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1. chinaXiv:201909.00023 [pdf]


Subjects: Biology >> Ecology

以玛纳斯河流域的硫酸盐―氯化物盐型、氯化物―硫酸盐型、碳酸盐型、硫酸盐型4种盐碱土壤为研究对象,利用高通量测序技术对细菌进行测序,研究表明:4种盐碱土壤样品共获得137 822条细菌基因序列,Shannon指数和Chao1指数表现为:碳酸盐型>硫酸盐型>硫酸盐―氯化物盐型>氯化物—硫酸盐型,说明碳酸盐型土壤细菌群落的多样性和丰度均显著高于其他3个样品。4种盐碱土壤细菌群落主要包括10个门类,其中变形菌门(Proteobacteria)、拟杆菌(Bacteroidetes)、放线菌门(Actinobacteria)是硫酸―氯化物盐型、氯化―硫酸盐型、硫酸盐型土壤的优势菌门,碳酸盐型以厚壁菌门(Firmicutes)、变形菌门(Proteobacteria)、放线菌门(Actinobacteria)为优势菌门,而在属的水平上,各样品的群落组成差异较大。通过聚类分析将4个细菌群落分为3类,其中硫酸―氯化物盐型和氯化―硫酸盐型分为一类,硫酸盐型和碳酸盐型各为一类。环境因子中全盐、氯离子、硫酸根离子和硝酸根离子对物种分布影响显著(P<0.05)。玛纳斯河流域不同类型盐碱土壤中的细菌群落存在显著差异,存在较多类型的细菌群落,尤其在碳酸盐型土壤中。该研究结果揭示了干旱区不同类型盐碱土壤细菌群落组成及影响群落结构的主要环境因子,为挖掘盐碱土壤微生物资源和盐碱地改良提供科学依据。

submitted time 2019-09-05 From cooperative journals:《干旱区研究》 Hits1745Downloads17 Comment 0

2. chinaXiv:201904.00073 [pdf]


李雄; Supriyo Basak; 周睿; 张卫哲; 付瑶; 周新茂; 施超; 郗厚诚; 杨永平
Subjects: Biology >> Ecology


submitted time 2019-03-30 Hits3410Downloads238 Comment 0

3. chinaXiv:201903.00232 [pdf]

Conversion of cropland into agroforestry land versus naturally-restored grassland alters soil macro-faunal diversity and trophic structure in the semi-arid agro-pasture zone of northern China

LIU Rentao
Subjects: Biology >> Ecology

Restoration of cropland (termed 'Farm') after abandonment including shrubs (termed 'Shrub'), trees (termed 'Tree') and natural grassland (termed 'Grass') has become a routine process aimed to improve land productivity and control desertification. During this restoration process, soil macro-faunal diversity, and trophic structure were investigated at four types of sites (Farm, Shrub, Tree, and Grass) during growing season in the semi-arid agro-pasture zone of northern China. Results indicated that the Staphylinidae family was found to dominate at the Grass, Shrub, and Tree sites, whiles larval Pyralidae individuals were found at the Grass site only. The density of the omnivores (i.e., Formicidae family) was significantly (P<0.05) greater at the Grass site than at the Tree and Farm sites. The total density and richness of predator and phytophages were found to be markedly (P<0.05) greater at the Grass site than at the Farm site. Meanwhile, we found the taxon richness of predators was significantly (P<0.05) higher at the Shrub site than at the Farm and Tree sites. Compared with the Farm and afforested Shrub/Tree sites, the Grass site had greater density, taxon richness, and Shannon index (P<0.05). In conclusion, natural restoration of abandoned croplands toward grassland was an effective strategy relative to artificial afforestation for improvement of soil biological diversity. Moreover, planting shrub is a preferable measure in abandoned croplands for land development in the semi-arid agro-pasture zone of northern China.

submitted time 2019-03-28 From cooperative journals:《Journal of Arid Land》 Hits6274Downloads2440 Comment 0

4. chinaXiv:201901.00107 [pdf]

Spatial variability of soil water content and related factors across the Hexi Corridor of China

