Desert Species Research Articles

Habitat Suitability and Areal Dynamics of Rare Desert Species of Myxomycetes of the Genus Didymium under Global Climate Change in Asia

Habitat Suitability and Areal Dynamics of Rare Desert Species of Myxomycetes of the Genus Didymium under Global Climate Change in Asia

Effects of the Radicle Sheath on the Rhizosphere Microbial Community Structure of Seedlings in Early Spring Desert Species Leontice incerta

Most research on plant–microbe interactions emphasize the effects of micronutrients on the rhizosphere microbial community structure. However, the influence of seed structures, particularly the radicle sheath, on microbial diversity at the seedling root tips under varying temperatures and humidity has been less explored. This study conducted controlled indoor experiments in the northern desert of Xinjiang to assess the radicle sheath’s impact on microbial community composition, diversity, and function. The results indicated no significant changes in the Chao1 index for bacteria and fungi, but notable differences were observed in the Shannon and Simpson indices (p < 0.05). Under drought conditions, the radicle sheath significantly reduced bacterial infections without affecting fungi. Genus-level analysis showed an increased abundance of specific dominant bacterial groups when the radicle sheath was retained. NMDS analysis confirmed its significant effect on both bacterial and fungal community structures. LEfSe analysis identified 34 bacterial and 15 fungal biomarkers, highlighting the treatment’s impacts on microbial taxonomic composition. Functional predictions using PICRUSt 2 revealed that the radicle sheath facilitated the conversion of CH4 to CH3OH and various nitrogen cycle processes under drought. Overall, the radicle sheath plays a crucial role in maintaining rhizosphere microbial community stability and enhancing the functions of both bacteria and fungi under drought conditions.

Through a collapse to restoration: the non-stationary dynamics of the rodent community in a new cycle of desertification in Kalmykia

The grazing ecosystems of Kalmykia are extremely dynamic, this being associated with the high variability of grazing pressure in the region: a drastic reduction in the number of livestock in the 1990’s led to the restoration of pastures and the transition of their functioning from the “desert” to the “steppe” regime. Since the late 2000’s, new desertification processes have been gaining momentum, these being caused by increased grazing pressure and droughts. The vegetation cover of pastures quite quickly began to respond to the increase in livestock numbers by reducing the projective cover, while the species composition of plants sharply changed to “desert” only a few years later. Against the background of increasing desertification, the rodent community first collapsed and then recovered. Apparently, the collapse is a belated reaction to the steppefication of pastures that preceded desertification, this leading to a reduced number of desert species and an impoverished community, thereby slowing down its revival during a new cycle of desertification. Thus, both vegetation cover and rodent community demonstrated non-stationary dynamics with changing the regimes and a delayed response (inertia) in response to landscape desertification.

How to Cope With Stress in the Desert-The Date Palm Approach.

Increasing desertification constitutes a global environmental problem, mainly driven by climate change and inappropriate land-use that limits agriculture, forestry and human colonization. The selection of suitable plant species to mitigate desertification is particularly challenging, as it usually requires simultaneous counteraction against a whole set of unfavourable environmental conditions, including heat, drought, high tropospheric ozone and salinity. It therefore seems useful to identify the survival strategies of plants native in desert environments. Date palm constitutes a plant species native in desert environments and cultivated worldwide in arid regions that have been studied intensively for stress defence during the last decade. The present review summarizes the current state of biochemical stress defence mechanisms including avoidance, osmotic and metabolic adjustments and reactive oxygen species scavenging, addresses whole-plant regulations and trade-off between stress compensation/defence and growth of date palms. The review advances our knowledge about how this typical desert species copes with both individual and multiple environmental stresses at the cellular to the whole-plant level, and identifies areas of future research required to fully understand the strategies of this plant species to survive in the desert, thereby contributing to efforts for the mitigation of climate change and desertification.

Growing-Season Precipitation Is a Key Driver of Plant Leaf Area to Sapwood Area Ratio at the Global Scale.

