Desert Communities Research Articles

How ‘green energy’ is threatening biodiversity, human health, and environmental justice: An example from the Mojave Desert, California

In recent years, the Mojave Desert, which is known for its unique and endemic plant and animal diversity, has become a preferred area for renewable energy developments. However, an environmental impact that is not calculated into the production of green energy has emerged that not only puts an additional burden on already endangered species but also affects the quality of life for residents living in disadvantaged and underserved communities. Using the example of just another solar farm to be built on 2,300 acres of pristine desert land, we point out the negative impacts of unsustainable land development on community health and environmental justice, driven by the administration of Kern County, which promotes and prioritizes economic growth over residents’ concerns. In the eyes of the local population, several promises by the County to the community, as documented in the 2017–2020 County of Kern Strategic Goals, were broken. This study investigates the effects of unsustainable land development, particularly the threat to iconic Joshua trees (Yucca brevifolia), the increase in PM10 pollution, and the risk of contracting Valley fever for residents of two small desert communities, Boron, and Desert Lakes, in Kern County, California. This study focused on environmental justice issues due to the implementation of an ambitious renewable energy transition plan supported by the administration. This is the first study that documented the presence of the causative agent of Valley fever in soils to be disturbed for ambitious renewable energy development in eastern Kern County using a molecular, culture-independent, approach.

Blown Away: Extreme Wind Events Impact Grass Mortality

Understanding extremes in ecological change is critical given the anticipated increasing frequency of such events. This is especially true when extreme events trigger transitions to alternative stable states, as in drylands that have seen conversion from grass- to shrub-dominated states. We examined the responses of a Chihuahuan Desert community after record winds in 2019 killed grasses and reduced greenness. We argue that wind has two faces like Janus, aptly the Roman god of transitions, because it participates in change as both a forcing and a feedback and that, similarly, other types of extremes can alter the character of ecological interactions. Photo 1. Record-breaking wind in southern New Mexico in the spring of 2019 had major impacts on grass at the Jornada Long Term Ecological Research site in Las Cruces, New Mexico. The exposed roots of two Sporobolus spp. grasses are a result of these storms. Photo credit: G.S. Okin. Photo 2. In some cases, grasses, like the one on the left in this image, were able to green up following rain in the early summer. Other grasses appear to have been killed by the root exposure and sandblasting that occurred during the extreme wind events in the spring of 2019. Photo credit: G.S. Okin. Photo 3. UCLA undergraduate, Sarah Payne (shown here indicating the extent of root exposure on a native bunchgrass), conducted an NSF-supported summer research project that resulted in a publication of an article in Ecology. Photo credit: G.S. Okin. These photographs illustrate the article “The two faces of Janus: Processes can be both exogenous forcings and endogenous feedbacks with wind as a case study” by Sarah A. R. Payne, Gregory S. Okin, Abinash Bhattachan, and Michael R. Fischella published in Ecology. https://doi.org/10.1002/ecy.3998

Metabarcoding reveals seasonal and spatial patterns of arthropod community assemblages in two contrasting habitats: Desert and oasis of the Baja California Peninsula, Mexico

AbstractAimDesert springs or oases are the only permanent mesic environments in highly water‐limited arid regions. Oases have immense cultural, evolutionary and ecological importance for people and a high number of endemic and relic species. Nevertheless, they are also highly vulnerable ecosystems, with invasive species, overexploitation and climate change being the primary threats. We used the arthropod communities' spatiotemporal diversity and distribution patterns as a proxy to understand biodiversity dynamics in two geographically close but ecologically contrasting and highly threatened ecosystems: deserts and oases.LocationBaja California Peninsula, Mexico.MethodsArthropod communities at five oases and surrounding desert scrub areas were sampled in two seasons. Using DNA metabarcoding and traditional taxonomic surveys, we tried to identify what biotic and abiotic characteristics of the habitat are important drivers of arthropod diversity and how these characteristics can change across spatial and temporal scales.ResultsOver 6200 individuals representing 23 orders were collected. In oasis samples, the community composition fluctuated more in space (i.e. among sites) than in time (i.e. seasons). Thus, seasonal changes did not affect oasis community diversity and composition, but the dissimilarity among sites increased with geographic distance. Moreover, anthropic activities negatively correlated with arthropod diversity in oases. On the other hand, the season, geography (e.g. latitude) and biotic characteristics of the habitat (e.g. sampled scrub species) significantly affected the diversity and composition of the desert arthropod communities.Main ConclusionsNeutral dynamics (e.g. historical climatic events, dispersal limitation and spatial component) and human impact significantly influenced the biodiversity patterns of each oasis. In contrast, the habitat's seasonal variation and biotic characteristics were the most important variables influencing the diversity of the desert communities. Baja California oases harbour distinct invertebrate communities; therefore, each oasis should be conserved individually to preserve these unique assemblages.