LI Xiangdong; SHAO Ming'an
Subjects: Biology >> Ecology

Soil water content (SWC) is a key factor limiting ecosystem sustainability in arid and semi-arid areas of the Hexi Corridor of China, which is characterized by an ecological environment that is vulnerable to climate change. However, there is a knowledge gap regarding the large-scale spatial distribution of SWC in this region. The specific objectives of this study were to determine the spatial distribution patterns of SWC across the Hexi Corridor and identify the factors responsible for spatial variation of SWC at a regional scale. This study collected and analyzed SWC in the 0–100 cm soil profile from 109 field sampling sites (farmland, grassland and forestland) across the Hexi Corridor in 2017. We selected 17 factors, including land use, topography (latitude, longitude, elevation, slope gradient, and slope aspect), soil properties (soil clay content, soil silt content, soil bulk density, saturated hydraulic conductivity, field capacity, and soil organic carbon content), climate factors (mean annual precipitation, potential evaporation, and aridity index), plant characteristic (vegetation coverage) and planting pattern (irrigation or rain-fed), as possible environmental variables to analyze their effects on SWC. The results showed that SWC was 0.083 (±0.067) g/g in the 0–100 cm soil profile and decreased in the order of farmland, grassland and forestland. The SWC in the upper soil layers (0–20, 20–40 and 40–60 cm) had obvious difference when the mean annual precipitation differed by 200 mm. The SWC decreased from southeast to northwest following the same pattern as precipitation, and had a moderate to strong spatial dependence in a large effective range (75–378 km). The SWC showed a similar distribution and had no significant difference between soil layers in the 0–100 cm soil profile. The principal component analysis showed that the mean annual precipitation, geographical position (longitude and latitude) and soil properties (soil bulk density and soil clay content) were the main factors dominating the variance of environmental variables. A stepwise linear regression equation showed that plant characteristic (vegetation coverage) and soil properties (soil organic carbon content, field capacity and soil clay content) were the optimal factors to predict the variation of SWC. Soil clay content could be better to explain the SWC variation in the deeper soil layers compared with the other factors.

submitted time 2019-01-17 From cooperative journals:《Journal of Arid Land》 Hits2819Downloads280 Comment 0

5. chinaXiv:201901.00108 [pdf]

Derivation of salt content in salinized soil from hyperspectral reflectance data: A case study at Minqin Oasis, Northwest China

Subjects: Biology >> Ecology

Soil salinization is a serious ecological and environmental problem because it adversely affects sustainable development worldwide, especially in arid and semi-arid regions. It is crucial and urgent that advanced technologies are used to efficiently and accurately assess the status of salinization processes. Case studies to determine the relations between particular types of salinization and their spectral reflectances are essential because of the distinctive characteristics of the reflectance spectra of particular salts. During April 2015 we collected surface soil samples (0–10 cm depth) at 64 field sites in the downstream area of Minqin Oasis in Northwest China, an area that is undergoing serious salinization. We developed a linear model for determination of salt content in soil from hyperspectral data as follows. First, we undertook chemical analysis of the soil samples to determine their soluble salt contents. We then measured the reflectance spectra of the soil samples, which we post-processed using a continuum-removed reflectance algorithm to enhance the absorption features and better discriminate subtle differences in spectral features. We applied a normalized difference salinity index to the continuum-removed hyperspectral data to obtain all possible waveband pairs. Correlation of the indices obtained for all of the waveband pairs with the wavebands corresponding to measured soil salinities showed that two wavebands centred at wavelengths of 1358 and 2382 nm had the highest sensitivity to salinity. We then applied the linear regression modelling to the data from half of the soil samples to develop a soil salinity index for the relationships between wavebands and laboratory measured soluble salt content. We used the hyperspectral data from the remaining samples to validate the model. The salt content in soil from Minqin Oasis were well produced by the model. Our results indicate that wavelengths at 1358 and 2382 nm are the optimal wavebands for monitoring the concentrations of chlorine and sulphate compounds, the predominant salts at Minqin Oasis. Our modelling provides a reference for future case studies on the use of hyperspectral data for predictive quantitative estimation of salt content in soils in arid regions. Further research is warranted on the application of this method to remotely sensed hyperspectral data to investigate its potential use for large-scale mapping of the extent and severity of soil salinity.

