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Summary: Plant–plant positive interactions are key drivers of community structure. Yet, the underlying molecular mechanisms of facilitation processes remain unexplored. We investigated the 'nursing' effect of Maihueniopsis camachoi, a cactus that thrives in the Atacama Desert between c. 2800 and 3800 m above sea level. We hypothesised that an important protective factor is thermal amelioration of less cold‐tolerant species with a corresponding impact on molecular phenotypes.To test this hypothesis, we compared plant cover and temperatures within the cactus foliage with open areas and modelled the effect of temperatures on plant distribution. We combined eco‐metabolomics and machine learning to test the molecular consequences of this association.Multiple species benefited from the interaction with M. camachoi. A conspicuous example was the extended distribution of Atriplex imbricata to colder elevations in association with M. camachoi (400 m higher as compared to plants in open areas). Metabolomics identified 93 biochemical markers predicting the interaction status of A. imbricata with 79% accuracy, independently of year.These findings place M. camachoi as a key species in Atacama plant communities, driving local biodiversity with an impact on molecular phenotypes of nursed species. Our results support the stress‐gradient hypothesis and provide pioneer insights into the metabolic consequences of facilitation. [ABSTRACT FROM AUTHOR]

sand burial is an important environmental stress affecting the distribution of plants in desert areas. It can change the spatial patterns of the population by affecting the environmental conditions. Nitraria tangutorum and Reaumuria songarica are dominant species in desert regions, and it is important to study their spatial patterns under different sand burial conditions to clarify the adaptive strategies of xerophytes. Unmanned aerial vehicles are ideal tools for the measurement of ecological phenomena. We here used an unmanned aerial vehicle to study the spatial patterns of the two species. Results show that (1) unmanned aerial vehicles can provide high-resolution (≤0.1 m) data and allow more efficient measurements than conventional ground-based survey methods; (2) with an increase in sand burial depth, the distribution of N. tangutorum showed aggregation, whereas R. songarica transformed from a clumped distribution at certain scales to a random distribution at all scales; and (3) the interspecific relationship between the two species changed from uncorrelated at all scales to correlated at a small scale. Our results suggest that the adaptability of N. tangutorum to a sandy environment is stronger than that of R. songarica. This may reflect the adaptive mechanism of xerophytes in desert areas. [ABSTRACT FROM AUTHOR]

Aim: Dryland ecosystems are exceedingly sensitive to climate change. Desertification induced by both climate changes and human activities seriously threatens dryland vegetation. However, the impact of climate change on distribution of dryland plant species has not been well documented. Here, we studied the potential distribution of four representative dryland plant species (Haloxylon ammodendron, Anabasis aphylla, Calligonum mongolicum, and Populus euphratica) under current and future climate scenarios in a temperate desert region, aiming to improve our understanding of the responses of dryland plant species to climate change and provide guidance for dryland conservation and afforestation. Location: Junggar Basin, a large desert region in northwestern China. Methods: Occurrence data of the studied species were collected from an extensive field investigation of 2,516 sampling sites in the Junggar Basin. Ensemble species distribution models using 10 algorithms were developed and used to predict the potential distribution of each studied species under current and future climate scenarios. Result: Haloxylon ammodendron and A. aphylla were likely to lose most of their current suitable habitats under future climate scenarios, while C. mongolicum and P. euphratica were likely to expand their ranges or remain relatively stationary. Variable importance evaluation showed that the most important climate variables influencing species distribution differed across the studied species. These results may be explained by the different ecophysiological characteristics and adaptation strategies to the environment of the four studied species. Main conclusions: We explored the responses of the representative dryland plant species to climate change in the Junggar Basin in northwestern China. The different changes in suitability of different species imply that policymakers may need to reconsider the selection and combination of the afforestation species used in this area. This study can provide valuable reference for the management and conservation of dryland ecosystems under future climate change scenarios. [ABSTRACT FROM AUTHOR]

