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Context Shifting agricultural operations to more sustainable management practices is needed in the face of a changing climate. Aims In this study, the short-term effects of three tillage systems (no tillage, minimum tillage and conventional tillage) on a wide selection of soil properties in a semi-arid agrosystem of eastern Tunisia were assessed. Methods The studied soil properties included saturation percentage, bulk density, penetration resistance, mean weight diameter, electric conductivity, soil reaction, soil organic matter, carbonates, available phosphorus and exchangeable potassium. The impacts of tillage systems on soil quality indices (SQI) developed based on the total set of properties (SQI-T), or a minimum set (SQI-M) selected through principal component analysis, were also investigated. Key results Relative to conventional tillage, no tillage increased bulk density, penetration resistance and electrical conductivity, whereas minimum tillage affected only saturation percentage and pH. No tillage and minimum tillage did not enhance soil quality relative to conventional tillage. The SQI-T and SQI-M were highly correlated (r = 0.93) to each other suggesting that the outcomes of the two indices are comparable. Principal component analysis efficiently selected the most influential indicators of the effects of tillage systems on soil quality. Conclusions and implications Farmers in the study region are encouraged to consider minimum tillage during the early years of transition from standard to no tillage systems to avoid rapid decline in soil quality and consequent yield loss.

This editorial introduces the Australian Journal of Botany special issue ‘Vegetation science for decision-making’. Vegetation science and classification are crucial to understanding Australian landscapes. From the mulga shrublands of the arid interior to the monsoon rain forests of northern Australia, we have culturally and scientifically built upon the delineation of vegetation into recognisable and repeatable patterns. As remote sensing and database capacities increase, this improved capability to measure vegetation and share data also prompts collaboration and synthesis of complex, specialised datasets. Although the task faces significant challenges, the growing body of literature demonstrates a strong discipline. In Australia, purpose-driven products describe vegetation at broad scales (e.g. the National Vegetation Information System, the Terrestrial Ecosystem Research Network). At fine scales however (i.e. that of the vegetation community), no uniform framework or agreed protocols exist. Climate and landform dictate vegetation patterns at broad scales, but microtopography, microclimate and biotic processes act as filters at finer scales. This is the scale where climate-change impacts are most likely to be detected and effected; this is the scale at which a deeper understanding of evolutionary ecology will be achieved, and it is the scale at which species need to be protected. A common language and system for understanding Australian communities and impetus for collecting data at this scale is needed. In the face of ongoing climate and development pressures and an increasingly complex set of tools to manage these threats (e.g. offset policies, cumulative impact assessments), a nationally collaborative approach is needed. It is our hope that this special issue will help to achieve this.

In the present study, we tested the chronological and geographic origins of the mostly arid Australian Ptilotus (Amaranthaceae) and its close relatives (i.e. the ‘aervoids’) by reconstructing a dated phylogeny with near-comprehensive sampling for Ptilotus and estimating ancestral geographic ranges. We investigated climatic niche evolution within Ptilotus and identified likely climatic origins and subsequent niche shifts by reconstructing ancestral states of climatic variables on the phylogeny, which was visualised using a phyloecospace approach. Geospatial analyses were employed to identify probable diversification hotspots within Australia. We inferred that the aervoids originated in Oligocene Africa–Asia and that Ptilotus arrived in northern Australia by dispersal in the Early Miocene. Subsequent diversification of Ptilotus was rapid, giving rise to all major clades in the western Eremaean by the time of an aridification pulse in the Middle Miocene. Climatic niche shifts from the arid Eremaean into monsoonal northern and temperate southern Australia are apparent for multiple independent species groups. Our analyses support the hypothesis that a pre-adaptation to aridity and early arrival in an aridifying Australia were integral to the success of Ptilotus, and that the Eremaean has been a source of biodiversity in the genus and for independent radiations into neighbouring climatic zones.

The introduction of exotic pasture germplasm has formed the foundation of many Australian grazing systems. Scientists have searched the world for plants to improve the feedbase, amassing collections of diverse genetic material, creating genebanks that have made a large contribution to feedbase productivity. These genebanks contain a vast range of legumes, grasses, herbs and shrubs with growth habits ranging from small herbaceous plants to woody trees and life cycles from annuals to short- and long-term perennial plants. They have been collected from cool temperate to tropical climates and arid to high-rainfall zones. Hundreds of cultivars have been developed from material either collected by Australian plant breeders overseas or introduced from overseas genebanks. The collection of this germplasm has enabled plant breeders to extend the area of adaptation of species into climates, soils and systems previously considered marginal. The importance to Australian and world agriculture is increasing as plant breeders seek traits to meet the challenges of a changing climate and animal production systems. Furthermore, urbanisation, landscape degradation and political instability are making it increasingly difficult to collect pasture and forage germplasm from native grasslands in many countries. This emphasises the need to maintain and improve the capacity of the Australian Pastures Genebank (APG). The APG houses ~85 000 accessions and is a modern, online source of diversity for plant scientists around the world. This paper summarises the history of the founding genebank collections, their environment and farming systems focus, and the visionary and resourceful individuals that built them.

Construction works along a causeway at Mubarraz Island near Abu Dhabi, United Arab Emirates, in the Arabian Gulf necessitated the salvaging and replanting of 300 mangroves (Avicennia marina). Mangroves were excavated manually by shovel (smaller trees and saplings) or mechanically using a backhoe excavator (larger trees), transported with the root ball wrapped in burlap and replanted in a newly created tidal channel. Relocated mangroves were exposed to two different watering regimes and two tidal inundation levels, and were monitored for survival, plant height and leaf health (percentage of green leaves) at 0 and 1 weeks, and then at 3, 7 and 12.5 months. Tree mortality was high in the first week (24%) in mid-summer, with further losses (43%) during the next 3 months. After 12.5 months, 31% of the transplanted trees had survived. There was a significant effect of the duration of tidal inundation on survival and leaf health (higher survival in shallow than deeper plots). There were no significant effects of initial tree height or freshwater treatment on survival or plant performance. These results demonstrate that salvaging of larger mangroves is technically feasible, potentially providing faster ecosystem services (e.g. shoreline protection, source of new propagules) than newly planted seedlings in arid regions where growth is extremely slow.

