Semi-arid Habitats Research Articles

Critically Reckoning Spectrophotometric Detection of Asymptomatic Cyanotoxins and Faecal Contamination in Periurban Agrarian Ecosystems via Convolutional Neural Networks

Based on a systematic review of convolutional neural networks (CNN), this study explores the efficacy of small imaging sensors in monitoring the real-time presence of cyanotoxins and hazardous contaminants in urban ecosystems. To develop a machine learning-based CNN, this study first investigated the relationships between the prevalence of hazardous algal blooms (HABs) and faecal indicator bacteria (FIB) in waterways and aquifers of certain semi-arid zones of Sri Lanka, Sweden and New York (United States). By incorporating a popularly known AbspectroscoPY framework to effectively process the spectrophotometric data of the obtained samples, the formulation subsequently reveals strong positive correlations between FIB coliforms and nutrient loads (particularly nitrate and phosphate). A corroborative association with the incidence of chronic kidney disease of uncertain aetiology (CKDu) among the residents of the studied regions further affirms the reliability of the methodology. These findings underline the need for policymakers to consider the geographical and land-use traits of urban habitats in strategies aimed at reducing water-borne health hazards. HIGHLIGHTS This study examines the link between hazardous algal blooms (HABs) and faecal indicator bacteria (FIB) in the semi-arid habitats of Sri Lanka, Sweden, and New York, USA. Quantitative Phase Imaging based on a convolutional neural network (CNN) model helps monitor cyanobacterial incursions in peri-urban agrarian ecosystems. AbspectroscoPY-enabled spectrophotometric data analysis reveals strong positive correlations between the prevalence of FIB coliforms and nutrient loads, particularly those of nitrates and phosphates. Reliability of proposed machine learning-based CNNs is validated by the corroborative incidences of chronic kidney diseases among residents of the studied regions. GRAPHICAL ABSTRACT

Soil properties predict below-ground community structure, but not nematode microbiome patterns in semi-arid habitats.

Microbial and microeukaryotic communities are extremely abundant and diverse in soil habitats where they play critical roles in ecosystem functioning and services that are essential to soil health. Soil biodiversity is influenced by above-ground (vegetation) and below-ground factors (soil properties), which together create habitat-specific conditions. However, the compound effects of vegetation and soil properties on soil communities are less studied or often focused on one component of the soil biota. Here, we integrate metabarcoding (16S and 18S rRNA genes) and nematode morphology to assess the effects of habitat and soil properties shaping microbial and microeukaryotic communities as well as nematode-associated microbiomes. We show that both vegetation and soil properties (soil bulk density) were major factors structuring microbial and microeukaryotic communities in semi-arid soil habitats. Despite having lower nutrients and lower pH, denser soils displayed significantly higher alpha diversity than less dense soils across datasets. Nematode-associated microbiomes have lower microbial diversity, strongly differ from soil microbes and are more likely to respond to microscale variations among samples than to vegetation or soil bulk density. Consequently, different nematode lineages and trophic groups are likely to display similar associated microbiomes when sharing the same microhabitat. Different microbiome taxa were enriched within specific nematode lineages (e.g. Mycobacterium, Candidatus Cardinium) highlighting potentially new species-specific associations that may confer benefits to their soil nematode hosts. Our findings highlight the importance of exploring above- and below-ground effects to assess community structure in terrestrial habitats, and how fine-scale analyses are critical for understanding patterns of host-associated microbiomes.

Associations among MHC genes, latitude, and avian malaria infections in the rufous-collared sparrow (Zonotrichia capensis).