Prospects for the introduction of fodder species Artemisia into culture

In many desert communities, the basis of pasture ecosystems are species of the genus Artemisia, which are edifiers of plant communities in the vast territories of the Central Asia desert zone. Sagebrush pastures with a diverse set of plant species and life forms are used in desert animal husbandry all year round. Artemisia spp. is good fodder pastures plants. Green twigs contain 16.9% protein, 4.4% fat, 39% nitrogen-free extractives. Artemisia diffusa, А. turanica are common on desert graybrown and gray-earth soils with different granulometric composition, Artemisia halophila has a narrow ecological area confined to saline soils. The fodder mass of Artemisia spp. serves as the main type of sheep fodder and is especially appreciated in the autumn, winter and early spring periods. As a result of irrational use, the natural sagebrush pastures of deserts are degraded and need to restore their fodder productivity. All three wild–growing species – Artemisia turanica, Artemisia diffusa, Artemisia halophyla in culture conditions accelerate the passage of phenological phases in the process of ontogenesis. Individuals of species populations of sagebrush develop faster in cultural conditions than in natural sagebrush communities. In the culture conditions the process of ontogenesis, skeletal axes of the shrub are laid at the base of the maternal shoots in young individuals, in the second or third year of life, the tested species of sagebrush form a morphologically full-fledged life form of a semishrub with a feed productivity 3-5 times higher than the yield of natural pastures. In the conditions of Artemisia spp. culture, they grow well and quickly. Many individuals enter the fruiting season in the first year of life.

古尔班通古特沙漠藻类结皮中微生物群落空间分异特征

PDF HTML阅读 XML下载 导出引用 引用提醒 古尔班通古特沙漠藻类结皮中微生物群落空间分异特征 DOI: 10.5846/stxb202112313720 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（31860149）；新疆自然科学基金项目（2018D01C069） Spatial differentiation of microbial communities in Gurbantunggut Desert algae crust, Xinjiang, China Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:古尔班通古特沙漠短命和旱生植物在沙漠东西走向上形成明显的种群变化梯度，那么沙漠藻类结皮土壤中微生物是否也具有类似地空间分布特征？为研究该科学问题，采用高通量测序技术，探究沙漠东西走向上藻类结皮土壤中细菌和真菌群落结构分布规律。在古尔班通古特沙漠西部、中部和东部区域分别采集藻类结皮土样，进行土壤理化因子分析及细菌和真菌扩增子测序，对比不同区域土壤理化性质和微生物群落空间分异特征，分析微生物多样性与环境因子相关性，最后根据微生物物种种类对其功能进行预测分析。结果表明：藻类结皮土壤氮素、全磷、全钾、pH以及土壤化学计量比碳磷比（C ： P）和氮磷比（N ： P）在沙漠不同区域存在显著性差异，其余指标空间尺度上变化梯度较小。微生物α多样性结果显示3个区域藻类结皮土壤中细菌群落丰富度和多样性存在显著性差异，东部与西部区域产生明显分化；而真菌α多样性指数无显著性差异，群落结构较为均匀，未产生分化。β多样性结果显示细菌群落在西部与东部藻类结皮间存在显著性差异，沙漠中部为沙漠西部和东部的过渡带。门水平细菌优势菌群为蓝藻门、变形菌门和拟杆菌门；真菌为子囊菌门和担子菌门。属水平上，丰度前30个属在沙漠不同区域表现出不同的菌群结构。Spearman相关性分析结果表明，多个理化因子与藻类结皮微生物群落呈正相关关系。此外，功能预测结果显示沙漠中、西部细菌功能基因聚类关系较近，并与东部部分功能基因具有显著性差异，但真菌群落功能在沙漠不同区域无显著性差异。研究结果表明，古尔班通古特沙漠藻类结皮土壤理化性质的改变驱动沙漠东部藻类结皮土壤中细菌群落与中、西部已产生显著适应性分化，且部分功能基因也逐步产生分化，但这些理化指标差异未能驱动真菌群落结构及功能产生显著分化。 Abstract:Ephemeral plants and xerophyte develop an obvious gradient change of population in the east-west direction of Gurbantunggut Desert. Whether the microorganism of the algae crust soil has the similar distribution characteristics like that? This paper discusses the bacterial and fungal community structures distribution characteristics of algal crust soil in the east-west direction of the desert by using high-throughput sequencing technology. We tested physical and chemical factors of the algae crust soil samples which were collected separately in the western, middle, and eastern regions of desert and compared the spatial differentiation of soil properties. Then, we conducted the bacterial and fungal amplicon sequencing, so as to analyze the microbial communities differentiation in different regions of the desert and the correlation between microbial diversity and environmental factors. At last the function was predicted according to the types of microorganism. The results indicate that there are significant differences in soil total nitrogen (TN), total phosphorus (TP), total potassium (TK), pH and C:P and N:P in algae crust soil, with fewer gradient changes of other indicators regarding spatial scale of the desert. According to the alpha diversity of microorganism, there are significant differences in the bacterial communities' richness and diversity in three regions, among which the diversity of east and west regions are obviously differentiated. However, there is no significant difference in α-diversity indexes of the fungi, whose community structure is relatively uniform without differentiation. The β-diversity results present that the bacterial communities are significantly different between the western and eastern areas, while the middle of the desert is the transition zone. At the phylum level, the dominant bacterial populations are Cyanobacteria, Proteobacteria and Bacteroidetes, and fungi are mainly Ascomycota and Basidiomycota. From the perspective of the genus of bacteria, top 30 in genus abundance appear different microbial community structure. From the Spearman analysis result, several physical and chemical factors are positively correlated with algal crusts microbial community. In addition, the clustering relationship of bacterial functional genes in the middle and west of the desert is closer, and having significant difference with some functional genes in the east. However, fungal community functions don't have significant difference in different regions of the desert. This paper finds that the change of soil properties have caused divergence of bacterial communities in the eastern Gurbantunggut Desert, adaptive differentiation significantly occurring in the central and western regions and some gradually differentiated functional genes. However, these changes can't lead to significant differentiation of fungal community structure and function. 参考文献 相似文献 引证文献

