Desert Ecosystems Research Articles

Sphingomonas clade and functional distribution with simulated climate change.

Microbes are essential for the functioning of all ecosystems, and as global warming and anthropogenic pollution threaten ecosystems, it is critical to understand how microbes respond to these changes. We investigated the climate response of Sphingomonas, a widespread gram-negative bacterial genus, during an 18-month microbial community reciprocal transplant experiment across a Southern California climate gradient. We hypothesized that after 18 months, the transplanted Sphingomonas clade and functional composition would correspond with site conditions and reflect the Sphingomonas composition of native communities. We extracted Sphingomonas sequences from metagenomic data across the gradient and assessed their clade and functional composition. Representatives of at least 12 major Sphingomonas clades were found at varying relative abundances along the climate gradient, and transplanted Sphingomonas clade composition shifted after 18 months. Site had a significant effect (PERMANOVA; P < 0.001) on the distribution of both Sphingomonas functional (R2 = 0.465) and clade composition (R2 = 0.400), suggesting that Sphingomonas composition depends on climate parameters. Additionally, for both Sphingomonas clade and functional composition, ordinations revealed that the transplanted communities shifted closer to the native Sphingomonas composition of the grassland site compared with the site they were transplanted into. Overall, our results indicate that climate and substrate collectively determine Sphingomonas clade and functional composition.IMPORTANCESphingomonas is the most abundant gram-negative bacterial genus in litter-degrading microbial communities of desert, grassland, shrubland, and forest ecosystems in Southern California. We aimed to determine whether Sphingomonas responds to climate change in the same way as gram-positive bacteria and whole bacterial communities in these ecosystems. Within Sphingomonas, both clade composition and functional genes shifted in response to climate and litter chemistry, supporting the idea that bacteria respond similarly to climate at different scales of genetic variation. This understanding of how microbes respond to perturbation across scales may aid in future predictions of microbial responses to climate change.

Rapid recovery of desert shrubs is attributed to imbalance of water supply to demand after disturbance in Northwest China

BackgroundDisturbance is a key driver of changes in terrestrial ecosystems, especially in water limited regions. In the desert ecosystem of Northwest China, shrubs are often foraged by camels and this causes the shrubs lost their aboveground tissues. Although the aboveground tissue could recover after the disturbance, the mechanisms of resprouts’ recovery after the disturbance are still poorly understood. We investigated the morphological and physiological characteristics and root water uptake sources of resprouts and non-disturbed seedlings of four desert shrub species that were often foraged by camels.ResultsThe results showed that the resprouts grew rapidly after the removal of aboveground tissue. The height and aboveground biomass of resprouts reached the level of 5-year-old seedlings following a growing season. Compared to un-disturbed seedlings, higher leaf water potential, leaf hydraulic conductance and photosynthesis rate were observed in resprouts, indicating that resprouts grew rapidly after disturbance. Furthermore, we found that the root water uptake source did not change after disturbance. This indicated that the roots of resprouts kept intact water uptake capacity after disturbance, which could keep supplying sufficient water to the aboveground tissue. Due to the removal of aboveground tissue of the resprouts, the water demand of aboveground tissue decreased, which induced an imbalance of water supply from roots to demand of aboveground tissues of resprouts. This explained the improved physiological performance and rapid recovery of resprouts after disturbance.ConclusionsThe imbalance of water supply to demand contributes to the rapid recovery of desert shrubs after disturbance. The findings provide insight into the eco-physiological mechanism for the maintenance of desert ecosystems that are facing disturbance.

