Earth’s land cover consists of forests, agricultural land, urban settlements and a large, heterogeneous category that includes deserts, grasslands, savannas, shrublands and tundra. This heterogeneous category has eluded a collective designation comparable to that of forests, which has contributed to its omission from multilateral programs and critical global initiatives. Potential designations for this land category – drylands, grasslands, grassy biomes, open ecosystems and rangelands – were evaluated for their relative advantages and disadvantages. Grassy biome is recommended as the most appropriate designation because it conveys a meaning that is distinct from forests, emphasizes that grasses often coexist with other plant growth forms and has great utility for use by multilateral organizations. However, the criteria of tree canopy cover >10% used by the Food and Agriculture Organization (FAO) to define forests represents a major obstacle to implementation of the grassy biome designation. This minimal canopy cover infringes on global savannas that occupy 20–25% of global land area. An assessment of the functional plant traits determining the shade and fire tolerance of savanna and forest trees indicates that a minimal tree canopy cover of 45% represents an ecologically appropriate demarcation between savannas and forests.

Bibliometric research illuminates the scientific development of soil health (SH) studies in the Brazilian Semiarid, which are crucial for sustainable agriculture and mitigating climate change impacts. However, research trends on SH in the Brazilian Semiarid are still not well understood. This study aimed to illustrate how SH has been addressed in research concerning the Brazilian Semiarid. Terms such as ‘soil health,’ ‘soil quality,’ ‘biological quality,’ ‘chemical quality,’ ‘physical quality,’ as well as ‘Caatinga,’ ‘Brazilian Semiarid,’ and ‘Brazilian Northeast’ were searched in the Scopus® database. Bibliometric parameters were catalogued by the number of publications per year, most cited articles, primary institutions, main journals, and keyword frequency. The articles were evaluated based on the examination of chemical, physical, and biological indicators, and a similarity test was conducted to group articles according to these indicators. The bibliometric analysis reveals a significant increase in scientific output since 2020. Embrapa research centres contribute significantly to this expanding body of knowledge, with the leading journal ‘Revista Caatinga’ reflecting a specialized focus on the region’s unique challenges. The most evaluated indicators were pH, soil organic carbon, P, Ca2+, Mg2+, K+, and bulk density, but the prevalence of biological indicators, such as soil organic carbon (SOC), activity of enzymes such as alkaline and acid phosphatase, and ß-glucosidase, microbial activity, and soil fauna, underscores key research themes. These findings highlight the practical implications of SH research, but while increased research is commendable and increasingly necessary, studies are still scarce. Increased research is vital for the development of strategies that contribute to the long-term sustainability of the Brazilian Semiarid region.

Contrary to the common perception of hyperarid drylands as barren and lifeless, these regions are home to some of the planet’s most unique biodiversity and support over 100 million people. Despite their ecological and human significance, hyperarid drylands remain among the least studied biomes in the world. In this article, we explore how improving our understanding of hyperarid ecosystems in the Middle East can yield valuable insights applicable to other hyperarid regions. We examine how ongoing greening initiatives in the Middle East offer a unique opportunity to deepen our knowledge of dryland ecology and advocate for the establishment of a comprehensive research program in the region. This program would focus on ecosystem functionality across spatial and temporal scales, setting the stage for a global monitoring network for hyperarid drylands. Such efforts would inform conservation strategies and climate change mitigation, while also shedding light on the resilience and adaptability of hyperarid ecosystems to environmental change. Ultimately, this monitoring would guide management practices to preserve biodiversity, enhance ecosystem services and promote sustainable development in hyperarid regions worldwide.

We combined tools of phylogeography, population genetics and biogeographical interpretation to analyse a group of phylogenetically independent lineages (animals and plants) that coexist within the same geographical region, yet under markedly different environments, in order to identify generalized barriers for gene flow. We tested the hypothesis that major geographic features have produced a concordant genetic structure in phylogenetically independent lineages. A rigorous bibliographic search was performed, selecting available molecular information from six taxa occupying distinct southern biomes of South America: Yungas, Prepuna, Puna and northern Monte. We estimated within-population genetic diversity, the genetic structure and haplotype phylogenies to assemble distribution maps of genetic barriers for each species. We found a strong association between genetic variation and latitudinal distribution of populations. We detected a major barrier for six taxa at 27°S latitude and a second one for a group of three species at 25–26°S. Two alternative non-exclusive hypotheses – geology and/or climate – explain concordant genetic barriers in divergent lineages. We suggest that the term ‘biogeographically significant units’ portrays a group of populations of phylogenetically unrelated taxa that inhabit the same geographic region that have been similarly impacted by major physical events, which can be used to identify priority areas in landscape conservation.

Rain-fed cultivation in drylands—especially in arid and hyper-arid areas—is often considered to play a minor role in human subsistence. Drawing upon the results of ethnoarchaeological research in North Africa, this paper reviews non-irrigated agricultural practices in the absence of anthropogenic water-harvesting structures, and presents a proposal for how such practices can be identified in the drylands of the past. An improved understanding of the long-term development of rain-fed cultivation augments our knowledge of past land-use strategies and can inform future models of sustainable agriculture in some of the world's driest regions.

