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2.
Int J Syst Evol Microbiol ; 70(10): 5445-5452, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32886595

RESUMO

A Gram-stain-positive, aerobic, catalase-positive, oxidase-negative, non-mycelium-forming, motile, rod-shaped with one polar flagellum actinobacterium, designated E918T, was isolated from a desert soil collected in Cholistan desert, Pakistan. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain E918T belonged to the genus Arthrobacter and was most closely related to Arthrobacter deserti CGMCC 1.15091T (97.2 % similarity). The peptidoglycan was of the A3α type and the whole-cell sugar profile was found to contain galactose. The major menaquinone was MK-9(H2). The polar lipid profile consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol and two unidentified glycolipids. The major fatty acids identified were anteiso-C15 : 0 and anteiso-C17 : 0. The G+C content of the genomic DNA was 68.69 mol%. The digital DNA-DNA hybridization and average nucleotide identity values between strain E918T and A. deserti CGMCC 1.15091T were 28.0 and 83.4%, respectively. On the basis of its phylogenetic, phenotypic and chemotaxonomic features, strain E918T was considered to represent a novel species of the genus Arthrobacter, for which the name Arthrobacter mobilis sp. nov. is proposed. The type strain of Arthrobacter mobilis is E918T (=JCM 33392T=CGMCC 1.16978T).


Assuntos
Arthrobacter/classificação , Clima Desértico , Filogenia , Microbiologia do Solo , Arthrobacter/isolamento & purificação , Técnicas de Tipagem Bacteriana , Composição de Bases , DNA Bacteriano/genética , Ácidos Graxos/química , Glicolipídeos/química , Hibridização de Ácido Nucleico , Paquistão , Peptidoglicano/química , Fosfolipídeos/química , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Vitamina K 2/análogos & derivados , Vitamina K 2/química
3.
PLoS One ; 15(9): e0239268, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32991580

RESUMO

Nitraria sibirica Pall. is a shrub species belonging to the family of Nitrariaceae. It plays pivotal role in arid ecosystems since it is tolerant to high salinity and drought. This species is widely distributed throughout Mongolia and it is mostly found in arid ecosystems of Mongolian Gobi Desert. In this study, we developed allometric equations for estimating above-ground biomass of N. sibirica using various structural descriptors and pinpointed the best models. Variables that precisely predicted above-ground biomass were a combination of basal diameter, crown area, and height. The allometric growth equation constructed is not merely helpful to achieve accurate estimations of the above-ground biomass in shrub vegetation in the Gobi Desert of Mongolia, but also can provide a reference for the above-ground biomass of Nitraria species growing in analogous habitats worldwide. Therefore, our research purposes an important advance for biomass estimation in Gobi ecosystems and complements previous studies of shrub biomass worldwide. This study provides reasonable estimates of biomass of N. sibirica, which will be valuable in evaluations of biological resources, especially for quantifying the main summer diet of Gobi bears, and also can be an alternative tool for assessing carbon cycling in Gobi Desert.


Assuntos
Clima Desértico , Ecossistema , Magnoliopsida/crescimento & desenvolvimento , Biomassa , Mongólia , Estações do Ano
4.
PLoS One ; 15(8): e0235469, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32845880

RESUMO

Random sampling is an important approach to field vegetation surveys. However, sampling surveys in desert areas are difficult because determining an appropriate quadrat size that represent the sparse and unevenly distributed vegetation is challenging. In this study, we present a methodology for quadrat size optimization based on low-altitude high-precision unmanned aerial vehicle (UAV) images. Using the Daliyaboyi Oasis as our study area, we simulated random sampling and analyzed the frequency distribution and variation in the fractional vegetation cover (FVC) index of the samples. Our results show that quadrats of 50 m × 50 m size are the most representative for sampling surveys in this location. The method exploits UAV technology to rapidly acquire vegetation information and overcomes the shortcomings of traditional methods that rely on labor-intensive fieldwork to collect species-area relationship (SAR) data. Our method presents two major advantages: (1) speed and efficiency stemming from the application of UAV, which also effectively overcomes the difficulties posed in vegetation surveys by the challenging desert climate and terrain; (2) the large sample size enabled by the use of a sampling simulation. Our methodology is thus highly suitable for selecting the optimal quadrat size and making accurate estimates, and can improve the efficiency and accuracy of field vegetation sampling surveys.


