Artemisia Sacrorum Research Articles

Soil infiltration properties affected by typical plant communities on steep gully slopes on the Loess Plateau of China

Soil infiltration plays an important role in the processes of soil moisture, runoff generation, erosion, and nutrient movement under different climatic zones. Vegetation restoration may greatly affect soil infiltration process via altering soil and vegetation properties in arid and semi-arid region. However, few studies have been carried out to evaluate soil infiltration properties on steep gully slopes covered by typical plant communities in this region. This study was conducted to quantify the effects of typical plant communities on soil infiltration properties, and identify the main influencing factors on steep gully slopes of the Loess Plateau, China. Six typical plant communities of two shrubs (Caragana korshinskii and Hippophae rhamnoide) and four grasses (Artemisia sacrorum, Artemisia giraldii, Bothriochloa ischaemum, and Carex lanceolata) were selected to measure soil infiltration rate by a disc infiltrometer under four pressure heads of 0, −3, −6, and −12 cm. The results showed that soil infiltration properties of initial infiltration rate (IIR), steady infiltration (SIR), and hydraulic conductivity (Ks) were significantly affected by plant communities. IIR, SIR, and Ks varied from 1.54 to 0.27 mm min−1, 0.94 to 0.09 mm min−1, and 0.80 to 0.07 mm min−1 with the means of 0.78, 0.42, and 0.33 mm min−1. Plant communities of Artemisia sacrorum had the maximum IIR, SIR, and Ks, whereas Carex lanceolata had the minimum ones. Overall, IIR, SIR, and Ks of shrub communities were 14.7%, 4.9%, and 3.0% higher than those of grass communities. IIR, SIR, and Ks of shrub and grass communities with tap root systems were 1.90, 2.36, and 2.28 times greater than those with fibrous root systems. Variations in soil infiltration properties under different plant communities can be explained by the changes in soil texture, organic matter content, plant litter density, and root mass density. And plant litter and root were the main factors attributing to the changes in soil infiltration properties between different plant communities. The results are helpful to understand the differences in soil water storage, runoff, and erosion between different plant communities on steep gully slopes in arid and semi-arid regions.

Temporal variation in soil erodibility indices for five typical land use types on the Loess Plateau of China

Near soil surface characteristics of different land use types changed greatly during a growing season and thus likely affect soil erodibility index in arid and semi-arid regions. However, few studies have been conducted to quantify the temporal variations in soil erodibility indices under different land use types at small watershed scale. This study was carried out to detect the seasonal variations in soil erodibility indices reflected by soil cohesion (Coh), saturated conductivity (Ks), the number of drop impact (NDI), the mean weight diameter of soil aggregates (MWD), soil penetration resistance (PR), soil erodibility K factor and a comprehensive soil erodibility index (CSEI) from different standpoints under five typical land use types (cropland, orchard, grassland, shrubland and woodland) on the Loess Plateau. The results showed that Coh, Ks, NDI, MWD, PR and K increased generally during one growing season for most of land use types. While, K was almost stable or decreased slightly under all five tested land use types. On average, CSEI decreased by 15.4%, 20.0%, 17.8%, 17.9%, 17.4%, 23.2% and 17.8% during one growing season for cropland, orchards of Juglans regia L. and Malus pumila Mill., grasslands of Bothriochloa ischaemum (L.) Keng, and Artemisia sacrorum Ledeb., shrubland and woodland. The variations in soil erodibility indices over time were attributed to the temporal changes in biological soil crust thickness, plant litter density, root mass density, soil organic matter content and soil bulk density during one growing season. The results demonstrate that the seasonal variation in soil erodibility need to be considered when soil loss is predicted in small watershed scale.