Russian-thistle (Salsola tragus L.), is a nonnative, C4 photosynthesizing, annual plant that infests disturbed and natural areas in the arid U.S. Southwest. Land managers of natural areas may need to decide whether a S. tragus infestation is potentially harmful and whether it should be actively managed. One factor informing that decision is an understanding of the conditions under which this weed emerges and establishes and how those processes affect where and when infestations occur. We studied S. tragus establishment on aeolian (windblown) sandy soils at Petrified Forest National Park, AZ. Our sites were a previously disturbed sand sheet and a semistabilized sand dune. Measurements in plots on these sites over two growing seasons revealed a similar number of S. tragus seedlings emerging on both sites early in the 2015 growing season. As the season progressed, S. tragus cover (seedling survival and growth) was lower on the sand dune, except for a plot placed entirely on a coppice mound. In 2016, S. tragus seedling emergence and development of cover, measured on plots at both sites, was exceptionally low, as was summer rainfall. A growth chamber assay of seedling emergence from soil and litter samples collected at each site showed emergence was greatest from samples collected where S. tragus litter remained on the soil surface, and otherwise was infrequent. Our study suggests that S. tragus emergence and early establishment are sensitive to low precipitation and that soil-surface microtopography and grass and shrub cover may be determinants of the spatial pattern of infestation on sandy soils. As aeolian sands occur throughout drylands of the U.S. Southwest, deeper understanding of the conditions under which S. tragus seedlings emerge and establish can inform management of this invasive annual in those habitats.

Genetic diversity is the raw material for species’ persistence over time, providing the potential to survive stochastic events, as well as climate and/or human-induced environmental changes. Biodiversity in dry rangelands is decreasing due to intensification of livestock production, but its effects on the genetic diversity of the consumed biota have seldom been assessed. We examined livestock effects on the genetic diversity of two dominant creosote species of the Patagonian Monte Desert, Larrea divaricata and Larrea cuneifolia. We deployed competing hierarchical regression models to assess the relationship between genetic variation within natural populations as a function of increasing stocking rates on ten arid rangelands. These species exhibit similar levels and patterns of genetic structure, with high levels of both inbreeding and divergence among locations. We found that increased stocking reduces genetic variation and increases genetic subdivision between populations. Our results indicate that grazing pressures are impoverishing the gene pool of these dominant native species of the Monte Desert, decreasing the evolutionary potential of the primary plant producers and increasing the desertification risk for a vulnerable habitat. We highlight the importance of considering livestock as a major driver of genetic losses in dry rangelands under overgrazing pressure, especially given current forecasts of climate change.

Mammal species contribute in different ways to seed dispersal effectiveness, acting as endozoochorous dispersers, scatter-hoarders and seed predators. Seed removal by these functional mammal groups could be affected by anthropogenic drivers, such as grazing management, a common practice in drylands. We evaluated removal of seeds from a native tree species (Prosopis flexuosa) by terrestrial wildlife mammals with different functional roles, on grazed and ungrazed sites and at different times during the fruiting period of Prosopis. We offered Prosopis fruits, each containing 15 seeds, to animals and used camera traps to identify the species removing them. We obtained the number of seeds removed (1 fruit removed = 15 seeds removed) by each animal species and each functional group. Native and domestic mammals removed 65.4% of the total seeds offered; 69.5% of offered seeds were removed from the grazed area and 61% from the ungrazed site. Considering removal times, 64.25% of offered seeds were removed during the beginning of the fruiting period of Prosopis and 67% towards the end of this period. Small mammals acting either as seed predators (Graomys griseoflavus and Akodon dolores) or scatter-hoarders (Microcavia australis) were the functional mammal groups removing the highest amount of seeds. Seed predators removed more seeds from the ungrazed site, whereas the scatter-hoarder did so at the grazed site. In the ungrazed area, it would be important to ensure habitat heterogeneity in order to improve seed removal by functional groups that disperse seeds, such as endozoochorous dispersers and scatter-hoarders.

Mimosa luisana is functionally important in the Tehuacán-Cuicatlán Valley, Mexico, since it is able to create favourable microsites for the establishment of other plant species. The endozoochory of M. luisana seeds by goats was evaluated in terms of excrement deposition pattern, seed survival and germination. The excrement deposition pattern was evaluated by collecting pellets in four plots of 25 × 2 m randomly placed in a grazing area and recording the microhabitat where pellets were found. Seed survival and germination were evaluated by feeding the goats with seeds and collecting dung pellets at 8-h intervals for 80 h. Seeds from goat pellets (treatment) and seeds collected from pods (control) were placed in a germination chamber for 24 d. Goats mainly deposited M. luisana seeds in viable sites (open areas) for growth. Mimosa luisana seeds survived the goat digestive treatment (5.91% ± 2.86%) and most of them (67% ± 25.9%) were recovered 8–32 h after ingestion. Goat gut treatment increased M. luisana final germination (47.5% ingested, 5.83% control) and shortened initial and mean time of germination. Our results indicate that goats may be an efficient disperser of M. luisana seeds.

Investigations into the potential impacts of selectively managing Apis mellifera on pollination ecology were carried out in several sites in Tsavo National Park of southern Kenya, a typical arid African environment. Temperature alone contributed significantly to the foraging patterns of both managed honeybees and wild bee species within the acacia–commiphora community. Honeybees, vulnerable to heat stress, foraged earlier in the day than wild bee species. Foraging patterns of the latter ranged from oligolectic to broadly non-specialized. Floral biology and adaptations were also considered in the analysis of divergent foraging trends. Observations suggest that honeybees potentially out-compete highly specialized wild bee species for scarce seasonal floral resources. No evidence was found of direct interaction on abundant seasonal floral resources such as the mass synchronous flowering of Acacia spp. at current managed honeybee densities. Investigation of visitors revealed a high diversity of potential insect pollinators, particularly high in wild bee species (Apoidea) diversity. Suggestions for the improved management of honeybees in arid African environments include shading of hives, providing access to water with protection from predators, and cultivation of indigenous, nectariferous plants close to hive colonies.