Assuntos
Clima Desértico , Monitorização de Parâmetros Ecológicos/métodos , Fenômenos Fisiológicos Vegetais , Biodiversidade , Biomassa , Monitorização de Parâmetros Ecológicos/instrumentação , Monitorização de Parâmetros Ecológicos/normas , Tecnologia de Sensoriamento Remoto/instrumentação , Tamanho da Amostra
5.
Sci Total Environ ; 739: 139958, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32758943

RESUMO

The ecological environment in China's arid and semi-arid regions has been improving over the past few decades. Using the Mu Us Sandy Land (MUSL) as a case study, we examine the consequent climate feedbacks and the impacts of revegetation on regional climate by incorporating high-resolution remote-sensing vegetation data into the WRF-Noah model. From 2001 to 2010, although a small portion of the grassland was degraded in MUSL, vegetation overall improved, with green fraction and leaf area index increased and surface albedo decreased. The model simulation suggests a cooling of the near-surface temperature by 0.12-0.32 °C on average and up to >0.5 °C in summer, with a reduction in nighttime minimum of 0.15-0.46 °C and in daytime maximum of <0.13 °C. The cooling is accompanied by a slight increase in 2-m air humidity. The near-surface cooling and wetting are induced by revegetation-enhanced evapotranspiration, but they have insignificant effect on the local precipitation. The results of this study imply that while revegetation has positive effects on the ecological systems in MUSL, it bears the cost of an increase in evapotranspiration of 51 mm per summer, which may exacerbate the water shortages in the region.


Assuntos
Ecossistema , Areia , China , Mudança Climática , Clima Desértico
6.
Sci Total Environ ; 747: 141146, 2020 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-32771782

RESUMO

Climate models for semiarid and arid regions predict increasing average temperatures and reduced amounts of total annual rainfall. This warming and drying trend could have critical, adverse effects on natural vegetation activity and survival in arid and semiarid zones. We investigated the long-term effects of climate change and surface-runoff variations on the production of natural vegetation in a dry, undisturbed, first-order watershed in the northern Negev, Israel. Vegetation dynamics were estimated by normalized difference vegetation index. Yearly annual vegetation cover varied greatly during the monitoring period (2000-2013), but a significant positive regression was found with annual rainfall and runoff amounts, suggesting a strong relationship between annual vegetation dynamics and rainfall amount in a given year. A significant positive linear regression was found between annual ET0 values and year of measurement (1994-2013), with no corresponding decrease in vegetation condition. Surface runoff in the watershed affected the vegetation's water source. Large variation in annual runoff amounts was observed for 1994-2011, averaging 22.3 and 9 mm for the first (2000-2006) and second (2007-2013) vegetation-monitoring subperiods, respectively. Perennial vegetation was less sensitive to drought years than annual vegetation, likely due to differences in water-source availability. Perennials also benefited from the arrival of nutrients, organic matter, and fertile soil flowing with the surface runoff and eroded soil into their growing area.


Assuntos
Mudança Climática , Hidrologia , Clima Desértico , Israel , Solo
7.
PLoS One ; 15(8): e0238202, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32846428

RESUMO

The immune system of ectotherms, particularly non-avian reptiles, remains poorly characterized regarding the genes involved in immune function, and their function in wild populations. We used RNA-Seq to explore the systemic response of Mojave desert tortoise (Gopherus agassizii) gene expression to three levels of Mycoplasma infection to better understand the host response to this bacterial pathogen. We found over an order of magnitude more genes differentially expressed between male and female tortoises (1,037 genes) than differentially expressed among immune groups (40 genes). There were 8 genes differentially expressed among both variables that can be considered sex-biased immune genes in this tortoise. Among experimental immune groups we find enriched GO biological processes for cysteine catabolism, regulation of type 1 interferon production, and regulation of cytokine production involved in immune response. Sex-biased transcription involves iron ion transport, iron ion homeostasis, and regulation of interferon-beta production to be enriched. More detailed work is needed to assess the seasonal response of the candidate genes found here. How seasonal fluctuation of testosterone and corticosterone modulate the immunosuppression of males and their susceptibility to Mycoplasma infection also warrants further investigation, as well as the importance of iron in the immune function and sex-biased differences of this species. Finally, future transcriptional studies should avoid drawing blood from tortoises via subcarapacial venipuncture as the variable aspiration of lymphatic fluid will confound the differential expression of genes.


