Desert Species Research Articles

Effects of Salt Stress on Growth, Proline and Mineral Content in Native Desert Species

Implementing large-scale restoration programs requires in-depth understanding about the salinity tolerance of native species, especially in the Arabian Peninsula where salinity is one of the most serious problems. Seedlings of four native species, namely Vachillea pachyceras, Haloxylon salicornicum, Rhanterium epapposum, and Farsetia aegyptia, were subjected to different salinity treatments (1.6 (control), 3, 5, 7, and 10 dS/m). Survival, growth performance, biomass and proline accumulation were assessed after six months of salinity exposure. Different mineral concentrations in the shoot and root tissues were assessed before and after the salinity exposure. Our results showed that salinity influenced the growth parameters, enhanced proline accumulation and changed the contents of essential elements. However, the effects of salinity stress on the growth and other parameters were largely species-specific. Proline accumulation increased with an increase in the salinity level in all the species. However, the mineral content in the root and shoot tissues showed variation, depending on the species and the level of salinity stress. Overall. H. salicornicum appeared to be the most tolerant species, as its seedling survival (100% at EC 10), and root and shoot biomass were impacted minimally; meanwhile, F. aegyptia (16.7% seedling survival at EC 10) appeared to be highly sensitive to the salinity. Data generated from this study will be helpful in screening the suitable species according to their salinity tolerance in salt-affected areas.

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Ecological ApplicationsVolume 33, Issue 3 e2659 COVER IMAGEFree Access Cover Image First published: 03 April 2023 https://doi.org/10.1002/eap.2659AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Graphical Abstract COVER PHOTO: Pictured is a Cape hare (Lepus capensis) photographed in 2018 in Wadi Tznifim within the Nehalim Gdolim Nature Reserve, situated in the southern Negev Desert and Arava mountains of Israel. The Cape hare is native to the region. In their study published in this issue, Lewin et al. (Article e2804; doi:10.1002/eap.2804) show that nearby intensive agroecosystems have impacted these and other native desert species, as well as invasives, through added agricultural resources mediated by trophic cascades. Photo credit: Doron Nissim. Volume33, Issue3April 2023e2659 RelatedInformation

Wood trait trade‐offs in desert plants: A triangular model to understand intra‐ and interspecific variations along an aridity gradient

AbstractThe hydraulic architecture of woody plants may show intra‐ and interspecific variations along aridity gradients as a result of wood trait trade‐offs, which depend on species‐specific abilities to withstand or evade drought. Plant hydraulic architecture can be defined as the set of different cell types involved in water transport through the soil–plant‐atmosphere continuum. At the present time, there are two models designed to understand trade‐offs among xylem wood functional traits, developed by Baas and Pratt, respectively. The first model presents a triangular trade‐off space where three main plant xylem functions are linked to each other to provide resistance to embolism in evolutionary time. The second model depicts xylem cell types associated with their main functions, namely vessel‐transport, parenchyma‐storage and fibre‐support. We propose here a new model considering the same relative xylem cell trait abundance for three desert species with different drought tolerance strategies along an aridity gradient of more than 300 mm. Hence, our model may account for both intra‐ and interspecific variations in wood traits for species from different localities along an aridity gradient. The tree Neltuma flexuosa showed little intraspecific variation in the medium drought resistance portion of the trade‐off space, suggesting this species is independent from rainfall. Larrea divaricata showed a similar low intraspecific variation, but the spatial location in the trade‐off space suggests it has a high tolerance to drought. The third species, Bulnesia retama, showed a higher intraspecific variation within the trade‐off space, changing its hydraulic architecture in more fibre area with increasing aridity. Our model seems to be a generalized tool to assess both intra‐ and interspecific variations in trade‐offs for hydraulic architecture among woody plants as a response to drought.

Long-term seed bank persistence in a stochastic desert environment.