Effect of Plant Morphological Traits on Throughfall, Soil Moisture, and Runoff

Plant canopy morphology plays an important role in water balance, peculiarly in semiarid environments. Through a field experiment, the impact of plant morphology of two native plant species, Artemisia sacrorum Ledeb (ASL) and Spiraea pubescens Turcz (SPT), on partitioning rainwater was revealed. The results indicated that a fragmented leaf shape and apparently high stem density of ASL reduced the throughfall and its intensity effectively but facilitated soil moisture replenishment. Although SPT has a greater canopy cover and canopy depth than ASL does, larger throughfall, a smaller throughfall threshold, and stronger throughfall intensity were observed in the SPT site. Moreover, the SPT site has a higher soil steady infiltration rate, but produced more surface runoff and caused lower soil moisture content. This study highlights the importance of plant morphological traits, peculiarly leaf morphology, in partitioning rainwater in this semiarid region. We argue that plant morphological traits should be considered when selecting plant species for revegetation and assessing water balance.

Influence of slope aspect on the macro- and micronutrients in Artemisia sacrorum on the Loess Plateau in China.

Slope aspect is an important topographic factor for a micro-ecosystem environment that may affect macro- and micronutrients in plants and soil. The south-, northwest-, and north-facing slopes were selected to investigate the influence of slope aspect on the concentrations, storage, and allocation of macro- and micronutrients in Artemisia sacrorum on the Loess Plateau in China. The concentrations of available manganese (Mn) in both rhizosphere and non-rhizosphere soils reached their maximum on the north-facing slope. The concentrations of available iron (Fe) in rhizosphere soil and available copper (Cu) in non-rhizosphere soil reached their maximum on the south-facing slope. Slope aspect significantly affected the total concentrations of potassium (K), calcium (Ca), magnesium (Mg), Cu, and Mn in rhizosphere and non-rhizosphere soils, and all of these elements reached their maximum on the northwest-facing slope. Slope aspect significantly influenced the concentrations of aboveground K, Ca, and Mg, sodium (Na), Mn, and belowground K in A. sacrorum, and the concentrations of aboveground K, Ca, Mg, and Na and belowground Mn, Na, Fe, Ca, and Mg in weed. Most elements in A. sacrorum and the weeds reached their maximum on the south-facing slope. Slope aspect significantly changed the aboveground-to-belowground concentration ratios of K, Ca, and Na in A. sacrorum and weed. Slope aspect significantly affected the storage of macro- and micronutrients in A. sacrorum and weed but not the storage in the plants of the entire plot. Slope aspect predominantly affected the storage allocation of macro- and micronutrients in A. sacrorum but not those in weed. Slope aspect is an important topographic factor that affects the macro- and micronutrients in plants and soil in micro-ecosystem environments.

Quantifying the effects of plant litter in the topsoil on the soil detachment process by overland flow in typical grasslands of the Loess Plateau, China

AbstractPlant litter can be incorporated into topsoil by a natural process, affecting the soil erosion process. This is a widespread phenomenon in erosion‐prone areas. This study was conducted to investigate the effect of litter incorporation on the process of soil detachment on the Loess Plateau, China. Four common plant litters (Bothriochloa ischaemum L. Keng., Artemisia sacrorum Ledeb., Setaria viridis L. Beauv., and Artemisia capillaris Thunb.) were collected, then incorporated into the silt loam soil at five rates (0.1, 0.4, 0.7, 1.0, and 1.3 kg m−2) on the basis of our field investigation. Twenty litter–soil treatments and one bare soil control were prepared. After 50 days of natural stabilization, 30 soil samples of each treatment were collected. We used a flume test to scour the soil samples under six flow shear stress conditions (5.66, 8.31, 12.21, 15.55, 19.15, and 22.11 Pa). The results showed that the different incorporated litter masses and morphological characteristics, such as litter tissue density (ranging from 0.52 to 0.68 g cm−3), length density (2.34 to 91.00 km m−3), surface area density (LSAD; 27.9 to 674.2 m2 m−3), and volume ratio (0.003 to 0.050 m3 m−3), caused varied soil detachment capacities (0.043 to 4.580 kg·m−2·s−1), rill erodibilities (0.051 to 0.237 s m−1), and critical shear stresses (2.02 to 6.83 Pa). The plant litter incorporated within the soil reduced the soil detachment capacities by 38%–59%, lowered the rill erodibilities by 32%–46%, and increased the critical shear stresses by 98%–193% compared with the bare soil control. The soil containing B. ischaemum (L.) Keng. litter was more resistant to erosion. By comparing different parameters, we found that the contact area between the litter and soil was the main factor affecting the soil detachment process. The soil erosion resistance increased with the increasing contact area between the soil and litter. Furthermore, the litter incorporation effect on rill erodibility can be comprehensively reflected by LSAD (R2 = .93; Nash–Sutcliffe efficiency = 0.79), which could be used to adjust the rill erodibility parameter in physical process‐based soil erosion models.