Assessing current and potential future grassland vegetation types and distribution has important practical implications in grassland management. In this study, historical and projected climate data from Inner Mongolia were used to classify grassland classes for two historical (1960–1986 and 1986–2011) and two future periods (2021–2024 and 2041–2060) using the Comprehensive and Sequential Classification System (CSCS). Changes of grassland classes in these time periods were investigated. The results indicated that (1) using the CSCS provided an efficient approach to investigate the impact of historical and future climate on grassland classes and their distribution in Inner Mongolia over time and space; (2) since 1986, the precipitation in Inner Mongolia has declined, decreasing the semi-humid zone area and expanding that of arid and semi-arid areas. The area of Tundra and alpine steppe, Temperate zonal humid grassland and Temperate zonal forest steppe decreased, and that of Frigid desert, Semi-desert, and Steppe group increased; and (3) under the projected increase in temperature and decrease in precipitation in large areas in Inner Mongolia by 2060, the area of arid grassland classes will likely expand (Frigid desert, Semi-desert, and Steppe), and the grassland classes of Tundra and alpine steppe may gradually disappear. Government investment in infrastructure and grassland management measures such as introducing drought tolerant grass species and improved precipitation utilisation through irrigation are needed to adapt to the changing climate. Inner Mongolia should take advantage of the benefits of the increase in temperature in the eastern semi-humid region that would permit reduced grazing pressure in the western arid region.

Context Lethal control through the application of 1080 baits is widely used in Australia to manage the negative impacts of wild dogs (dingoes, wild domestic dogs and their hybrids) on cattle production, but its effectiveness in this regard is not well understood. Aims To evaluate the efficacy of once yearly 1080 baiting on dingoes and its effects in mitigating predation and sublethal impacts on beef cattle. Methods A replicated experiment with two paired treatments (1080 poisoned and non-poisoned) was conducted on each of four cattle stations of 3782–10 850 km2, over 2.5 years (2000–02) in the southern Northern Territory. The study was undertaken in relatively good rainfall years. Key results Track-based surveys indicated that dingo abundance declined on poisoned relative to non-poisoned areas immediately following a single baiting episode. However, there was no detectable difference about 8 months after baiting. No difference was detected in observed levels of calf damage or calf loss between poisoned and non-poisoned areas. Conclusions The results add to the growing body of consistent evidence that contemporary dingo control practices yield little benefit to rangeland beef producers most of the time. Implications Routine dingo baiting (as currently undertaken) may be largely unnecessary for beef cattle producers in arid and semiarid areas. Alternative strategies and practices to reduce dingo mauling and predation impacts should be investigated using replicated and controlled field studies.

The heterogeneity of resource distribution in arid environments plays an important role in habitat selection by consumers. The productivity of the riparian zones of intermittently flowing creeks is typically prolonged, relative to the hinterland, as moisture and nutrients concentrate there. Short-beaked echidnas, Tachyglossus aculeatus, sustain arid populations, attributed to ant and termite availability, low predation, and an ability to exploit habitat remnants. However, the scale of their movements in arid habitats is poorly understood. Thus, we investigated echidna home ranges and the importance of food and shelter availability in habitat selection over one winter. We focussed on the riparian zone of a creek at Mount Wood in Sturt National Park, north-western New South Wales, Australia. Radio tracking (VHF and GPS), scat and habitat selection analyses were conducted. Mean core and peripheral home range areas were 0.16 and 1.042 km2, respectively, with a mean home range overlap of 0.56 km2. Habitat selection differed between juveniles and adults and may have been driven by prey availability (predominantly ants). The preferred shelter was thick leaf litter. We concluded that habitat selection patterns were driven by prey availability (ants) and shelter (leaf litter).

Ring-forming species of spinifex grasses (Triodia spp.) are a dominant feature across much of Australia’s arid and semi-arid zone. Researchers have long been curious about the mechanisms underpinning their striking growth form. However, none of the factors investigated to date provide a convincing explanation for ring formation. Here, we asked whether an accumulation of pathogenic soil microbes might impede seedling emergence and subsequent growth in the centre of Triodia basedowii rings. We collected soil from inside and outside naturally occurring spinifex rings and compared plants grown in soil with live microbes to plants grown in sterilised soil. Consistent with our hypothesis, we found that emergence of T. basedowii seedlings was lower in live soil from inside the rings than in live soil from outside the rings. Further, seedling emergence in soil from inside the rings increased significantly in response to soil sterilisation. We found no significant difference in growth between sterile and live soils. However, this might be due to a lack of power caused by high rates of seedling mortality in all treatments. Overall, our study provides evidence for the role of soil pathogens in shaping this iconic Australian grass.

Environmental flows are increasingly being used to restore degraded floodplain vegetation; however, the type of flow regime required for recovery to healthy condition can vary depending on the extent of degradation before restoration. Regulation of the River Murray has affected floodplain ecosystems at many locations, including Bottle Bend Reserve, in south-western New South Wales, Australia. Within Bottle Bend Reserve, tangled lignum (Duma florulenta) dominates sections of the higher floodplain elevations. Lignum is an important and widely distributed Australian shrub occurring in arid and semiarid river systems within the Murray–Darling and Lake Eyre Basins. In an effort to restore floodplain vegetation, three environmental flows were delivered to Bottle Bend Reserve between 2013 and 2016. Flows varied in magnitude, leading to a mosaic of different regimes across the area. Condition surveys were undertaken over 1 year, namely, before, during and after delivery of the September 2016 environmental flow. This study found that the greatest response occurred in lignum plants with no recent environmental water, although lignum plants with one or two recent environmental flows still responded relative to the control. Lignum was in a better condition at sites that received more environmental flows, demonstrating the value of increased frequency of flows in recovering vegetation health.

Rodent populations are dynamic, and fluctuate with environmental conditions and threatening processes, so their numbers and distributions are not spatially static. Many arid and semi-arid areas also remain poorly surveyed, limiting our understanding of species’ distributions. Fauna surveys in the western division of New South Wales recorded new localities for a previously undetected species – Forrest’s mouse (Leggadina forresti) – in Culgoa and Ledknapper National Parks, equating to an easterly range extension of 430 km. Forrest’s mouse appears to persist in riverine plains, and this habitat may serve as important residual intact habitat within the rangelands of NSW. As a native and vulnerable rodent species that occurs at low density, has low trapping success and occurs in an area that is poorly sampled outside of the reserve system, it should be the target of future survey and conservation efforts within the region.