Analyzing how climate change affects vegetation distribution is one of the central issues of global change ecology as this has important implications for the carbon budget of terrestrial vegetation. Mapping vegetation distribution under historical climate scenarios is essential for understanding the response of vegetation distribution to future climatic changes. The reconstructions of palaeovegetation based on pollen data provide a useful method to understand the relationship between climate and vegetation distribution. However, this method is limited in time and space. Here, using species distribution model (SDM) approaches, we explored the climatic determinants of contemporary vegetation distribution and reconstructed the distribution of Chinese vegetation during the Last Glacial Maximum (LGM, 18,000 14C yr BP) and Middle-Holocene (MH, 6000 14C yr BP). The dynamics of vegetation distribution since the LGM reconstructed by SDMs were largely consistent with those based on pollen data, suggesting that the SDM approach is a useful tool for studying historical vegetation dynamics and its response to climate change across time and space. Comparison between the modeled contemporary potential natural vegetation distribution and the observed contemporary distribution suggests that temperate deciduous forests, subtropical evergreen broadleaf forests, temperate deciduous shrublands and temperate steppe have low range fillings and are strongly influenced by human activities. In general, the Tibetan Plateau, North and Northeast China, and the areas near the 30°N in Central and Southeast China appeared to have experienced the highest turnover in vegetation due to climate change from the LGM to the present. [ABSTRACT FROM AUTHOR]

Aim: To test whether novel and previously hypothesized biogeogaphic barriers in the Australian Tropics represent significant disjunction points or hard barriers, or both, to the distribution of plants. Location: Australian tropics: Australian Monsoon Tropics and Australian Wet Tropics. Methods: The presence or absence of 6,861 plant species was scored across 13 putative biogeographic barriers in the Australian Tropics, including two that have not previously been recognised. Randomizations of these data were used to test whether more species showed disjunctions (gaps in distribution) or likely barriers (range limits) at these points than expected by chance. Results: Two novel disjunctions in the Australian Tropics flora are identified in addition to eleven putative barriers previously recognized for animals. Of these, eleven disjunction points (all within the Australian Monsoon Tropics) were found to correspond to range-ending barriers to a significant number of species, while neither of the two disjunctions found within the Australian Wet Tropics limited a significant number of species’ ranges. Main conclusions: Biogeographic barriers present significant distributional limits to native plant species in the Australian Monsoon Tropics but not in the Australian Wet Tropics. [ABSTRACT FROM AUTHOR]

Background: Habitat fragmentation, water resources and biological characteristics are important factors that shape the genetic structure and geographical distribution of desert plants. Analysis of the relationships between these factors and population genetic variation should help to determine the evolutionary potential and conservation strategies for genetic resources for desert plant populations. As a traditional Chinese herb, Glycyrrhiza inflata B. (Fabaceae) is restricted to the fragmented desert habitat in China and has undergone a dramatic decline due to long-term over-excavation. Determining the genetic structure of the G. inflata population and identifying a core collection could help with the development of strategies to conserve this species. Results: We investigated the genetic variation of 25 G. inflata populations based on microsatellite markers. A high level of population genetic divergence (FST = 0.257), population bottlenecks, reduced gene flow and moderate genetic variation (HE = 0.383) were detected. The genetic distances between the populations significantly correlated with the geographical distances, and this suggests that habitat fragmentation has driven a special genetic structure of G. inflata in China through isolation by distance. STRUCTURE analysis showed that G. inflata populations were structured into three clusters and that the populations belonged to multiple water systems, which suggests that water resources were related to the genetic structure of G. inflata. In addition, the biological characteristics of the perennial species G. inflata, such as its long-lived seeds, asexual reproduction, and oasis ecology, may be related to its resistance to habitat fragmentation. A core collection of G. inflata, that included 57 accessions was further identified, which captured the main allelic diversity of G. inflata. Conclusions: Recent habitat fragmentation has accelerated genetic divergence. The population genetic structure of G. inflata has been shaped by habitat fragmentation, water resources and biological characteristics. This genetic information and core collection will facilitate the conservation of wild germplasm and breeding of this Chinese medicinal plant. [ABSTRACT FROM AUTHOR]