Land surface roughness affected by vegetation restoration age and types on the Loess Plateau of China

Land surface roughness (LSR) plays a critical role in hydrological and erosion processes. The changes in near soil surface characteristics induced by vegetation restoration likely affect LSR greatly. However, few studies have been performed to quantify these potential effects. This study was conducted to investigate the changes in LSR under different restoration age and types, and identify the influencing factors contributing to those changes on the Loess Plateau, China. The photogrammetric method was applied to measure random roughness (RR) in one sloped farmland (as control), six abandoned farmlands with different restoration age, and five abandoned farmlands with different restoration types. The results showed that RR increased significantly after vegetation restoration. Random roughness increased exponentially with vegetation restoration age (R2 = 0.93), and reached a steady state when the restoration age was approximately 25 years. Random roughness was greatly influenced by vegetation restoration types. The mixed forest of Amorpha fruticosa and Pinus tabuliformis had the maximum RR, followed by Caragana korshinskii, Pinus tabuliformis, Robinia pseudoacacia, and Artemisia sacrorum. Compared to control, RR increased by 1.66 to 4.68 mm and 3.68 to 6.67 mm for different restoration age and types. The variations in RR were closely related to the changes in near soil surface characteristics induced by vegetation restoration. Random roughness increased linearly with plant litter coverage, thickness, density, stem diameter, soil organic matter content, soil median grain size, sand content, and water stable aggregates. While, it decreased linearly with soil bulk density, silt and clay contents. The measured RR could be well estimated by plant litter density, soil organic matter content, silt content, and water stable aggregates (NSE = 0.77). These results are helpful to understand the influencing mechanism of vegetation restoration on hydrological and erosion processes on hillslope.

Effects of soil-incorporated plant litter morphological characteristics on the soil detachment process in grassland on the Loess Plateau of China

The Loess Plateau of China is one of the most eroded areas in the world. In the past 20 years, effective vegetation restoration measures have significantly changed the near-surface characteristics of soil. In natural conditions, plant litter is widespread in the topsoil. The effects of litter incorporated into soil on the process of soil detachment, which is closely related to plant litter morphology, are still not well known. This study aimed to detect the variation of litter morphological characteristics and quantify their effects on soil detachment capacity and rill erodibility when litter is incorporated into the soil. Four plant litters (Bothriochloa ischaemum (L.) Keng., Artemisia sacrorum Ledeb., Setaria viridis (L.) Beauv., and Artemisia capillaris Thunb.) with five length levels (<0.5, 0.5–2, 2–4, 4–6, and 6–8 cm) were incorporated into soil (idle for 50 days) at the same litter biomass rate (0.7 kg m−2). Then the soil was sampled and cores were subjected to overland flow under six flow shear stress levels (5.66, 8.31, 12.21, 15.55, 19.15 and, 22.11 Pa) using a hydraulic flume (4.0 m × 0.35 m). The results showed that the litter morphological characteristics of litter length density (LLD), litter surface area density (LSAD) and litter volume ratio (LVR) differed in plant species at the same litter biomass rate. Correspondingly, soil detachment capacity (ranging from 0.414 to 2.179 kg m−2 s−1) and rill erodibility (ranging from 0.037 to 0.177 s m−1) varied significantly and mean values from the Bothriochloa ischaemum (L.) Keng. treatments were the minimums, which were 28% to 37% and 23% to 35% less than that of the other treatments, respectively. The soil detachment capacity and rill erodibility were significantly correlated with the litter morphological characteristics of LLD, LSAD and LVR (p < 0.01). The contact area between litter and soil was the most critical factor affecting soil detachment. Incorporated plant litter residue litter effect on rill erodibility could be well estimated by LSAD.