Гнездовые группировки орлов на ключевой орнитологической территории «Чинк Донызтау» в 2022 году

Гнездовые группировки орлов на ключевой орнитологической территории «Чинк Донызтау» в 2022 году

Identifying the chaîne opératoire of club-rush (Bolboschoenus glaucus (Lam.) S.G.Sm) tuber exploitation during the Early Natufian in the Black Desert (northeastern Jordan)

Club-rush (Bolboschoenus spp. (Asch.) Palla) is one of the most common edible wild plant taxa found at Epipaleolithic and Neolithic sites in southwest Asia. At the Early Natufian site of Shubayqa 1 (Black Desert, Jordan) thousands of club-rush rhizome-tuber remains and hundreds of fragments of prepared meals were found. The evidence indicated that the underground storage organs of this plant were recurrently used as a source of food 14,600 years ago. To determine how Early Natufian communities gathered, processed and transformed club-rush tubers into food, we designed an interdisciplinary study that combined experimental archaeology, archaeobotany, and ground and chipped stone tool analyses. We conducted more than 50 specific experiments over three years, and based on the experimental materials produced we inferred that 1) the best season for club-rush rhizome-tuber collection in the region was spring-summer time; 2) that the primary method to harvest the plant would have been uprooting; and 3) that the most efficient approaches to obtain perfectly peeled and clean rhizome-tubers could have entailed drying, roasting and gentle grinding of the tubers. Overall, our work provides important information to reconstruct the chaîne opératoire for club-rush tuber exploitation in the past. The experimental data and modern reference datasets allow us to interpret the archaeological material found at Shubayqa 1, and start identifying some of the activities that Natufian communities in the Black Desert undertook in relation to the exploitation of this particular source of food.

Aridity drives the loss of dung beetle taxonomic and functional diversity in three contrasting deserts