Leaf area to sapwood area ratio (AL/AS) influences carbon sequestration, community composition, and ecosystem functioning in terrestrial vegetation and is closely related to leaf economics and hydraulics. However, critical predictors of AL/AS are not well understood. We compiled an AL/AS data set with 1612 species-site combinations (1137 species from 285 sites worldwide) from our field experiments and published literature. We found the global mean AL/AS to be 0.63 m2 cm-2, with its variation largely driven by growing-season precipitation (Pgs), which accounted for 18% of the variation in AL/AS. Species in tropical rainforests exhibited the highest AL/AS (0.82 m2 cm-2), whereas desert species showed the lowest AL/AS (0.16 m2 cm-2). Soil factors such as soil nitrogen and soil organic carbon exhibited positive effects on AL/AS, whereas soil pH was negatively correlated with AL/AS. Tree density accounted for 7% of the variation in AL/AS. All biotic and abiotic predictors collectively explained up to 45% of the variation in AL/AS. Additionally, AL/AS was positively correlated to the net primary productivity (NPP) of the ecosystem. Our study provides insights into the driving factors of AL/AS at the global scale and highlights the importance of AL/AS in ecosystem productivity. Given that Pgs is the most critical driver of AL/AS, alterations in global precipitation belts, particularly seasonal precipitation, may induce changes in plant leaf area on the branches.

Networking the desert plant microbiome, bacterial and fungal symbionts structure and assortativity in co-occurrence networks

In nature, microbes do not thrive in seclusion but are involved in complex interactions within- and between-microbial kingdoms. Among these, symbiotic associations with mycorrhizal fungi and nitrogen-fixing bacteria are namely known to improve plant health, while providing resources to benefit other microbial members. Yet, it is not clear how these microbial symbionts interact with each other or how they impact the microbiota network architecture. We used an extensive co-occurrence network analysis, including rhizosphere and roots samples from six plant species in a natural desert in AlUla region (Kingdom of Saudi Arabia) and described how these symbionts were structured within the plant microbiota network. We found that the plant species was a significant driver of its microbiota composition and also of the specificity of its interactions in networks at the microbial taxa level. Despite this specificity, a motif was conserved across all networks, i.e., mycorrhizal fungi highly covaried with other mycorrhizal fungi, especially in plant roots—this pattern is known as assortativity. This structural property might reflect their ecological niche preference or their ability to opportunistically colonize roots of plant species considered non symbiotic e.g., H. salicornicum, an Amaranthaceae. Furthermore, these results are consistent with previous findings regarding the architecture of the gut microbiome network, where a high level of assortativity at the level of bacterial and fungal orders was also identified, suggesting the existence of general rules of microbiome assembly. Otherwise, the bacterial symbionts Rhizobiales and Frankiales covaried with other bacterial and fungal members, and were highly structural to the intra- and inter-kingdom networks. Our extensive co-occurrence network analysis of plant microbiota and study of symbiont assortativity, provided further evidence on the importance of bacterial and fungal symbionts in structuring the global plant microbiota network.

Fractions of soil phosphorus mediated by rhizospheric phoD‐harbouring bacteria of deep‐rooted desert species are determined by fine‐root traits