Echidnas are commonly known as ‘spiny ant-eaters’, but long-beaked echidnas (Zaglossus spp.) do not eat ants, whereas short-beaked echidnas (Tachyglossus aculeatus) eat other invertebrates as well as ants. The differences in skull morphology between short- and long-beaked echidnas are related to the differences in their diets, and I tested the hypothesis that there would be differences in beak length of short-beaked echidnas from populations with different diets. Published data on diet from echidnas from different parts of Australia show that echidnas from arid and semi-arid areas (subspecies acanthion) and Kangaroo Island (subspecies multiaculeatus) principally eat ants and termites, whereas the main dietary items of echidnas from south-eastern Australia (subspecies aculeatus) and Tasmania (subspecies setosus) are ants and scarab larvae. Using museum specimens and photographs I measured skull dimensions on echidnas from different parts of Australia: acanthion and multiaculeatus have narrower skulls and shorter beaks than aculeatus and setosus, with setosus being the only Australian subspecies where beak length exceeds cranium length. Australian short-beaked echidnas fall into two groups: aculeatus and setosus from the wetter east and south-east, which eat ant and scarab larvae, and the arid and semi-arid zone acanthion and multiaculeatus, with shorter, narrower skulls, and which eat ants and termites.

Cutoff lows (COLs) are infrequent events in the tropics that can cause extreme rainfall, flash flooding and landslides in arid areas, such as western South America. In this study, the life cycle of a COL in the southeastern Pacific at the beginning of April 2012 was analysed using the ERA-Interim reanalysis dataset. This paper examines: (1) the precursor flow evolution prior to the COL, its development and dissipation by applying the quasi-geostrophic and vorticity equations; and (2) the influence of the COL in the heavy precipitation events over the western Peruvian Andes. During April 2012, the highest amount of precipitation was recorded in Chosica (850 masl) with 37 mm on 5 April. Days prior to the formation of the COL, a subtropical trough deepened by the amplification of a ridge over the tropical Pacific and the incursion of cold air from medium and low levels into the trough. The strong cyclonic vorticity advection was intensified by a short-wave trough embedded inside a long-wave one that strengthened the system on 5 April 2012. In the dissipation stage, warm vertical advection predominated, resulting in the reabsorption of the COL by a new trough. Understanding the behaviour COL systems is important for reducing the impact of these extreme weather events on lives and infrastructure in densely populated areas.

In Australia, climate change and continental drift have given rise to a complex biota comprising mesic specialists, arid-adapted lineages, and taxa that have arrived on the continent from Asia. We explore the phylogenetic diversity and biogeographic history of the Australian trapdoor spider genus Conothele Thorell, 1878 that is widespread in Australia’s monsoonal tropics and arid zone. We sequenced three mtDNA and five nuDNA markers from 224 specimens. We reconstructed the phylogenetic relationships among specimens and estimated the number of operational taxonomic units (OTUs) using species delimitation methods. The timing of divergences was estimated and ancestral area reconstructions were conducted. We recovered 61 OTUs, grouped into four major clades; a single clade represented by an arboreal ecomorph, and three fossorial clades. The Australian Conothele had a crown age of ~19 million years, and ancestral area reconstructions showed a complex history with multiple transitions among the monsoonal tropics, central arid zone, south-west and Pilbara bioregion. Conothele arrived on the continent during periods of biotic exchange with Asia. Since then, Conothele has colonised much of the Australian arid and monsoonal zones, during a period of climatic instability. The Pilbara bioregion harbours high lineage diversity, emphasising the role of climate refugia.

Biological monitoring requires a comprehensive baseline of assemblage distribution patterns and their environmental drivers. In this study we evaluated benthic macroinvertebrates in a regulated river, located in a semi-arid region, which has a seasonal flood pulse and is affected by several anthropogenic pressures. Taxonomic and trophic structures of benthic macroinvertebrate assemblages were analysed in terms of their longitudinal distribution, hydrological regime and environmental factors, including the effects of hydromorphology, riparian land use and water abstraction. Most taxa were generalists and classified in the collector–gatherer functional feeding group. A large taxonomic replacement was associated with hydromorphological characteristics. Local environmental variables were critical for macroinvertebrate assemblages. There was significant temporal variability regarding seasonal flood pulse. Water abstraction for irrigation had a strong effect on assemblage structure. We suggest some challenges and issues for successful implementation of biomonitoring tools in the Dulce River, related primarily to high spatiotemporal variability.

The southern hairy-nosed wombat has a fragmented distribution across the arid and semiarid regions of southern South Australia and south-eastern Western Australia. Its distribution and abundance are highly patchy, with large clusters of warrens in some areas but few to no warrens in adjacent areas. In order to understand why this occurs, we mapped the species’ distribution and correlated the locations of over 8130 data points (5349 presence points and 2781 absence points) with environmental and landscape data. Overall, the wombat distribution is influenced by rainfall, with no wombats in areas where the mean annual rainfall is 227mm per annum. At the regional/local scale, warrens are found only in areas where the soil clay content is between 9 and 40%, and warren abundance is higher in open vegetation classes (saltbush/bluebush shrublands, grasslands) than in closed vegetation (mallee woodlands with shrubby understorey). Over-riding all of these environmental influences are anthropogenic land-use practices: although 38% of the wombats are located in protected areas and 51% are located on grazing land, they are virtually absent from croplands (~2%).

Plant growth is often constrained by low availability of water and phosphorus (P) in soils in arid and semi-arid areas. Aeolian sandy soils cover >90% of the sandy area of the Mu Us Sandy Land (MUSL) in Northwest China. These soils have low water- and nutrient-retention capacity, limiting their ability to support plant growth. Pisha sandstone, a type of loose rock widely distributed in the MUSL, is regarded as an environmental hazard because it easily weathers, resulting in severe soil erosion and water loss. However, the retention capacity of the aeolian sandy soil can be significantly improved through blending with Pisha sandstone. We investigated the impacts of water supply (35% and 70% of soil water-holding capacity) and P supply (0, 5 and 20 mg P kg–1 soil) on plant growth and P and nitrogen (N) nutrition by growing lucerne (Medicago sativa L.) in MUSL aeolian sandy soil amended or not with Pisha sandstone. Soil type and P supply had greater effects than water supply on lucerne growth and on P and N nutrition. Biomass accumulation and shoot P and N concentrations were increased by amending the aeolian sandy soil with Pisha sandstone and increasing P supply. The N:P ratios in shoots indicated that plant growth was limited by P but not by N. Aeolian sandy soil amended with Pisha sandstone and supplied with P at 5 mg kg–1 enhanced lucerne growth; this practice is feasible for pasture development in the MUSL.