AbstractAimAridity gradients are of great interest for understanding the responses of biodiversity to water availability and water stress. However, little is known about the responses of many animal groups, which are crucial for assessing the effects of climate change. Here, we study the effects of aridity on dung beetle communities, a group with well‐known responses to large‐scale environmental gradients.LocationSahara, Kalahari and Chihuahuan deserts.TaxaDung beetles of the family Scarabaeidae.MethodsWe conducted standardized surveys along approximately 400 km aridity gradients in each of the three deserts, and measured species richness, abundance, evenness and three aspects of trait‐based functional diversity (functional richness, functional evenness and functional dispersion). By using randomization tests and linear mixed models, we compared observed with expected values for functional diversity indices from null models that hierarchically incorporate additional assembly constraints.ResultsOverall, we found a decrease of both taxonomic richness and functional dispersion along the three aridity gradients. Also, aridity seems to have mild effects on functional richness and functional evenness. Besides these general trends, we identified differences between deserts in the responses of both taxonomic and functional diversity.Main conclusionsAridity shows greater importance than competition and other processes of limiting similarity or stochastic processes in community assembly. Also, the functional hypervolume of dung beetle desert communities decreases with aridity not only due to species loss, but also because of selection of a few distinct phenotypes under harsh environmental conditions. Last, we observed that the different regional pools respond to aridity in different ways. Therefore, understanding future responses of dung beetle communities to the progressive decreases in water availability driven by climate change requires determining how the characteristics of the species in the regional pool interact with aridity‐driven assembly processes.

Differential Influences of Wind-Blown Sand Burial on Bacterial and Fungal Communities Inhabiting Biological Soil Crusts in a Temperate Desert, China.

Biological soil crusts (BSCs) are an integration of external photoautotrophs and internal heterotrophic communities. Sand burial is a ubiquitous disturbance that affects the biodiversity and ecological function of BSCs, but little is known about the influence of sand burial on microbial communities in arid sandy deserts. Here, based on a long-term field experiment and utilizing high-throughput sequencing, we assessed the influence of sand burial on bacterial and fungal communities inhabiting two typical successional stages of BSCs (cyanobacterial crusts for early successional stage and mixed crusts for late successional stage) at the three-sand buried depth (0, 0.5, and 10 mm) in the Tengger Desert, Northern China. We found that the diversity, abundance, and composition of the bacterial and fungal communities were all altered by the sand burial treatment. Different indicator taxa were identified in unburied and buried (shallow and deep) BSCs. Changes in soil properties caused by sand burial have been suggested as a possible cause of changes in the bacterial and fungal community composition in BSCs.

A Spring in the Desert: Infertility and Merciful Accompaniment.

The mystery of love as it unfolds in marriage is an adventure filled with wonder and anticipation for what the future holds. Such is the excitement and optimism of the couple embarking on family life by actively trying to conceive a child. For the couple struggling with infertility, however, joyful anticipation can soon devolve into anguish as they realize that their hoped-for children might not come. Though the pain of infertility is a shared experience in marriage, it is to the woman that evaluation, testing, and treatment is often directed. She may experience infertility as an assault on her feminine identity, her marriage, and her faith, leaving her vulnerable to reliance on scientific and technological solutions as the only relief for her pain. This turn toward science, if not integrated into the larger framework of overall health and well-being, has the danger of making the natural, good desire for a child into a quest to achieve a single-minded goal. When the child becomes a "goal," husband, wife, and potential offspring become (unintentionally) objectified, and the woman's identity and the future of her marriage rest precariously on the shoulders of an ideal. It is within the context of the authors' lived experience of infertility, as well as hundreds of encounters with women in the Springs in the Desert community, that the authors contend that it is necessary to integrate the pain of infertility into a framework of merciful accompaniment. Pastors, physicians, and Fertility Care Providers are all uniquely well-placed to offer support and encouragement that affirm the intrinsic dignity of the wife and her husband, and the truth of their marriage as a witness to Christ in the world. When they meet the woman amidst her pain and longing, they can help her to understand infertility as a circumstance and not her identity. When the pain of infertility is seen and acknowledged, the medical and pastoral care she receives can positively impact her overall health and wellbeing, help her to turn to her husband, and ultimately encourage her to find God in the midst of the struggle.

Contribution of Fine Roots to Soil Organic Carbon Accumulation in Different Desert Communities in the Sangong River Basin.