Climate, litter quality and radiation duration jointly regulate the net effect of UV radiation on litter decomposition

Photodegradation via ultraviolet (UV) radiation is an important factor driving plant litter decomposition. Despite increasing attention to the role of UV photodegradation in litter decomposition, the specific impact of UV radiation on the plant litter decomposition stage within biogeochemical cycles remains unclear at regional and global scales. To clarify the variation rules of magnitude of UV effect on plant litter decomposition and their regulatory factors, we conducted a meta-analysis based on 54 published papers. Our results indicated that UV significantly promoted the mass loss of litter by facilitating decay of carbonaceous fractions and release of nitrogen and phosphorus. The promotion effect varied linearly or non-linearly with the time that litter exposed to UV, and with climatic factors. The UV effect on litter decomposition decreased first than increased on precipitation and temperature gradients, reaching its minimum in the area with a precipitation of 400–600 mm, and a temperature of 15–20 °C. This trend might be attributed to a potential equilibrium between the photofacilitation and photo-inhibition effects of UV under this condition. This variation in UV effect on precipitation gradient was in agreement with the fact that UV photodegradation effect was weakest in grassland ecosystems compared to that in forest and desert ecosystems. In addition, initial litter quality significantly influenced the magnitude of UV effect, but had no influence on the correlation between UV effect and climate gradient. Litter with lower initial nitrogen and lignin content shown a greater photodegradation effect, whereas those with higher hemicellulose and cellulose content had a greater photodegradation effect. Our study provides a comprehensive understanding of photodegradation effect on plant litter decomposition, indicates potentially substantial impacts of global enhancements of litter decomposition by UV, and highlights the necessity to quantify the contribution of photochemical minerallization pathway and microbial degradation pathway in litter decomposition.

Combining different species in restoration is not always the right decision: Monocultures can provide higher ecological functions than intercropping in a desert ecosystem

Vegetation restoration in deserts is challenging due to these ecosystems' inherent fragility and harsh environmental conditions. One approach for active restoration involves planting native species, which can accelerate the recovery of ecosystem functions. To ensure the effectiveness of this process, carefully selecting species for planting is crucial. Generally, it is expected that a more diverse mix of species in the plantation will lead to the recovery of a greater number of ecosystem functions, especially when the selected species have complementary niche traits that facilitate maximum cooperation and minimize competition among them. In this study, we evaluated the planting of two native species from the hyper-desert of Taklamakan, China, which exhibit marked morpho-physiological differences: a phreatophytic legume (Alhagi sparsifolia) and a halophytic non-legume (Karelinia caspia). These species were grown in both monoculture and intercrop communities. Monoculture of the legume resulted in the highest biomass accumulation. Intercropping improved several ecosystem functions in the 50 cm-upper soil, particularly those related to phosphorus (P), carbon (C), and sulfur (S) concentrations, as well as soil enzyme activities. However, it also increased soil sodium (Na+) concentration and pH. Halophyte monocultures enhanced ecological functions associated with nitrogen concentrations in the upper soil and with P, S, C, and cation concentrations (K+, Ca2+, Mg2+, Cu2+, Fe2+, Zn2+, Co2+, Ni2+), along with enzyme activities in the deep soil. It also maximized Na+ accumulation in plant biomass. In summary, we recommend legume monoculture when the primary goal is to optimize biomass accumulation. Conversely, halophyte monoculture is advisable when the objective is to extract sodium from the soil or enhance ecosystem functions in the deep soil. Intercropping the two species is recommended to maximize the ecosystem functions of the upper soil, provided there is no salinization risk. When planning restoration efforts in desert regions, it is essential to understand the impact of each species on ecosystem function and how complementary species behave when intercropped. However, these interactions are likely species- and system-specific, highlighting the need for more work to optimize solutions for different arid ecosystems.

Characteristics of Soil Particle Sizes and Fractal Parameters under Different Plantation Types of Populus alba

Vegetation plays a leading role in restoring desert ecosystems and increasing productivity. In this study, we elucidate the improvement effects of different restoration areas of Populus alba on the soil particle distribution, sedimentation environment, and fractal characteristics. We selected the restoration areas of P. alba × Caragana korshinskii (YN), P. alba × Hedysarum leave (YY), and P. alba × Hedysarum scoparium (YH), which have a history of twenty-one years. We analyzed the soil nutrients, soil particle size, soil particle size parameters, soil fractal dimension (D) values, and soil multifractal parameters at soil depths of 0–80 cm. We found that the YN, YY, and YH significantly increased the soil nutrients and soil fine particles (p &lt; 0.05) and changed the deposition pattern of the soil particles in the sandy area. The YN, YY, and YH promote soil particle refinement and reduce the sorting performance of the soil particles. The vegetation promotes extremely positive-skewed and very leptokurtic soil particle distributions. The D values in the YN, YY, and YH restoration areas increased by 7.62%–27.94%, 7.36%–26.28%, and 7.10%–17.92%, respectively, relative to those of the LS. The construction of the different restoration areas of P. alba has made the distribution of the soil particles nonuniform. Compared with the YY and YH plantations, the distribution range of the soil particles in the YN plantation is wider, and the distribution heterogeneity is greater. In addition, we found that the fractal parameters are influenced by the soil physicochemical properties, the depositional environment, and vegetation factors. Therefore, we believe that D values and multifractal parameters are necessary as additional information for desert soil texture improvement. The results of this study provide a scientific and theoretical basis for the future revegetation of deserts.