Seed banks, the collection of viable seeds in the soil, are particularly important determinants of population survival in highly variable environments. Predictions of increased stochasticity in the amount and timing of precipitation in desert environments raise the question of how seed banks of desert species will respond to climate change, and ultimately, whether these species will persist. Here, we present data from our long-term studies of germination requirements and seed bank dynamics in a rare desert gypsophile perennial, Arctomecon californica (Las Vegas bearpoppy). Arctomecon californica is a relatively short-lived plant that recruits from seed in sequences of unusually favorable years. We used germination experiments, an in situ seed bank study, and a 15-year field seed retrieval study to examine factors affecting seed bank persistence. In the germination study, a majority of seeds remained dormant, despite a wide variety of treatments, suggesting that a large proportion of the seed dispersed each year has cue-nonresponsive dormancy. Our in situ seed bank study showed that seed density varied widely between sites, among transects, and among samples within a transect. The patchiness of seeds in the soil highlights the importance of protecting large areas where A. californica populations are known to have existed in the past. The seed retrieval study provided strong evidence that this species has a long-lived seed bank in which only a small fraction of seeds (roughly 5%) become nondormant each year, allowing seed banks of this species to last up to 20 years without a seed production event. Whether this impressive life-history strategy can maintain the species in the face of climate change depends on the future frequency of the well-timed precipitation that allows for the establishment of new cohorts of adult plants.

Threats affecting the distribution of Lygeum spartum Loefl. ex L. and its associated species in the Western Mediterranean desert of Egypt: Perspectives of conservation

The current study intends to evaluate the many hazards affecting the spread of the significant fodder grass Lygeum spartum Loefl. ex. L. and its associated species in Egypt's Western Mediterranean Desert over the past 60 years (from 1958 to 2020); depending on the data of the previous literature and the current situation evaluation by recent field trips. It also aims to assess its ecosystem services. Sixty-nine stands were collected from previous studies and unpublished data, in addition to 30 stands (10 m2) were added including 5 field trips during the period from spring 2019 to spring 2020. Measurements were taken to create a classification of this vegetation and to determine the main threats that affect its distribution composition. There are 142 species associated with the distribution of the studied plant in 6 habitats. While only 107 species were recorded in the recent stands in 7 habitats. Vegetation groups (G1- G8) obtained from TWINSPAN classification indicating that G1 (wadis) is the most diverse group with a species richness 34.7 species per stand, while G6 (dune) has the highest species turnover (4.57) during the period of 1958 to 2014. But in recent stands; G5 (saline and non-saline depression) is the most diverse group (30.875), while G2 (dunes) has the highest species turnover (4.819). Medicinal plants are the most represented (79.86%), followed by grazing plants (72.9%). The most common service is sand stabilization (92% of total services), followed by windbreak (natural) (40%). Threatened species represent 92.4%; habitat loss is the most affected threat (95 species), followed by over-collecting and over-cutting (82 species). Twenty out of 99 stands (20.2% of the total stands) have been destroyed due to human activity. Continuous monitoring of remaining patches of Egypt’s northwestern Mediterranean coast was required to save its natural flora from extinction.

Vein network redundancy and mechanical resistance mitigate gas exchange losses under simulated herbivory in desert plants.

Herbivory can impact gas exchange, but the causes of interspecific variation in response remain poorly understood. We aimed to determine (1) what effects does experimental herbivory damage to leaf midveins have on leaf gas exchange and, (2) whether changes in leaf gas exchange after damage was predicted by leaf mechanical or venation traits. We hypothesized that herbivory-driven impacts on leaf gas exchange would be mediated by (1a/1b) venation networks, either by more vein resistance, or possibly trading off with other structural defenses; (2a/2b) or more reticulation (resilience, providing more alternate flow pathways after damage) or less reticulation (sectoriality, preventing spread of reduced functionality after damage). We simulated herbivory by damaging the midveins of four leaves from each of nine Sonoran Desert species. We then measured the percent change in photosynthesis (ΔAn%), transpiration (ΔEt%) and stomatal conductance (Δgsw%) between treated and control leaves. We assessed the relationship of each with leaf venation traits and other mechanical traits. ΔAn% varied between +10 % and -55%, similar to ΔEt% (+27%, -54%) and Δgsw% (+36%, -53%). There was no tradeoff between venation and other structural defenses. Increased damage resilience (reduced ΔAn%, ΔEt%, Δgsw%) was marginally associated with lower force-to-tear (P < 0.05), and higher minor vein density (P < 0.10) but not major vein density or reticulation. Leaf venation networks may thus partially mitigate the response of gas exchange to herbivory and other types of vein damage through either resistance or resilience.

Patterns of carbon, nitrogen, and phosphorus stoichiometry of three life-form desert plants and responses to soil and microbial biomass factors in a hyper-arid desert ecosystem.