The major histocompatibility complex (MHC) is a genetic region in jawed vertebrates that contains key genes involved in the immune response. Associations between the MHC and avian malaria infections in wild birds have been observed and mainly explored in the Northern Hemisphere, while a general lack of information remains in the Southern Hemisphere. Here, we investigated the associations between the MHC genes and infections with Plasmodium and Haemoproteus blood parasites along a latitudinal gradient in South America. We sampled 93 rufous-collared sparrows (Zonotrichia capensis) individuals from four countries, Colombia, Ecuador, Peru, and Chile, and estimated MHC-I and MHC-II allele diversity. We detected between 1-4 (MHC-I) and 1-6 (MHC-II) amino acidic alleles per individual, with signs of positive selection. We obtained generalized additive mixed models to explore the associations between MHC-I and MHC-II diversity and latitude. We also explored the relationship between infection status and latitude/biome. We found a non-linear association between the MHC-II amino acidic allele diversity and latitude. Individuals from north Chile presented a lower MHC genetic diversity than those from other locations. We also found an association between deserts and xeric shrublands and a lower prevalence of Haemoproteus parasites. Our results support a lower MHC genetic in arid or semi-arid habitats in the region with the lower prevalence of Haemoproteus parasites.

Turnover of bird species along the Nullarbor Plain: Insights from taxonomic, phylogenetic, and functional beta diversity

AbstractThe Nullarbor Plain constitutes one of the main biogeographic barriers of Australia, and it has been suggested to have played a key role in the disjunct distribution of numerous southern Australian species. Although previous research has shown that the origin of this barrier coincides with the timing of the speciation events in some plant lineages, it is not clear whether the uplift of this barrier promoted divergence events in vertebrates. We addressed the role of the Nullarbor barrier and its fringing semiarid habitats as drivers of beta diversity in bird assemblages. Specifically, we determined the effect of distance from the Nullarbor barrier, environmental conditions, and isolation by distance on the composition of local communities on both sides of the plain. We measured beta diversity using taxonomic, phylogenetic, and functional metrics of composition. The influence of precipitation, geographic distance, and distance to the Nullarbor barrier on these metrics was addressed using generalized dissimilarity models and a moving‐window approach. We also tested for differences in local extinction, dispersal and speciation rates, and lineage diversity between two regions, southeastern (SE) and southwestern (SW) Australia. Geological and orogenetic dynamics linked to the appearance of the Nullarbor Plain may have spurred speciation events in SE. However, evidence suggests that subsequent periods in which this region was wetter and forested favored dispersal, mainly from SE to SW. Accordingly, observed dissimilarity in species composition was lower than expected at random, suggesting the existence of considerable turnover between regions. Our results suggest that precipitation deficit (and the xeric vegetation that it promotes) was the most important predictor of beta diversity, whereas the distance to the barrier explained some variation in terms of phylogenetic composition. This study shows that the uplift of the Nullarbor barrier played a minor role in shaping present‐day bird diversity in southern Australia. Recent speciation events coupled with historical connectivity can explain the observed patterns.

Adaptive convergence and divergence underpin the diversity of Asteraceae in a semi-arid lowland region

Asteraceae is the most diverse family primarily found in semi-arid areas and species from the same botanical family have comparable phenotypes, occupy semi-arid habitats, and have adaptive convergences to environmental stress. Such characteristics aid in understanding adaptive radiations of recent groups on a regional scale and their successful establishment in habitats with challenging climatic and edaphic conditions. We investigated the adaptive convergence of the family as well as the fragile balance between fine-scale variation in adaptive traits and general convergence towards stress-tolerance and adaptation to aridity, using thorough field surveys and trait-based ecological approaches. Data was collected between 2020 and 2022 using the quadrat approach encompassed across 60 sites and five habitat types. Multivariate statistical methodologies were applied to analyze plant traits and soil variables. The tribes Cichorieae, Cardueae, and Heliantheae emerged as dominant contributors to the flora, illustrating their adaptability to varied ecological conditions. Microphyll emerged as the dominant leaf type, and therophytes prevailed as the most abundant life form. Urban habitats exhibited heightened sensitivity to Asteraceae species, as reflected in diversity indices. Canonical Correspondence Analysis demonstrated the significant influence of soil moisture, pH, phosphorus, and soil saturation on species distribution, with indicator species analysis highlighting habitat-specific plant-environment relationships. The study further classified species into adaptive strategies using CSR (competitive strategy-stress tolerant strategy-ruderal strategy) categorization. While some species exhibited pronounced R or S strategies, a majority demonstrated mixed strategies, such as R/CR, R/CSR, CS/CSR, emphasizing the versatility of adaptation strategies within the Asteraceae family. The findings underscore the intricate interplay between environmental variables and Asteraceae phylogenetic and functional diversity, highlighting the significance of soil properties in influencing plant distribution in semi-arid ecosystems. This research contributes valuable insights into the ecological dynamics of Asteraceae, shedding light on their responses to diverse environmental conditions and providing a nuanced understanding of the factors influencing their spatial distribution.