Geographical patterns and environmental influencing factors of variations in Asterothamnus centraliasiaticus seed traits on Qinghai-Tibetan plateau.

Seed traits related to recruitment directly affect plant fitness and persistence. Understanding the key patterns and influencing factors of seed trait variations is conducive to assessing plant colonization and habitat selection. However, the variation patterns of the critical seed traits of shrub species are usually underrepresented and disregarded despite their vital role in alpine desert ecosystems. This study gathered seeds from 21 Asterothamnus centraliasiaticus populations across the Qinghai-Tibetan Plateau, analyzing geographical patterns of seed traits to identify external environmental influences. Additionally, it explored how seed morphology and nutrients affect germination stress tolerance, elucidating direct and indirect factors shaping seed trait variations. The results present substantial intraspecific variations in the seed traits of A. centraliasiaticus. Seed traits except seed length-to-width ratio (LWR) all vary significantly with geographic gradients. In addition, the direct and indirect effects of climatic variables and soil nutrients on seed traits were verified in this study. Climate mainly influences seed nutrients, and soil nutrients significantly affect seed morphology and seed nutrients. Furthermore, climate directly impacts seed germination drought tolerance index (GDTI) and germination saline-alkali tolerance index (GSTI). Seed germination cold tolerance index (GCTI) is influenced by climate and soil nutrients (mostly SOC). GDTI and GSTI are prominently influenced by seed morphology (largely the seed thousand-grain weight (TGW)), and GCTI is evidently affected by seed nutrients (mainly the content of soluble protein (CSP)). The findings of this study amply explain seed trait variation patterns of shrubs in alpine desert ecosystems, possessing significant importance for understanding the mechanism of shrub adaptation to alpine desert ecosystems, predicting the outcomes of environmental change, and informing conservation efforts. This study can be a valuable reference for managing alpine desert ecosystems on the Qinghai-Tibetan Plateau.

Divergent Nitrogen, Phosphorus, and Carbon Concentrations among Growth Forms, Plant Organs, and Soils across Three Different Desert Ecosystems

Quantifying the dryland patterns of plant carbon (C), nitrogen (N), and phosphorus (P) concentrations and their stoichiometric values along environmental gradients is crucial for understanding ecological strategies. To understand the plant adaptive strategies and ecosystem nutrient concentrations across three desert ecosystems (e.g., desert, steppe desert, and temperate desert), we compiled a dataset consisting of 1295 plant species across three desert ecosystems. We assessed the element concentrations and ratios across plant growth forms, plant organs, and soils and further analysed the leaf vs. root N, P, and N:P scaling relationships. We found that the leaf N, P, and C concentrations were significantly different only from those of certain other growth forms and in certain desert ecosystems, challenging the generality of such differences. In leaves, the C concentrations were always greater than the N and P concentrations and were greater than those in soils depending on the soil chemistry and plant physiology. Thus, the element concentrations and ratios were greater in the organs than in the soils. The values in the leaf versus the root N, P, and N:P scaling relationships differed across the three desert ecosystems; for example, αN (1.16) was greater in the desert, αP (1.10) was greater in the temperate desert ecosystem, and αN:P (2.11) was greater in the desert ecosystem. The mean annual precipitation (MAP) and mean annual temperature (MAT) did not have significant effects on the leaf elemental concentrations or ratios across the desert ecosystems. This study advances our understanding of plant growth forms and organs, which support resource-related adaptive strategies that maintain the stability of desert ecosystems via divergent element concentrations and environmental conditions.

