Biological soil crusts (biocrusts) are a coherent, thin soil surface layer, engineered and inhabited by a diverse community of moss, lichen, cyanobacteria, and other microorganisms. Biocrusts provide critical functions in dryland systems and may be lost from the ecosystem through physical disturbance or other global change drivers. Once biocrusts are lost, natural recovery can occur very slowly. This has led to the development of biocrust rehabilitation strategies, including cultivation of biocrust propagules to inoculate degraded sites. As the need for biocrust restoration grows in scale and across different regions, inoculum cultivation and application methods are being asked to keep up. In this work, we evaluate cyanobacterial community composition and abundance in greenhouse and field cultivation systems, with and without growth substrate and shade treatments. We also consider cultivation of locally and non-locally sourced biocrust inocula at a single cultivation facility on the Colorado Plateau. We found that field cultivation is a viable option for biocrust cultivation. For almost all cyanobacteria, habitat amelioration was necessary for growth in the field. Despite differences in inocula composition following cultivation, restoration outcomes five months after inoculation were poor with no significant increases in cyanobacterial abundance, soil chlorophyll a, or soil exopolysaccharide content. Thus, more work is needed to boost the initial growth and survival of biocrust inocula, regardless of the method of cultivation (i.e., greenhouse or field). Future work focused on assessing opportunities for habitat amelioration during application to improve biocrust establishment during this critical restoration phase would be highly valuable.

Six years remain to achieve the Sustainable Development Goals (SDGs). Despite some progress, institutional effectiveness for SDG achievement has not been delivered at a national level. Identification and establishment of an institutional framework to operationalise the 2030 Agenda within national plans, giving science-based coordination of SDG implementation a central role, is urgently required to accelerate progress. This paper tackles this challenge. Drawing on literature analysis, it asks: 1) What are the deficiencies in institutional national arrangements that hinder SDG implementation? 2) How can existing institutional deficiencies in SDG implementation be addressed? and 3) How can institutional changes support fast-tracking of SDG implementation processes at national level? Findings show that country-specific horizontal institutional arrangements are usually advanced. However, national visions to improve mainstreaming across decision-making at different levels to enable whole-of-government and whole-of-society approaches to SDG implementation are commonly under-developed. Deficiencies are due to poor systematic engagement of scientific and technical expertise in operational day-to-day communication, as well as in the design, validation, implementation, monitoring and reporting of domestic SDG-related multi-stakeholder actions. Vertical institutional arrangements are complex, and risk resource-consuming, uncoordinated implementation. Our analyses suggest countries may benefit from establishing a national, centralised independent scientific and technical coordinating body for SDG implementation at national level, within existing science-based institutional arrangements. Such a body would not be led by governmental processes but would provide technical support to government agencies. We argue that scientific and technical skills in data and information management and quality control are central to coordinated and evidence-informed support, and could help to accelerate national SDG implementation. Such a supporting body would also enable a more joined-up approach between stakeholders working in the areas of science and technology, government and practice, improving orchestrated science-based actions and their auditing across sectors and stakeholder communities at national and sub-national levels. It would further guide actions to reduce trade-offs within national sustainable development aspirations, and would facilitate consideration of diverse values in advancing towards a durable and just transformative future. Such efforts are vital given the rapidly closing window of time for SDG achievement.

Granivores, such as rodents and harvester ants, are common in dryland ecosystems. In intact dryland ecosystems, the effects of such granivores on soil seed banks, plant community structure, and ecosystem functioning are well established. However, the effects of granivores on dryland restoration have received much less attention. In this study, we evaluated the seasonality of seed removal by harvester ants, seed preference of harvester ants, and effects of granivore exclosure on the soil seed bank at four sites in southeastern Utah. We studied two species of harvester ants, Pogonomyrmex rugosus and P. occidentalis . The foraging behavior of Pogonomyrmex spp. was temperature‐dependent; they removed no seeds during winter months, and up to 80% of seeds during high activity in the summer. Despite seasonal differences in seed removal, Pogonomyrmex spp. did not show significant preferences for seed species. However, their seasonal foraging behavior translated into measurable differences in an experimental soil seed bank. Over the summer months, ants reduced the number of seeds in the seed bank by approximately 20%, but when ants were excluded during the winter, the number of seeds in the seed bank remained the same. This finding supports the timing of business‐as‐usual seeding practices of applying seeds in late fall. If seeds germinate in the first season after application, ant granivory is unlikely to pose a large barrier to establishment. However, if seeds remain dormant during the first year, as is common in many dryland species, seeds are vulnerable to ant granivory.