Fog oases in western South America (locally named lomas) are distributed in a kind of fragmented or patchy way into the coastal desert. Their origin, as well as their current ecological connections in terms of species' dispersal capability, remains an open question. We analyzed the latitudinal pattern in plant species and phylogenetic similarities of 13 lomas, which cover the latitudinal extent of these habitats, from 7°58′ to 26°15′ S. A data-set of 1004 species from available checklists was considered. Plant species composition and phylogenetic relationships among lomas were analyzed by non-metric multidimensional scaling. Our results show three main groups of lomas (northern Peruvian, southern Peruvian, and North-Central Chilean lomas) that are aligned along a complex, nonlinear north–south gradient in ordination space. The weak species overlap between Peruvian and Chilean lomas, together with the higher content in endemic species of the Chilean communities, supports the hypothesis that, at least recently, species composition of the three main groups of lomas has been shaped by desert barriers limiting plant dispersal. [ABSTRACT FROM AUTHOR]

This paper describes the vegetation of the Carson Desert (Nevada, USA) based on a phytosociological analysis of its major plant associations, as determined by the Braun-Blanquet method. Diagnostic tables, climatic, edaphic, and biogeographical data were used to establish floristic affinities among identified plant communities and to interpret their distributions in zonal gradients. Their syntaxonomic positions in the classesAllenrolfeetea occidentalisandArtemisio tridentatae–Juniperetea osteospermae, and in the new classSarcobatetea vermiculatiwere also established. Three associations (Atriplici confertifoliae–Sarcobatetum baileyi,Atriplici canescentis–Psorothamnetum polydenii, andSuaedo moquinii–Sarcobatetum vermiculati) are described here for the first time along with the orderSarcobatetalia vermiculatiand the allianceSarcobation vermiculati. [ABSTRACT FROM AUTHOR]

The hydraulic redistribution (HR) of deep-rooted plants significantly improves the survival of shallow-rooted shrubs and herbs in arid deserts, which subsequently maintain species diversity. This study was conducted in the Ebinur desert located in the western margin of the Gurbantonggut Desert. Isotope tracing, community investigation and comparison analysis were employed to validate the HR of Populus euphratica and to explore its effects on species richness and abundance. The results showed that, P. euphratica has HR. Shrubs and herbs that grew under the P. euphratica canopy (under community: UC) showed better growth than the ones growing outside (Outside community: OC), exhibiting significantly higher species richness and abundance in UC than OC (p<0.05) along the plant growing season. Species richness and abundance were significantly logarithmically correlated with the P. euphratica crown area in UC (R2 = 0.51 and 0.84, p<0.001). In conclusion, P. euphratica HR significantly ameliorates the water conditions of the shallow soil, which then influences the diversity assembly in arid desert communities. [ABSTRACT FROM AUTHOR]

Abstract: In arid environments, soil fertility exhibits a high degree of spatial and temporal heterogeneity, which results from high climatic variability seasonally and heterogeneous plant distribution. However, because most desert areas have been altered by human activities, heterogeneous fertility would originate from grazing or logging activities. We evaluated spatial and temporal heterogeneity of soil fertility in cattle-excluded sites under and outside woody plant cover (Prosopis flexuosa and Larrea divaricata), and in sites disturbed by tree removal during wet and dry season in Ñacuñán Biosphere Reserve (Central Monte desert of Argentina). Soil organic matter, fulvic acids, bioavailable organic matter, and nitrate were lower outside plant canopy (8.9mgg−1, 0.03mgg−1, 8.2mgg−1, and 4.17mgkg−1, respectively). Total N, humic acids, and abundance of microbial functional groups did not show differences among sites. Most parameters differed between seasons, tending to be higher in the wet season. Overall soils of Ñacuñán Reserve are characterized by: a) more homogenous spatial pattern than expected from woody plant presence; b) very heterogeneous temporal pattern; and c) after two years, tree removal does not seem to induce infertile soil formation. [Copyright &y& Elsevier]