Geographic variation in reproductive traits and germination-niche dynamics in conservation-dependent Banksia arborea populations restricted to banded ironstone formations

The temperature and moisture requirements for reproduction (i.e. seed production and germination) underpin the biogeographical relationships between climate, distribution and population dynamics of plants, particularly narrow range endemic species. We aimed to investigate reproductive outputs and the responses of seeds to temperature and moisture availability across three Banksia arborea populations that are distributed over a narrow range (< 200 km2) of semi-arid habitat on banded ironstone formations of Western Australia. We conducted reproductive trait assessments by quantifying follicles per cone, proportion of viable seed and associated seed mass followed by hydrothermal germination assessments for each population to characterise temperature and water stress tolerance. We found the southern-most population, that receives marginally higher rainfall, had heavier seeds (10 ± 0.02 mg), a cooler optimum temperature (16.1 °C) and wider germination capacity under water stress at 10 °C and 15 °C (Ψb50 = -0.66 to -0.87 MPa) compared to the two northern populations (Ψb50 = -0.60 to -0.65 MPa). By contrast, both northern populations had slightly warmer optimum temperatures for germination (16.9–17.5 °C) and a higher capacity to germinate under water stress at warmer temperatures of 22.5 °C (Ψb50 = -0.43 to -0.56 MPa, compared to -0.29 MPa). Our work highlights that, even within the specific requirements of a narrow range endemic, different populations adapt to marginally different temperature and water stress tolerances. Warming of the southern populations could impact on future recruitment, and conservation action to promote resilient ecosystems are suggested.

Open-cup nesters in the Kalahari: Incubation and egg-shading behaviour in passerines cannot be detected with temperature dataloggers during hot periods

Birds that build open-cup nests in semi-arid or arid habitats have difficulty in maintaining clutch temperatures during incubation in a suitable incubation range due to high air temperatures and solar radiation, resulting in either embryo death or behavioural responses to preserve clutch viability. We investigated how Southern Fiscals (Lanius collaris), open-cup nesting passerines with female-only incubation in the Kalahari basin, allocated time for self-care (off-bouts) and incubation (on-bouts) and whether egg shading, a previously described behaviour in this species, is a widespread response during hot periods. We used a dual approach combining temperature dataloggers in the nest and behavioural observations during the hottest hours of the day. We found that in the early morning and late evening, Southern Fiscals behaved similarly to species incubating in temperate habitats by alternating off- and on-bouts, but during the hottest hours of the day, shading became the main activity. Behavioural observations were key to describing this behaviour indicating that it is necessary to combine different data collection strategies to successfully assess the behaviour of open-cup nesters in hot environments.

Thriving in dry conditions: on the Neotropical spider genus Galapa (Araneae: Pholcidae).

The genus Galapa Huber, 2000 includes tiny spiders (body length <1.5 mm) restricted to semi-arid habitats. It has long been thought to be endemic to the Galapagos Islands until G. spiniphila Huber, 2020 was described from the Venezuelan Paraguan Peninsula. Here, we support this generic assignment with molecular (CO1) data and describe two new species from Colombia (G. gabito Huber sp. n.) and Costa Rica (G. murphyi Huber sp. n.), showing that the genus is actually widely distributed. Distribution modelling identifies several high suitability areas for Galapa, all of which are poorly sampled with respect to Pholcidae (ranging from Nicaragua to northern Peru and Guiana). Our results suggest a strong sampling bias against spiders restricted to dry tropical regions and habitats.