Up to 35% of global drylands have experienced degradation due to anthropogenic impacts, including physical disturbances like trampling and soil removal. These physical disturbances can result in the loss of soil communities known as biological soil crusts (biocrusts) and the important functions they provide, such as soil stability and fertility. The reestablishment of biocrust organisms after disturbance is determined by many factors, including propagule availability, climate, and vascular plant community structure. The role of these factors in natural recovery may be intensified by the extent (or size) of a disturbance. For example, large disturbances can result in reduced propagule availability or enhanced erosion, which impact both the dispersal and establishment of biocrust organisms on disturbed soils, leading to a slower natural recovery. To test how disturbance extent impacts biocrust's natural recovery, we installed four disturbance extents by completely removing biocrust from the mineral soil in plots ranging from 0.01 m2 to 1 m2 and measured productivity and erosion resistance. We found that small disturbance extents did not differ in chlorophyll a content, total exopolysaccharide content, or soil stability after 1.5 years of natural recovery. However, the concentration of glycocalyx exopolysaccharide was higher in the smallest disturbances after the recovery period. Our results indicate that disturbances <1 m2 in scale recover at similar rates, with soil stability returning to high levels in just a few years after severe disturbance. Our findings align with prior work on biocrust natural recovery in drylands and highlight the opportunity for future work to address (1) cyanobacteria, moss, and lichen propagule dispersal; (2) rates and mechanisms of biocrust succession; and (3) the role of wind or water in determining biocrust colonization patterns as compared to lateral growth.

Land use practices and climate change have driven substantial soil degradation across global drylands, impacting ecosystem functions and human livelihoods. Biological soil crusts, a common feature of dryland ecosystems, are under extensive exploration for their potential to restore the stability and fertility of degraded soils through the development of inoculants. However, stressful abiotic conditions often result in the failure of inoculation-based restoration in the field and may hinder the long-term success of biocrust restoration efforts. Taking an assisted migration approach, we cultivated biocrust inocula sourced from multiple hot-adapted sites (Mojave and Sonoran Deserts) in an outdoor facility at a cool desert site (Colorado Plateau). In addition to cultivating inoculum from each site, we created an inoculum mixture of biocrust from the Mojave Desert, Sonoran Desert, and Colorado Plateau. We then applied two habitat amelioration treatments to the cultivation site (growth substrate and shading) to enhance soil stability and water availability and reduce UV stress. Using marker gene sequencing, we found that the cultivated mixed inoculum comprised both local- and hot-adapted cyanobacteria at the end of cultivation but had similar cyanobacterial richness as each unmixed inoculum. All cultivated inocula had more cyanobacterial 16S rRNA gene copies and higher cyanobacterial richness when cultivated with a growth substrate and shade. Our work shows that it is possible to field cultivate biocrust inocula sourced from different deserts, but that community composition shifts toward that of the cultivation site unless habitat amelioration is employed. Future assessments of the function of a mixed inoculum in restoration and its resilience in the face of abiotic stressors are needed to determine the relative benefit of assisted migration compared to the challenges and risks of this approach.