Panicum turgidum is one of the most drought resistant plants in the Egyptian desert. Five habitat types were selected for the study: sand dunes (North Sinai and in Wady El-Natrun), gravel desert, coastal plain, and water runnels of a wadi bed (South Sinai and Eastern Desert). About 47.4% of the studied sites were subjected to high grazing pressure, 26.3% to moderate grazing pressure; the remaining 26.3% were subjected to low grazing pressure. Concentration of the nutrients (K, Na, Ca, P and Ca/P ratio) in the grazeable parts of P turgidum populations exhibited insignificant variability between habitats and phytogeographical regions. Meanwhile, concentration of potassium showed significant variability between the phytogeographical regions. Ca/P ratio of the grazeable parts of P. turgidum was significantly related to the soil silt and organic matter content. The percentage of crude protein was higher than the minimum required for the maintenance of the grazing animals, i.e. P. turgidum has a good or excellent forage quality. Due to its high nutritive value and ease of cultivation, P turgidum grains could be considered as a potential crop, which may serve as a supplementary food to the common cereals. It worth noting that the variation in the nutritive values among the cultivated populations was insignificant as all the cultivated populations had a high nutritive value, indicating the effect of edaphic factors on the wild population nutritive value which was proved also from the correlation between the edaphic factors and nutritive variable. [ABSTRACT FROM AUTHOR]

To characterize the Australian desert vine flora and to compare it with that of deserts in other continents.The Stony Deserts, the Simpson Desert and the four main deserts of Western Australia.The Western Australian Herbarium data base and published papers were used to develop vine checklists for each Australian desert studied. A literature search was used to classify the families and genera into phytogeographical elements and to provide data for intercontinental comparisons.Thirty-seven vine species are listed for the six Australian deserts studied. They constitute from 0.8 to 2.7% of the vascular flora, which is within the normal range for arid zone floras. Comparing Australian data with those from the Sonoran and Chihuahuan deserts (North America), for non-vine taxa, very different phylogenetic lines are present. However, for vines, three of the four most important families are the same in each case, viz. Convolvulaceae, Fabaceae and Asclepiadaceae. This reflects large pantropical and cosmopolitan families shared between all three data sets. At the generic level, in Australia pantropical taxa and taxa from the Old World tropics far outnumber endemic ones, as do pantropical and neotropical genera in North America. Herbaceous vines predominate in Australian deserts as they do in North American ones, but nevertheless, the percentage of woody vines is higher in Australia (32%) than in North America (highest value of 24%). Earlier views that Australian deserts are rich in annual vines are not supported.For many life-forms, the Australian flora is composed of very different phylogenetic lines to the floras of other continents. However, for desert vines, at the level of family and even of genus, there are surprising similarities between Australia and even a continent as distant as North America, because of shared pantropical and cosmopolitan taxa. [ABSTRACT FROM AUTHOR]

Plants face different environmental pressures in different patches of vegetation mosaics, so their demography cannot he completely understood if it is not studied in each patch-type. Banded patterns of vegetation surrounded by bare areas occur in semiarid landscapes. At one level, two phases of the mosaic are the banded vegetation- patches (vegetation arcs) and the hare areas, hut at another level two phases can he distinguished inside the vegetation arc. One phase (frontal zone) is always in the upslope boundary of the arc, has only herbs and it has been suggested that it functions as a colonization area, while the other one (central zone) is at the middle of the arcs and has both shrubs and herbs. The demography of a tussock grass (Hilaria mutica) growing in the two phases of the vegetation arcs was studied under the hypothesis that it will show the demographic parameters of a ruderal species in the frontal zone and those of a more competitive species in the central zone. Temporal variability was assessed through annual, average, periodic and stochastic matrices. K-values are higher in the frontal than in the central zone, and lower in dry years than in years with moderate precipitation. The influence of the demographic processes on K-values shows spatial and temporal variation. In dry years, K-values are more sensible to stasis (permanence in the same size class) and retrogression (transition to a smaller size class) in both zones, whereas in years of moderate precipitation the influence of fecundity and growth increases in the frontal zone and the influence of stasis and retrogression continue to he the most important in the central zone. Variations in the demographic parameters observed in the frontal zone are evidences of a life history plasticity finely tuned with environmental variation, and these results support the hypothesis that frontal zones function as colonization areas. [ABSTRACT FROM AUTHOR]