Plant, soil, and microbial biomass ratios of carbon (C), nitrogen (N), and phosphorus (P) are crucial in maintaining stability of desert ecosystems. Nevertheless, variation in relations of elemental ratios between different life forms of plants and soil and microbial biomass in desert ecosystems remains unclear. In a hyper-arid desert ecosystem, C, N, and P concentrations and ratios were analyzed in the plant-soil-microbial biomass system of three perennial desert species (Alhagi sparsifolia Shap. [Herb, Fabaceae], Karelinia caspica Pall. [Herb, non-Fabaceae], and Tamarix ramosissima Ledeb. [Shrub]). Concentrations of N and P in Alhagi sparsifolia leaf, stem, and root were significantly greater than those in Karelinia caspica and Tamarix ramosissima, whereas plant C and soil organic C (SOC) were highest with Tamarix ramosissima. Alhagi sparsifolia and Tamarix ramosissima were P-limited, whereas Karelinia caspica was N-limited. According to correlation analysis, SOC rather than soil total P (STP) regulated plant N:P ratios, and microbial biomass C, N, and P rather than SOC, soil total N, and STP regulated plant C:N:P ratios. Soil water content also affected plant nutrient balance. Thus, in a hyper-arid desert ecosystem, the plant-soil-microbial biomass system and the balance of C, N, and P are closely related, and the role of soil microbial biomass in affecting plant nutrient balance should receive increased attention.

Similar adaptative mechanism but divergent demographic history of four sympatric desert rodents in Eurasian inland

Phenotypes associated with metabolism and water retention are thought to be key to the adaptation of desert species. However, knowledge on the genetic changes and selective regimes on the similar and divergent ways to desert adaptation in sympatric and phylogenetically close desert organisms remains limited. Here, we generate a chromosome level genome assembly for Northern three-toed jerboa (Dipus sagitta) and three other high-quality genome assemblies for Siberian jerboa (Orientallactaga sibirica), Midday jird (Meriones meridianus), and Desert hamster (Phodopus roborovskii). Genomic analyses unveil that desert adaptation of the four species mainly result from similar metabolic pathways, such as arachidonic acid metabolism, thermogenesis, oxidative phosphorylation, insulin related pathway, DNA repair and protein synthesis and degradation. However, the specific evolved genes in the same adaptative molecular pathway often differ in the four species. We also reveal similar niche selection but different demographic histories and sensitivity to climate changes, which may be related to the diversified genomic adaptative features. In addition, our study suggests that nocturnal rodents have evolved some specific adaptative mechanism to desert environments compared to large desert animals. Our genomic resources will provide an important foundation for further research on desert genetic adaptations.

Influence of grazing on the activity pattern and temporal niche of two dominant rodent species in Alxa desert

Grazing by large herbivores can potentially affect interspecific interactions between small herbivores by reducing the ecological fitness of animals. Desert rodents are important components in desert ecosystems and indicators of environmental change. Grazing reduces food resources, but rodents can decrease interspecific niche overlap by adaptive behavior. However, the key factors driving rodent behavioral activities and coexistence in the Alxa desert remains unstudied. We monitored population density and behavioral activities of Midday gerbil (Meriones meridianus) and northern three-toed jerboa (Dipus sagitta) in a grazing exclusion experiment in Alxa desert, Inner Mongolia, China, in 2017. We assessed the relationship between environmental factors (such as plant height, density, coverage, rainfall and temperature) and the behavioral activities of two coexisting rodent species. The results showed that: (1) In summer, grazing significantly reduced the activity time of gerbil and jerboa compared to that in grazing exclusion areas (gerbil: F = 5.98, p &amp;lt; 0.05, η2 = 0.22; jerboa: F = 8.57, p &amp;lt; 0.01, η2 = 0.28). Grazing reduced the temporal niche overlap with an obvious shifting of activity peaks between two species. (2) Grazing exclusion enhanced the temporal niche overlap between the two rodent species due to greater food availability which relieved inter-specific competition in each season. (3) Grazing strengthened the sensitivity of rodents to environmental changes in all seasons. These results indicated that grazing affected competition between the rodent species by altering vegetation conditions, which in turn affected the temporal niche and activity patterns of rodents.