Regulation of alien invasive species by indigenous generalist herbivores is a strong component of ecosystem biotic resistance. Globally, Australian Acacia species are highly invasive trees that are regulated by specialist invertebrate herbivores, granivorous birds and consumption by indigenous and exotic vertebrates in their native ranges. Australian Acacias have become highly invasive in the Cape Floristic Region (CFR) of South Africa where seeds are consumed by generalist bird, ant, and rodent species, but there is as yet no evidence that generalist herbivores consume the seedlings. Despite this, indigenous mice are common in the CFR and we consequently hypothesised that seedling herbivory by indigenous herbivores may limit survival of Acacia cyclops in relatively undisturbed indigenous ecosystems. Acacia cyclops seedlings were transplanted into indigenous CFR coastal “strandveld” vegetation at two distinct study sites and monitored for eight days in one of three caged treatments (i) no cage, (ii) partially caged excluding large mammalian herbivores or (iii) fully caged excluding all mammalian herbivores. Herbivory-induced seedling mortality without a cage and for partially caged plants was significantly greater than for fully caged plants (all contrasts P < 0.001). Rapid herbivory of A. cyclops seedlings in the uncaged and partially caged treatments was largely attributable to highly abundant striped mice, Rhabodmys pumilio. Seedling herbivory was not dependent on rodent density, which was consistently high (200–300 mice ha−1). However, seedling herbivory was higher in areas with dense vegetation and lower in open-canopy areas, probably because R. pumilio is known to avoid foraging in open areas. These generalist herbivores reduced A. cyclops recruitment in relatively undisturbed indigenous ecosystems, contributing to a degree of ecosystem resistance.

Studies of biological soil crusts (biocrusts) have proliferated over the last few decades. The biocrust literature has broadened, with more studies assessing and describing the function of a variety of biocrust communities in a broad range of biomes and habitats and across a large spectrum of disciplines, and also by the incorporation of biocrusts into global perspectives and biogeochemical models. As the number of biocrust researchers increases, along with the scope of soil communities defined as 'biocrust', it is worth asking whether we all share a clear, universal, and fully articulated definition of what constitutes a biocrust. In this review, we synthesize the literature with the views of new and experienced biocrust researchers, to provide a refined and fully elaborated definition of biocrusts. In doing so, we illustrate the ecological relevance and ecosystem services provided by them. We demonstrate that biocrusts are defined by four distinct elements: physical structure, functional characteristics, habitat, and taxonomic composition. We describe outgroups, which have some, but not all, of the characteristics necessary to be fully consistent with our definition and thus would not be considered biocrusts. We also summarize the wide variety of different types of communities that fall under our definition of biocrusts, in the process of highlighting their global distribution. Finally, we suggest the universal use of the Belnap, Büdel & Lange definition, with minor modifications: Biological soil crusts (biocrusts) result from an intimate association between soil particles and differing proportions of photoautotrophic (e.g. cyanobacteria, algae, lichens, bryophytes) and heterotrophic (e.g. bacteria, fungi, archaea) organisms, which live within, or immediately on top of, the uppermost millimetres of soil. Soil particles are aggregated through the presence and activity of these often extremotolerant biota that desiccate regularly, and the resultant living crust covers the surface of the ground as a coherent layer. With this detailed definition of biocrusts, illustrating their ecological functions and widespread distribution, we hope to stimulate interest in biocrust research and inform various stakeholders (e.g. land managers, land users) on their overall importance to ecosystem and Earth system functioning.

In 2013, the United Nations Convention to Combat Desertification (UNCCD) established a science–policy interface (SPI) to address Parties’ need for demand-driven, timely, interdisciplinary science and technical knowledge to tackle problems of desertification, land degradation and drought. Since then, a comprehensive assessment of the SPI’s impacts on policy decision-making has been lacking, despite perceptions that the SPI is vital to the Convention’s success. Addressing this gap, this paper evaluates whether the SPI and its processes and outputs have provided the necessary scientific and technological knowledge and advice to Parties to support timely, evidence-informed decision-making. It applies an analytical framework to assess performance metrics, considering associated documents and evidence of societal relevance and social quality. The findings indicate that SPI outputs have improved implementation of the UNCCD since 2015, particularly in the context of Sustainable Development Goal Target 15.3. SPI outputs have supported scientific cooperation between the Convention and its strategic partners while enhancing its science and technology profile in line with Article 16 and Article 17. The findings indicate that further formalization of the SPI’s status within the UNCCD is vital to improve its functions, undertake its work, and enable the UNCCD to maintain its global lead in providing knowledge and advice on combating desertification, land degradation and drought.