The vegetation and the vascular plants of an ecotonal zone between the floristic provinces of the Desert Plateau (Chihuahuan Desert) and Gulf Coastal Plain in northeastern México were studied. The study zone has a surface of 2,526.25 km² and it is located in the northern part of the state of Nuevo León. On the basis of physiognomy, ecological characteristics and dominant species, seven types of vegetation were recognized. With the aid of 50 sampling plots, aerial photographs and floristic composition, the units of vegetation were delimited and mapped. 405 species (varieties and subspecies included) were identified. The study zone showed geographical affinity with the vegetation of the Chihuahuan Desert in the Desert Plateau of México (Hilaria mutica grassland, low thornless scrub of Flourensia cernua and medium size mixed scrub of Acacia-Prosopis-Flourensia-Larrea) and with the Gulf Coastal Plain (medium size mixed scrub of Leucophyllum frutescens and Acacia rigidula and high mixed scrub of Helietta parvifolia). The medium size and high thorny scrubs of Prosopis-Acacia showed no clear relationships with any of the floristic provinces. The coexistence of shrubby vegetation characteristic of the lowlands in the Gulf Coastal Plain and the vegetation usually present in the Chihuahuan Desert, can be explained in view of the increment of aridity and gentle raising of the continental surface in east-west direction, and of the absence of notable topographic accidents in the northeastern region of México. [ABSTRACT FROM AUTHOR]

1 The present study provides quantitative estimates of soil, vegetation structure and species distribution in 144 stands along two transects in two extreme desert zones of western Egypt. This study had two aims: (1) to describe the floristic composition of the accidental type of vegetation growing in parts of the Western Desert of Egypt; and (2) to analyse the distribution of species in relation to certain environmental factors by multivariate data analysis. 2 Eight environmental variables were recorded: salinity, pH, calcium carbonate, soil moisture, organic matter content, and percentages of sand, silt and clay. A total of 60 species belonging to 19 families of the angiosperms and Ephedra alata was recorded. Chamaephytes and therophytes were the most frequent, denoting a typical desert life-form spectrum, mainly of Saharo-Arabian distribution. 3 The samples were classified into eight TWINSPAN groups. Detrended correspondence analysis (DCA) showed that these groups could be distinguished by the first two DCA axes. They could also be effectively interpreted and explained with canonical correspondence analysis (CCA). Based on forward regression, salinity, fine sediments, organic matter and soil moisture content related closely to the first three canonical axes, and accounted for 84.1% of the species-environment relationship among the stands. 4 Both classification and ordination resulted in a clear demonstration of the vegetation pattern in the study area. Other TWINSPAN groups were characterized in addition to those identified previously. In conclusion, the study area has a transitional character where the Nubian Desert and the Northern Mediterranean vegetation meet. [ABSTRACT FROM AUTHOR]

(1) The distribution of species of cacti along gradients of aspect and angle of slope is described and compared for a species-rich community in the Sonoran Desert and for a species-poor community in the Mohave Desert. (2) No differences were found between the two sites in the ecological ranges of cactus species along these gradients. (3) In the Sonoran Desert there were larger overlaps in the distribution of species among the aspect-gradient than in the Mohave Desert, however, no differences in overlap were found between the two areas along the gradient of angle of slope. (4) More species of cacti are packed into the Sonoran Desert study area, either by utilizing portions of the environmental gradients unavailable in the Mohave Desert, or by addition of species with different growth-form and maximum size. (5) The cylindropuntias (the group with the largest number of species in the two areas) illustrate the latter effect. [ABSTRACT FROM AUTHOR]

The article offers information on water-table, sand movement and plant distribution in a North African oasis. It states that the Oasis of Jalo fills a shallow depression in the Libyan desert about 250 miles south of Benghazi in Libya. It also forwards that this oasis owes its origin and continuance to the proximity to the sand surface of an extensive underlying water-table, and to some extent of protection from drifting sand. Moreover, the depth of water-table and boundaries of the oasis, an analysis of its water content, as well as the zonation of different species are also discussed. Various tables which illustrate the findings of the study are also presented.

The puna desert of the high Andes of South America is the second most extensive high altitude desert in the world, after the high altitude desert of SE Central Asia. Compared with the latter, which apparently holds only three species of true desert birds (sensu Cowan, 1996),from a larger list of fourteen desert species for the Caspio-CentralAsian desert as a whole, the puna desert is richer in desert birds, having twenty species. The reasons for the higher bird species richness of the puna desert, compared to the lower species richness of the high altitude deserts of Central Asia, may include both (1) spurious differences in species numbers due to differences in the definitions of 'desert species', and (2) 'true' biological differences due to thedifferent biogeographical histories of these two regions. [ABSTRACT FROM AUTHOR]