Stoichiometric characteristics of Artemisia sacrorum communities under different site conditions and their correlation with soil nutrients

We explored the stoichiometric characteristic of Artemisia sacrorum communities and its correlation with soil characters by considering the aspect and slope position, and variation of soil nutrient in Yangqingchuan catchment of Wuqi. Our results showed that total carbon, total nitrogen, total phosphorus contents and C:N ratio in A. sacrorum (both shoot and root) in the top of hillock>sunny slope>semi-shady slope>shady slope. The C:P ratio in shoot and the N:P ratio in root decreased consistently. The N:P ratio in shoot and the C:P ratio in root decreased first and then increased. While the total nitrogen and total phosphorus in shoot, and the organic carbon in root increased first and then decreased with the decreases of slope position, the C:N ratio and N:P ratio in shoot decreased first and then increased. The stoichiometric characteristic of A. sacrorum communities was positively correlated with the soil stoichiometric characteristics. However, the C:N ratio, C:P ratio and N:P ratio of A. sacrorum and the total phosphorus of root were negatively correlated to corresponding soil indices. The correlation between shoot nutrition and soil was greater than that between soil and root nutrition. In conclusion, middle position of shady slope was optimal for the growth of A. sacrorum. The stoichiometric characteristics of plants were significantly correlated with soil nutrient condition. Aspect and slope position had a significant effect on the stoichiometric cha-racteristics of A. sacrorum community and soil. Proper A. sacrorum community could help restore soil nutrition.

Response of rhizosphere microbial communities to plant succession along a grassland chronosequence in a semiarid area

Changes in microbial communities during natural succession in semiarid areas have been widely studied but their association with plant and soil properties remains elusive. In the present study, we investigated plant characteristics, rhizosphere soil variables, and microbial communities along a chronosequence of grasslands forming on abandoned farmland on the Chinese Loess Plateau. Rhizosphere samples were collected from the early-stage dominant plant Artemisia capillaris from farmland abandoned for 5, 10, and 15 years and from the late-stage dominant plant Artemisia sacrorum from farmland abandoned for 10, 15, 20, and 30 years. Microbial community composition, including bacteria and fungi, was determined by high-throughput sequencing. Microbial succession rates represented by temporary turnover were assessed using the slope (w value) of linear regressions, based on log-transformed microbial community similarity over time. Cover and aboveground biomass of A. capillaris tended to decrease, whereas those of A. sacrorum increased during the succession. Although the rhizosphere bacteria of A. capillaris transitioned from Proteobacteria-dominant to Actinobacteria-dominant, the bacteria of A. sacrorum exhibited the opposite trend. Bacterial and fungal community diversity tended to increase logarithmically with increasing plant aboveground biomass, indicating that an increase in plant biomass could lead to enhanced rhizosphere microbial diversity, but the rate of enhancement decreased gradually. A lower temporary turnover rate of bacterial and fungal communities in the rhizosphere than that in the bulk soil indicated a higher successional rate of the rhizosphere microbial community. Levels of soil nutrients, such as organic carbon, nitrate nitrogen, and ammonium nitrogen, were closely associated with the abundance and diversity of bacterial and fungal communities, indicating their critical role in shaping the rhizosphere microbial community. Our results indicate a close association between plant succession and rhizosphere microbial succession in a semiarid area. Plants affect the microbial communities possibly by changing the nutrient input into the rhizosphere.

