratica forest ecosystems. Westudied the P. euphratica forest in the middle reaches of the Tarim River and the content changes of organiccarbon and measured and analyzed the active components of the riparian P. euphratica forest at four differentstages (1 m before (W1); 4 days after (W2); 17 days after (W3); and after (W4)). We found that the soil organiccarbon (SOC) content was higher before and after overflow. The effect of flood overflow on the SOC content inthe 0-20 cm soil layer was more significant than that of the 20-100 cm soil layer. During the same stage, theSOC content decreased with soil layer depth. The dissolved organic carbon (DOC) and microbial biomass carbon(MBC) in the 0-10 cm and 40-100 cm soil layers were significantly increased on the 4th day of the overflowcompared to before the overflow. The contents decreased gradually with the extension of the overflow time. Thedifferences between each stage were significant (P < 0.05). The DOC/SOC and MBC/SOC in the same soil layerdiffered significantly as time since the overflow extended (P < 0.05). The extracted organic carbon (EOC) contentin the 0-10 cm soil layer before the overflow was higher than after the overflow. The EOC content in other soillayers during the overflow period was higher than before or after the overflow. The EOC/SOC in the 0-10 cmand 20-60 cm soil layers were significantly different at each overflow stage (P < 0.05). There was a significantlypositive correlation between SOC and DOC content from before the overflow to day 17 of the overflow (r > 0.69,n = 15) and a significantly positive correlation between EOC and DOC content after discharge (r = 0.54, n = 15).There was a significant correlation between SOC and DOC content before the overflow and at various stagesafter the overflow. Based on the above analysis, the flooding process in the middle reaches of the Tarim River hada significant effect on the distribution of SOC and the active components of the riparian poplar forest, withdifferences found in the sensitive soil layers of each component. SOC was most significant in the 0-20 cm soillayer. DOC and MBC were most significant in the 0-10 cm soil layer and the 40-100 cm soil layer, respectively,and EOC was most significant in the 20-60 cm soil layer. Thus, the observed change regularity has the dualcharacteristics of forest and wetland.
Subjects: Agriculture, Forestry,Livestock & Aquatic Products Science >> Soil Science submitted time 2023-08-25 Cooperative journals: 《干旱区研究》
Abstract： Water use efficiency (WUE) is an important indicator of the carbon- water cycle of farmlandecosystems and is of great significance for guiding agricultural irrigation and improving water productivity.Ningxia Irrigation area is a large-scale irrigation district located in the arid climate zone of China, where the cornplanting area is the largest. Based on eddy flux observation of actual evapotranspiration (ET) of farmlandecosystems, this paper used the hydrogen and oxygen stable isotope method to segment evapotranspiration andestimated the total primary productivity (GPP) of typical maize farmland ecosystems in the Yellow Riverirrigation area of Ningxia using the LUE (Light Use Efficiency) model. Population Water Use Efficiency WUET =GPP/T, Ecosystem Water Use Efficiency WUEET = GPP/T, and Intrinsic Water Use Efficiency IWUEVPD = (GPP·VPD)/ET were calculated. Then, the relationship between different WUE and environmental factors, such as airtemperature, saturated water vapor pressure difference, CO2 concentration, effective photosynthetic radiation, andsoil water content was analyzed from three aspects: functional response relationship, correlation, and sensitivity.The result showed that the variation of actual evapotranspiration in the growing season of the maize agroecosystemin the Ningxia yellow irrigation area was single- humped, and the trends of crop transpiration andactual evapotranspiration were consistent. The variation of water use efficiency in the growing season wasdifferent among the three species, with WUET showing a“W-shaped”variation pattern during the growing seasonwhile WUEET and IWUEVPD showed a“single-hump”variation pattern. All three WUE peaks occurred at the maletasseling stage, reaching (5.90 kg C·m−3·H2O, 5.02 kg C·m−3·H2O, 32.9 kg C·hPa·m−3·H2O) respectively. Thethree kinds of water use efficiency began to decrease in the late filing period, and WUET increased slightly in thelate ripening period due to weak transpiration. Among the five environmental factors, WUET, WUEET andIWUEVPD were positively correlated with soil water content, and the correlation and sensitivity were the strongest.The three water use efficiencies were significantly negatively correlated with VPD, with the second strongestcorrelation and sensitivity. Air temperature, photosynthetically active radiation, and CO2 concentration werenegatively correlated with the three kinds of WUE but not critical factors. Therefore, soil moisture and VPD arethe key factors affecting the WUE of the maize farmland ecosystem in the Yellow River irrigation area of Ningxia.