Following European settlement of Australia, numerous plant species were deliberately introduced for use in crops, pastures, gardens and horticulture, and others arrived by chance. Many subsequently escaped and became weedy. Of the 54 weed species of natural environments of arid and semi-arid Australia that are considered here, 27 were apparently accidentally introduced, 20 were intentionally introduced and 7 were probably introduced both accidentally and intentionally. Livestock including camels and their harness, and contaminated seed and hay were the most common vectors for accidental introduction. Amongst intentional introductions, rather more ornamental species appear to have invaded successfully than pasture species, but the former generally occupy niche habitats. Recent new introductions are few due to pre-border, border and post-border protections, but many current arid zone weeds continue to spread. Understanding the history of weed invasions can help to guide current and future management by clarifying pathways for introduction.

The Eremaean region, Australia’s arid biome and biogeographic region, has been discussed by botanists (and as the Eyrean, its counterpart for zoogeographers) for over 150 years, yet little progress was made in defining it as an area of endemism until the 2000s. As Australia’s largest biome and biogeographic region, the Eremaean has been defined in a climate sense, but is a historically composite biogeographic area. Taxa that inhabit the Eremaean (Eyrean) tend to display sister relationships to those outside the biome in temperate and monsoonal biome areas, indicating that two or more temporally discordant distributional patterns exist in the Australian flora and fauna. The future of Eremean and Eyrean bioregionalisation will need to incorporate these temporal patterns when constructing new bioregionalisations and historical and climate-based biogeographic models.

The climate of the south-western United States and northern Mexico borderlands is marked by a bimodal precipitation regime with the majority of moisture arriving during the cool season via Pacific frontal storm systems, and intense convective storms during the North American Monsoon (NAM). The fire season occurs primarily during the arid foresummer in May and June, before the development of the NAM. Most tree-ring studies of fire climatology in the region have evaluated only the role of winter precipitation. We used tree-ring-width-based reconstructions of both winter and monsoon precipitation, coupled with fire scar reconstructions of fire history from mountain ranges in the US and Mexico, to quantify the historical role and interactions of both seasons of precipitation in modulating widespread fire years. Winter precipitation was the primary driver of widespread fire years in the region, but years with drought in both seasons had the highest fire frequency and most widespread fires. These relationships define a unique monsoon fire regime, in which the timing and amount of monsoon precipitation are important factors in limiting the length of fire season and regulating widespread fire years.

Optimisation of photosynthesis for environmental fitness is one of the most important approaches to increase productivity and acclimate plants to unfavourable environmental conditions. In this paper, the pathways of optimisation of photosynthesis are considered using novel tools both at the level of an individual plant and plant communities. Fast acclimation of photosynthetic apparatus to the environmental stresses and fluctuations of light intensity and light quality plays an important role in supporting effective photosynthesis. The bioengineered photosynthetic systems responsible for energy dissipation (non-photochemical quenching) and stomatal functioning, as well as some enzymes of CO2 fixation system alongside with introduction of effective mechanisms found in algae or cyanobacteria into chloroplasts, can be used for conservation of effective photosynthesis during such fluctuations. The conversion of some C3 crops grown in hot and arid climates into C4 plants may be a goal for the future. Special focus has been directed towards the detailed description of the photosynthetic optimisation under stress conditions taking into account the specifics of the most common stress factors.

Plants from arid environments have some of the most diverse morphological and anatomical modifications of any terrestrial plants. Most perennials are classified as xerophytes, and have structures that limit water loss during dry weather, provide structural support to help prevent cell collapse during dry periods or store water in photosynthetic tissues. Some of these traits are also found in sclerophyllous plants and traits that may have developed due to evolution of taxa on nutrient poor soils may also benefit the plants under arid conditions. We examined the morpho-anatomical features of photosynthetic organs of three tree and four shrub species with reduced leaves or photosynthetic stems that occur in arid or semiarid sites in Australia to see if there were patterns of tissue formation particularly associated with xeromorphy. In addition, we reviewed information on succulent and resurrection species. In the tree species (Callitris spp.) with decurrent leaves clothing the stems, the close association between the water transport system and stomata, along with anisotropic physiology would allow the species to fix carbon under increasingly dry conditions in contrast to more broad-leaved species. The shrub species (Tetratheca species and Glischrocaryon flavescens) with photosynthetic stems had extensive sclerenchyma and very dense chlorenchyma. The lack of major anatomical differences between leafless species of Tetratheca from arid areas compared with more mesic sites indicates that quite extreme morphological modifications may not exclude species from growing successfully in competition with species from less arid areas. The sclerophyll flora now characteristic of Australian vegetation from seasonally arid climates may have evolved during mesic times in the past but with relatively minor modifications was able to adjust to the gradually drying climate of much of Australia up to the present time.

Accurately estimating and mapping vegetation cover for monitoring land degradation and desertification of arid and semiarid areas using remotely sensed images is promising but challenging in remote, sparsely vegetated and large areas. In this study, a novel method – geographically weighted logistic regression (GWLR – integrating geographically weighted regression (GWR) and a logistic model) was proposed to improve vegetation cover mapping of Kangbao County, Hebei of China using Landsat 8 image and field data. Additionally, a new method to determine the bandwidth of GWLR is presented. Using cross-validation, GWLR was compared with a globally linear stepwise regression (LSR), a local linear modelling method GWR and a nonparametric method, k-nearest neighbours (kNN) with varying numbers of nearest plots. Results demonstrated (1) the red and near infrared relevant band ratios and vegetation indices significantly improved mapping; (2) the GWLR, GWR and kNN methods led to more accurate predictions than LSR; (3) GWLR reduced overestimations and underestimations compared with LSR, kNN and GWR, and also eliminated negative and very large estimates caused by GWR and LSR; and (4) The maximum distance of spatial autocorrelation could be used to determine the bandwidth for GWLR. Overall, GWLR proved more promising for mapping vegetation cover of arid and semiarid areas.