Unveiling the diversity, composition, and dynamics of phyllosphere microbial communities in Alhagi sparsifolia across desert basins and seasons in Xinjiang, China.

Phyllosphere microbes residing on plant leaf surfaces for maintaining plant health have gained increasing recognition. However, in desert ecosystems, knowledge about the variety, composition, and coexistence patterns of microbial communities in the phyllosphere remains limited. This study, conducted across three basins (Turpan-TLF, Tarim-CL, and Dzungaria-MSW) and three seasons (spring, summer, and autumn) in Xinjiang, China, aimed to explore the diversity and composition of microbial communities in the phyllosphere, encompassing both bacteria and fungi in Alhagi sparsifolia. We also investigated the co-occurrence patterns, influencing factors, and underlying mechanisms driving these dynamics. Results indicate that phyllosphere bacteria exhibited lower diversity indices (ACE, Shannon, Simpson, Fisher phylogenetic diversity, and Richness) in spring compared to summer and autumn, while the Goods Coverage Index (GCI) was higher in spring. Conversely, diversity indices and GCI of phyllosphere fungi showed an opposite trend. Interestingly, the lowest level of multi-functionality and niche width in phyllosphere bacteria occurred in spring, while the highest level was observed in phyllosphere fungi. Furthermore, the study revealed that no significant differences in multi-functionality were found among the regions (CL, MSW, and TLF). Network analysis highlighted that during spring, phyllosphere bacteria exhibited the lowest number of nodes, edges, and average degree, while phyllosphere fungi had the highest. Surprisingly, the multi-functionality of both phyllosphere bacteria and fungi showed no significant correlation with climatic and environmental factors but displayed a significant association with the morphological characteristics and physicochemical properties of leaves. Structural Equation Model indicated that the morphological characteristics of leaves significantly influenced the multi-functionality of phyllosphere bacteria and fungi. However, the indirect and total effects of climate on multi-functionality were greater than the effects of physicochemical properties and morphological characteristics of leaves. These findings offer new insights into leaf phyllosphere microbial community structure, laying a theoretical foundation for vegetation restoration and rational plant resource utilization in desert ecosystems.

Shrub and patch size of moss crusts regulate soil multifunctionality in a temperate desert of Central Asia

AbstractThe shrub and patch size of moss crusts can significantly affect plant and soil nutrients. The effects and relationships of shrubs and moss crusts on soil multifunctionality are unclear. This study aimed to understand the spatial heterogeneity of soil multifunctionality in moss crust patches and shrubs. Soil organic carbon, nutrient, and enzyme activities under moss crust patches were measured. Interestingly, the soil polyphenol oxidase (PPO) and peroxidase (POD) activities, carbon‐related soil multifunctionality index (C‐SMF), nitrogen‐related soil multifunctionality index (N‐SMF), phosphorus‐related soil multifunctionality index (P‐SMF), and soil multifunctionality index (SMF) increased with increasing patch size in moss crusts. The patch size of moss crusts had no significant effect on the C‐SMF, N‐SMF, P‐SMF, and SMF under the shrub. The soil C‐SMF, N‐SMF, P‐SMF, and SMF under shrubs were significantly higher than that in exposed areas (EAs). The soil PPO, POD, N‐SMF, P‐SMF, and SMF under dead shrubs were significantly higher than those under living shrubs and in EAs. Evaluation and composition analysis of C‐SMF, N‐SMF, and P‐SMF indicated that moss crust promotes the increase of P‐SMF, and that shrub promotes the increase of C‐SMF and N‐SMF. Moss crust patches mainly affected phosphorus functionality, increasing phosphorus cycling. Shrub promotes soil carbon and nitrogen functionality. This study elucidates the effect of moss crust patch size on soil multifunctionality influenced by shrub growth in desert ecosystems and provides further new insights into the soil processes and functions. Results are beneficial for the comprehensive utilization of fertile islands and its enhancement of beneficial ecological functions, such as maintaining soil nutrition, quality, health, and vegetation restoration, and lay a foundation for future research on nutrient absorption and utilization between mosses and shrubs.