Abstract Soil phosphorus (P) availability is a crucial factor determining primary productivity in terrestrial ecosystem. Plant functional traits and microbes under P‐deficient conditions can respond positively to increase soil P bioavailability. Whether and/or how the fine‐root traits (FRTs) of deep‐rooted desert species affect the rhizosphere and bulk soil community of phoD‐harbouring bacteria and thus improve the availability of soil P, however, remains unclear. We conducted a three‐year artificial outdoor pot experiment of P supply using Alhagi sparsifolia Shap. (hereafter Alhagi) to address this gap. Fine‐root samples from 1‐ and 3‐year‐old Alhagi seedlings and samples of the rhizospheres and bulk soil were collected. High‐throughput sequencing, sequential extraction and root system scanning were used to determine soil phoD‐harbouring bacteria community, Hedley‐P fractions and the FRTs. Fine‐root surface area (RSA), specific root length, foliar Mn concentration (indicating the quantities of root carboxylates that are released) and acid phosphatase (APase) activity were significantly higher in the no‐P supply compared with the high‐P supply conditions. APase activity was significantly higher by 27%, but the foliar Mn concentration was remarkably lower by 26%, in the 3‐ than the 1‐year‐old seedlings. The rhizospheric concentrations of labile P, moderately labile P, inorganic P and organic P in the no‐P supply condition were 5%, 11%, 10% and 21% higher, respectively, in the 3‐ than the 1‐year‐old seedlings. RSA and the foliar Mn concentration were dominated root predictors for the rhizospheric phoD‐harbouring bacteria community for the 1‐year‐old seedlings, whereas fine‐root P concentration was the dominated root predictor for the rhizospheric and bulk soil phoD‐harbouring bacteria communities for the 3‐year‐old seedlings. Soil water content, as the most dominant soil factor driving the variation of phoD‐harbouring bacteria community, notably could not be ignored. FRTs were the main factors that directly and positively determined rhizospheric phoD‐harbouring bacteria community and thus influenced soil P availability, but bulk soil phoD‐harbouring bacteria community were dominated by inorganic P concentration. The importance of fine‐root morphological traits to soil P availability gradually increased as the plants grew. Overall, our results emphasize the significance of rhizospheric phoD‐harbouring bacteria determined by the effect of FRTs on the bioavailability of soil P. Read the free Plain Language Summary for this article on the Journal blog.

Drying and rewetting affect the chemical speciation and bioavailability of soil phosphorus in a hyper-arid desert ecosystem

Climate change is expected to alter the frequency and intensity of drying and rewetting cycles, impacting water availability and consequently soil nutrient availability. However, the effects of these fluctuations on the chemical speciation and bioavailability of phosphorus (P) in soil with or without desert species remain uncertain. We conducted a pot experiment involving bare soil and two desert species (Alhagi sparsifolia and Calligonum mongolicum) to determine the short-term impacts of drought (no water supply), drying-rewetting-1 (D-RW1, high frequency of low water amounts), and drying-rewetting-2 (D-RW2, low frequency of high-water amounts) treatments on soil Hedley-P pools, plant P concentration and biomass accumulation. Results demonstrated that the presence of plants significantly increased soil labile-P and organic P (Po) concentrations by 60–150% and 1–68%, respectively, compared to bare soil. Both D-RW1 and D-RW2 treatments significantly increased soil dissolved organic carbon concentration by 2–35% relative to the drought treatment. Moreover, soil resin-P and NaHCO3-Pi concentrations under Alhagi sparsifolia in D-RW1 treatment significantly increased by 31% and 75%, respectively, when compared to the drought treatment, with NaHCO3-Po and NaOH-Po concentrations under D-RW2 treatment rising by 14% and 32%, respectively. Furthermore, D-RW2 treatment significantly increased leaf P concentration and biomass compared to D-RW1 and drought treatments. Overall, compared to drought treatment, frequent low-intensity drying-rewetting cycles enhanced soil Pi turnover, whereas infrequent high-intensity drying-rewetting cycles increased Po turnover and P bioavailability. These findings will inform better water management strategies for desertification restoration in hyper-arid desert ecosystems.

Climate change will lead to range shifts and genetic diversity losses of dung beetles in the Gobi Desert and Mongolian Steppe

Desertification is known to be a major threat to biodiversity, yet our understanding of the consequent decline in biodiversity remains insufficient. Here, we predicted climate change-induced range shifts and genetic diversity losses in three model dung beetles: Colobopterus erraticus, Cheironitis eumenes, and Gymnopleurus mopsus, distributed across the Gobi Desert and Mongolian Steppe, areas known for desertification. Phylogeographic analyses of mitochondrial COI sequences and species distribution modeling, based on extensive field investigations spanning 14 years, were performed. Species confined to a single biome were predicted to contract and shift their distribution in response to climate change, whereas widespread species was predicted to expand even if affected by range shifts. We indicated that all species are expected to experience significant haplotype losses, yet the presence of high singleton frequencies and low genetic divergence across geographic configurations and lineages mitigate loss of genetic diversity. Notably, Cheironitis eumenes, a desert species with low genetic diversity, appears to be the most vulnerable to climate change due to the extensive degradation in the Gobi Desert. This is the first study to predict the response of insects to desertification in the Gobi Desert. Our findings highlight that dung beetles in the Gobi Desert and Mongolian Steppe might experience high rates of occupancy turnover and genetic loss, which could reshuffle the species composition.