Micromorphological Characterization of Seeds of Dicot Angiosperms from the Thal Desert (Pakistan)

Micromorphological and ultrastructural data have been helpful in determining the evolution, classification, ecology, and phylogeny of seed plants. Taxonomic utility of seed characters has been explored, although the value of micro-structure in selected dicot angiosperms from desert areas has not been adequately addressed. We conducted a comparative morphometric analysis of internal and external seed features in the 16 dicot species representing 10 families from the Thal desert (Pakistan) using scanning electron microscopy. Seeds were mostly minute and small and slightly larger than 1 mm in length except for Acacia nilotica, Astragalus hamosus and Prosopis juliflora. Seeds varied in shape from elliptical to obovate, D-shaped, reniform, rhomboid, and ellipsoidal. The cell outline, periclinal boundaries, and sculpture pattern of the anticlinal wall were generally rugulate, reticulate and striate, papillate and rugose, or rarely undulating granulate. The seed coat also comprises diverse forms of epicuticular projections and texture. The phenetics of 84 character-states using principal component and dendrogram statistics supported the affinities among desert species. Here, we identified micromorphological similarities and differences among dicot angiosperms to determine their systematic relationships.

Pollen Micromorphology among Amaranthaceous Species from Desert Rangeland: Exine Stratification and their Taxonomic Significance

The aim of the study was to visualize the micromorphology of Amaranthaceous pollen using scanning electron microscopy collected from the Thal Desert. Field collection was conducted from July to September 2021. A total of 14 taxa of the family Amaranthaceae were collected which belong to nine genera. Achyranthes aspera, Aerva javanica, Aerva lanata, Amaranthus graecizans, Amaranthus retroflexus, Amaranthus viridis, Bassia indica, Chenopodium album, Chenopodium ficifolium, Chenopodium murale, Digera muricata, Haloxylon stocksii, Salsola tragus, and Suaeda fruticosa were studied in terms of pollen morphotypes. Pollen were acetolyzed and observed under optical and scanning microscopy. Qualitative and quantitative characters were measured to analyze the pollen to uncover its taxonomic significance. Qualitative characters observed were the shape of pollen in polar and equatorial views; the most frequent shape observed was spheroidal in the polar view, whereas in the equatorial view, prolate spheroidal was the dominant shape. Exine ornamentation is the key characteristic of pollen which is very helpful, and eight different types of ornamentations were observed in collected taxa: smooth sparsely granulate, scabrate‐spinulose, microspinulose perforate, microechinate scabrate to metareticulate, granulate, nanospinulate, granulate‐spinulose perforate, granulate‐perforate echinate, and microechinate perforate. Periporate‐type aperture was observed among all taxa. Mesoporia, ektexinous bodies, and tectum features also show variations among Amaranthaceous grains. In quantitative character, A. retroflexus recorded highest in polar view 26.3 μm and the lowest was of C. album 12.2 μm. Highest P/E index ratio was recorded in S. fruticosa (1.12) whereas the lowest for D. muricta (0.94). Exine thickness was highest in S. tragus 2.15 μm and lowest in A. graecizans 0.78 μm. The maximum number of pores was recorded as 32‐36 in D. muricata. Artificial taxonomic keys were constructed based on findings that reinforce the importance of the micromorphological ultrastructural diversity of pollen among Amaranthaceous taxa. It was concluded that the descriptions of pollen morphotypes presented greatly contribute to our understanding of desert species identification.

Сравнение видового состава отрядов Lagomorpha и Rodentia Самур-Девечинской низменности и Закатала-Лагычского физико-географического района Азербайджана