Assuntos
Infecções por Mycoplasma/imunologia , Infecções por Mycoplasma/veterinária , Mycoplasma/imunologia , Tartarugas/genética , Tartarugas/imunologia , Animais , Anticorpos Antibacterianos/sangue , California , Citocinas/genética , Citocinas/imunologia , Clima Desértico , Feminino , Regulação da Expressão Gênica/genética , Regulação da Expressão Gênica/imunologia , Interferon Tipo I/genética , Interferon Tipo I/imunologia , Transporte de Íons/genética , Ferro/metabolismo , Masculino , Infecções por Mycoplasma/microbiologia , Nevada , Fatores Sexuais
8.
Proc Natl Acad Sci U S A ; 117(31): 18161-18168, 2020 08 04.
Artigo em Inglês | MEDLINE | ID: mdl-32719142

RESUMO

While tree rings have enabled interannual examination of the influence of climate on trees, this is not possible for most shrubs. Here, we leverage a multidecadal record of annual foliar carbon isotope ratio collections coupled with 39 y of survey data from two populations of the drought-deciduous desert shrub Encelia farinosa to provide insight into water-use dynamics and climate. This carbon isotope record provides a unique opportunity to examine the response of desert shrubs to increasing temperature and water stress in a region where climate is changing rapidly. Population mean carbon isotope ratios fluctuated predictably in response to interannual variations in temperature, vapor pressure deficit, and precipitation, and responses were similar among individuals. We leveraged the well-established relationships between leaf carbon isotope ratios and the ratio of intracellular to ambient CO2 concentrations to calculate intrinsic water-use efficiency (iWUE) of the plants and to quantify plant responses to long-term environmental change. The population mean iWUE value increased by 53 to 58% over the study period, much more than the 20 to 30% increase that has been measured in forests [J. Peñuelas, J. G. Canadell, R. Ogaya, Glob. Ecol. Biogeogr. 20, 597-608 (2011)]. Changes were associated with both increased CO2 concentration and increased water stress. Individuals whose lifetimes spanned the entire study period exhibited increases in iWUE that were very similar to the population mean, suggesting that there was significant plasticity within individuals rather than selection at the population scale.


Assuntos
Asteraceae/fisiologia , Mudança Climática , Água/metabolismo , Dióxido de Carbono , Clima Desértico , Secas
9.
PLoS One ; 15(7): e0235928, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32697785

RESUMO

Several species of dryland cyanobacteria are known to occur as hypoliths under semi-translucent rocks. In the Mojave Desert, these organisms find refuge from intense solar radiation under milky quartz where moisture persists for a longer period of time than in adjacent soil surface habitat. Desert mosses, which are extremely desiccation-tolerant, can also occur in these hypolithic spaces, though little is known about this unique moss microhabitat and how species composition compares to that of adjacent soil surface communities. To address this question, we deployed microclimate dataloggers and collected moss samples from under and adjacent to 18 milky quartz rocks (quartz mean center thickness 26 ± 15 mm) in a western high elevation Mojave Desert site. Light transmission through Mojave quartz rocks may be as low as 1.2%, and data from microclimate loggers deployed for five months support the hypothesis that quartz provides thermal buffering and higher relative humidity compared to the soil surface. Of the 53 samples collected from hypolith and surface microhabitats, 68% were Syntrichia caninervis, the dominant bryophyte of the Mojave Desert biological soil crust. Tortula inermis accounted for 28% of the samples and 4% were Bryum argenteum. In a comparison of moss community composition, we found that S. caninervis was more likely to be on the soil surface, though it was abundant in both microhabitats, while T. inermis was more restricted to hypoliths, perhaps due to protection from temperature extremes. In our study site, the differences between hypolithic and surface microhabitats enable niche partitioning between T. inermis and S. caninervis, enhancing alpha diversity. This work points to the need to thoroughly consider microhabitats when assessing bryophyte species diversity and modelling species distributions. This focus is particularly important in extreme environments, where mosses may find refuge from the prevailing macroclimatic conditions in microhabitats such as hypoliths.