This study explored the relationship between soil organic carbon (SOC) and root distribution, with the aim of evaluating the carbon stocks and sequestration potential under five plant communities (Alhagi sparsifolia, Tamarix ramosissima, Reaumuria soongorica, Haloxylon ammodendron, and Phragmites communis) in an arid region, the Sangong River watershed desert ecosystem. Root biomass, ecological factors, and SOC in different layers of a 0–100 cm soil profile were investigated. The results demonstrated that almost all living fine root biomass (11.78–34.41 g/m2) and dead fine root biomass (5.64–15.45 g/m2) levels were highest in the 10–20 cm layer, except for the P. communis community, which showed the highest living and dead fine root biomass at a depth of 60–70 cm. Fine root biomass showed strong seasonal dynamics in the five communities from June to October. The biomass levels of the A. sparsifolia (138.31 g/m2) and H. ammodendron (229.73 g/m2) communities were highest in August, whereas those of the T. ramosissima (87.76 g/m2), R. soongorica (66.29 g/m2), and P. communis (148.31 g/m2) communities were highest in September. The SOC of the five communities displayed strong changes with increasing soil depth. The mean SOC value across all five communities was 77.36% at 0–30 cm. The highest SOC values of the A. sparsifolia (3.08 g/kg), T. ramosissima (2.35 g/kg), and R. soongorica (2.34 g/kg) communities were found in June, and the highest value of the H. ammodendron (2.25 and 2.31 g/kg, p > 0.05) community was found in June and September. The highest SOC values of the P. communis (1.88 g/kg) community were found in July. Fine root production and turnover rate were 50.67–486.92 g/m2/year and 1.25–1.98 times per year. The relationships among SOC, fine root biomass, and ecological factors (soil water content and soil bulk density) were significant for all five communities. Based on the results, higher soil water content and soil conductivity favored the decomposition of root litter and increased fine root turnover, thereby facilitating SOC formation. Higher pH and bulk density levels are not conducive to soil biological activity and SOC mineralization, leading to increased SOC levels in desert regions.

Death of the Desert: Monastic Memory and the Loss of Egypt’s Golden Age by Christine Luckritz Marquis

Reviewed by: Death of the Desert: Monastic Memory and the Loss of Egypt’s Golden Age by Christine Luckritz Marquis Daniel F. Caner Death of the Desert: Monastic Memory and the Loss of Egypt’s Golden Age. By Christine Luckritz Marquis. [Divinations: Rereading Late Ancient Religion.] (Philadelphia: University of Pennsylvania Press. 2022. Pp. 224. $65.00. ISBN: 9780812253627.) “When Scetis was laid desolate, he left crying, saying, ‘The world has lost Rome, and the monks Scetis’” (Apoph. patr. coll. alph. Arsenius 21). Readers of the Sayings of the Desert Fathers will be familiar with their nostalgic tone and vague historicizing. Most scholars have followed Hugh Evelyn-White’s explanation that such anecdotes ultimately look back to the abandonment of the original monastic desert communities of Nitria, Kellia, and Scetis in northwest Egypt after three successive “barbarian” raids in the early fifth century. Those mentioning the death of a desert father named Moses and his disciples during a barbarian attack would seem to support that reconstruction. Marquis, however, argues that we have been misled by deliberate efforts of the later monks who crafted the Sayings collections in Palestine to forget the gang violence that Bishop Theophilus of Alexandria instigated against the settlements in 401 A.D., due to their regard for Origen and protection of Origenist monks. The collections themselves are not anti-Origenist, Marquis maintains, but seek to construct a more comfortable, if still remorseful, remembrance of a ruined utopian experiment. “Through memory sanctions and nostalgia, emerging out of and in response to acts of violence, the Sayings collections became textualized, portable images of a paradise lost” (p. 156). [End Page 792] This is a deeply researched, heavily theorized, fascinating, and provocative book. I am not entirely persuaded by its historical contention that stories of barbarian attacks against the monk Moses were constructed to displace memories of episcopal violence, or that Evelyn-White’s reconstruction should be dismissed as pure speculation: Sayings quoted by Marquis herself refer to a series of attacks (“first,” p. 115; “third,” p. 117), and ancient towers at the sites, though not securely dated, indicate the possibility of them happening.1 Indeed, the sentences in the last chapters of Marquis’ book are full of speculations and conditional constructions (e.g., “quite plausibly would have,” p.145). Yet her reasoning is always cogent, and in any case, there are really two books here. Her first three chapters, on the desert in the monastic imagination, on psalmody and prayer as ascetic weapons, and on the problematic role of memory in monastic training, will be essential reading for those interested in understanding early monastic culture. This is because of their novel focus on the theme of violence. Marquis made me appreciate how extensively this culture was infused by imagery and instructions involving or promoting violence, against oneself as much as against one’s demons. Such emphasis could, of course, lead to fanaticism and mob violence, but what Marquis brings out (partly by using her own translations of Greek, Coptic, and Syriac Sayings, whose force has been softened and obscured by other translators) is how intrinsic such language was not only to traditional educational practices but also to the Psalms, to Evagrian theories, and to the ways monks were taught to imagine how to transform themselves and their desert from an abode of demons to one of angels. Marquis then relates all this to practices of damnatio memoriae against idols both internal and external. It is a shame that this central theme of the book is not signaled in its title, because it explores episodes and dimensions of late antique religious violence that have been ignored by recent scholarship on the subject. Daniel F. Caner Indiana University Bloomington Footnotes 1. Hjalmar Torp, “Murs d’enceinte des monastères coptes prímitifs et couvents-fortresses,” École française de Rome. Mélanges d’archéologie et d’histoire, 76 (1964), 173–200. Copyright © 2022 The Catholic University of America Press