Subjects: Agriculture, Forestry,Livestock & Aquatic Products Science >> Soil Science submitted time 2023-08-25 Cooperative journals: 《干旱区研究》
Abstract： To explore the trend of the change of the soil respiration flux and main influencing factors in theprocess of desertification reversal, 9 a, 18 a and 30 a ages of Hedysarum laeve shrubbery and no afforestationquicksand land (CK) were selected at Mu Us sandy land in Northern China. Using the Li-8100 carbon fluxobservation system which produced in the United States, measured soil respiration from May to October. At thesame time, the main influencing factors were determined and analyzed. The results showed that: (1) Both soilrespiration rate and flux increased first and then decreased in the growth season from May to October, and thehighest value appeared in July. (2) The soil respiration rate and flux showed a continuous increasing trend withthe age of the Hedysarum laeve shrubbery, the Q10 value shows a continuous downward trend. From May toOctober in the growing season, the order of average soil respiration rate was: 30 a（2.16 μmol·m-2·s-1）>18 a（1.98μmol·m-2 ·s-1）>9 a（1.41 μmol·m-2 ·s-1）>CK（0.24 μmol·m-2 ·s-1）; the soil respiration carbon flux was 30 a(365.74 g C·m-2)>18 a (313.63 g C·m-2)>9 a (218.66 g C·m-2)>CK (40.08 g C·m-2). (3) The seasonal variationof soil respiration rate in CK, 9 a and 18 a plots was mainly affected by the coupling effect of soil temperatureand water (P<0.01), while the main control factor in 30 a plots was soil temperature (P<0.01). (4) Soil respirationflux was positively correlated with vegetation biomass, soil organic carbon and total nitrogen content (P<0.05).
Subjects: Agriculture, Forestry,Livestock & Aquatic Products Science >> Soil Science submitted time 2023-08-25 Cooperative journals: 《干旱区研究》
Abstract： Rainfall is an important factor affecting water supply and soil respiration in wetland areas. Increases inextreme rainfall variability caused by global climate change are thus expected to impact wetland ecosystems. Toinvestigate this, the changes in soil organic carbon (SOC), total nitrogen (TN), and total phosphorus (TP) inresponse to altered rainfall frequencies (weekly, fortnightly, three- weekly, four- weekly, and control irrigationtreatments) were assessed in a wet meadow in the Gahai-Zecha Nature Reserve on the north-eastern edge of theTibetan Plateau. The SOC was found to increase with increasing rainfall frequency, while TP and TN decreased.SOC and TN decreased with increasing soil depth and TP was inconsistent across the different soil layers. As aresult, the ratios of C:P and N:P decreased with the soil layers, but the ratio of C:N did not show a significantchange. The ratios of C:N, C:P, and N:P did not show significant responses to the rainfall treatments. The SOC,TN, and TP showed obvious seasonal variations, as the SOC showed an increasing and then decreasing trend, theTN showed a decreasing and then increasing trend, and the TP content showed an“M”-shaped decreasing trend.The results suggest that continuous changes in global rainfall, including an increased rainfall frequency, willaggravate the loss of nitrogen and phosphorus in the shallow soil of the alpine wet meadow, likely resulting inaggravated damage due to eutrophication in the water environment surrounding the alpine wet meadows.