Interrelationships and Environmental Influences of Photosynthetic Capacity and Hydraulic Conductivity in Desert Species Populus pruinosa

An improved understanding of the mechanisms underlying plant adaptation to habitat heterogeneity can be achieved by clarifying the climate-driving factors of the hydraulic and photosynthetic traits of different populations. With a focus on Populus pruinosa Schrenk, which is the predominant tree species in the desert riparian forests of the Tarim Basin, Xinjiang, this study investigated the hydraulic and photosynthetic trait relationships and their interactions with environmental factors in 11 P. pruinosa populations using a Pearson correlation analysis, plant trait networks, a redundancy analysis, and a least squares linear regression analysis. The results showed that the degree of variation in the hydraulic traits was higher than that in the photosynthetic traits. The net photosynthetic rate (Pn) showed a significantly positive correlation with leaf-specific conductivity (Kl) and the Huber value (Hv). The Hv exhibited a significantly positive correlation with the water-use efficiency and Kl, and the branch–leaf mass ratio significantly affected the hydraulic traits. The groundwater depth (GD) in natural P. pruinosa forest habitats ranged from 3.4 to 7.9 m. With an increase in the annual average temperature, the hydraulic conductivity of the xylem significantly increased; with an increase in GD, Pn and Kl significantly decreased. The temperature annual range, temperature seasonality (standard deviation), min temperature of the coldest month, and GD were significantly correlated with the diameter and average path length of the overall trait network parameters, and these environmental factors affected the coordination of the functional traits of P. pruinosa.

Population regeneration of two Haloxylon species in central Asian deserts as affected by groundwater depth

Haloxylon ammodendron and Haloxylon persicum are the dominant species in the deserts of Central Asia. As groundwater exploration has resulted in a decline in groundwater depth in this region, the impact on the regeneration of these two Haloxylon populations calls for urgent attention. Therefore, we conducted an intensive vegetation survey, including population density, age structure and seed production and seed characteristics, along a groundwater depth gradient in the Gurbantunggut Desert of Central Asia. The result shows that for H. ammodendron, groundwater depth of 15 m is its survival and regeneration limit, beyond which this species cannot grow. However, for H. persicum, this limit does not apply. Instead, declined groundwater depth promotes a reproduction strategy with low seed quantity, high quality, and a high germination rate for H. ammodendron. Ultimately, H. ammodendron exhibits a tighter regeneration trait coordination, with a reasonable age structure being crucial for its population continuation and environmental adaptation. In contrast, H. persicum demonstrates higher resource acquisition and reproductive ability, along with tolerance to groundwater depth decline. In conclusion, if the groundwater depth decline continues, the continuation of H. ammodendron will be seriously threatened but H. persicum will not be. This study is beneficial for evaluating the future trend of vegetation cover in desert region and planning water resources management in Central Asia.

Dominance structure and constancy of spiders in the Indian Thar desert

BackgroundThe knowledge about the species of a habitat (both resident and transient/dominant and rare) is a vital step to plan the conservation measures. Being generalist predators, spiders help controlling the population of their prey and maintain ecosystem stability. This makes spiders excellent bio-indicators for assessing the impact of anthropogenic disturbance factors on natural ecosystems (De, Siliwal, Uniyal and Hussain in Trop. Ecol. 63: 1–7, 2021). The aim of this study was to assess the dominance structure and constancy of spiders in three different habitats (Sand dunes, Riparian and Rocky) of the Thar desert. Study was conducted from March 2017 to February 2019 covering all seasons.ResultsThe eudominant species in sand dunes and rocky desert belonged to the family Thomisidae. These species were Tmarus sp. 1 and Tmarus kotigeharus Tikader, 1963, respectively. There were two eudominants in Riparian habitat (Oecobius putus O. Pickard-Cambridge, 1876 and Menemerus bivittatus (Dufour, 1831)). Through the analysis of constancy of all the species in the Thar desert, it was revealed that three species were constant in all the three habitats. The number of accessory and accidental species was far higher than constant species in all the habitats.ConclusionsThe number of accessory and accidental spider species in all habitats was far higher than constants due to the unstability of spider population. Therefore, this study highlights the necessity for conservation of these habitats of the Thar desert.