Soil microbial functional profiles of P-cycling reveal drought-induced constraints on P-transformation in a hyper-arid desert ecosystem

Soil water conditions are known to influence soil nutrient availability, but the specific impact of different conditions on soil phosphorus (P) availability through the modulation of P-cycling functional microbial communities in hyper-arid desert ecosystems remains largely unexplored. To address this knowledge gap, we conducted a 3-year pot experiment using a typical desert plant species (Alhagi sparsifolia Shap.) subjected to two water supply levels (25 %–35 % and 65 %–75 % of maximum field capacity, MFC) and four P-supply levels (0, 1, 3, and 5 g P m−2 y−1). Our investigation focused on the soil Hedley-P pool and the four major microbial groups involved in the critical phases of soil microbial P-cycling. The results revealed that the drought (25 %–35 % MFC) and no P-supply treatments reduced soil resin-P and NaHCO3-Pi concentrations by 87.03 % and 93.22 %, respectively, compared to the well-watered (65 %–75 % MFC) and high P-supply (5 g P m−2 y−1) treatments. However, the P-supply treatment resulted in a 12 %–22 % decrease in the soil NH4+-N concentration preferred by microbes compared to the no P-supply treatment. Moreover, the abundance of genes engaged in microbial P-cycling (e.g. gcd and phoD) increased under the drought and no P-supply treatments (p < 0.05), suggesting that increased NH4+-N accumulation under these conditions may stimulate P-solubilizing microbes, thereby promoting the microbial community's investment in resources to enhance the P-cycling potential. Furthermore, the communities of Steroidobacter cummioxidans, Mesorhizobium alhagi, Devosia geojensis, and Ensifer sojae, associated with the major P-cycling genes, were enriched in drought and no or low-P soils. Overall, the drought and no or low-P treatments stimulated microbial communities and gene abundances involved in P-cycling. However, this increase was insufficient to maintain soil P-bioavailability. These findings shed light on the responses and feedback of microbial-mediated P-cycling behaviors in desert ecosystems under three-year drought and soil P-deficiency.

Plant root mechanisms and their effects on carbon and nutrient accumulation in desert ecosystems under changes in land use and climate.

Deserts represent key carbon reservoirs, yet as these systems are threatened this has implications for biodiversity and climate change. This review focuses on how these changes affect desert ecosystems, particularly plant root systems and their impact on carbon and mineral nutrient stocks. Desert plants have diverse root architectures shaped by water acquisition strategies, affecting plant biomass and overall carbon and nutrient stocks. Climate change can disrupt desert plant communities, with droughts impacting both shallow and deep-rooted plants as groundwater levels fluctuate. Vegetation management practices, like grazing, significantly influence plant communities, soil composition, root microorganisms, biomass, and nutrient stocks. Shallow-rooted plants are particularly susceptible to climate change and human interference. To safeguard desert ecosystems, understanding root architecture and deep soil layers is crucial. Implementing strategic management practices such as reducing grazing pressure, maintaining moderate harvesting levels, and adopting moderate fertilization can help preserve plant-soil systems. Employing socio-ecological approaches for community restoration enhances carbon and nutrient retention, limits desert expansion, and reduces CO2 emissions. This review underscores the importance of investigating belowground plant processes and their role in shaping desert landscapes, emphasizing the urgent need for a comprehensive understanding of desert ecosystems.

‘Fertile island’ effects on the soil microbial community beneath the canopy of Tetraena mongolica, an endangered and dominant shrub in the West Ordos Desert, North China