Bosnia and Herzegovina (BIH) is developing country facing extensive land degradation. As a post-conflict society with underlying poor socio-economic conditions, the value of land and its degradation status are not perceived to be an important problem neither a priority to address. BIH currently exists as a decentralized state, where land and land resources are under exclusive jurisdiction of two entities and one district, rather than state-level legislation. Complex land related administration between entities functioning independently from each other, and thus not sinchronized, leads to frequent political conflicts about land property, and limited data exchange which may exacerbate current land degradation. This paper investigates (i) the institutional setting and policy framework related to land, discussing the effectiveness and limitations of the current policies in this post-conflict society; (ii) stakeholders’ perception of land degradation under such complex institutional and policy structures; and (iii) the current state of land degradation, with a focus on soil erosion as one of the most important indicators in BIH. Communication and cooperation are major challenges for sustainable land management in post conflict societies. The existence of a policy framework is important, but not sufficient if implementation is weak and the perception of decision makers differs. Limited data on the impact of 1992 War on soil and land status represents an additional challenge to combat land degradation. Reliable national data on land degradation are crucial for assessment and development of strategic and policy frameworks devoted to those issues and to raise awareness on how to foster their implementation.

Fire suppression has increased fuel load and the risk of catastrophic wildfire in forest and woodland ecosystems across the Western United States. In an effort to reduce fuel load and restore historical structure and function, land managers have implemented fuel reduction treatments on millions of acres. Reducing fuel loads protects people, structures, and in some cases, improves ecosystem health. However, the ecological risks of soil surface disturbance related to fuel reduction strategies, and subsequent soil erosion, may be significant in some cases. Here, we examined the effects of common fuel reduction strategies (mechanical mastication and two techniques for prescribed burning) on wind and water erosion in two upland piñon-juniper woodlands in SE Utah over 2 years. We also tested the impact of broadcast seeding coupled with fuel reduction as a way to mitigate erosional soil loss. Finally, we analyzed biotic and abiotic predictor variables to evaluate important drivers of soil erosion following fuel treatments. We found that both techniques for prescribed burning—pile burning and broadcast burning—increased wind-related sediment fluxes by an average of 11-fold and 58-fold, respectively. Mastication did not increase wind-related losses over untreated controls. Erosional fluxes measured at silt fences, that captured both wind- and water-driven sediments, followed similar trends with moderate increases from pile burning (fivefold) but larger increases from broadcast burning (17-fold). Seeding did not affect erosion rates. Our results suggest that prescribed fire significantly increases soil erosion in fuel-treated piñon-juniper woodlands and may be a degradation pathway when implementing treatments.

Restoration of degraded drylands is urgently needed to mitigate climate change, reverse desertification and secure livelihoods for the two billion people who live in these areas. Bold global targets have been set for dryland restoration to restore millions of hectares of degraded land. These targets have been questioned as overly ambitious, but without a global evaluation of successes and failures it is impossible to gauge feasibility. Here we examine restoration seeding outcomes across 174 sites on six continents, encompassing 594,065 observations of 671 plant species. Our findings suggest reasons for optimism. Seeding had a positive impact on species presence: in almost a third of all treatments, 100% of species seeded were growing at first monitoring. However, dryland restoration is risky: 17% of projects failed, with no establishment of any seeded species, and consistent declines were found in seeded species as projects matured. Across projects, higher seeding rates and larger seed sizes resulted in a greater probability of recruitment, with further influences on species success including site aridity, taxonomic identity and species life form. Our findings suggest that investigations examining these predictive factors will yield more effective and informed restoration decision-making. The seeding of native species is critical to the success of dryland restoration efforts. Here the authors evaluate success of seeding establishment at 174 sites on six continents, finding that some sites had nearly 100% of species successfully recruit, while 17% of sites had zero seedling success.