宁南山区典型植物根系分解特征及其对土壤养分的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 宁南山区典型植物根系分解特征及其对土壤养分的影响 DOI: 10.5846/stxb201710101807 作者: 作者单位: 西北农林科技大学,西北农林科技大学,中国科学院水利部水土保持研究所,西北农林科技大学 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然基金面上项目（41671280）；国家十二五科技支撑（2015BAC01B01） Effects of typical plant root decomposition on soil nutrients in southern Ningxia Author: Affiliation: North West Agriculture and Forestry University,North West Agriculture and Forestry University,Institute of Soil and Water Conservation, Chinese Academy of Sciences,North West Agriculture and Forestry University Fund Project: The National Natural Science Foundation of China (General Program, Key Program, Major Research Plan) 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:根系分解是陆地生态系统碳和养分循环的重要地下生态过程，研究宁南山区典型植物根系分解特征及其对土壤养分的影响，能够丰富和完善陆地生态系统的物质和能量循环机制，为我国黄土高原植被恢复过程中植物与土壤之间的养分循环提供依据。连续2年研究了宁南山区3种典型植物（长芒草、铁杆蒿和百里香）根系的分解特征及其对土壤养分的影响。结果表明，长芒草、铁杆蒿和百里香根系年分解指数（K）分别0.00891、0.01128、0.01408，分解速率依次表现为百里香 > 铁杆蒿 > 长芒草。分解16个月后3种典型植物根系释放大量养分，其中碳的释放量在57.05-124.39 g/kg；氮的释放量在0.12-0.47 g/kg。3种典型植物根系对土壤养分的影响主要表现为：试验结束时，0-5 cm表层土壤有机碳含量提高了0.17-0.35 g/kg，5-20 cm土层土壤有机碳含量提高了0.26-0.35 g/kg。相关性分析可知，植物根系养分释放量与土壤养分含量之间存在一定的负相关关系，当土壤养分含量较低时，根系会增加养分释放量进行补充。由此可知，根系分解提高了土壤养分含量，有效的促进了养分在根系-土壤中的循环。 Abstract:Root decomposition is an important underground ecological process of carbon and nutrient cycling in terrestrial ecosystems. Studying the root decomposition characteristics of typical plants and their effects on soil nutrients in the mountainous area of southern Ningxia can provide a basis for nutrient cycling between plants and soil in vegetation restoration in Loess Plateau of China. The decomposition characteristics of three typical plant roots and the trend for soil nutrient change in the South Ningxia Loess Hilly Region of Northwest China, were studied for 2 years using the buried bag method. The results showed that the annual decomposition indices (K) of Stipa bungeana, Artemisia sacrorum, and Thymus mongolicus roots were 0.00891, 0.01128, and 0.01408, respectively, and the decomposition rate in turn showed as Thymus mongolicus > Artemisia sacrorum > Stipa bungeana. After 16 months, a substantial amount of root nutrients had been released. The release amount of carbon was 57.05-124.39 g/kg while for nitrogen it was 0.12-0.47 g/kg. The effects of three typical plant roots on soil nutrients were as follows: the contents of soil organic carbon increased by 0.17-0.35 g/kg in a 0-5 cm soil layer, and by 0.26-0.35 g/kg in a 5-20 cm soil layer. Correlation analysis showed that some negative correlation exists between the release amount of root nutrients and soil nutrient content. When the soil nutrient content is low, roots will increase nutrient release to supplement soil nutrients. This indicates that root decomposition increases soil nutrient content and effectively promotes nutrient cycling in the root-soil system. 参考文献 相似文献 引证文献

Relationship Between the Vegetation Community and Soil Nutrient and Enzyme Activity During the Restoration of Abandoned Land in the Loess Hilly Region

The trends of and relationships among the plant community, soil nutrients, and four soil enzymes were investigated after being abandoned for 10, 15, 20, 30, and 45 years to reveal the soil properties during the restoration in the Loess Hilly Region. The results indicate the following ranking of dominant plant community species:Artemisia scoparia→Lespedeza dahurica+Artemisia sacrorum→Artemisia giraldii+irons Artemisia annua→Bothriochloa flaccidum+Artemisia selengensis. The ranking reflects an increase along the chronosequence of abandoned land. Moreover, the ratio of the total species of Compositae, Poaceae, and Leguminosae decreases from 66.67% to 50% and then increases up to 75%. The SOC, TN, TP, AN, AP, and four enzyme activity types (ALP, CAT, UE, and SC) increase but respond differently to restoration, while the stoichiometric ratio fluctuates. In contrast to the number of plant families, genus, species, and plant diversity, Compositae, Poaceae, and Leguminosae have major effects on the soil nutrient and enzyme activity, which explains the total variation of 72.8%, 69.1%, and 66.0%, respectively. The effects of these three families on the soil enzymes are greater than that on soil nutrients. Poaceae and Leguminosae have a positive effect on the nutrient and enzyme activity, while the family Compositae has a negative effect. Overall, the changes of dominant species of grassland communities during restoration significantly affect the soil enzyme and thereby are responsible for the soil nutrient dynamics.