Structural characteristics of the leaves of two species of Tetramerium an endemic to Mexico

In taxonomic studies, in addition to floral characteristics, the structural characteristics of the vegetative organs also contribute to the taxonomic determination of the species. To provide information regarding these characteristics in the genus Tetramerium, a structural, micromorphological and histochemical analysis of cross sections of the leaves was performed using histochemical techniques and optical and scanning electron microscopy of two of its species, T. glutinosum, endemic to Mexico, and the widely distributed T. tenuissimum, was conducted. The two species presented amphistomatic leaves; double palisade chlorenchyma on adaxial and abaxial surfaces, leaf unifacial; vascular bundle sheaths with kranz anatomy; intradermal and subepidermal cystoliths of various shapes and sizes; nonglandular trichomes osteolate with a thin-walled conical head, glandular trichomes, including a new type, the straight, bright-ringed tricellular trichomes, and a variety of multicellular glandular trichomes. The glandular trichomes secrete waxes or oleoresins and mucilage deposited on the surfaces abaxial and adaxial in the form of platelets, granules and threads or strands. The histochemistry of the cystoliths highlights the presence of proteins and polysaccharides as a product of the possible superposition of the cell wall and plasmalemma lamellae. All these characteristics are typical of species from semi-arid habitats and correspond to the defense function against biotic and abiotic agents assigned to trichomes and their secretions in other studies of various genera and families, as well as to the adaptation function to these habitats of the kranz structure, which was novel for the genus Tetramerium.

Seasonal Diet Composition of Goitered Gazelle (Gazella subgutturosa) in an Arid and Semi-Arid Region of Western China.

Global climate change, habitat fragmentation, and human interference have resulted in a significant, ongoing decline in the population of goitered gazelles. Effective conservation strategies require an understanding of resource requirements of threatened species, such as dietary needs. Therefore, we aimed to elucidate the food composition and seasonal dietary changes of goitered gazelles through microhistological analyses of fresh feces. Fabaceae (11.5%), Gramineae (9.4%), Chenopodiaceae (20.2%), Asteraceae (10.1%), and Rosaceae (19.5%) formed the primary dietary components of goitered gazelle. Additionally, Krascheninnikovia arborescens (13.4%) and Prunus sibirica (16.3%) were identified as the key forage plants. Forbs (50.4%) were the predominant plants for grazing throughout the year, particularly in the spring (72.9%). The proportion of trees in the diet was highest in the autumn (36.7%) and comparatively lower in other seasons. Furthermore, the proportions of shrubs (22.0%) and graminoids (14.8%) both reached their peaks in the winter. Our findings indicate that goitered gazelles strategically forage seasonally to cope with resource bottlenecks, enhancing their adaptability to arid and semi-arid habitats. Our study provides essential ecological information for the conservation of goitered gazelles and emphasizes the importance of dietary studies of species of ecological significance in environmentally sensitive areas.

An effective hydrodynamic description of marching locusts

A fundamental question in complex systems is how to relate interactions between individual components (‘microscopic description’) to the global properties of the system (‘macroscopic description’). Furthermore, it is unclear whether such a macroscopic description exists and if such a description can capture large-scale properties. Here, we address the validity of a macroscopic description of a complex biological system using the collective motion of desert locusts as a canonical example. One of the world’s most devastating insect plagues begins when flightless juvenile locusts form ‘marching bands’. These bands display remarkable coordinated motion, moving through semiarid habitats in search of food. We investigated how well macroscopic physical models can describe the flow of locusts within a band. For this, we filmed locusts within marching bands during an outbreak in Kenya and automatically tracked all individuals passing through the camera frame. We first analyzed the spatial topology of nearest neighbors and found individuals to be isotropically distributed. Despite this apparent randomness, a local order was observed in regions of high density in the radial distribution function, akin to an ordered fluid. Furthermore, reconstructing individual locust trajectories revealed a highly aligned movement, consistent with the one-dimensional version of the Toner-Tu equations, a generalization of the Navier–Stokes equations for fluids, used to describe the equivalent macroscopic fluid properties of active particles. Using this effective Toner–Tu equation, which relates the gradient of the pressure to the acceleration, we show that the effective ‘pressure’ of locusts increases as a linear function of density in segments with the highest polarization (for which the one-dimensional approximation is most appropriate). Our study thus demonstrates an effective hydrodynamic description of flow dynamics in plague locust swarms.