Patterns and driving factors of functional traits of desert species with different elevational distributions in the Tibetan Plateau and adjacent areas

Variations in functional traits serve as measures of plants’ ability to adapt to environment. Exploring the patterns of functional traits of desert plants along elevational gradients is helpful to understand the responses and adaptation strategies of species to changing environments. However, it is unknown whether the relationship between functional traits and elevation is affected by differences in the species’ elevational distributions (elevation preference and species’ range). Importantly, most researches have concerned with differences in mean trait values and ignored intraspecific trait variation. Here, we measured functional traits of desert plants along a wide elevational gradient in the Tibetan Plateau and adjacent areas and explored functional trait patterns over elevation in species with different elevational distributions. We decomposed trait variation and further investigated characterizations of intraspecific variation. Ultimately, the main drivers of trait variation were identified using redundancy analysis. We found that species’ elevational distributions significantly influenced the relationship of functional traits such as plant height, leaf dry matter content, leaf thickness, leaf nitrogen and carbon content with elevation. Species with a lower elevational preference showed greater trait variation than species with a higher elevational preference, suggesting that species that prefer high elevation are more conservative facing environmental changes. We provide evidence that interspecific trait variation in leaf thickness and leaf carbon content decreased with increasing species’ range, indicating that increased variations in resistance traits within species make greater responsiveness to environmental changes, enabling species a wider range. Elevation, temperature and precipitation were the main drivers of trait variation in species with a low elevational preference, while the effect of precipitation on trait variation in species with a high elevational preference was not significant. This study sheds new insights on how plants with different elevational distributions regulate their ecological strategies to cope with changing environments.

First report of Fusarium verticillioides causing blight on Ammopiptanthus mongolicus in China.