Biocrust communities promote soil surface roughness, a key functional characteristic for soil ecology. However, the spatial scales at which biocrust communities contribute to surface roughness are not well understood. To refine our understanding of the spatial dynamics between biocrust and soil surface roughness, we used mm-resolution terrestrial LiDAR to measure micro-topographic roughness at seven sub-meter, 3-dimensional kernels (spatial scales) for undisturbed and disturbed biocrusts within the cool Great Basin and the hot Chihuahuan Deserts of western North America. This multi-scalar approach applied within the different desert regions allowed us to explore two objectives: 1) assess the relative importance of climate and disturbance on biocrust roughness, and 2) evaluate how soil surface roughness evolves with biocrust recovery. For objective 1, we found that undisturbed cool desert biocrust was up to three times rougher than hot desert biocrust. Much of the difference in roughness between the two desert biocrust communities appeared to be from climate or other regional factors. However, positive correlations between roughness and biocrust indicators, including soil chlorophyll-a and the field-based Level of Development (LOD) index, suggested that differences in roughness at spatial scales <= 10 cm are directly related to biocrust development. Mechanical disturbance aimed at removing biocrust resulted in significant reductions in roughness and removed much of the observed differences in roughness between cool and hot desert soils. We evaluated biocrust recovery within the cool desert study area two years after mechanical disturbance and found that the disturbed soil increased in roughness up-to 300%. The increased surface roughness at spatial scales <= 10 cm were positively correlated with increased aggregate stability and indicators of biocrust reestablishment. We found that topographic change area was also an important contributor to roughness at all spatial scales, particularly at spatial scales >= 20 cm where it was the most important factor evaluated. These results provide insight into how biocrust interacts with other biophysical processes to influence soil surface roughness and how soil surfaces evolve at time scales relevant to soil restoration activities.

Biological soil crusts (biocrusts) are a complex community of algae, cyanobacteria, lichens, bryophytes, and assorted bacteria, fungi, archaea, and bacteriophages that colonize the soil surface. Biocrusts are particularly common in drylands and are found in arid and semiarid ecosystems worldwide. While diminutive in size, biocrusts often cover large terrestrial areas, provide numerous ecosystem benefits, enhance biodiversity, and are found in multiple configurations and assemblages across different climate and disturbance regimes. Biocrusts have been a focus of many ecologists, especially those working in semiarid and arid lands, as biocrusts are foundational community members, play fundamental roles in ecosystem processes, and offer rare opportunities to study biological interactions at small and large spatial scales. Due to these same characteristics, biocrusts have the potential to serve as an excellent teaching tool. The purpose of this paper is to demonstrate the utility of biocrust communities as a model system in science education. Functioning as portable, dynamic mini ecosystems, biocrusts can be used to teach about organisms, biodiversity, biotic interactions, abiotic controls, ecosystem processes, and even global change, and can be easy to use in nearly every classroom setup. For example, education principles, such as evolution and adaptation to stress, or structure and function (patterns and processes) can be applied by bringing biocrusts into the classroom as a teaching tool. In addition, discussing the utility of biocrusts in the classroom – including theory, hypothesis testing, experimentation, and hands-on learning – this document also provides tips and resources for developing education tools and activities geared toward impactful learning.

Human activities are causing unprecedented disturbances in terrestrial ecosystems across the globe. To reverse soil deterioration in drylands, a promising tool is the ex situ cultivation of biological soil crusts, topsoil geobiological assemblages that provide key ecosystem services. One approach is to transplant biocrusts cultivated in greenhouse nursery facilities into degraded sites to accelerate recovery. Lichen‐ and moss‐dominated biocrusts have been successfully grown using a common, sandy soil. We compared the use of a common, sandy soil versus native soils as a substrate for the cultivation of cyanobacteria‐dominated biocrusts. In greenhouse experiments, we inoculated natural biocrusts collected from three Southwestern USA dryland sites on to either a common, sandy soil or on their respective native soils. The common substrate resulted in a moderate enhancement of growth yield relative to native soils. While changes in bacterial phyla composition remained low in all cases, the use of a common substrate introduced larger shifts in cyanobacterial community composition than did using native soils. The shift increase attributable to the common, sandy soil was not catastrophic—and typical cyanobacteria of field biocrusts remained dominant—unless textural differences between the common substrate and native soils were marked. Because collecting native soils adds a significant effort to growing cyanobacterial biocrusts in greenhouses for restoration purposes, the use of a common, sandy substrate may be considered by land managers as a standard practice. But we recommend to regularly monitor the composition of the grown biomass.