One key tool to manage fragile ecosystems in arid lands is knowledge of land degradation. For this purpose, field-based soil and vegetation characteristics were related to remote sensing information extracted from Landsat OLI moving standard deviation index (MSDI), normalised difference vegetation index (NDVI), soil-adjusted vegetation index (SAVI) and modified soil-adjusted vegetation index (MSAVI) in degraded (watering points and livestock camps) and reference sites of arid rangelands of Iran. Values of spectral indices along grazing gradients at a distance of 50–1500m from the centre of degradation were also extracted and analysed. Statistical analysis (t-test and ordination analysis) shows that MSDI is a sensitive index of landscape heterogeneity and, unlike other indices, exhibits a significant difference between degraded and reference sites. MSDI was sensitive to grazing gradients around watering points and livestock camps, and declined with increasing distance from these areas, although this varied between different sites due to grazing intensity and characteristics of soil and vegetation cover. Soil analysis showed that the amount of organic carbon, mean weight diameter (MWD), geometric mean diameter (GMD) and soil stability indicator (SSI) at reference sites were significantly higher than those at degraded areas. Ordination analysis confirmed the results of t-test regarding the high potential capability of MSDI in separating degraded areas. This simple and practical index can be used to determine ecological thresholds and investigating rangeland condition in arid ecosystems.

Assessing wildfire regimes and their environmental drivers is critical for effective land management and conservation. We used Landsat imagery to describe the wildfire regime of the north-eastern Simpson Desert (Australia) between 1972 and 2014, and to quantify the relationship between wildfire extent and rainfall. Wildfires occurred in 15 of the 42 years, but only 27% of the study region experienced multiple wildfires. A wildfire in 1975 burned 43% of the region and is the largest on record for the area. More recently, a large wildfire in 2011 reburned areas that had not burned since 1975 (47% of the 2011 wildfire), as well as new areas that had no record of wildfires (25% of the 2011 wildfire). The mean minimum wildfire return interval was 27 years, comparable with other spinifex-dominated grasslands, and the mean time since last wildfire was 21 years. Spinifex-dominated vegetation burned most frequently and over the largest area. Extreme annual rainfall events (> 93rd percentile) effectively predicted large wildfires occurring 2 years after those events. Extreme rainfall is predicted to increase in magnitude and frequency across central Australia, which could alter wildfire regimes and have unpredictable and far-reaching effects on ecosystems in the region’s arid landscapes.

Understanding the modalities of aquatic species introductions is important in predicting and preventing new invasions. Australia’s Pilbara Province is an arid region with no naturally occurring freshwater crayfishes. We assessed the population demographics and reproductive potential of redclaw crayfish (Cherax quadricarinatus) in Lake Poongkaliyarra, a major Pilbara water supply reservoir, in which public access and fishing are prohibited. We found the population to have a high relative abundance with a range of size-cohorts present. The species was believed to have first been introduced into the reservoir from at least 2010 and has subsequently been introduced and established in other lotic systems in the region, probably through deliberate releases from the lake for the purposes of providing fishing opportunities to areas where public access is permitted. Introductions of C. quadricarinatus in other parts of Australia and the world have also initially established in reservoirs before subsequently colonising natural systems. The study highlights the potential for reservoirs to act as primary stepping stones for invasion by freshwater crayfish.

ContextThe niche reduction hypothesis (NRH) predicts that the realised niche of declining species is reduced by threats that are mediated by environmental, biotic and evolutionary processes, explaining why species decline in some locations but not others. The critically endangered central rock-rat (CRR) survives only in rugged mountain range habitat in central Australia and is highly vulnerable to cat predation. We predicted that cat density and ranging behaviour, and, hence, predation risk, is mediated by habitat complexity, thus explaining the mechanism maintaining the CRR refuge. AimsWe sought to determine whether cat densities were lower in the rugged CRR refuge than in an adjacent valley dominated by less complex rocky habitats and no longer occupied by CRRs. MethodsWe installed arrays of camera traps along two parallel mountain ranges in the refuge and in the intervening valley habitats. We identified uniquely patterned individual cats and compared spatially explicit capture–recapture (SECR) models to evaluate our hypothesis that cat density varies with topographic complexity. Key resultsThe dominant effect in all models was the significant negative relationship between cat detection probability and fine-scale topographic ruggedness. Two of the best three SECR models indicated lower cat densities and relative home-range sizes in the refuge than in the valley. In total, 17% of cats were detected in both habitat types. ConclusionsWe found some evidence that cat density and home-range size were mediated by habitat complexity. Further, the negative relationship between cat detection probability and topographic complexity suggests that cats spend less time foraging in CRR refuge habitat. ImplicationsCat management programs, aimed at reducing predation pressure on the CRR, must include the refuge and surrounding habitats to control cats that pose a threat to CRR subpopulations.

Finger millet has gained considerable attention worldwide due to its nutritional and health benefits. Being a rainfed crop of semiarid and arid regions, drought is one of the major constraints to its yield stabilisation. To address this, a set of 38 accessions of finger millet were evaluated in both field and mini-lysimeters under both well-watered (WW) and water-stressed (WS) conditions. The objectives of the study were to identify the range of variations for yield components, water-use (WU) and transpiration efficiency (TE) and to examine the potential of the mini-lysimeter system in assessing the genotypic performance in the field conditions. Approximately 2-fold variations in shoot biomass and ~9-fold variations in grain yield under WS conditions were observed. Reproductive growth was more sensitive to WS than the vegetative growth. Our results indicate that in addition to yield potential under WW conditions, WU followed by TE were the other two major contributors toward shoot biomass, whereas, HI followed by TE were the major contributors toward grain yield under WS. The close association between the yield components recorded in the field and in mini-lysimeters suggests that the lysimetric system has the great potential to reflect the genotypic performance under field conditions. Regression analyses suggest that HI explained almost all the variations in grain yield under WW conditions, whereas under WS treatment, next to HI, both TE and WU had also contributed significantly to grain yield. The absence of interrelationship between WU and TE suggests that both these components contribute independently toward the yield components under WW or WS conditions. The accessions with higher shoot biomass and grain yield extract much more water during the post-anthesis stages than the poor performers under WS. Results also suggests that higher WU contributed more towards shoot biomass and higher TE contributed more towards grain yield by improving the harvest index.