Rock glacier Oasis: An alternative for agro‐pastoralism in a changing environment in the Himalayan cold desert

AbstractThe unprecedented climate change has catastrophic repercussions for high mountain communities and these issues need a multi‐disciplinary understanding for adaptation and mitigation strategies. The limited cultivable agricultural land and pastures along with an abridged cultivation season and water scarcity, all have severely impacted local communities in the cold desert of Ladakh. The indigenous people relying on glacier and snow‐melt have developed unique water management and agro‐pastoralism practices and are searching for additional alternatives owing to continuous climate and lifestyle changes. People are increasingly relocating to higher valleys in search of adequate cultivable land. In this endeavour, people are found to be practicing agro‐pastoral activities adjacent to the thermokarst lakes (Oasis) present on the rock glaciers. The present study is a one‐of‐a‐kind overview of such innovative and adaptive farming strategies to encourage research towards the water storage in such features, and how long it will remain sustainable.

Identification of far-red light acclimation in an endolithic Chroococcidiopsis strain and associated genomic features: Implications for oxygenic photosynthesis on exoplanets.

Deserts represent extreme habitats where photosynthetic life is restricted to the lithic niche. The ability of rock-inhabiting cyanobacteria to modify their photosynthetic apparatus and harvest far-red light (near-infrared) was investigated in 10 strains of the genus Chroococcidiopsis, previously isolated from diverse endolithic and hypolithic desert communities. The analysis of their growth capacity, photosynthetic pigments, and apcE2-gene presence revealed that only Chroococcidiopsis sp. CCMEE 010 was capable of far-red light photoacclimation (FaRLiP). A total of 15 FaRLiP genes were identified, encoding paralogous subunits of photosystem I, photosystem II, and the phycobilisome, along with three regulatory elements. CCMEE 010 is unique among known FaRLiP strains by undergoing this acclimation process with a significantly reduced cluster, which lacks major photosystem I paralogs psaA and psaB. The identification of an endolithic, extremotolerant cyanobacterium capable of FaRLiP not only contributes to our appreciation of this phenotype’s distribution in nature but also has implications for the possibility of oxygenic photosynthesis on exoplanets.

Testing the Functional and Phylogenetic Assembly of Plant Communities in Gobi Deserts of Northern Qinghai-Tibet Plateau.

The mechanism governing plant community assembly across large-scale Gobi deserts remains unclear. Here, we inferred the roles of different assembly processes in structuring plant communities in the Gobi deserts of the Qinghai–Tibet Plateau by using a phylogenetic tree, and leaf and root traits. The functional and phylogenetic structures of 183 plant communities were assessed, and their distributions were linked with environmental gradients. Our results demonstrated that functional convergence was prevalent in most functional traits (75% of the traits) and accentuated when all traits were combined. The phylogenetic structure exhibited significant divergence. We observed the contrasting response of functional and phylogenetic assembly structures to environmental gradients. More importantly, we found that the shifts in the functional assembly along environmental gradients were trait-specific, with dominant roles of local factors, such as gravel coverage and soil attributes, in determining the distribution patterns of most traits. However, the distribution patterns of leaf P concentration (LPC), root N concentration (RNC), and root P concentration (RPC) were mainly driven by climatic factors. These results reveal that niche-based processes, such as abiotic filtering and weaker competitive exclusion, are the major drivers of species co-occurrence, which results in the widespread coexistence of phylogenetically distinct but functionally similar species within the Gobi plant community. Our findings could improve the understanding of plant community assembly processes and biodiversity maintenance in extremely harsh drylands.