BackgroundThe fertile islands formed by shrubs are major drivers of the structure and function of desert ecosystems, affecting seedling establishment, plant–plant interactions, the diversity and productivity of plant communities, and microbial activity/diversity. Although an increasing number of studies have shown the critical importance of soil microbes in fertile island formation, how soil microbial community structure and function are affected by the different fertile island effect intensities is still unknown. As an endangered and dominant shrub species in the West Ordos Desert, Tetraena mongolica was selected for further exploration of its fertile island effect on the soil microbial community in the present study to test the following two hypotheses: (1) T. mongolica shrubs with different canopy sizes exert fertile island effects of different strengths; (2) the soil microbial community structure and function beneath the T. mongolica canopy are affected by the fertile island, and the strength of these effects varies depending on the shrub canopy size.ResultsThe contents of soil total nitrogen (TN) and available phosphorus (AVP) were significantly greater beneath T. mongolica shrub canopy than outside the shrub canopy. With increasing shrub canopy size, the enrichment of soil TN and AVP increased, indicating a stronger fertile island effect. The structure and function of soil microbial communities, including fungal, archaeal and bacterial communities, are affected by the fertile island effect. An increase in canopy size increased the relative abundance of Ascomycota (Fungi) and Thaumarchaeota (Archaea). For the soil microbial functional groups, the relative abundance of endophytes in the fungal functional groups; steroid hormone biosynthesis, sphingolipid metabolism, and steroid biosynthesis genes in the bacterial functional groups; and nonhomologous end-joining and bisphenol degradation functional genes in the archaeal functional groups increased significantly with increasing T. mongolica canopy size.ConclusionsThese results revealed that T. mongolica had a fertile island effect, which affected the soil microbial community structure and functions, and that the fertile island effect might increase with increasing shrub canopy size. The fertile island effect may strengthen the interaction between T. mongolica shrubs and microbes, which may be beneficial to the growth and maintenance of T. mongolica.

Microbiological impact of long-term wine grape cultivation on soil organic carbon in desert ecosystems: a study on rhizosphere and bulk sandy soils.

The improvement of nutrients in soil is essential for using deserts and decertified ecosystems and promoting sustainable agriculture. Grapevines are suitable crops for desert soils as they can adapt to harsh environments and effectively impact soil nutrients; however, the mechanisms underlying this remain unclear. This study explored the impact of the different duration(3, 6, and 10 years) of grape cultivation on soil organic carbon, physicochemical properties, enzyme activities, microbial communities, and carbon cycle pathways in both rhizosphere and bulk soils. Partial least squares path modeling was used to further reveal how these factors contributed to soil nutrient improvement. Our findings indicate that after long-term grape cultivation six years, soil organic carbon, total nitrogen, total phosphorus, microbial biomass carbon and nitrogen, and enzyme activities has significantly increased in both rhizosphere and bulk soils but microbial diversity decreased in bulk soil. According to the microbial community assembly analysis, we found that stochastic processes, particularly homogenizing dispersal, were dominant in both soils. Bacteria are more sensitive to environmental changes than fungi. In the bulk soil, long-term grape cultivation leads to a reduction in ecological niches and an increase in salinity, resulting in a decrease in soil microbial diversity. Soil enzymes play an important role in increasing soil organic matter in bulk soil by decomposing plant litters, while fungi play an important role in increasing soil organic matter in the rhizosphere, possibly by decomposing fine roots and producing mycelia. Our findings enhance understanding of the mechanisms of soil organic carbon improvement under long-term grape cultivation and suggest that grapes are suitable crops for restoring desert ecosystems.

Population genomics and morphological data bridge the centuries of cyanobacterial taxonomy along the continuum of Microcoleus species

The filamentous cyanobacterium Microcoleus is among the most important global primary producers, especially in hot and cold desert ecosystems. This taxon represents a continuum consisting of a minimum of 12 distinct species with varying levels of gene flow and divergence. The notion of a species continuum is poorly understood in most lineages but is especially challenging in cyanobacteria. Here we show that genomic diversification of the Microcoleus continuum is reflected by morphological adaptation. We compiled a dataset of morphological data from 180 cultured strains and 300 whole genome sequences, including eight herbarium specimens and the type specimen of Microcoleus. We employed a combination of phylogenomic, population genomic, and population-level morphological data analyses to delimit species boundaries. Finally, we suggest that the shape of the filament apices may have an adaptive function to environmental conditions in the soil.

High-throughput sequencing reveals the structure and metabolic resilience of desert microbiome confronting climate change.