In order to predict the livestock carrying capacity in meadow steppe, a method using back propagation neural network is proposed based on the meteorological data and the remote-sensing data of Normalised Difference Vegetation Index. In the proposed method, back propagation neural network was first utilised to build a behavioural model to forecast precipitation during the grass-growing season (June–July–August) from 1961 to 2015. Second, the relationship between precipitation and Normalised Difference Vegetation Index during the grass-growing season from 2000 to 2015 was modelled with the help of back propagation neural network. The prediction results demonstrate that the proposed back propagation neural network-based model is effective in the forecast of precipitation and Normalised Difference Vegetation Index. Thus, an accurate prediction of livestock carrying capacity is achieved based on the proposed back propagation neural network-based model. In short, this work can be used to improve the utilisation of grassland and prevent the occurrence of vegetation degradation by overgrazing in drought years for arid and semiarid grasslands.

In the present study we selected the endangered species Amygdalus mongolica to investigate the influence of climatic fluctuations on the spatial genetic patterns and evolutionary history of organisms in arid northwest China. The intraspecific genetic variation and demographic history of A. mongolica were investigated using two cpDNA sequences (psbK-psbI and trnL-trnF) from 174 individuals in 15 populations across most of its covered range. Significant genetic differentiation among populations was identified, which resulted from fragmented populations coupled with the enhanced aridification and desertification of the Pleistocene. Twelve haplotypes clustered into two clades, corresponding to the Western region (northernmost Gansu, Hexi Corridor and Alxa Left Banner) and the Eastern region (Urad Houqi, Yinshan Mountains, Urad Zhongqi and Daqing Mountains) respectively. Five independent Pleistocene refugia in different mountainous areas were identified. Amygdalus mongolica has likely experienced westward shifts from refugia along the margins of the Ulanbuhe and Tengger deserts, and also postglacial re-colonisation northward along the Hexi Corridor.

Soil organic matter (SOM) plays a major role in agricultural and ecological processes. For this reason, accurate quantification of SOM is important for precision agriculture and environmental management. Inexpensive sensor technology could be a potential approach to achieving the accurate prediction of SOM. The objective of this study was to evaluate inexpensive colour sensor (Nix™ Pro) data for prediction of SOM in arid and semiarid areas of Iran. A total number of 85 and 152 soil samples from the soil surface (0–20 cm) were collected from the Semnan (arid area) and Qazvin (semiarid area) regions respectively. The nonlinear random forest (RF) method and linear regression were conducted to predict SOM using NixTM pro colour sensor data. The partial least-squares approach was also utilised to reduce the dimensions of the dataset, decrease the number of input variables and avoid multi-collinearity. Soil colour was measured in moist and dry conditions. Root mean square error (RMSE), correlation coefficient (r), r-square (R2), mean square prediction error (MSPE) and ratio of performance to interquartile distance (RPIQ) were used to assess the RF and the linear regression models for prediction of SOM. Moist sample data was used for estimation of the SOM because of the larger correlation between SOM and colour sensor data in moist than dry samples. In estimation of SOM, the RF model represented lower dispersion between the estimated and the actual values of SOM (RMSE = 0.42, 0.43, RPIQ = 2.2, 2.06 and MSPE = 0.19, 0.19 in semiarid and arid regions respectively). In contrast, more dispersion was obtained by applying the linear regression model (RMSE = 0.61 and 0.51, RPIQ = 1.47 and 1.76, and MSPE = 0.39 and 0.26 in semiarid and arid regions respectively). The RPIQ values for linear regression in arid and semiarid areas were 1.76 and 1.47 respectively. Hence, the use of a linear regression model for prediction of SOM in arid areas would result in acceptable reliability; however, its utilisation should be avoided in semiarid areas due to less reliable results.

The aim of this study was to describe the morphology, anatomy and function of underground structures associated with colonies of Solanum centrale J.M.Black (Australian bush tomato), a perennial sub-shrub found in arid areas of Australia and an important traditional staple food for Aboriginal people. It is known that this species forms clonal communities, but there is little understanding of the mechanisms of formation in either natural or cultivated situations. The underground connections within seven clonal communities from Central and South Australia were documented and samples of secondary roots, thick lateral roots and stems were examined under both laboratory and glasshouse conditions. Clonal communities were observed at all sites with individual ramets arising from lateral roots (root-suckers) that ranged from 2–10 mm in diameter growing in a network 5–15 cm below the soil surface. Lateral roots have dicotyledonous root anatomy and rapidly resprout to form new clonal ramets. They also have the capacity to accumulate starch in parenchyma cells. The morphology and root-suckering ability resemble those of weedy Solanum spp. from other parts of the world, as well as species from a variety of genera adapted to arid climates. Methods to capitalise on the ability of lateral roots to form clonal ramets in cultivated situations, particularly given the difficulties in establishing crops from seed, are discussed.

Introduced livestock may indirectly affect bird species by decreasing vegetation structure and affecting the selection of nesting sites. This is especially true for birds that use shrubs as the raw material for nest construction or for nest placement. Nesting in inadequate supporting structures or the use of inadequate raw material for nest building may increase nest vulnerability (e.g. increasing structure weakness, falling and nest exposure to predation). Accordingly, bird species show a great variation in the selectivity of nesting sites and the raw material they use. Furnariidae family members exhibit an extraordinary diversity in nest placement and structure, which allows them to survive in different arid environments. I report here on a study of nest site selection of two common furnariid species, Leptasthenura aegithaloides and Pseudoseisura gutturalis, across a grazing gradient composed by nine independent paddocks within the same arid habitat. These species use large closed-nests (>40 cm long) built with thorny branches, placed on spiny shrubs. I measured nest abundance and supporting plants characteristics, vegetation structure, browsing intensity and compared the plants selected by the birds with the surrounding vegetation. These bird species used only few plant species for nest building and location. Livestock significantly reduced vegetation cover of the species used to build and place the nests, affecting nest site selection and reducing nest abundance. As livestock density increased, both species selected aggregated plants and the tallest plants for nesting, which may increase nest exposure. Therefore, livestock may indirectly affect nest-site selection of birds ultimately affecting their nesting ecology. This work illustrates how domestic livestock, through decreasing plant cover, may affect native biota with consequences on key species within an ecosystem.