Subjects: Agriculture, Forestry,Livestock & Aquatic Products Science >> Soil Science submitted time 2023-08-25 Cooperative journals: 《干旱区研究》
Abstract： To elucidate soil bacterial network interactions within Pinus sylvestris var. mongolica plantations inthe Hulunbuir Desert. P. sylvestris plantations representing three different age groups (25 a, 34 a, and 43 a) andtwo soil layers (0- 10 and 10- 20 cm) were selected to assess their soil bacterial networks using molecularecological network analysis and data from a referenced grassland. The numbers of network edges increased, theaverage path length reduced from 25 a to 43 a. While the number of network edges reduced and the average pathlength increased with soil layers from 0-10 cm to 10-20 cm. Compared with the grassland, the P. sylvestrisplantations had a lower network edge, and the soil bacterial network was less complicated. The soil bacteria werefound to belong to the Acidimicrobiales, RB41, and MB-A2-108 in the 25 a plantation, Gaiellales in the 34 aplantation, and Gaiellales, RB41, Subgroup_7, Subgroup_6, and DA101_soil_group in the 43 a plantation,Latescibacteria in the grassland. The soil bacterial network was significantly positively correlated with ammonianitrogen, total nitrogen, microbial carbon content, and urease activities and significantly negatively correlatedwith invertase and catalase activities, soil water content and available phosphorus (P < 0.05). The soil organicmatter had both positive and negative effects (P < 0.05). The soil bacterial network complexity and compactnessincreased from 25 a to 43 a. The opposite was found for the soil layers from 0-10 cm to 10-20 cm. Comparedwith the grassland, the soil bacterial network of the P. sylvestris plantation was less complicated. The keystonesoil bacteria species were different among the three stand ages, and were greatest in stand 43 a. There were morekeystone species in the plantation than the grassland. Soil physicochemical properties and enzymatic activityderived the soil bacterial network, and soil organic matter was the major influencing factor. This improvedinformation contributed to a deep understanding of the soil bacterial community and provided a scientific andtechnological basis for the sustainable management of P. sylvestris plantations in the Hulunbuir Desert.
Subjects: Agriculture, Forestry,Livestock & Aquatic Products Science >> Soil Science submitted time 2023-05-30 Cooperative journals: 《干旱区研究》
Abstract： Abstract：This study was conducted to explore the influence of desert shrubs and their associated species on soil particle size and nutrient spatial heterogeneity under shrubs. The mixed community of Ammopiptanthus mongolicus and Sarcozygium xanthoxylon and a single plant of A. mongolicus in the Western Ordos National Nature Reserve were selected as the research samples. The surrounding bare sandy land without vegetation cover was used as control. The soil particle size characteristics, nutrient accumulation changes, and the relationship between nutrients and particle size composition under different shrub distribution types were analyzed. The results were as follows: (1) Compared with the mixed community of A. mongolicus-S. xanthoxylon, the volume percentages of soil clay, silt, and fine sand of the single A. mongolicus increased by 0.8%, 0.8%, and 0.71%, respectively. As the types of shrubs decrease, soil particle size became smaller in turn, sorting deteriorated, the fractal dimension became smaller, the soil particle distribution gradually became asymmetric, and the particle composition was concentrated at fine particles. (2) The contents of soil organic matter and alkali- hydrolyzable nitrogen increased by 1.85 g·kg-1 and 8.18 g·kg-1, respectively, with the increase in shrub species. The accumulation of organic matter and available phosphorus by a single A. mongolicus was stronger than that by A. mongolicus-S. xanthoxylon; however, the accumulation of alkali- hydrolyzable nitrogen was slightly poor than that of A. mongolicus-S. xanthoxylon. (3) A. mongolicus-S. xanthoxylon available soil phosphorus content was significantly positively correlated with fine sand content (P<0.05), and A. mongolicus available soil nitrogen and potassium were significantly positively correlated with coarse sand (P<0.05). A. mongolicus-S. xanthoxylon can effectively promote soil granulation and significantly improve soil nutrients. However, the presence of the associated species S. xanthoxylon reduced the enrichment of organic matter and available phosphorus by A. mongolicus.