Ammopiptanthus mongolicus is the only evergreen broadleaf shrub and constructive species in the northwest desert of China (Hu et al. 2021). It also is listed as one of the national second-class endangered plants. Ammopiptanthus mongolicus has a good effect of water conservation, windbreak and sand fixation because its deep root system (Zhou et al. 2012; Dong et al. 2023). A large number of dead plants of Ammopiptanthus mongolicus were found in Etuoke county, Inner Mongolia Autonomous Region, China (40°4'28″-40°4'34″ N, 106°53'5″-106°53'31″ E). In September 2023, the investigation and research in the region found that the incidence of diseased plants in this field was about 30%, and for individual plant, the incidence of diseased branches was about 60%. The leaves of diseased branches initially became from green to yellow and then wilt and fall. Eventually the plant dies. (Figure 1). The miter cut of the root showed that the root steles of diseased plants had obvious black and brown color (Figure 2). For isolation, the 30 tissue blocks (10×10 mm) of from 10 symptomatic roots diseased were surface sterilized with 70% ethanol for 3 minutes and sodium hypochlorite (2.5% available chlorine) for 5 minutes, and rinsed three times with sterilized distilled water. Then, these tissue blocks were placed on potato dextrose agar (PDA) medium, and incubated from 3 to 5 days at 25°C. After 3 days on PDA, the surface of the colony was rough, the color were white-pink at the beginning, and deep purple pigment were produced in the later stage, making the colony bluish-purple to gray-purple, their undersides were bluish-purple. Mycelia were white. After 7 days on SNA, Microconidia were typical of the clavicular type, 8.5 ± 2.5 μm × 2.3 ± 0.2 μm(×400). Microconidia were usually very long conidial chains, sometimes the spore chain collapses and the conidia clump together to form an approximate pseudocephaly. The macroconidia were slender and long, slightly falcate or straight, 42.8 ± 3.4 μm × 3.8 ± 0.7 μm(×400) (Figure 4). Species identity was confirmed by sequencing the EF1-α gene (EF1 and EF2 primers)(O'Donnell et al. 1998), RPB1 (F5 and G2R primers)(O'Donnell et al. 2022) and RPB2 (5F2 and 11AR)(O'Donnell et al. 2022). The amplified sequences of a representative isolate (AmP10) have deposited in GenBank with accession number OR594338 (EF1-α), OR841329 (RPB1) and OR841331 (RPB2). Thee results of pairwise alignment in Fusarioid-ID datebase(Crous et al. 2021) showed that EF1-α sequence was 99.54% similarity and 89.96% overlap to the corresponding sequence KF499582 of ex-epitype CBS 218.76 of Fusarium verticillioides, Fusarium fujikuroi species complex (FFSC, previously GFSC) (Lecellier et al. 2014), RPB1 sequence was 100% similarity and 100% overlap to the corresponding sequence MW402638 of ex-epitype CBS 218.76 of Fusarium verticillioides, Fusarium fujikuroi species complex (FFSC, previously GFSC) (Yilmaz et al. 2021), RPB2 sequence was 99.94% similarity and 87.83% overlap to the corresponding sequence MW928835 of ex-epitype CBS 218.76 of Fusarium verticillioides, Fusarium fujikuroi species complex (FFSC, previously GFSC) (Crous et al. 2021). Moreover, the result of polyphasic identification in Fusarioid-ID datebase also showed EF1-α, RPB1 and RPB2 sequences were 100% similarity to the corresponding sequences of ex-epitype CBS 218.76 of Fusarium verticillioides, Fusarium fujikuroi species complex (FFSC, previously GFSC). To test the pathogenicity, the healthy green seedlings (64 days old) were planted into plastic pots containing sterilized soil in the greenhouse after the seeds of Ammopiptanthus mongolicus were surface sterilized with 70% ethanol for 3 minutes and 2.5% sodium hypochlorite for 3 minutes. The roots of 3 seedlings were inoculated with 1×106 /ml of the conidial suspension, and another 3 used as controls with inoculated sterile water. Then, all pots were placed in a greenhouse maintained at 18°C to 25°C. After incubation for 3-5 days, the typical symptoms similar to the symptoms in the field (Figure 5), brown root steles (Figure 6), developed on the plants inoculated with conidial suspension, whereas no symptoms were observed on the control plants. The same pathogen was consistently reisolated from the inoculated roots and confirmed as Fusarium verticillioides based on morphological and molecular analyses. To our knowledge, this is the first report of Fusarium verticillioides on Ammopiptanthus mongolicus in China. This study provides a basis for identifying pathogens causing blight on Ammopiptanthus mongolicus and managing the disease.

The effect of litter decomposition mostly depends on seasonal variation of ultraviolet radiation rather than species in a hyper-arid desert

Introduction: Ultraviolet (UV) radiation is believed to play a significant role in accelerating litter decomposition in water-limited ecosystems. Litter traits also influence the decomposition. However, the dominance of litter traits and ultraviolet radiation on litter decomposition in hyper-arid deserts (annual precipitation: potential evaporation < 0.05) with diverse species and seasonal variations remain unclear.Methods: To address this knowledge gap, we examined the decomposition of three dominant litter species (Karelinia caspia, Alhagi sparsifolia, and Populus euphratica) in the southern edge of the Taklimakan Desert, Northwest China.Results: Our results revealed that under UV radiation conditions, K. caspia, A. sparsifolia, and P. euphratica experienced mass losses of 45.4%, 39.8%, and 34.9%, respectively, and 20%, 22.2% and 17.4%, respectively under UV filtering treatment. Specifically, the loss rate of carbon and lignin under UV radiation, was 2.5 and 2.2 times higher than under UV filtering treatment, respectively.Conclusion: UV radiation did not dominate decomposition throughout the year in our study area, and the loss rate of litter traits was significantly higher in summer than in winter under UV radiation. Moreover, this photodegradation is related to the intensity of UV exposure, but not to precipitation or temperature. Surprisingly, species type had no significant effect on litter decomposition. However, when we applied a UV filtering treatment, we observed higher loss rates of nitrogen compared with the ambient treatment, suggesting the involvement of other spectra in the litter decomposition process. Overall, our findings elucidate that UV radiation is a crucial factor that affects litter mass loss. The magnitude of this effect mostly varies with the season rather than the species of litter.