This paper presents an integrated model of the variation over a continental landmass of myxomycetes, a single-celled organism in the phylum Amoebozoa. Bark samples were collected on long traverses across Australia, and cultivated in Petri dishes by the moist chamber technique to obtain large assemblages of common species. The results of this survey and previous surveys are consistent with there being four major myxomycete assemblages: Tropical, Northern Arid, Southern Arid and Temperate. Where mapped, these species assemblage regions are consistent with the Australian phytogeographical regions. The myxomycetes differ between arid and non-arid areas; the arid areas have slightly higher productivity per wetting event, with members of the Physarales and Liceales relatively important and the Stemonitidales, Trichiales and Cribrariales less important. When the bark samples are placed in a moist culture there is a myxomycete growth cycle and then the population declines to resting phases. The population increase during a growth phase can be modelled by a linear plot of log(abundance) against species rank, where abundance is total harvested spore volume of a species. The population decline appears to be linear from two weeks after watering, declining to negligible activity 4 weeks after watering.

Mulga (Acacia aneura) woodlands dominate much of arid and semiarid Australia. Although mulga woodlands are floristically and structurally diverse, the composition of the mulga avifauna is consistent across the continent, with 50–70% of bird species shared between sites and a high proportion of migratory and nomadic species. A comparison of avian foraging guilds in mulga woodlands in the Murchison and Gascoyne Bioregions of Western Australia with those in the Northern Territory identified nine guilds. All guilds occurred at the three locations studied during wet years. The number of bird species, species’ abundances, and the number of guilds declined on the Western Australian sites when there was less rain. Despite the commonality of guilds and species between sites, there were differences between sites and years in the grouping of species, with many species best associated with two or more guilds. These differences reflected differences between locations and wet and dry years in the food resources available to birds, which affected how species foraged. Particularly noticeable were the differences between sites and years in migratory and nomadic birds, which in Western Australia and the Northern Territory were the most abundant birds during wet conditions, but largely absent when conditions were drier.

In arid Australia, fires in different seasons often result in markedly different recruitment rates of woody plants, and this can have important and long-lasting impacts on post-fire community structure and composition. The current study investigated ecological mechanisms behind this effect in four widespread arid Acacia species: Acacia aptaneura, Maslin & J.E.Reid Acacia kempeana F.Muell., Acacia maitlandii F.Muell. and Acacia melleodora Pedley. Specifically, the study examined whether increased recruitment after summer compared with winter burning relates to (1) higher soil temperatures during summer fires having increased capacity to overcome dormancy of seeds with heat-stimulated germination; (2) warmer soil temperature conditions after summer fires providing more favourable incubation temperatures for germination; and/or (3) summer fires coinciding with seasonal fluxes in seedbank densities, which may occur in response to granivory and/or rapid rates of seed deterioration after dispersal. Results supported hypotheses (1) and (2), as germination of all species responded positively to heat shock and warmer incubation temperatures. Some support was also demonstrated for hypothesis (3), as seedbank densities were shown to fluctuate seasonally, most likely in response to strong granivory. This multi-species study provides insights into mechanisms behind enhanced shrub recruitment after arid zone summer fires; and reinforces the notion that season of burn can be a strong determinant of regeneration trajectories of woody plants after fire.

Describing, classifying and quantifying vegetation communities is fundamental for understanding their current distribution, rarity, interrelationships and ecosystem functions. In the present study, we apply a consistent objective classification system for ephemeral wetlands of arid and semi-arid areas of New South Wales (NSW), Australia. Our approach uses a two-step statistically based, hierarchical, multiscale classification of environmental data at broad scales and floristics data at intermediate scales. At broad scales, ecoregionalisation methods were used to describe three wetland macrogroups. Within these groups, we performed unsupervised analyses of 640 floristic survey plots using the Bray–Curtis algorithm, clustering by group averaging and testing of clusters using similarity profile analysis (SIMPROF). From this we delineated 18 vegetation groups with class definition based on a combination of diagnostic and non-diagnostic similarity percentage analysis (SIMPER) outputs and dominant taxa. We show that a consistent classification system can be effectively created for subsets of vegetation that have adequate plot data within a general matrix that is poorly sampled if outputs are restricted to appropriate scales of resolution. We suggest that our approach provides a stable and robust classification system that can be added to as more data become available.

Pale field-rats have long disappeared from Australia’s arid and semiarid zones, other than for some Pilbara islands and a single mainland population of indeterminate status and extent identified at Shark Bay in 1968. Hence, it was noteworthy when a field-rat was first caught at Heirisson Prong in 1994, 40 km north-east of the previous location at Shark Bay. Further individuals were caught regularly from late 1995. The population peaked in July–October 2000 (with captures of ~190 individuals per month) and had collapsed by July 2001 (with only the occasional animal caught thereafter). None were caught beyond 2006, despite regular trapping to 2013. This irruption and collapse was beyond the established range of the species and was in atypical habitat. Widespread trapping after the collapse suggested that the population inhabited few localised ‘source’ areas and a broad area of ‘sink’ habitat, with the latter occupied only after extraordinarily high rainfall events leading to higher grass cover. A return to dry years and the consequent loss of cover (aided by an abundant rabbit population) and strong growth in predator numbers (feral cats and small birds of prey) in response to the high number of field-rats appears to have facilitated the collapse.

Climate change will affect how the Normalised Difference Vegetation Index (NDVI), which is correlated with climate factors, varies in space and over time. The Mongolian Plateau is an arid and semi-arid area, 64% covered by grassland, which is extremely sensitive to climate change. Its climate has shown a warming and drying trend at both annual and seasonal scales. We analysed NDVI and climate variation characteristics and the relationships between them for Mongolian Plateau grasslands from 1981 to 2013. The results showed spatial and temporal differences in the variation of NDVI. Precipitation showed the strongest correlation with NDVI (43% of plateau area correlated with total annual precipitation and 44% with total precipitation in the growing season, from May to September), followed by potential evapotranspiration (27% annual, and 30% growing season), temperature (7% annual, 16% growing season) and cloud cover (10% annual, 12% growing season). These findings confirm that moisture is the most important limiting factor for grassland vegetation growth on the Mongolian Plateau. Changes in land use help to explain variations in NDVI in 40% of the plateau, where no correlation with climate factors was found. Our results indicate that vegetation primary productivity will decrease if warming and drying trends continue but decreases will be less substantial if further warming, predicted as highly likely, is not accompanied by further drying, for which predictions are less certain. Continuing spatial and temporal variability can be expected, including as a result of land use changes.