Пресмыкающиеся пустынных равнин Юго-Западного Таджикистана: пространственное распределение, плотность населения и структура сообществ

Population density of reptiles in four desert areas of southwestern Tajikistan was estimated in spring 2018–2019. The structure of reptile communities in seven typical landscapes was described. The highest species diversity and population density were observed in sandy landscapes. Seven species of psammobionts formed the basis of these reptile communities. Among them Phrynocephalus interscapularis (56.4), Crossobamon eversmanni (27.8), Eremias lineolata (15.6), Eremias scripta (13.0) had the highest distribution and high population density (individuals/hectare). The relationship of cohabitating species was considered. The highest total population density of reptiles (89.0 ind./ha) was discovered on sandy ridges along the Amu Darya. On the loamy plain the population density of four species was 8.4 ind./ha, and on the foothill plain 2.4 ind./ha. Eremias nigrocellata (2.0 ind./ha) dominated in reptile communities on solid ground. In total, 25 species of reptiles inhabit the desert plains of Southwestern Tajikistan. 17 out of 25 (68%) species are included in the national Red Data Book. The level of endemism and similarity of reptile fauna in desert areas were high. Fauna similarity indices calculated according to Sørensen were 0.9–0.8. These values indicate close contact and connection between desert communities. The formation of the reptile fauna in southwestern Tajikistan occurred as a result of dispersal of Turanian species across the left bank of the Amu Darya River from Turkmenistan. They moved to the right bank due to the changes in the riverbed at the Pleistocene Epoch. The absence of some reptile species (Teratoscincus scincus, C. eversmanni, Phrynocephalus mystaceus, E. lineolata, Eremias grammica, E. scripta, etc.) in Northern Afghanistan along the border with Tajikistan is explained by the lack of herpetological study of this territory. Their habitat in the area is highly probable. Isolation and autonomy of desert areas in the Amu Darya valley create the opportunity for formation of new taxonomic forms. Examples are lizards E. scripta ladzinni and P. interscapularis sogdianus. The desert plains of Southwest Tajikistan have a small area and are subjected to significant anthropogenic pressure. Protection of small species, including lizards (Phrynocephalus raddei, P. mystaceus, Varanus griseus) and snakes (Eryx tataricus, Spalerosophis diadema, Boiga trigonatum, Naja oxiana, Echis carinatus) is needed. For widespread and numerous psammobiont species (P. interscapularis, E. lineolata, E. grammica, E. scripta, C. eversmanni) there is no threat of extermination at the moment.

Climate shapes community flowering periods across biomes

AbstractAimClimate shapes the composition and function of plant communities globally, but it remains unclear how this influence extends to floral traits. Flowering phenology, or the time period in which a species flowers, has well‐studied relationships with climatic signals at the species level but has rarely been explored at a cross‐community and continental scale. Here, we characterise the distribution of flowering periods (months of flowering) across continental plant communities encompassing six biomes, and determine the influence of climate on community flowering period lengths.LocationAustralia.TaxonFlowering plants.MethodsWe combined plant composition and abundance data from 629 standardised floristic surveys (AusPlots) with data on flowering period from the AusTraits database and additional primary literature for 2983 species. We assessed abundance‐weighted community mean flowering periods across biomes and tested their relationship with climatic annual means and the predictability of climate conditions using regression models.ResultsCombined, temperature and precipitation (annual mean and predictability) explain 29% of variation in continental community flowering period. Plant communities with higher mean temperatures and lower mean precipitation have longer mean flowering periods. Moreover, plant communities in climates with predictable temperatures and, to a lesser extent, predictable precipitation have shorter mean flowering periods. Flowering period varies by biome, being longest in deserts and shortest in alpine and montane communities. For instance, desert communities experience low and unpredictable precipitation and high, unpredictable temperatures and have longer mean flowering periods, with desert species typically flowering at any time of year in response to rain.Main conclusionsCurrent climate conditions shape flowering periods across biomes, with implications for phenology under climate change. Shifts in flowering periods across climatic gradients reflect changes in plant strategies, affecting patterns of plant growth and reproduction as well as the availability of floral resources for pollinators across the landscape.

Plant diversity and structure in desert communities of the Andean piedmont in Ica, Peru