‘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.

Ecological significance of marcescence in Himalayan plants: Why is standing dead phytomass more important in demanding, resource‐limited environments?

Abstract Understanding mechanisms allowing plants to thrive in challenging conditions is critical for predicting their responses to global environmental change. An often overlooked ecological adaptation is marcescence, where leaves and stems are retained beyond their typical shedding time, with implications for nutrient recycling and carbon sequestration. Marcescence can be expected in plants with conservative resource‐use strategies, especially in environments with limited resources and marked seasonality, such as deserts and alpine regions. However, the extent to which marcescence occurs in different taxa across different habitats and its relationship to seasonality and plant functioning as reflected in ecophysiological traits remains understudied. We studied 600 individuals across 40 Himalayan herb species found in desert, steppe, alpine and subnival habitats, spanning 3000–5400 m elevation. Marcescence was observed in 37 of the 40 species evaluated, with 57% of the sampled individuals displaying dead phytomass, indicating the widespread nature of this phenomenon in Himalayan ecosystems. Environment and plant traits emerged as significant factors influencing the amount of dead‐standing biomass. These findings remained robust after accounting for intraspecific variation and phylogenetic inertia. Desert and steppe species exhibited greater marcescent biomass, characterized by 10‐fold more dead stem biomass than alpine and subnival plants. In contrast, the proportion of dead phytomass increased with elevation due to increased dead leaf fraction. Taller desert species with heavily lignified stems and limited nitrogen and phosphorus content had high levels of stem marcescence, which not only may aid litter photodegradation and nutrient recycling but also deter herbivory and promote seed dispersal (tumbleweed). Conversely, slow‐growing alpine and subnival plants with higher water‐use efficiency, foliar C:N ratios and parenchymatic storage tissue rich in mobile carbohydrates had a high proportion of marcescent leaves, which may aid survival in these resource‐limited environments by providing delayed nutrients through moisture‐conserving mulch that also provides insulation and protection from frost. This study provides new insights into the complex interplay of habitat, seasonality and plant traits in dead phytomass retention in Himalayan plants. Marcescence is prevalent in resource‐conservative species in highly seasonal, resource‐limited habitats and may significantly shape the functioning and biodiversity of Himalayan ecosystems. Read the free Plain Language Summary for this article on the Journal blog.

A systematic review on the morphology structure, propagation characteristics, resistance physiology and exploitation and utilization of Nitraria tangutorum Bobrov.

Nitraria tangutorum Bobrov., belonging to the family Nitrariaceae, is a drought-tolerant and salt-loving plant and has drawn attention for its good economic and ecological value. As one of the main group species and dominant species in China's desert and semi-desert regions, N. tangutorum possesses superior tolerance to drought, high temperature, cold, barren, high salinity and alkalinity and wind and sand. Its root system is well developed, with many branches and a strong germination capacity. Once buried in sandy soil, N. tangutorum can quickly produce a large number of adventitious roots, forming new plants and continuously expanding the shrubs, forming fixed and semi-fixed shrub sand dunes. Sand dune shrubs can trap and fix a large amounts of quicksand, prevent desert expansion and erosion, and play an important role in maintaining regional ecosystem balance and improving ecological environmental quality. In addition, the phytochemical screening studies report that N. tangutorum contains an abundance of various compounds including flavonoids, alkaloids, phenolic acids and polysaccharides. These compounds confer a range of beneficial bioactivities such as antioxidant, anti-inflammatory, anti-tumor, anti-fatigue, liver protection, neuroprotection, cardiovascular protection, lowering blood lipid, regulating blood sugar level and immunoregulation. The fruits of N.tangutorum also contain vitamin C, amino acids, minerals and microelements. It has been traditionally used as a nutritional food source and in folk medicine to treat diseases of the spleen and stomach, abnormal menstruation, indigestion, and hyperlipidemia. N. tangutorum, as a wild plant with medicinal and edible homology, possesses remarkable economic and medicinal values. This detailed, comprehensive review gathers and presents all the information related to the morphological structure, propagation characteristics, resistance physiology and exploitation and utilization of N.tangutorum, providing a theoretical basis for the researchers to conduct future in-depth research on N.tangutorum.