Assuntos
Briófitas/crescimento & desenvolvimento , Clima Desértico , Quartzo/química , Briófitas/fisiologia , Ecossistema , Umidade , Microclima , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/fisiologia , Brotos de Planta/crescimento & desenvolvimento , Brotos de Planta/fisiologia , Solo/química
10.
J Environ Manage ; 270: 110795, 2020 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-32721290

RESUMO

The role of cyanobacteria from soil biocrusts in restoring degraded land is gaining interest in recent years because of their critical role in enhancing soil fertility and preventing erosion. However, soil restoration through cyanobacterial inoculation remains a challenge for large-scale restoration efforts and new methodologies for effective cyanobacterial application need to be developed. Here, we propose a bioenvironmental approach to inoculate soils with pelletized cyanobacteria from soil biocrusts. Fresh cultures of three soil native cyanobacteria strains from two representative N-fixing genera (Nostoc and Scytonema) and a non-heterocystous filamentous genus (Leptolyngbya) were added into a substrate composed of commercial bentonite powder and sand (1:10 wt ratio) and extruded into pellets. Then, in two multifactorial microcosm experiments under glasshouse conditions, we evaluated (i) the survival and establishment over time of the cyanobacteria encapsulated in pellets, and ii) the viability of pelletized cyanobacteria after drying and storing for 30 d, on soils from three arid regions in Australia. Our results showed that pellets can dissolve completely and spread out in all treatments. Scytonema and the consortium of the three cyanobacteria species showed significant (P < 0.001) deeper CR680 peaks, higher chlorophyll a contents and lower albedo compared to the other inoculation treatments. Storing the pellets for 30 d significantly affected the viability of the cyanobacteria inoculum with reductions of approximately 50% in chlorophyll a content (a proxy for cyanobacteria biomass). Overall, our results showed that some cyanobacteria species can be successfully incorporated into extruded pellets and survive on degraded soils. This technology opens a wide range of opportunities for application in large scale restoration programs although further testing and refining through field trials is recommended.


Assuntos
Cianobactérias , Microbiologia do Solo , Austrália , Clorofila A , Clima Desértico , Ecossistema , Solo
11.
Proc Natl Acad Sci U S A ; 117(29): 17112-17121, 2020 07 21.
Artigo em Inglês | MEDLINE | ID: mdl-32647058

RESUMO

Resilience to environmental stressors due to climate warming is influenced by local adaptations, including plastic responses. The recent literature has focused on genomic signatures of climatic adaptation, but little is known about how plastic capacity may be influenced by biogeographic and evolutionary processes. We investigate phenotypic plasticity as a target of climatic selection, hypothesizing that lineages that evolved in warmer climates will exhibit greater plastic adaptive resilience to upper thermal stress. This was experimentally tested by comparing transcriptomic responses within and among temperate, subtropical, and desert ecotypes of Australian rainbowfish subjected to contemporary and projected summer temperatures. Critical thermal maxima were estimated, and ecological niches delineated using bioclimatic modeling. A comparative phylogenetic expression variance and evolution model was used to assess plastic and evolved changes in gene expression. Although 82% of all expressed genes were found in the three ecotypes, they shared expression patterns in only 5 out of 236 genes that responded to the climate change experiment. A total of 532 genes showed signals of adaptive (i.e., genetic-based) plasticity due to ecotype-specific directional selection, and 23 of those responded to projected summer temperatures. Network analyses demonstrated centrality of these genes in thermal response pathways. The greatest adaptive resilience to upper thermal stress was shown by the subtropical ecotype, followed by the desert and temperate ecotypes. Our findings indicate that vulnerability to climate change will be highly influenced by biogeographic factors, emphasizing the value of integrative assessments of climatic adaptive traits for accurate estimation of population and ecosystem responses.