Synergistic Inhibitory Effects of Acacetin and 11 Other Flavonoids Isolated from Artemisia sacrorum on Lipid Accumulation in 3T3-L1 Cells.

Artemisia sacrorum Ledeb., a Compositae forage plant in China, has been found to have an inhibitory effect on lipid accumulation. We selected 12 flavonoids, which we had isolated from A. sacrorum and had the potential to inhibit lipid accumulation in the literature or in our preliminary experiments, and grouped them into 11 compound combinations; we investigated their synergistic inhibitory effects on lipid accumulation in 3T3-L1 cells. In screening experiments, Oil-Red O staining, triglyceride levels, and lipid accumulation levels all indicated that combined acacetin and apigenin displayed a significant synergistic inhibitory effect and the best repeatability. Subsequent research showed that this combination could synergistically promote the phosphorylations of AMPK and ACC. Furthermore, to a different extent, that combination had significant synergistic inhibitory effects on various genes or proteins related to adipogenesis and lipogenesis. Thus, that combination could significantly reduce triglyceride levels and lipid accumulation compared with acacetin or apigenin acting alone.

Influence of slope aspect on the microbial properties of rhizospheric and non-rhizospheric soils on the Loess Plateau, China

Abstract. Slope aspect is an important topographic factor in the micro-ecosystem environment, but its effect on the microbial properties of grassland rhizospheric soil (RS) and non-rhizospheric soil (NRS) remain unclear. A field experiment was conducted at the Ansai Research Station on the Loess Plateau in China to test the influence of slope aspects (south-facing, north-facing, and northwest-facing slopes, all with Artemisia sacrorum as the dominant species) on RS and NRS microbial biomass carbon (MBC) contents, phospholipid fatty acid (PLFA) contents, and the rhizospheric effect (RE) of various microbial indices. Soil samples were collected from the three slope aspects, including rhizospheric and non-rhizospheric region, and analyzed to determine the various related microbial indices. The results showed that MBC content differed significantly among the slope aspects in RS but not in NRS, and the RE for MBC content in the south-facing slope was larger than that in the north-facing slope. RS total, bacterial, and Gram-positive bacterial PLFA contents in the south-facing slope were significantly lower than those in the north- and northwest-facing slopes, and RS Gram-negative bacterial (G−) and actinomycete PLFA contents in the south-facing slope were significantly lower than those in the north-facing slope. In contrast, NRS total, bacterial, and G− PLFA contents in the north-facing slope were significantly higher than those in the south- and northwest-facing slopes, and NRS fungal and actinomycete PLFA contents in the north- and south-facing slopes were significantly higher than those in the northwest-facing slope. RE for all PLFA contents except fungal in the northwest-facing slope were higher than those in the south-facing slope. Slope aspect significantly but differentially affected the microbial properties in RS and NRS, and the variable influence was due to an evident RE for most microbial properties.

Changes in soil properties and erodibility of gully heads induced by vegetation restoration on the Loess Plateau, China