Simplified microbial network reduced microbial structure stability and soil functionality in alpine grassland along a natural aridity gradient

Increasing aridity is known to influence the diversity and function of soil microbiome. However, how it affects the microbial co-occurrence network are poorly understood, particularly in alpine ecosystem, which is one of the most vulnerable ecosystems. Here, we investigated the co-occurrence networks of soil microbiomes based on 60 sites along a natural aridity gradient across the Tibetan Plateau and evaluated their relationship with soil functionality. We hypothesized that increasing aridity could lead to a reduction in the complexity of microbial networks (e.g., the decreased number of nodes and edges, lower connectance, average degree, clustering coefficient and centralization degree), and this changed network complexity is strongly relate to microbial structure stability (network robustness and vulnerability) and soil functionality. Our results supported the hypothesis that the network complexities of bacteria, fungi and protists decreased along the aridity gradient. Microbial network complexity was significantly correlated with network robustness and vulnerability, suggesting that soil network complexity supports structure stability. Bacterial and fungal network complexities were strongly related to community functional traits (e.g., enzymes activities, carbohydrate and amino acid metabolism, C degradation genes), soil processes (e.g., CO2 and CH4 emission, N mineralization) and multifunctionality. This suggests a key relationship of microbial networks to alpine soil functionality, with a more significant impact observed in semi-arid and arid habitats than that in humid and semi-humid habitats. Plants played key roles in driving microbial network through altering soil organic C, with plant diversity having a greater impact in humid habitats, while plant biomass was more influential in semi-arid and arid habitats. Our results indicate that aridity-induced simplification of microbial communities can potentially weaken community stability and alpine soil functionality. Therefore, preserving the complexity of belowground communities is critical for ecosystem management and for predicting the ecological consequences of future aridification.

Symbiotic fungi from a wild grass (Celtica gigantea) increase the growth, grain yield and quality of tritordeum under field conditions.

Plants function in symbiosis with numerous microorganisms, which might contribute to their adaptation and performance. In this study, we tested whether fungal strains in symbiotic interaction with roots of Celtica gigantea, a wild grass adapted to nutrient-poor soils in semiarid habitats, could improve the field performance of the agricultural cereal tritordeum (Triticum durum × Hordeum chilense). Seedlings of tritordeum were inoculated with 12 different fungal strains isolated from roots of Celtica gigantea that were first proved to promote the growth of tritordeum plants under greenhouse conditions. The inoculated seedlings were transplanted to field plots at two locations belonging to different climatic zones in terms of mean temperatures and precipitation in the Iberian Peninsula. Only one strain, Diaporthe iberica T6, had a significant effect on plant height, number of tillers and grain yield in one location. This result showed a substantial divergence between the results of greenhouse and field tests. In terms of grain nutritional quality, several parameters were differentially affected at both locations: Diaporthe T6, Pleosporales T7, Zygomycota T29 and Zygomycota T80 increased the content of total carotenoids, mainly lutein, in the colder location; whereas gluten proteins increased with several treatments in the warmer location. In conclusion, early inoculation of tritordeum plants with fungal symbionts had substantial beneficial effects on subsequent plant growth and development in the field. Regarding grain nutritional quality, the effect of inoculation was affected by the agroclimatic differences between both field locations.

New species and new record of the genus Poa L. (Poaceae, Pooideae, Poeae) from India

Poa sachensis, a new species from the Sach Pass, Western Himalaya, is described and illustrated. It is a member of P. subg. Ochlopoa sect. Alpinae, and closely allied to P. alpina, but differs from the latter by its lower glume one‐nerved, callus scantly hairy, lemma (3.87–) 4.18–4.54 (–4.65) mm long, purplish, surface between nerves glabrous, palea proliferate and keels ciliate 1/2nd to 1/3rd part, and two stamens in fertile floret with anther (2.42–) 2.67–3.08 (–3.21) mm long. Further, we have added P. diaphora var. alpina for the first time to the flora of India based on specimens collected from the semiarid habitats of Spiti Valley. Information on the distribution, habitat, flowering, and fruiting cycles is provided along with a distribution map for each taxon.Keywords: alpine grasses, Poa alpina, P. subg. Pseudopoa, P. subg. Ochlopoa, Western Himalaya

Phylogenetic Analyses of Lizards from the Chilean Humboldt Archipelago Reveal a New Species for the Chañaral Island (Squamata: Liolaemidae).