Assuntos
Adaptação Fisiológica/genética , Mudança Climática , Ecossistema , Temperatura Alta , Animais , Austrália , Clima Desértico , Ecótipo , Peixes/genética , Peixes/fisiologia , Genômica , Transcriptoma/genética
12.
Sci Total Environ ; 742: 140498, 2020 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-32623167

RESUMO

The intensive introduction of shrubs to drylands can alter species composition and affect a series of biotic and abiotic processes. This topic has attracted increasing attention by researchers. To assess the response of soil properties to vegetation succession in arid regions of China, we measured the soil water content (SWC) to a depth of 5-m and determined soil properties of surface (0-5 cm) and subsurface (20-25 cm) layers in areas of natural grasses (NGs) and planted shrubs (PSs). The patch size of Caragana korshinskii shrubs resulted in different soil water storage losses (small shrub patch: 206.67 ± 35.58 mm; medium shrub patch: 416.88 ± 35.12 mm; large shrub patch: 588.63 ± 72.00 mm; degraded shrub patch: 740.54 ± 17.00 mm). Shrub cover showed an initial increase but then decreased as shrubs extracted soil water from the deep soil layers (>1 m). The species richness index in the PSs decreased with increasing shrub patch sizes. Surface soil organic carbon (SOC), extractable nitrogen (NH4+-N and NO3--N), and available phosphorous contents and saturated soil hydraulic conductivity (Ks) in the PSs were all significantly (p < 0.05) lower than those in NGs. Soil particles in the range of 0.002-0.2 mm explained 28.0% and 47.3% of the total variability of these surface indices under NGs and PSs, respectively. The differences in SOC, NH4+-N, NO3--N, Ks, and field capacity between the surface and subsurface layers declined significantly (p < 0.05). The introduction of shrubs affected the plant community by increasing the spatial heterogeneity of soil resources (e.g. water and nutrient contents). Therefore, the strong feedback between SWC and vegetation succession should be carefully considered when revegetating drylands. The evaluation of regional soil property responses to vegetation succession aids in a better understanding of soil water-vegetation feedback and provides important implications for future revegetation in arid regions.


Assuntos
Caragana , Solo , Carbono/análise , China , Clima Desértico , Ecossistema
13.
Artigo em Inglês | MEDLINE | ID: mdl-32630392

RESUMO

Grazing is one of the most common causes of grassland degradation, therefore, an assessment of soil physicochemical properties and plant nutrients under grazing is important for understanding its influences on ecosystem nutrient cycling and for formulating appropriate management strategies. However, the effects of grazing on grassland soil physicochemical properties and plant nutrients in mountain meadow and temperate typical steppe in the arid regions are still unclear. Therefore, we investigated the vegetation nutrient concentrations of nitrogen, phosphorus and potassium (N, P, and K) as well as soil physicochemical properties in the topmost 40 cm depth soil, to evaluate how these factors respond to grazing disturbance in a mountain meadow and temperate typical steppe within a mountain basin system in arid regions. Our results revealed that the soil bulk density values at depth of 0-40 cm increased after grazing in the mountain meadow and temperate typical steppe, whereas the soil water content decreased in the mountain meadow and increased in the temperate typical steppe after grazing. In the mountain meadow, soil total N and available P in addition to vegetation N and P concentrations increased in response to high-intensity grazing, while soil available N, available K and vegetation K decreased after grazing; in addition, soil pH, soil total P and K showed no significant changes. In the temperate typical steppe, the soil total P, soil available N, P, and K, and vegetation N, P, and K increased under relatively low-intensity grazing, whereas soil pH and soil total K showed no significant changes except for the deceasing soil total N. Our findings showed the different responses of different grassland ecosystems to grazing. Moreover, we propose that further related studies are necessary to better understand the effects of grazing on grassland ecosystems, and thereby provide a theoretical basis for the sustainable use of animal husbandry and ecological restoration of grasslands.