submitted time 2019-01-17 From cooperative journals:《Journal of Arid Land》 Hits2636Downloads264 Comment 0

6. chinaXiv:201901.00110 [pdf]

Eco-physiological studies on desert plants: germination of Halothamnus iraqensis Botsch. seeds under different conditions

Arvind BHATT; Narayana R BHAT; Valentina MURRU
Subjects: Biology >> Ecology

With the aim to investigate if the halophyte Halothamnus iraqensis Botsch. can be suitable for re-vegetation and remediation of salt-affected lands, this study evaluated (1) the effects of photoperiod, thermoperiod, storage period and wings' presence on its seed germination, and (2) the ability of its seeds to have successful germination recovery after salt stress. Germination tests in different photoperiods (12 h light/12 h darkness and total darkness) and thermoperiods (15°C/20°C and 20°C/25°C) were conducted for seeds collected in 2012, 2013, 2014, 2015 and 2016. The seeds collected in 2016 were sown under different salinity levels (0, 100, 200, 400 and 600 mM NaCl) to assess the salinity tolerance during the germination. Wings' presence highly inhibited seed germination of this species in both photoperiods and thermoperiods under all salinity level treatments. In addition, the germination recovery occurred well when seeds were deprived of their wings. The photoperiod of 12 h light/12 h darkness and the thermoperiod of 15°C/20°C were the best conditions for seed germination. Germination percentages of H. iraqensis seeds decreased with the increasing storage duration, especially after three years of the collection. In addition, H. iraqensis seeds were able to germinate under different salinity levels, and their germination percentages decreased with increasing salinity levels. H. iraqensis seeds have the ability to recover their germination after alleviating the salt stress, irrespective of photoperiod, highlighting the halophilous character of this species.

submitted time 2019-01-17 From cooperative journals:《Journal of Arid Land》 Hits3007Downloads233 Comment 0

7. chinaXiv:201901.00111 [pdf]

Variation and heritability of morphological and physiological traits among Leymus chinensis genotypes under different environmental conditions

YANG Xue; LI Junpeng; ZHAO Tingting
Subjects: Biology >> Ecology

Intraspecific trait variation and heritability in different environmental conditions not only suggest a potential for an evolutionary response but also have important ecological consequences at the population, community, and ecosystem levels. However, the contribution of quantitative trait variation within a grassland species to evolutionary responses or ecological consequences is seldom documented. Leymus chinensis is an important dominant species in semi-arid grasslands of China, which has seriously suffered from drought and high temperature stresses in recent decades. In the present study, we measured variation and heritability of 10 quantitative traits, namely the number of tillers, maximum shoot height, number of rhizomes, maximum rhizome length, rhizome mass, aboveground mass, root mass, maximum net photosynthetic rate (Pmax), specific leaf area (SLA), and leaf length to leaf width ratio (LL/LW), for 10 genotypes of L. chinensis under one non-stress (Ck) condition and three environmental stress conditions (i.e., drought (Dr), high temperature (Ht), and both drought and high temperature (DrHt)). Result indicated that (1) the interaction of genotype and environmental condition (G×E) was significant for 6 traits but not significant for the other 4 traits as shown by two-way analysis of variance (ANOVA), suggesting that different selection forces were placed for different traits on the factors dominating phenotypic responses to different environmental conditions. Moreover, these significant G×E effects on traits indicated significantly different phenotypic adaptive responses among L. chinensis genotypes to different environmental conditions. Additionally, individuals could be grouped according to environmental condition rather than genotype as shown by canonical discriminant analysis, indicating that environmental condition played a more important role in affecting phenotypic variation than genotype; (2) by one-way ANOVA, significant differences among L. chinensis genotypes were found in all 10 traits under Ck and Dr conditions, in 8 traits under DrHt condition and only in 4 traits under Ht condition; and (3) all 10 traits showed relatively low or non-measurable broad-sense heritability (H2) under stress conditions. However, the lowest H2 value for most traits did not occur under DrHt condition, which supported the hypothesis of 'unfavorable conditions have unpredictable effects' rather than 'unfavorable conditions decrease heritability'. Results from our experiment might aid to improve predictions on the potential impacts of climate changes on L. chinensis and eventually species conservation and ecosystem restoration.