Aims: There is extensive documentation of the floristic composition and plant diversity patterns in the South American coastal deserts and the adjoining arid Puna. Surprisingly, the vegetation along the transition zone from these deserts in the coastal lowlands to the Puna highlands has been little studied. The main goal of this study was to characterize and compare the structure of plant communities in two localities in the Ica department, with the aim of contributing to the floristic knowledge of the desertic western Andean slopes along the lowlands to Andean transition zone.Study area: Huancacasa and La Bolivar localities located at approximately 740 and 3,000 m a.s.l. in the Ica department, Peru.Methods: We sampled 10 plots of 100 m × 60 m located between 740–1,600 m a.s.l. in La Bolivar and 15 modified Whittaker plots (MWPs) of 20 m × 5 m located between 2,800–3,000 m a.s.l. in Huancacasa and recorded species richness and abundance. We estimated alpha diversity, performed Non-Metric Multidimensional Scaling (NMDS) and one-way Similarity (ANOSIM) analyses and plotted rank-abundance curves.Results: We recorded 215 species and morphospecies with coastal and Andean distribution, including 43 species (21.3%) that are either considered endemic to Peru or have been considered under some form of threat by Peruvian or international standards. Both plant communities differed in terms of composition, species richness, abundance, and dominant growth form, with higher values in the communities located at higher elevations. We added 83 species as new records for the Ica department.Conclusions: Our research reinforced the need to increase exploration and documentation of the vegetation within the lowland to highland transition zone along the dry western slopes of the Andes. Our results from such a transition in Ica department in southern Peru, show that much of its plant diversity seems to be, as yet, largely unknown.Taxonomic reference: The Plant List (2013).Abbreviations: ANOSIM = one-way Analysis of Similarities; BMAP = Biodiversity Monitoring and Assessment Program; IUCN = International Union for Conservation of Nature; NMDS = Non-Metric Multidimensional Scaling; USM = Universidad Nacional Mayor de San Marcos (Herbarium).

The Edaphic and Vegetational Properties Controlling Soil Aggregate Stability Vary with Plant Communities in an Arid Desert Region of Northwest China

The stability of soil aggregates is the basis for supporting ecosystem functions and related services provided by the soil. In order to explore the mechanism of the influence of soil and vegetation properties on the stability of soil aggregates in desert communities, the particle size distribution and aggregate in different communities were compared, and the contribution of soil physical and chemical properties (soil salinity, soil water content, soil pH, soil organic carbon, soil total phosphorus, soil total nitrogen, etc.) and vegetation properties (species richness, phylogenetic richness, plant height and coverage, etc.) to the stability of soil aggregates was determined by using a structural equation model. The results show the following: Soil water content, organic carbon, and salt in river bank plant communities have significant direct positive effects on the mean weight diameter of soil, with path coefficients of 0.50, 0.11, and 0.24, respectively (p < 0.01). Water also indirectly affects soil stability by affecting plant height, soil salt, and soil organic carbon; species richness and vegetation coverage have significant direct positive effects on the soil stability index, with path coefficients of 0.13 and 0.11, respectively (p < 0.01). In the desert marginal plant community, the plant coverage and species richness have significant positive effects on soil stability, with path coefficients of 0.43 (p < 0.001) and 0.35 (p < 0.001), respectively. Phylogenetic richness has a significant direct negative effect on soil stability (p < 0.05), with an effect value of −0.27. Phylogenetic richness indirectly affects soil stability by adjusting the coverage, with an indirect effect value of 0.23. Moisture, ammonium nitrogen, and nitrate nitrogen have significant direct positive effects on soil stability, with effect values of 0.12, 0.09, and 0.15, respectively. Our research shows that the process of soil stabilization is mainly controlled by soil factors and vegetation characteristics, but its importance varies with different community types.

Lithic cyanobacterial communities in the polyextreme Sahara Desert: implications for the search for the limits of life

The hyperarid Sahara Desert presents extreme and persistent dry conditions with a limited number of hours during which the moisture availability, temperature and light allow phototrophic growth. Some cyanobacteria can live in these hostile conditions by seeking refuge under (hypolithic) or inside (endolithic) rocks, by colonizing porous spaces (cryptoendoliths) or fissures in stones (chasmoendoliths). Chroococcidiopsis spp. have been reported as the dominant or even the only phototrophs in these hot desert lithic communities. However, the results of this study reveal the high diversity of and variability in cyanobacteria among the sampled habitats in the Sahara Desert. The chasmoendolithic samples presented high coccoid cyanobacteria abundances, although the dominant cyanobacteria were distinct among different locations. A high predominance of a newly described cyanobacterium, Pseudoacaryochloris sahariense, was found inhard, compact, and more opaque stones with cryptoendolithic colonization. On the other hand, the hypolithic samples were dominated by filamentous, non-heterocystous cyanobacteria. Thermophysiological bioassays confirmed desiccation and extreme temperature tolerance as drivers in the cyanobacterial community composition of these lithic niches. The results of the present study provide key factors for understanding life strategies under polyextreme environmental conditions. The isolated strains, especially the newly described cyanobacterium P. sahariense, might represent suitable microorganisms in astrobiology studies aimed at investigating the limits of life.