Assuntos
Ecossistema , Solo , Animais , China , Clima Desértico , Pradaria , Poaceae
14.
J Biosci Bioeng ; 130(4): 382-389, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32682699

RESUMO

High-throughput sequencing was used to investigate the archaeal community structure and diversity, and associated influencing factors in the 5 subtypes and 13 genera of saline-alkali soil in Gansu Province, China. The results indicated the analysis of chemical parameters demonstrated statistically significant differences in these soils. Operational taxonomic units (OTUs), Chao 1, ACE, Simpson, and Shannon indexes of the archaeal community varied significantly in the 5 subtypes and 12 genera of soil except for chloride-type orthic solonchaks. The abundance was highest for sulfate-chloride-type meadow solonchaks and lowest for chloride-sulfate-type dry solonchaks. The diversity was highest for chloride-sulfate-type orthic solonchaks and lowest for sulfate-type orthic solonchaks. The archaeal community was dominated by the Euryarchaeota and Crenarchaeota. Except chloride-type orthic solonchaks; Halomicrobium in chloride-type meadow solonchaks (12.7%); Halobacterium in sulfate-chloride-type and chloride-sulfate-type dry solonchaks (11.1% and 9.2%, respectively); Candidatus Nitrososphaera in sulfate-chloride-type, chloride-sulfate-type, and sulphate-type meadow solonchaks; sulfate-type orthic solonchaks; and chloride bog solonchaks (9.0%, 21.6%, 27.0%, 45.3%, and 30.0%, respectively); Halorhabdus in sulfate-chloride-type orthic solonchaks, magnesium alkalized solonchaks, chloride-type dry solonchaks (15.7%, 11.5%, and 5.9%, respectively); and Haloarcula in chloride-sulfate-type orthic solonchaks (8.1%) were the most dominant archaea. Redundancy analysis showed that archaeal diversity was influenced by soil organic matter, total salt, sulfate anion, and zinc contents and pH. These results will lead to more comprehensive understanding of how 5 subtypes and 13 soil genera of saline-alkali soil affects microbial distribution.


Assuntos
Álcalis/análise , Archaea/isolamento & purificação , Biodiversidade , Clima Desértico , Solo/química , Archaea/genética , China , Filogenia , RNA Ribossômico 16S/genética
15.
Sci Total Environ ; 745: 140970, 2020 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-32731072

RESUMO

The topsoil cyanobacteria in biological soil crusts (BSCs) play a vital role in stabilizing soil surface of disturbed habitats in water and nutrient-poor ecosystems. Currently, artificial inoculation of BSCs is considered as an effective approach to restore habitats and accelerate ecosystem regeneration. Understanding the character of cyanobacterial communities is the necessary prerequisite to explore the artificial inoculation of BSCs. For this reason, cyanobacterial communities in BSCs were compared between two mid-latitute temperate deserts with distinct precipitation patterns. The results showed that Oscillatoriales and Nostocales dominated crusts in the Tengger desert with majority of rainfall in summer and early autumn while Oscillatoriales dominated crusts in the Kyzyl kum desert with more rainfall in winter and early spring. Moreover, filamentous Microcoleus vaginatus overwhelmingly dominated all the crusts in both deserts with Mastigocladopsis sp. and Chroococcidiopsis spp. as the dominant heterocystous cyanobacteria. Of note, genus Wilmottia kept a relative stable and high abundance in both deserts. The top two abundantly shared cyanobacteria (> 1% of total sequences) were M. vaginatus and Mastigocladopsis sp. in both deserts, while 16 genera with significant variances were found between the two deserts (P <0.05). Total variations of cyanobacterial communities across the deserts were largely explained by a combination of biotic factors (microbial biomass C and N) and abiotic factors (soil pH, soil water content, soil water holding capacity, and soil available potassium). Compared to better-developed crusts, cyanobacterial abundance was higher in cyanobacterial crusts. BSC type and/or geographic location significantly affected cyanobacterial Shannon diversity without significantly influencing species richness. Our data suggest that the basic and major groups (e.g. M. vaginatus, Wilmottia spp., Mastigocladopsis sp., and Chroococcidiopsis spp.), and the abundantly shared phylotypes which showed significant difference in cyanobacterial communities between deserts, should be focused on to further explore the artificial inoculation of BSCs in temperate drylands.