Urban developments affect neighbouring ecosystems in multiple ways, usually decreasing native biodiversity. Arabian arid rangeland was studied to identify the primary causes of biodiversity variation. Al Marmoum is a 990km2 area on the urban edge of Dubai, designated for ecological ‘enhancement’ and outdoor recreational use. The area lacks historical biodiversity data, but is thought to be primarily influenced by Arabian camel (Camelus dromedarius Linnaeus, 1758) herbivory. Perennial floral and faunal diversity was assessed at 54 sites. Counts of reintroduced ungulates (Arabian oryx Oryx leucoryx (Pallas, 1777), Arabian gazelle Gazella gazella cora (C.H. Smith, 1827) and sand gazelle G.subgutturosa marica (Thomas, 1897)) were made at 79 separate sites. Correlations of observed biodiversity with substrate type, anthropogenic structures, and ungulate distribution were assessed. Native biodiversity was substantially higher in north-north-west locations near recreational facilities, with the most likely cause being differential browsing pressure. Camel browsing faced greater communal regulation in the north-north-west, whereas oryx and gazelles congregated at feed points in the south-south-east that were farther from human activity. Arid rangeland in this socioecological landscape exhibits greater natural biodiversity at the urban fringe. Human activity reduces ungulate density, enabling a greater diversity of perennial flora, which then attracts non-ungulate fauna. Anthropogenic features can therefore offer conservation value in landscapes where ungulate populations are artificially elevated.

White horehound (Marrubium vulgare L.), is a troublesome weed of arid zones, particularly in cropping and grazing areas. Understanding the seed ecology of white horehound is relevant to its management. The present study investigated the effects of temperature, light, osmotic potential, salinity, pH, and seeding depth on seed germination and seedling emergence of white horehound. Seeds germinated over a wide range of temperatures, with highest germination (100%) occurring at 25/20°C in either 12-h alternating light/dark or complete darkness. Germination decreased from 92% to 10% as the osmotic potential decreased from 0 to minus 0.6 MPa and germination was completely inhibited at minus 0.8 MPa. Increasing concentration of sodium chloride (salinity) from 50 to 150 mM reduced germination from 68% to 11% but was completely inhibited at 200 mM. Germination was not limited by variation of pH in solutions of pH 5 to pH 10. Maximum germination (99%) occurred at pH 7, but slightly decreased (90%) in acidic or alkaline media. Surface located seeds were highly germinable (87%) where seedling emergence significantly declined as seeding depth increased from 0.5 to 3 cm. Nil seedling emergence was occurred at 4 cm burial depth. Light significantly affected germination, time to 50% germination, mean germination time and germination index. Increasing osmotic and salinity stress both significantly increased the time to start germination, time to 50% germination, mean germination time, but decreased germination index. Burial depth adversely affected seedling emergence with surface located seedlings emerging earlier (4.2 days) compared with 20 days for seeds buried at 3 cm. Results suggest that effective management of white horehound should consider targeting surface located seeds in combination with tools that induce minimal soil disturbance, particularly in relatively non-saline environments.

Santalum spicatum (R.Br.) A.DC is a West Australian sandalwood species highly valued for the sesquiterpene-rich oil in mature heartwood. The oil composition, particularly levels of the valuable sesquiterpenoids α- and β-santalol and the allergenic E,E-farnesol, are known to vary across its natural distribution. Our study investigated associations of oil characteristics in 186 S. spicatum trees in semiarid and arid regions of Western Australia with genetic structure, environmental parameters and morphological features. We found associations between oil composition and genetic structure, as well as between oil composition and environmental factors. Analysis of individuals using STRUCTURE revealed two major genetic clusters (K = 2), comprising trees from the arid north clustered together, and the semiarid south-west clustered separately. Mantel tests revealed a significant association between oil characteristics and genetic distance (r = 0.129, P = 0.02). There was considerable variation in the growing environment of S. spicatum. An Adonis test showed a significant association between oil composition and provenance (P = 0.001) and between oil composition and soil type (P = 0.002) but not oil composition and other environmental characters. Soil type was significantly related to santalol and E,E-farnesol content. No significant associations between oil composition and morphological features were identified.

Australia’s deserts can appear to be desolate and harsh environments, but they are extremely dynamic places that support a range of species adapted to the boom and bust conditions. Despite the resilience of the arid zone, extinction rates in arid Australia are the highest in the country and the majority of medium-sized mammals have been lost since European settlement. Katherine Moseby is a conservation biologist who lives and works in the Australian arid zone, with a particular focus on threatened species and reintroductions. She provides a brief background on arid zone ecology in Australia and the story of how she went from city slicker to desert dweller. A discussion on what it means to be a woman in conservation science is included with some insights into juggling a career and a family in a remote location.

Populations of many arid-zone rodents are known to fluctuate dramatically in response to the boom–bust cycles of the dynamic landscapes in which they occur. This constrains their study, particularly efforts to determine the location and functioning of important refuge areas. The nationally vulnerable plains mouse (Pseudomys australis) undergoes dramatic population changes in response to rainfall and associated resource abundance. At low population density during resource shortages, the species can be present yet undetectable by conventional trapping methods. We piloted the use of hair tubes as an alternative to trapping, trialling designs effective in detecting P. australis. Baited 25-mm- or 32-mm-diameter × 200-mm-long tubes with double-sided cloth tape in the entrance were effective in collecting P. australis hair. Each of the 21 detections of the species’ presence through hair tubes was confirmed using other methods. Hair tubes effectively detected the species, including during times when Elliott trapping yielded low capture rates and observational techniques failed to detect them. Hair tubes may present a time- and cost-efficient tool for determining the presence of P. australis and other cryptic small mammals in remote arid landscapes.