Stoichiometric patterns of assimilative branches of four dominant shrubs and the drivers in a Central Asian desert

Shrubs with assimilative branches (ABs) are unique, drought-resistant, and constructive species in temperate deserts in Central Asia. Understanding the nutrient traits and drivers of ABs are crucial to predict the response and adaptation of desert shrubs to environmental changes. Four dominant shrub species with ABs (i.e., Ephedra przewalskii, Calligonum mongolicum, Haloxylon ammodendron, and Haloxylon persicum) widely distributed in the Junggar Desert in northwestern China were selected as the research objects, and then the intra- and interspecific differences in C, N, and P stoichiometric traits, variation patterns and the drivers were comparatively explored. The ABs had lower C, N, P, and N:P, but higher C:N and C:P than leaves of most terrestrial plants worldwide. The variability of C and N:P in ABs was relatively low, whereas N, P, C:N, and C:P showed great variation. According to the theory of stoichiometric ratio, E. przewalskii and C. mongolicum were most likely limited by N, whereas H. ammodendron and H. persicum were co-limited by N and P. A common N–P scaling exponent (1.171) among the four shrubs was determined, revealing that all the four shrubs faced strong environmental stress. The intra- and interspecific stoichiometric traits exhibited different longitudinal and latitudinal patterns, and their relationships with climatic and soil factors also differed. Soil properties presented the greatest influence on E. przewalskii, whereas C. mongolicum were mainly affected by the interaction of soil properties and climate. The influencing factors on different stoichiometric traits of two saxaul species were diverse and inconsistent, and climatic, soil, and geographic factors played different roles. Consequently, during the long-term adaptation to the desert environment, the shrubs with ABs have formed unique, differentiated but partly convergent stoichiometric patterns. The results are greatly significant for deep understanding of the survival strategy of desert shrubs. In the future, researches on the anatomical structure, physiological traits, trait association of assimilative branches, and the responses to changing environment should be strengthened to comprehensively reveal the adaptation strategies of these desert shrubs.

Unprecedented distribution data for Joshua trees (Yucca brevifolia and Y. jaegeriana) reveal contemporary climate associations of a Mojave Desert icon

IntroductionForecasting range shifts in response to climate change requires accurate species distribution models (SDMs), particularly at the margins of species' ranges. However, most studies producing SDMs rely on sparse species occurrence datasets from herbarium records and public databases, along with random pseudoabsences. While environmental covariates used to fit SDMS are increasingly precise due to satellite data, the availability of species occurrence records is still a large source of bias in model predictions. We developed distribution models for hybridizing sister species of western and eastern Joshua trees (Yucca brevifolia and Y. jaegeriana, respectively), iconic Mojave Desert species that are threatened by climate change and habitat loss.MethodsWe conducted an intensive visual grid search of online satellite imagery for 672,043 0.25 km2 grid cells to identify the two species' presences and absences on the landscape with exceptional resolution, and field validated 29,050 cells in 15,001 km of driving. We used the resulting presence/absence data to train SDMs for each Joshua tree species, revealing the contemporary environmental gradients (during the past 40 years) with greatest influence on the current distribution of adult trees.ResultsWhile the environments occupied by Y. brevifolia and Y. jaegeriana were similar in total aridity, they differed with respect to seasonal precipitation and temperature ranges, suggesting the two species may have differing responses to climate change. Moreover, the species showed differing potential to occupy each other's geographic ranges: modeled potential habitat for Y. jaegeriana extends throughout the range of Y. brevifolia, while potential habitat for Y. brevifolia is not well represented within the range of Y. jaegeriana.DiscussionBy reproducing the current range of the Joshua trees with high fidelity, our dataset can serve as a baseline for future research, monitoring, and management of this species, including an increased understanding of dynamics at the trailing and leading margins of the species' ranges and potential for climate refugia.