Assuntos
Cianobactérias , Solo , Sinais (Psicologia) , Clima Desértico , Ecossistema , Microbiologia do Solo
16.
Ying Yong Sheng Tai Xue Bao ; 31(4): 1083-1087, 2020 Apr.
Artigo em Chinês | MEDLINE | ID: mdl-32530181

RESUMO

Water use efficiency of plants in arid regions plays a key role in affecting the distribution and water use of plants. We analyzed the responses of water use efficiency of Populus euphratica and Tamarix sp. to different groundwater depths by measuring foliar δ13C of the two dominant species in a desert hinterland. The results showed that as the groundwater depth increased from 2.1 m to 4.3 m, foliar δ13C of Tamarix sp. increased slightly and remained relatively stable. Tamarix sp. had a more stable water use efficiency to adapt to the arid environment. Foliar δ13C of P. euphratica first slightly decreased and then increased. P. euphratica improved its water use efficiency to adapt to drought stress. At the same groundwater depth, foliar δ13C of Tamarix sp. was higher than that of P. euphratica, indicating that water use efficiency of Tamarix sp. was higher than that of P. euphratica.


Assuntos
Água Subterrânea , Populus , Tamaricaceae , Clima Desértico , Secas
17.
Ying Yong Sheng Tai Xue Bao ; 31(5): 1560-1570, 2020 May.
Artigo em Chinês | MEDLINE | ID: mdl-32530234

RESUMO

Based on the positioning monitoring data from 2017 to 2018, we analyzed the spatial-temporal dynamic characteristics of moisture in two different soil types (sierozem and aeolian sandy soil) in the Yanchi desert steppe in the eastern Ningxia. The results showed that the rainfall in the study area was 208.2 and 274.8 mm in the growing season of 2017 and 2018 (May-October), respectively. The distribution of rainfall varied across different months. Except for the extreme rainfall event (129.6 mm) in May in 2018, rainfall in other months was lower than that in 2017. The seasonal dynamics of soil water content was roughly divided into two phases: compensation period (early May to early June) and fluctuation period (mid June to late September). The soil moisture of 0-20 cm layer had a pulse characteristic of rapid increase and decrease after rainfall, while that of the deep soil was relatively stable. The soil water content of sierozem showed a "rise-fall-liter" change with increasing soil depth. The saeolian sandy soil increased sharply from 0 to 60 cm then increased slowly, whereas soil water content gradually increased with increasing soil depth. In 2017, soil moisture in the soil profile (0-100 cm) of the sierozem was accumulated, and the aeo-lian sand soil was in the consumption type. In 2018, both soil water across the full profile in both soil types were the consumption type. The temporal stability of soil moisture of two soil types increased with increasing soil depth. The average soil water content of the whole sections of sierozem and aeolian sandy soil were 80-100 and 40-60 cm, respectively. The two soil types had different spatial and temporal distributions of soil moisture. Aeolian sandy soil was more affected by precipitation than sierozem. Precipitation would reduce the variability of soil moisture and change its temporal stability.


Assuntos
Solo , Água , China , Clima Desértico , Chuva
18.
Ying Yong Sheng Tai Xue Bao ; 31(3): 778-786, 2020 Mar.
Artigo em Chinês | MEDLINE | ID: mdl-32537972

RESUMO

Under the background of global climate change, precipitation changes will have profound impacts on plant community dynamics. Through field experiment with precipitation manipulation in a desert steppe of western Loess Plateau, we examined the responses of species richness, density, coverage, height and aboveground biomass of different plant life-forms to precipitation changes. The results showed significant effects of precipitation on richness, density and coverage of annual herbs in the third year of manipulation experiment (2015), with lowest values in the decreased precipitation treatments. The height of annual herbs was more sensitive to precipitation changes, and was lowest in the -40% precipitation treatment during three years. The magnitudes of negative response of growth and aboveground biomass of annual herbs to decreased precipitation were larger than that to increased precipitation. Richness, density and coverage of perennial herbs in the decreased precipitation were significantly lower than those in the +40% precipitation in the 3rd year, but were insignificantly different from the control. The height of perennial herbs was lowest in the -40% precipitation treatment during three years. The magnitudes of negative response of richness, coverage and height of perennial herbs to decreased precipitation were larger than positive response to increased precipitation, while the positive response of aboveground biomass to the +40% precipitation treatment was stronger. The positive responses of richness, density, coverage and aboveground biomass of shrub to ±20% precipitation treatments were most obvious, which might be related to the relatively concentrated distribution of shrub in these treatments. The precipitation reduction inhibited the growth of herbaceous plants, particularly on the annual herbs, whereas increasing precipitation promoted perennial herbaceous growth and biomass accumulation to some extent. The annual herbaceous growth and biomass fluctuated with interannual variation of precipitation. Shrubs were relatively less affected by precipitation changes. Precipitation changes would have significant effects on plant community composition and function of desert steppe in western Loess Plateau.