submitted time 2019-01-17 From cooperative journals:《Journal of Arid Land》 Hits2728Downloads892 Comment 0

8. chinaXiv:201810.00168 [pdf]


赵明; 王文科; 王周锋; 陈立
Subjects: Biology >> Ecology

沙蒿是中国西北半干旱地区主要的固沙植物,其根系分布影响包气带水分运移过程,准确的植被特征和根系密度分布对根系吸水模型的建立十分重要。本研究采用整体挖掘法获取不同层位的根系和根际土壤含水量,引入冠级和龄级的概念对沙蒿根系分布特征进行研究。分析结果表明:沙蒿种群以低龄级沙蒿占优,其根系生物量随龄级呈‘S’型增长;根系长度分布和均一化根系密度分布均符合对数正太分布,最大值出现在浅层土壤20 cm处;沙蒿生长不依赖于地下水,其根系主要利用包气带中的水分,持续干旱条件下,为满足蒸腾作用根系出现两种调节方式:1、横向生长增加根系量,利用横向土壤剖面的水分;2、浅层根区由于水分胁迫造成的吸水量减少由深部相对湿润的根区补偿。因此沙蒿根系吸水模型中的根系密度分布函数应为对数正态分布,且吸水过程不仅依赖于根系密度分布,同时受土壤水分的影响。

submitted time 2018-10-23 From cooperative journals:《干旱区地理》 Hits634Downloads337 Comment 0

9. chinaXiv:201807.00032 [pdf]

Characteristics of soil organic carbon and total nitrogen under various grassland types along a transect in a mountain-basin system in Xinjiang, China

BI Xu; LI Bo; NAN Bo; FAN Yao; FU Qi; ZHANG Xinshi
Subjects: Biology >> Ecology

Soil organic carbon (SOC) and soil total nitrogen (STN) in arid regions are important components of global C and the N cycles, and their response to climate change will have important implications for both ecosystem processes and global climate feedbacks. Grassland ecosystems of Funyun County in the southern foot of the Altay Mountains are characterized by complex topography, suggesting large variability in the spatial distribution of SOC and STN. However, there has been little investigation of SOC and STN on grasslands in arid regions with a mountain-basin structure. Therefore, we investigated the characteristics of SOC and STN in different grassland types in a mountain-basin system at the southern foot of the Altai Mountains, north of the Junggar Basin in China, and explored their potential influencing factors and relationships with meteorological factors and soil properties. We found that the concentrations and storages of SOC and STN varied significantly with grassland type, and showed a decreasing trend along a decreasing elevation gradient in alpine meadow, mountain meadow, temperate typical steppe, temperate steppe desert, and temperate steppe desert. In addition, the SOC and STN concentrations decreased with depth, except in the temperate desert steppe. According to Pearson's correlation values and redundancy analysis, the mean annual precipitation, soil moisture content and soil available N concentration were significantly positively correlated with the SOC and STN concentrations. In contrast, the mean annual temperature, pH, and soil bulk density were significantly and negatively correlated with the SOC and STN concentrations. The mean annual precipitation and mean annual temperature were the primary factors related to the SOC and STN concentrations. The distributions of the SOC and STN concentrations were highly regulated by the elevation-induced differences in meteorological factors. Mean annual precipitation and mean annual temperature together explained 97.85% and 98.38% of the overall variations in the SOC and STN concentrations, respectively, at soil depth of 0–40 cm, with precipitation making the greatest contribution. Our results provide a basis for estimating and predicting SOC and STN concentrations in grasslands in arid regions with a mountain-basin structure.

submitted time 2018-07-05 From cooperative journals:《Journal of Arid Land》 Hits2516Downloads451 Comment 0

10. chinaXiv:201806.00049 [pdf]


康美美; 赵文武
Subjects: Biology >> Ecology


submitted time 2018-06-09 From cooperative journals:《生态学报》 Hits10358Downloads478 Comment 0

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