The Humboldt Archipelago, situated on Chile's north-central coast, is renowned for its exceptional biodiversity. However, lizards of the Liolaemus genus are a particularly understudied group in this archipelago. Liolaemus genus is divided into two clades: chiliensis and nigromaculatus. Within the nigromaculatus clade the zapallarensis group is restricted to the semi-arid and arid coastal habitats of the Atacama Desert in north-central Chile. While it has been reported that lizards from the zapallarensis group inhabit various islands within the Humboldt Archipelago, there has been limited knowledge regarding their specific species identification. To identify the lizard species inhabiting these islands, we conducted phylogenetic analyses using a mitochondrial gene and examined morphological characteristics. Our findings reveal that lizards from the Damas, Choros, and Gaviota islands belong to Liolaemus silvai. In contrast, the lizards on Chañaral Island form a distinct and previously unrecognised group, clearly distinguishable from Liolaemus silvai. In conclusion, our study not only confirms the presence of L. silvai on the Damas, Choros, and Gaviota islands but also describes a new lizard species on Chañaral Island named Liolaemus carezzae sp. nov. These findings contribute valuable insights into the biodiversity of these islands and introduce a newly discovered endemic taxon to the region, enriching our understanding of Chile's unique island ecosystems.

Development and validation of a photo-based attitudes scale towards the conservation of semi-arid habitats

Development and validation of a photo-based attitudes scale towards the conservation of semi-arid habitats

Invertebrate richness, diversity and hatching patterns from a semi-arid pool in peninsular India using field sampling and sediment re-hydration

Effective methods for finding the true species richness are necessary for biodiversity research. Such assessments are especially difficult for short-lived freshwater invertebrates found in arid and semi-arid temporary habitats. However, many of these animals produce “resting eggs” that remain viable for a long time and hatch when the habitats refill with water. This aspect can be used to assess the true species richness of these assemblages. We performed a simple, fast, cost-effective, and reliable method of laboratory sediment rehydration along with standard field sampling to understand the richness, diversity and hatching patterns of invertebrates like rotifers, cladocerans, copepods and ostracods and large branchiopods from a temporary pool located in the semi-arid part of peninsular India. Twenty-two rotifers, 5 large branchiopods and 6 micro-crustaceans were found in the study of which 4 species were only found from the rehydrated sediment. Variation in the species composition was higher in the field samples than the lab ones. Field and laboratory species communities were distinct from each other. Species community comparison with a similar habitat nearly 150 km away showed a dissimilarity of 0.70 between the two. Contrasting environmental conditions between the field and lab combined with temporal variation in the hatching patterns of species might explain the dissimilarities seen in the fauna. We propose that the sediment rehydration method along with the field sampling can be used to reveal the true species richness of the local temporary water bodies.

The unique buckspoor webs of Seothyra optimize silk use and capture efficiency

Buckspoor-web spiders of the genus Seothyra are southern African endemics predominantly occurring in arid and semi-arid habitats. They have evolved a uniquely shaped web, comprising a burrow in which the spider rests, linked to a slightly asymmetrical two- to four-lobed web on the soil surface. We investigated the association between three web parameters (periphery, surface area and compactness) and three body size parameters (carapace length, total length and mass) of S. schreineri in central South Africa. Using a novel pixel-seeding image analysis, we were able to accurately determine the surface area of individual webs and compare their area:periphery ratio with that of hypothetical circular webs with the same perimeter length to determine the isoperimetric quotient of each. Isoperimetric quotients across all life stages indicated an average reduction of approximately 25% in silk investment, being highest in juveniles (∼35%). Web periphery was related to web area by a power function, but web area increased at a progressively faster rate than periphery with increasing web size, indicating that larger spiders build less compact webs, i.e. web shape is affected by spider size. Web area and periphery scaled positively and allometrically with the three measures of spider body size, but no significant effect of body size on web compactness was found. We conclude that the unique shape of Seothyra webs evolved as a mechanism to optimize the periphery and concurrently reduce the surface area, thereby enhancing their potential to capture prey and reduce silk investment in the web structure.