Subjects: Agriculture, Forestry,Livestock & Aquatic Products Science >> Soil Science submitted time 2023-05-30 Cooperative journals: 《干旱区研究》
Abstract： After ecological restoration in Horqin Sandy Land, the soil moisture dynamics of the forest and its response to rainfall affect whether Pinus sylvestris var. mongolica(PSM) can be continuously used for the ecological restoration in the same type of area. To study the characteristics of soil moisture dynamics after vegetation restoration on the southern edge of Horqin Sandy Land, this study used the methods of in situ observation and numerical simulation and corrected the HYDRUS-1D model based on the measured data of soil moisture to explore its relationship with rainfall. We obtained the following results: (1) The regional moisture distribution was changed by the PSM plantation, deep soil recharge at 2.0 m in bare sand accounted for 44.16% of the annual rainfall, whereas deep soil recharge at 2.0 m in PSM land accounted for only 0.7% of the annual rainfall. (2) Soil moisture below a depth of 0.4 m had no response to light rain, but the response depth of soil moisture to moderate rain could reach 1.0 m. The response depth to heavy rain and rainstorm involved the entire observation profile. With increasing soil depth, a decreasing trend was observed in the variation in moisture fluctuation. (3) There was a strong correlation between rainfall and volumetric soil water content at shallow depth, and the cumulative rainfall at weekly and semi- monthly intervals was significantly correlated with the volumetric soil water content of each layer(P<0.05). Rainfall >50 mm can ensure the supply of soil moisture within 2.0 m. (4) The determination coefficient of the model was between 0.61 and 0.85, and the root mean square error ranged from 0.0061 to 0.0096 cm -3·cm -3. The accuracy of the deep layer simulation was higher than that of the shallow layer. These results have important implications for rain- fed vegetation afforestation in the Horqin Sandy Land.
Subjects: Agriculture, Forestry,Livestock & Aquatic Products Science >> Soil Science submitted time 2023-05-30 Cooperative journals: 《干旱区研究》
Abstract： This study was established to evaluate the influence of the Jilantai Salt Lake protection system on soil nutrient accumulation. This is a comparative study of soil nutrient accumulation in different protection system types under the salt lake protection system (zones for fixing shifting sand, fencing dunes for grass recovery, preventing wind and stopping sand, and a forest for protecting the salt lake) using the method of representative investigation and laboratory analysis. The goal was to provide a theoretical basis for the management of shelter forest in Jilantai Salt Lake. Our results showed the following: (1) The increases in soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), available nitrogen (AN), and available phosphorus (AP) contents were in the range of 0.45-1.92 g·kg-1, 0.03-0.58 g·kg-1, 0.15-0.43 g·kg-1, 1.33-13.31 mg·kg-1, and 0.12-12.94 mg· kg-1, respectively. Soil depth, protection system type, and their interaction had significant positive effects on the increase in the soil SOC, TN, TP, and AP contents. (2) Establishment of the salt lake protection system had a significant effect on soil nutrients at a depth of approximately 0-100 cm, and the soil depth, protection system type, and their interaction had a significant impact on soil TP relative interaction intense (RIITP), AN relative interaction intense (RIIAN), AP relative interaction intense (RIIAP), and total RII. (3) Nutrient restoration index showed that soil nutrients improved to different degrees in different protection system types of the salt lake protection system, and their nutrient restoration indexes of zones for fixing shifting sand, fencing dunes for grass recovery, preventing wind and stopping sand and a forest for protecting the salt lake were 7.83%, 37.72%, 185.12%, and 252.36%, respectively. This study showed that, in the 38 years since its establishment, the salt lake protection system could effectively promote soil nutrient accumulation and accelerate soil nutrient restoration in the salt lake area, benefitting the ecological restoration and reconstruction around Jilantai Salt Lake.
Subjects: Agriculture, Forestry,Livestock & Aquatic Products Science >> Soil Science submitted time 2023-05-30 Cooperative journals: 《干旱区研究》
Abstract： To probe into the effects of typical ecological projects on improving soil moisture and other physical properties like water retention in Ulan Buh Desert, the desertification combating projects included straw checkerboard barrier and two native tree species (Haloxylon ammodendron and Hedysarum scoparium), and the shifting sandy land as the research object. The soil mechanical composition, moisture content, bulk density, porosity, water holding capacity, and water storage capacity of different soil layers at a depth of 0-100 cm were analyzed based on field sampling and lab analysis methods. The results showed that the ecological projects have a certain effect on the improvement of soil water physical properties and water retention of the aeolian sandy soil. (1) Compared to the control, the implementation of ecological projects promoted the apparent refinement of the grain size composition of the surface soil, showing decreased bulk density, increased soil porosity, and significantly increased soil water holding capacity and water storage capacity. (2) After the implementation of the typical ecological projects, the soil water retention was significantly improved, and the desertification land management effect was good. The results can provide basic data for the effective evaluation of regional desertification combating, and provide a scientific basis and theoretical reference for the type of selection of regional desertification combating ecological projects.
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