Desert ecosystems harbor a unique microbial diversity that is crucial for ecological stability and biogeochemical cycles. An in-depth understanding of the biodiversity, compositions, and functions of these microbial communities is imperative to navigate global changes and confront potential threats and opportunities applicable to agricultural ecosystems amid climate change. This study explores microbial communities in the rhizosphere and endosphere of desert plants native to the Arabian Peninsula using next-generation sequencing of the 16S rRNA gene (V3-V4 hypervariable region). Our results reveal that each microbial community has a diverse and unique microbial composition. Based on alpha and beta diversity indices, the rhizosphere microbiome is significantly diverse and richer in microbial taxa compared to the endosphere. The data reveals a shift towards fast-growing microbes with active metabolism, involvement in nutrient cycling, nitrogen fixation, and defense pathways. Our data reveals the presence of habitat-specific microbial communities in the desert, highlighting their remarkable resilience and adaptability to extreme environmental conditions. Notably, we observed the existence of radiation-resistant microbes such as Deinococcus radiotolerans, Kocuria sp., and Rubrobacter radiotolerans which can tolerate high levels of ionizing radiation. Additionally, examples of microbes exhibiting tolerance to challenging conditions include Nocardioides halotolerans, thriving in high-salinity environments, and hyperthermophilic microbes such as Quasibacillus thermotolerans. Moreover, functional analysis reveals enrichment in chaperon biosynthesis pathways associated with correct protein folding under heat stress conditions. Our research sheds light on the unique diversity of desert microbes and underscores their potential applications to increase the resilience of agriculture ecosystems, offering a promising strategy to fortify crops against the challenges posed by climate change, ultimately supporting sustainable food production for our ever-expanding global population.

Genomic characterization of dryland adaptation in endangered Anxi cattle in China.

Local species exhibit distinctive indigenous characteristics while showing unique productive and phenotypic traits. However, the advent of commercialization has posed a substantial threat to the survival of indigenous species. Anxi cattle, an endangered native breed in China, have evolved unique growth and reproductive characteristics in extreme desert and semidesert ecosystems. In this study, we conducted a genomic comparison of 10 Anxi cattle genomes with those of five other global populations/breeds to assess genetic diversity and identify candidate genomic regions in Anxi cattle. Population structure and genetic diversity analyses revealed that Anxi cattle are part of the East Asian cattle clade, exhibiting higher genetic diversity than commercial breeds. Through selective sweep analysis, we identified specific genetic variations linked to the environmental adaptability of Anxi cattle. Notably, we identified several candidate genes, including CERS3 involved in regulating skin permeability and antimicrobial functions, RBFOX2 associated with cardiac development, SLC16A7 participated in the regulation of pancreatic endocrine function, and SPATA3 related to reproduction. Our findings revealed the distinctive genomic features of Anxi cattle in dryland environments, provided invaluable insights for further research and breed preservation, and had important significance for enriching the domestic cattle breeding gene bank.

Ecological Features and Adaptive Capabilities of Cyanobacteria in Desert Ecosystems: A Review

Ecological Features and Adaptive Capabilities of Cyanobacteria in Desert Ecosystems: A Review

Responses of plant diversity and soil microorganism diversity to nitrogen addition in the desert steppe, China

Nitrogen (N) deposition is a significant aspect of global change and poses a threat to terrestrial biodiversity. The impact of plant-soil microbe relationships to N deposition has recently attracted considerable attention. Soil microorganisms have been proven to provide nutrients for specific plant growth, especially in nutrient-poor desert steppe ecosystems. However, the effects of N deposition on plant soil microbial community interactions in such ecosystems remain poorly understood. To investigate these effects, we conducted a 6-year N-addition field experiment in a Stipa breviflora Griseb. desert steppe in Inner Mongolia Autonomous Region, northern China. Four N treatment levels (N0, N30, N50, and N100, corresponding to 0, 30, 50, and 100 kg N/(hm2•a), respectively) were applied to simulate atmospheric N deposition. The results showed that N deposition did not significantly affect the aboveground biomass of desert steppe plants. N deposition did not significantly reduce the alfa-diversity of plant and microbial communities in desert steppe, and low and mediate N additions (30 and 50 kg N/(hm2•a)) had a promoting effect on them. The variation pattern of plant Shannon index was consistent with that of the soil bacterial Chao1 index. N deposition significantly affected the beta-diversity of plants and soil bacteria, but did not significantly affect fungal communities. In conclusion, N deposition led to co-evolution between desert steppe plants and soil bacterial communities, while fungal communities exhibited strong stability and did not undergo significant changes. These findings help clarify atmospheric N deposition effects on the ecological health and function of the desert steppe.