Effect of global warming on the potential distribution of a holoparasitic plant (Phelypaea tournefortii): both climate and host distribution matter

Phelypaea tournefortii (Orobanchaceae) primarily occurs in the Caucasus (Armenia, Azerbaijan, Georgia, and N Iran) and Turkey. This perennial, holoparasitic herb is achlorophyllous and possesses one of the most intense red flowers among all plants worldwide. It occurs as a parasite on the roots of several Tanacetum (Asteraceae) species and prefers steppe and semi-arid habitats. Climate change may affect holoparasites both directly through effects on their physiology and indirectly as a consequence of its effects on their host plants and habitats. In this study, we used the ecological niche modeling approach to estimate the possible effects of climate change on P. tournefortii and to evaluate the effect of its parasitic relationships with two preferred host species on the chances of survival of this species under global warming. We used four climate change scenarios (SSP1-2.6, SSP2-4.5, SSP3-7.0, SSP5-8.5) and three different simulations (CNRM, GISS-E2, INM). We modeled the species’ current and future distribution using the maximum entropy method implemented in MaxEnt using seven bioclimatic variables and species occurrence records (Phelypaea tournefortii – 63 records, Tanacetum argyrophyllum – 40, Tanacetum chiliophyllum – 21). According to our analyses, P. tournefortii will likely contract its geographical range remarkably. In response to global warming, the coverage of the species’ suitable niches will decrease by at least 34%, especially in central and southern Armenia, Nakhchivan in Azerbaijan, northern Iran, and NE Turkey. In the worst-case scenario, the species will go completely extinct. Additionally, the studied plant's hosts will lose at least 36% of currently suitable niches boosting the range contraction of P. tournefortii. The GISS-E2 scenario will be least damaging, while the CNRM will be most damaging to climate change for studied species. Our study shows the importance of including ecological data in niche models to obtain more reliable predictions of the future distribution of parasitic plants.

Interspecific facilitation of micronutrient uptake between cluster-root-bearing trees and non-cluster rooted-shrubs in a Banksia woodland

Background and aimsBelowground interspecific plant facilitation is supposed to play a key role in enabling species co-existence in hyperdiverse ecosystems in extremely nutrient-poor, semi-arid habitats, such as Banksia woodlands in southwestern-Australia. Manganese (Mn) is readily mobilised by Banksia cluster root activity in most soils and accumulates in mature leaves of native Australian plant species without significant remobilisation during leaf senescence. We hypothesised that neighbouring shrubs are facilitated in terms of Mn uptake depending on distance to surrounding cluster root-forming Banksia trees.MethodsWe mapped all Banksia trees and selected neighbouring shrubs within a study site in Western Australia. Soil samples were collected and analysed for physical properties and nutrient concentrations. To assesses the effect of Banksia tree proximity on leaf Mn concentrations [Mn] of non-cluster-rooted woody shrubs, samples of similarly aged leaves were taken. We used multiple linear models to test for factors affecting shrub leaf [Mn].ResultsNone of the assessed soil parameters showed a significant correlation with shrub leaf Mn concentrations. However, we observed a significant positive effect of very close Banksia trees (2 m) on leaf [Mn] in one of the understorey shrubs. We found additional effects of elevation and shrub size.ConclusionsLeaf micronutrient concentrations of understorey shrubs were enhanced when growing within 2 m of tall Banksia trees. Our model predictions also indicate that belowground facilitation of Mn uptake was shrub size-dependent. We discuss this result in the light of plant water relations and shrub root system architecture.