This article presents the results of a comparative analysis of two physiographic regions of Azerbaijan. 19 species of lagomorphs and rodents are registered in the Samur-Davachi physiographic region. 7 Western Asian species predominate in this area (36.84%): Lepus europaeus, Hystrix indica, Allactaga euphratica, Cricetulus migratorius, Meriones libycus, Microtus sosialis, Sylvaemus witherbyi. 6 (31.58%) species (Glis glis, Dryomys nitedula, Microtus arvalis, Micromys minutus, Apodemus agrarius, Apodemus (Sylvaemus) uralensis) are of European origin, 3 (15.78%) species (Arvicola amphibius,Microtus majori, Mus musculus) are of widely distributed in Palearctic, 1 (5.26%) species (Allactaga elater) is of Turanian origin, 1 (5.26%) species (Rattus norvegicus) is listed as an alien species and 1(5.26%) species (Apodemus(Sylvaemus)ponticus) is Caucasus endemic. Major species are of Western Asian and European origin, and least ones of turanian origin. South Asian species are not found. An analysis carried out in the Zaqatala-Lahyj physiographic region showed that 4 (21.05%) species (Arvicola amphibius, Microtus majori, Mus musculus, Ratus rattus) are widespread in the Palearctic region, 5 (26.31%) species (Lepus europaeus, Hystrix indica, Cricetulus migratorius, Microtus socialis, Sylvaemus witherbyi) are widespread in the Western Asian region, 5 (26.31%) species (Glis glis, Dryomys nitedula, Mus macedonicus, Apodemus (Sylvaemus) uralensis, Microtus arvalis) are of European origin and 5 (26.31%) species (Sciurus anomalus,Microtus dagestanicus,Chionomys gud, Chionomysroberti, Apodemus (Sylvaemus) ponticus) are endemics. No desert species of Turanian origin were noted. In the Zaqatala-Lahyj physical-geographic region, species of European and Western Asian origin are also predominant. A total of 25 rodent species have been registered in these regions. Of the species distributed in the Samur-Davachi and Zaqatala-Lahyj physiographic regions, only 13 (52%) species are found in both physiographic regions. It should be noted that each physiographic region has its own specific species. 6 species (Sciurus anomalus, Microtus dagestanicus, Chionomys gud, Chionomys roberti, Mus macedonicus, Rattus rattus) are found in the Zaqatala-Lahyj physiographic region only, 6 species (Allactaga euphratica, Allactaga elater, Meriones libycus, Apodemus agrarius, Rattus norvegicus, Micromys minutus) are found in the Samur-Davachi physiographic region only.

Effect of nitrogen deposition on seed germination of ephemeral species in the cold desert

Seed germination is the key initial stage in the plant life cycle and strongly regulated by the external environment. Nitrogen deposition is an important environmental change factor that is increasing and affecting the structure and function of many ecosystems. This research aimed to investigate the effect of nitrogen deposition on the seed germination of nine ephemeral plants, including seed germination percentage, germination index and seed viability under four levels of nitrogen deposition. The germination percentage of the studied species differed significantly in response to nitrogen deposition, but nitrogen deposition has almost no significant effect on germination index. This study can provide information on the germination strategy of ephemeral plants in response to increasing nitrogen deposition in future, and the results can guide ecological conservation in arid areas.

Two new species of Anaptychia (Physciaceae) from western North America, with notes on the other species of section Protoanaptychia

Two new species belonging to the lichen genus Anaptychia are described from western North America. Anaptychia nevadensis is superficially similar to the Eurasian A. desertorum but is distinguished by having longer ascospores, in producing scant pruina only near the lobe tips, and in regularly producing variolaric acid. Anaptychia roemerioides is described to accommodate North American material which has previously been called A. ulotrichoides. It is macro-morphologically identical to the Asian species A. roemeri but differs in having longer ascospores and conidia. Both new species are strongly supported by phylogenetic analysis of ITS sequences. We also call attention to the existence of a further undescribed but possibly cryptic species within A. elbursiana. Variolaric acid is newly reported to occur occasionally in A. desertorum and A. elbursiana. A global key to the desert species of Anaptychia is provided.

Designing a large-scale track-based monitoring program to detect changes in species distributions in arid Australia.

Monitoring trends in animal populations in arid regions is challenging due to remoteness and low population densities. However, detecting species' tracks or signs is an effective survey technique for monitoring population trends across large spatial and temporal scales. In this study, we developed a simulation framework to evaluate the performance of alternative track-based monitoring designs at detecting change in species distributions in arid Australia. We collated presence-absence records from 550 2-ha track-based plots for 11 vertebrates over 13years and fitted ensemble species distribution models to predict occupancy in 2018. We simulated plausible changes in species' distributions over the next 15years and, with estimates of detectability, simulated monitoring to evaluate the statistical power of three alternative monitoring scenarios: (1) where surveys were restricted to existing 2-ha plots, (2) where surveys were optimized to target all species equally, and (3) where surveys were optimized to target two species of conservation concern. Across all monitoring designs and scenarios, we found that power was higher when detecting increasing occupancy trends compared to decreasing trends owing to the relatively low levels of initial occupancy. Our results suggest that surveying 200 of the existing plots annually (with a small subset resurveyed twice within a year) will have at least an 80% chance of detecting 30% declines in occupancy for four of the five invasive species modeled and one of the six native species. This increased to 10 of the 11 species assuming larger (50%) declines. When plots were positioned to target all species equally, power improved slightly for most compared to the existing survey network. When plots were positioned to target two species of conservation concern (crest-tailed mulgara and dusky hopping mouse), power to detect 30% declines increased by 29% and 31% for these species, respectively, at the cost of reduced power for the remaining species. The effect of varying survey frequency depended on its trade-off with the number of sites sampled and requires further consideration. Nonetheless, our research suggests that track-based surveying is an effective and logistically feasible approach to monitoring broad-scale occupancy trends in desert species with both widespread and restricted distributions.