Soil erosion on the Loess Plateau of China is effectively controlled due to the implementation of several ecological restoration projects that improve soil properties and reduce soil erodibility. However, few studies have examined the effects of vegetation restoration on soil properties and erodibility of gully head in the gully regions of the Loess Plateau. The objectives of this study were to quantify the effects of vegetation restoration on soil properties and erodibility in this region. Specifically, a control site in a slope cropland and 9 sites in 3 restored land-use types (5 sites in grassland, 3 in woodland and 1 in shrubland) in the Nanxiaohegou watershed of a typical gully region on the Loess Plateau were selected, and soil and root samples were collected to assess soil properties and root characteristics. Soil erodibility factor was calculated by the Erosion Productivity Impact Calculator method. Our results revealed that vegetation restoration increased soil sand content, soil saturated hydraulic conductivity, organic matter content and mean weight diameter of water-stable aggregate but decreased soil silt and clay contents and soil disintegration rate. A significant difference in soil erodibility was observed among different vegetation restoration patterns or land-use types. Compared with cropland, soil erodibility decreased in the restored lands by 3.99% to 21.43%. The restoration patterns of Cleistogenes caespitosa K. and Artemisia sacrorum L. in the grassland showed the lowest soil erodibility and can be considered as the optimal vegetation restoration pattern for improving soil anti-erodibility of the gully heads. Additionally, the negative linear change in soil erodibility for grassland with restoration time was faster than those of woodland and shrubland. Soil erodibility was significantly correlated with soil particle size distribution, soil disintegration rate, soil saturated hydraulic conductivity, water-stable aggregate stability, organic matter content and root characteristics (including root average diameter, root length density, root surface density and root biomass density), but it showed no association with soil bulk density and soil total porosity. These findings indicate that although vegetation destruction is a short-term process, returning the soil erodibility of cropland to the level of grassland, woodland and shrubland is a long-term process (8–50 years).

Changes of Soil Microbiological Properties during Grass Litter Decomposition in Loess Hilly Region, China.

Litter, the link between soil and plant, is an important part of nutrient return to soil. Deeply understanding the effect of litter decomposition on soil microbiological properties is important for the sustainable development of grasslands. Three plants (Thymus quinquecostatus Celak., Stipa bungeana Trin. and Artemisia sacrorum ledeb.) leaf litter were selected. A simulation experiment using the nylon bag method was conducted to measure the soil microbial biomass carbon and nitrogen, and soil enzyme activity during litter decomposition. The results showed that the decomposition of three leaf litter enhanced soil microbial carbon and nitrogen. The change rate of soil microbial carbon and nitrogen decreased as Ar.S > St.B > Th.Q. The activities of soil invertase, soil urease, and soil nitrate reductase were significantly improved by the coverage of leaf litter. After 741-day litter decomposition, the change rate of soil invertase was from 16.7% to 33.2%. The change rate of soil urease was highest in the Th.Q treatment; St.B treatment and Ar.S treatment followed, and lowest in the control. The change rates of soil nitrate reductase in the St.B and Ar.S treatment were >1000% higher than those of other treatments. The response of soil enzyme activity to litter decomposition “lagged” behind the change of soil microbial biomass. The significant increase of soil microbial biomass and enzyme activity demonstrated that litter decomposition played an important role in maintaining soil ecological function.

Characteristics of soil nutrients and their relationship with soil microbial properties in Artemisia sacrorum communities in the loess hilly region

Artemisia sacrorum communities with different growth years were selected to analyse soil nutrient characteristics, the variation in soil microbial properties, and their relationships in the loess hilly region. The results showed that with an increase in the number of growth years, soil microbial biomass carbon and nitrogen contents as well as soil phosphatase and urease activities initially decreased and then increased in the A. sacrorum communities. The soil organic carbon, organic nitrogen, and total nitrogen contents as well as soil respiration rate showed an increasing trend and reached a maximum at age (a) 37. The soil available phosphorus content first decreased and then increased, with the lowest level observed at 18 a. By contrast, soil available potassium initially increased and then decreased. Soil microbial biomass carbon had a significant positive correlation with soil organic carbon, total nitrogen and organic nitrogen, while soil respiration had a significant positive correlation with organic nitrogen, soil phosphatase and organic carbon. Soil respiration had a highly significant positive correlation with organic carbon and total nitrogen, while soil phosphatase had a highly significant positive correlation with total nitrogen and organic nitrogen. In the A. sacrorum communities, the soil organic carbon and total nitrogen contents were mainly affected by soil respiration, soil available potassium content was mainly affected by soil urease activity, and soil organic nitrogen content was mainly affected by soil phosphatase activity. These findings indicate that soil basal respiration, urease activity and phosphatase activity were the major microbial factors affecting the characteristics of the soil nutrients in the A. sacrorum communities. In conclusion, the natural restoration process of A. sacrorum communities can enhance soil microbial activity and improve soil quality. Keywords: loess hilly, soil nutrients, soil microbial biomass, soil enzyme activities, soil basal respiration rate DOI: 10.25165/j.ijabe.20181104.3942 Citation: Song L J, Liu W Y, Wu H F, Gao T, Hao W F. Characteristics of soil nutrients and their relationship with soil microbial properties in Artemisia sacrorum communities in the loess hilly region. Int J Agric & Biol Eng, 2018; 11(4): 127-134.