Assuntos
Biodiversidade , Desenvolvimento Vegetal , Biomassa , Mudança Climática , Clima Desértico , Ecossistema , Pradaria , Plantas , Chuva
19.
J Am Mosq Control Assoc ; 36(1): 37-42, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-32497479

RESUMO

Standard residual pesticides applied to US military materials such as camouflage netting can reduce mosquito biting pressure in the field but may contribute to the evolution of resistance. However, residual applications of a spatial repellent such as transfluthrin could allow mosquitoes the opportunity to escape, only inducing mortality if insects linger, for example after becoming trapped in a treated tent. In this study we investigated the capability of transfluthrin on 2 types of US military material to reduce natural populations of disease vector mosquitoes in a cool-arid desert field environment in southern California. We found that transfluthrin could reduce Culex tarsalis incursion into protected areas by up to 100% upon initial treatment and up to 45% for at least 16 days posttreatment, showing that this compound could be an effective element in the US Department of Defense integrated vector management system appropriate for further study.


Assuntos
Culex , Ciclopropanos , Fluorbenzenos , Inseticidas , Controle de Mosquitos , Animais , California , Clima Desértico , Equipamentos e Provisões , Instalações Militares
20.
Int J Syst Evol Microbiol ; 70(5): 3513-3527, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32374252

RESUMO

Three presumptive Modestobacter strains isolated from a high altitude Atacama Desert soil were the subject of a polyphasic study. The isolates, strains 1G4T, 1G51 and 1G52, were found to have chemotaxonomic and morphological properties that were consistent with their assignment to the genus Modestobacter. They formed a well supported clade in Modestobacter 16S rRNA gene trees and were most closely related to the type strain of 'Modestobacter excelsi' (99.8-99.9% similarity). They were also closely related to the type strains of Modestobacter caceresii (99.6 % similarity), Modestobacter italicus (99.7-99.9% similarity), Modestobacter lacusdianchii (98.4-99.2% similarity), Modestobacter marinus (99.4-99.5% similarity) and Modestobacter roseus (99.3-99.5% similarity), but were distinguished from their closest relatives by a combination of phenotypic features. Average nucleotide identity and digital DNA:DNA hybridization similarities drawn from comparisons of draft genome sequences of isolate 1G4T and its closest phylogenetic neighbours mentioned above, were well below the threshold used to assign closely related strains to the same species. The close relationship between isolate 1G4T and the type strain of M. excelsi was showed in a phylogenomic tree containing representative strains of family Geodermatophilaceae. The draft genome sequence of isolate 1G4T (size 5.18 Kb) was shown to be rich in stress related genes providing further evidence that the abundance of Modestobacter propagules in Atacama Desert habitats reflects their adaptation to the harsh environmental conditions prevalent in this biome. In light of all of these data it is proposed that the isolates be assigned to a novel species in the genus Modestobacter. The name proposed for this taxon is Modestobacter altitudinis sp. nov., with isolate 1G4T (=DSM 107534T=PCM 3003T) as the type strain.


Assuntos
Actinobacteria/classificação , Clima Desértico , Filogenia , Microbiologia do Solo , Actinobacteria/isolamento & purificação , Técnicas de Tipagem Bacteriana , Composição de Bases , Chile , DNA Bacteriano/genética , Ácidos Graxos/química , Hibridização de Ácido Nucleico , RNA Ribossômico 16S/genética , Análise de Sequência de DNA
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