The Responses of Four Typical Annual Desert Species to Drought and Mixed Growth

Soil desiccation is increasingly threatening the growth of vegetation in artificial forests at the margins of arid desert oases, where a variety of annual herbaceous plants coexist. It is important to understand the response of annual desert plants to droughts and mixed growth and the resulting patterns of change in photosynthetic and physiological properties. Our results showed that annual plants were primarily affected by drought stress, and the effect of interspecific competition was significant only under severe drought stress. In the sprouting stage, moderate drought increased seed germination rates, whereas severe drought stress decreased the germination rates. In the growth phase, the aboveground and belowground parts of annual herbaceous plants showed a synergistic response to drought. Under mild and moderate drought stress, annual herbaceous plants promoted photosynthesis by increasing chlorophyll content, thereby promoting plant stem growth. Following moderate and high drought, root vigor increased to maintain basic metabolic activities and annual herbaceous plants used the “shadow and avoid” response by increasing stem and root length to increase competitive ability. Under severe drought stress, planted seedling chlorophyll levels decreased, resulting in a simultaneous reduction in photosynthetic ability. The root growth of annual herbaceous plants depends on their photosynthesis ability but the decrease in biomass led to a decrease in root growth. The mixed habitat reduced the inhibition of seedling stem growth by drought stress and promoted plant growth.

Comparison of Trap Efficiency Using Suction Traps Baited With Either UV or CO2 for the Capture of Culicoides (Diptera: Ceratopogonidae) Species in the Southern California Desert, United States.

Culicoides Latreille (Diptera: Ceratopogonidae) biting midges are hematophagous flies that can transmit several disease-causing pathogens to animals. Surveillance of Culicoides is important for understanding pathogen transmission risk. The most commonly used traps for midge surveillance are suction traps baited with UV light or CO2. Culicoides species are understudied in the southern California desert region and trapping methods for these desert midges remain largely unexplored. In this study, capture rates of different Culicoides species were compared using suction traps baited with either UV or CO2 placed at two locations at a southern California desert site where a narrow canyon (Deep Canyon) drains the adjacent peninsular mountain range and leads to an expansive floodplain. Over all trap nights and locations, UV-baited traps outperformed CO2-baited traps for most Culicoides species captured at the study site, except for Culicoides sonorensis Wirth and Jones and C. mohave Wirth. Capture rates varied for each species by trap location, with desert Culicoides species captured in greater numbers at the canyon mouth while C. sonorensis and C. mohave were captured in greater numbers on the floodplain nearer to urban development including a golf course and small zoo. An interaction of trap type with trapping location on the capture rate was noted for some Culicoides species, especially for C. mohave which was captured in greater numbers using UV traps at the canyon mouth but captured in greater numbers using CO2 traps in the floodplain. This trap efficiency study will facilitate future research targeting Culicoides species in the southern California desert.

Mechanisms of flower coloring and eco-evolutionary implications of massive blooming events in the Atacama Desert

The Atacama Desert, one of the driest places on earth, holds a rich biodiversity that becomes most appreciable in years when unusual rainfall accumulation triggers a phenomenon of explosive development of ephemeral herbaceous and woody desert species known as “desierto florido” or “blooming desert.” Despite the scientific importance of this unique phenomenon only few studies have addressed the mechanisms of flower phenotypic divergence under the fluctuating environment provided by this recurrent event. We investigated the mechanisms of floral color diversity in Cistanthe longiscapa (Montiaceae), a dominant species across the ephemeral blooming landscape of Atacama Desert. Our analyses show that the variation in colors of C. longiscapa flowers result from petals containing betalain pigments with different absorption spectra. The different pigment composition of petals causes flower color differences in the visible and ultraviolet (UV) range of the spectrum. Through color vision models we show that C. longiscapa flowers are highly polymorphic in their color appearance for insect pollinators. Our results highlight the variable nature in flower color of C. longiscapa varieties blooming simultaneously in a geographical restricted area. Given the importance of color in attracting floral visitors, the observed color variability could contribute to increased cross pollination in extreme desert conditions, while accounting for complex and fluctuating histories of plant-pollinator interactions.