The hydromorphological effects of dams in an extreme desert environment - The Fish River Canyon, Namibia

Arid ecohydrology relies on sporadic rainfall and flooding to sustain linear river oases, crucial for supporting flora and fauna during the long dry season and drought years. Growing water demands have led to large reservoir constructions, severely impacting the fragile arid ecosystems. We analyse the hydro-geomorphological impacts of the large Neckartal Dam (completed in 2019) on the Fish River oasis based on existing dams, regional studies, field surveys, hydrological data, and modelling. The Neckartal Dam, along with three smaller dams, impounds 80 % of the desert oasis basin (1235 Mm3, 55,870 km2), exceeding the average annual runoff threefold. A gradient of dam-induced changes was identified, varying with distance from the dam wall. Immediate downstream, hydromorphological impacts include channel narrowing (⁓15 %) and reduce mean annual sediment yield (⁓20 %). Also, water distribution losses create chronic low flows, favour for invasive flora and fauna to spread, significantly disrupting the pristine nature of the desert ecosystem. This phenomenon has been observed over a 70 km stretch below the Hardap Dam. This situation is irreversible, as the invasive flora can withstand even large floods. As the distance increases, the dam suppresses low to moderate annual floods and prolongs droughts from months to years or even decades. Based on our flood routing model, only the largest floods (recurrence interval, RI >25 years) can exceed the dam storage, continue downstream, transport sediment and maintain the pool-bar morphology along 245 km of the oasis. The lack of significant flows between major floods means that sediment from smaller, lower arid basins accumulates in the Fish River valley, filling pools and further reducing water availability during dry periods. The Neckartal Dam's impact assessment demonstrates potential changes in arid river systems globally.

Patterns in Tree Cavities (Hollows) in Euphrates Poplar (Populus euphratica, Salicaceae) along the Tarim River in NW China

Populus euphratica Oliv., an indicator species for eco-environmental change in arid areas, plays a key role in maintaining the stability of fragile oasis–desert ecosystems. Owing to human interference as well as to the harshness of the natural environment, P. euphratica forests have suffered severe damage and degradation, with trunk cavities (i.e., hollows) becoming increasingly pronounced, and thus posing a great threat to the growth, health, and survival of the species. Currently, there is a gap in our understanding of cavity formation and its distribution in P. euphratica. Here, cavities in the trunks and branches of a P. euphratica in a typical transect (Arghan) along the lower Tarim River were studied based on field positioning observations combined with laboratory analysis. The results revealed a large number of hollow-bearing P. euphratica stands in the study area; indeed, trees with hollows accounted for 56% of the sampled trees, with approximately 159 trees/ha. Sixty-six percent of hollow trees exhibited large (15 cm ≤ cavity width (CW) &lt; 30 cm) or very large (CW &gt; 30 cm) hollows. The main types of cavities in the trees were trunk main (31.3%), trunk top (20.7%), branch end (19.5%), and branch middle (19.5%). Tree parameters, such as diameter at breast height (DBH), tree height (TH), east–west crown width (EWCW), height under branches (UBH), and crown loss (CL) were significantly different between hollow and non-hollow trees. Both cavity height and width were significantly and positively correlated with DBH and CL, as well as with average crown width (ACW) (p &lt; 0.001) and the distance from the tree to the river. The proportion of P. euphratica trees with cavities showed an overall increasing trend with increasing groundwater depth. Our findings show that cavities in P. euphratica varied with different tree architectural characteristics. Water availability is a major environmental factor influencing the occurrence of hollowing in desert riparian forests. The results provide scientific support for the conservation and sustainable management of existing desert riparian forest ecosystems.