Population spatial patterns of grassland plant communities in different slope aspects in the loess hilly area, China.

We investigated the species composition and diversity of four grassland communities with different slope aspects in the loess hilly area of China. The power law was used to analyze spatial heterogeneity of the community and spatial pattern of the population. The results showed that Artemisia sacrorum was the dominant species and occurred in each site. Other species had different status and contributed differently to the spatial pattern of communities. Moreover, the spatial patterns of communities responded differently to various slope aspects, with the degree of aggregation ranked as sunny > half-sunny > half-shady > shady. The spatial heterogeneity index of community was positively correlated with the Simpson diversity index, but was negatively correlated with Margalef richness, Shannon diversity and Pielou evenness. The relative spatial heterogeneity index of the dominant species (A. sacrorum), sub-dominant species (Lespedeza dahurica and Stipa bungeana), and a few associated species (Artemisia scoparia, Melica scabrosa) were larger than that of the community, which resulted in cluster distribution. However, the relative spatial heterogeneity index of most associated species (Phragmites communis, Sonchus arvensis, and Bothriochloa flaccidum) showed the similar trends with the distribution of the community. In contrast, the relative spatial heterogeneity index of Cephalanoplos segetum, Gueldenstaedtia multiflora and Artemisia giraldii was lower than that of the community. These differences reduced the aggregation degree of the community. In summary, the aggregation degree of community was determined by dominant species, sub-dominant species and occasional species. Specifically, the dominant species, sub-dominant species and some associated species could promote the aggregation of the community, but occasional species would reduce the cluster distribution.

Effects of rhizosphere interactions of grass interspecies on the soil microbial properties during the natural succession in the Loess Plateau

Natural vegetation succession is a process of interactions between plants and various environmental factors. The dynamics of soil microbes during successional stages have been intensively explored in the past two decades. The effect of rhizosphere interactions of interspecies on microbial properties, however, has received less attention. During the early stage of succession on a Loess Plateau soil from China, we investigated microbial properties in the rhizospheres of three dominant grass species: Artemisia capillaris, Artemisia sacrorum and Stipa bungeana. Experiments with monocultured and polycultured potted plants were designed to determine the effects of rhizosphere interactions on plant growth and soil microbial properties. The results showed that root biomass, shoot biomass, plant height, microbial biomass carbon (C), microbial biomass nitrogen (N), invertase and urease activities, Gram-negative and Gram-positive bacteria were significantly higher for A. capillaris than for A. sacrorum and S. bungeana in both monocultures and polycultures. Lower root biomass, shoot biomass, plant height, microbial biomass C, microbial biomass N, invertase and alkaline phosphatase activities, and levels of microbial phospholipid-derived fatty acids in polycultures relative to the monocultures indicated that rhizosphere interactions led to lower plant growth and soil microbial activities. Our study suggests that rhizosphere interactions had a significant effect on the microbial properties of plant rhizospheres. The advantage of A. capillaris over A. sacrorum and S. bungeana in growth characteristics and rhizosphere microbial conditions is likely responsible for the dominance of A. capillaris in the early stage of succession in abandoned cropland on the Loess Plateau.

黄土丘陵区退耕还草植被恢复阶段优势种铁杆蒿的化感效应

黄土丘陵区退耕还草植被恢复阶段优势种铁杆蒿的化感效应

Characteristics of soil nutrients and their relationship with soil microbial properties in Artemisia sacrorum communities in the loess hilly region

Characteristics of soil nutrients and their relationship with soil microbial properties in Artemisia sacrorum communities in the loess hilly region