Temporal variations in root-associated fungal communities of Potaninia mongolica, an endangered relict shrub species in the semi-arid desert of Northwest China.

The semi-arid region of the Western Ordos plateau in Inner Mongolia, China, is home to a critically endangered shrub species, Potaninia mongolica, which originates from ancient Mediterranean regions. Root-associated microbiomes play important roles in plant nutrition, productivity, and resistance to environmental stress particularly in the harsh desert environment; however, the succession of root-associated fungi during the growth stages of P. mongolica is still unclear. This study aimed to examine root-associated fungal communities of this relict plant species across three seasons (spring, summer and autumn) using root sampling and Illumina Miseq sequencing of internal transcribed spacer 2 (ITS 2) region to target fungi. The analysis detected 698 fungal OTUs in association with P. mongolica roots, and the fungal richness increased significantly from spring to summer and autumn. Eurotiales, Hypocreales, Chaetothyriales, Pleosporales, Helotiales, Agaricales and Xylariales were the dominant fungal orders. Fungal community composition was significantly different between the three seasons, and the fungal taxa at various levels showed biased distribution and preferences. Stochastic processes predominantly drove community assembly of fungi in spring while deterministic processes acted more in the later seasons. The findings revealed the temporal dynamics of root-associated fungal communities of P. mongolica, which may enhance our understanding of biodiversity and changes along with seasonal alteration in the desert, and predict the response of fungal community to future global changes.

Leaf chlorophyll parameters and photosynthetic characteristic variations with stand age in a typical desert species (Haloxylon ammodendron).

As a desert shrub, Haloxylon ammodendron combines ecological, economic, and social benefits and plays an important role in the ecological conservation of arid desert areas. Understanding its physiological characteristics and its mechanism of light energy utilization is important for the conservation and utilization of H. ammodendron. Therefore, we selected five stands (5-, 11-, 22-, 34-, and 46-year-old) of H. ammodendron as research objects in the study and measured their photosynthetic light response curves by a portable open photosynthesis system (Li-6400) with a red-blue light source (6400-02B). Then, we measured the leaf chlorophyll parameters in the laboratory, calculated the photosynthetic characteristics by using Ye Zipiao’s photosynthetic model, analyzed their variation patterns across stand ages, and explored the relationships between leaf chlorophyll parameters and photosynthetic characteristics. The results showed that leaf chlorophyll parameters and photosynthetic characteristics of H. ammodendron at different stand ages were significantly different. Chl content, P nmax, and LUEmax of H. ammodendron were V-shaped with the increase of stand age. The 5-year-old H. ammodendron was in the rapid growth period, synthesized more Chl a+b content (8.47 mg g−1) only by using a narrower range of light, and the Pnmax and LUEmax were the highest with values of 36.21 μmol m−2 s−1 and 0.0344, respectively. For the 22-year-old H. ammodendron, due to environmental stress, the values of Chl a+b content, P nmax, and LUEmax were the smallest and were 2.64 mg g−1, 25.73 μmol m−2 s−1, and 0.0264, respectively. For the older H. ammodendron, its Chl content, P nmax, and LUEmax were not significantly different and tended to stabilize but were slightly higher than those of the middle-aged H. ammodendron. On the other hand, the other photosynthetic parameters did not show significant variation patterns with stand age, such as R d, AQE, LSP, LCP, and I L-sat. In addition, we found that the relationships between Chl a+b content and P nmax and between Chl a+b content and LUEmax were highly correlated, except for the older H. ammodendron. Thus, using leaf chlorophyll content as a proxy for photosynthetic capacity and light use efficiency should be considered with caution. This work will provide a scientific reference for the sustainable management of desert ecosystems and vegetation restoration in sandy areas.