The capture and use of water are critically important in drylands, which collectively constitute Earth's largest biome. Drylands will likely experience lower and more unreliable rainfall as climatic conditions change over the next century. Dryland soils support a rich community of microphytic organisms (biocrusts), which are critically important because they regulate the delivery and retention of water. Yet despite their hydrological significance, a global synthesis of their effects on hydrology is lacking. We synthesized 2,997 observations from 109 publications to explore how biocrusts affected five hydrological processes (times to ponding and runoff, early [sorptivity] and final [infiltration] stages of water flow into soil, and the rate or volume of runoff) and two hydrological outcomes (moisture storage, sediment production). We found that increasing biocrust cover reduced the time for water to pond on the surface (-40%) and commence runoff (-33%), and reduced infiltration (-34%) and sediment production (-68%). Greater biocrust cover had no significant effect on sorptivity or runoff rate/amount, but increased moisture storage (+14%). Infiltration declined most (-56%) at fine scales, and moisture storage was greatest (+36%) at large scales. Effects of biocrust type (cyanobacteria, lichen, moss, mixed), soil texture (sand, loam, clay), and climatic zone (arid, semiarid, dry subhumid) were nuanced. Our synthesis provides novel insights into the magnitude, processes, and contexts of biocrust effects in drylands. This information is critical to improve our capacity to manage dwindling dryland water supplies as Earth becomes hotter and drier.

Fairy circles are striking regularly sized and spaced, bare circles surrounded by Stipagrostis grasses that occur over thousands of square kilometres in Namibia. The mechanisms explaining their origin, shape, persistence and regularity remain controversial. One hypothesis for the formation of vegetation rings is based on the centrifugal expansion of a single individual grass plant, via clonal growth and die-back in the centre. Clonality could explain FC origin, shape and long-term persistence as well as their regularity, if one clone competes with adjacent clones. Here, we show that for virtually all tested fairy circles the periphery is not exclusively made up of genetically identical grasses, but these peripheral grasses belong to more than one unrelated genet. These results do not support a clonal explanation for fairy circles. Lack of clonality implies that a biological reason for their origin, shape and regularity must emerge from competition between near neighbor individuals within each fairy circle. Such lack of clonality also suggests a mismatch between longevity of fairy circles versus their constituent plants. Furthermore, our findings of lack of clonality have implications for some models of spatial patterning of fairy circles that are based on self-organization.

Biological soil crusts (biocrusts) occur in drylands globally where they support ecosystem functioning by increasing soil stability, reducing dust emissions and modifying soil resource availability (e.g. water, nutrients). Determining biocrust condition and extent across landscapes continues to present considerable challenges to scientists and land managers. Biocrusts grow in patches, cover vast expanses of rugged terrain and are vulnerable to physical disturbance associated with ground‐based mapping techniques. As such, remote sensing offers promising opportunities to map and monitor biocrusts. While satellite‐based remote sensing has been used to detect biocrusts at relatively large spatial scales, few studies have used high‐resolution imagery from Unmanned Aerial Systems (UAS) to map fine‐scale patterns of biocrusts. We collected sub‐centimeter, true color 3‐band imagery at 10 plots in sagebrush and pinyon‐juniper woodland communities in a semiarid ecosystem in the southwestern US and used object‐based image analysis (OBIA) to segment and classify the imagery into maps of light and dark biocrusts, bare soil, rock and various vegetation covers. We used field data to validate the classifications and assessed the spatial distribution and configuration of different classes using fragmentation metrics. Map accuracies ranged from 46 to 77% (average 65%) and were higher in pinyon‐juniper (average 70%) versus sagebrush (average 60%) plots. Biocrust classes showed generally high accuracies at both pinyon‐juniper plots (average dark crust = 70%; light crust = 80%) and sagebrush plots (average dark crust = 69%; light crust = 77%). Point cloud density, sun elevation and spectral confusion between vegetation cover explained some differences in accuracy across plots. Spatial analyses of classified maps showed that biocrust patches in pinyon‐juniper plots were generally larger, more aggregated and contiguous than in sagebrush plots. Pinyon‐juniper plots also had greater patch richness and a lower Shannon evenness index than sagebrush plots, suggesting greater soil cover heterogeneity in this plant community type.

The Land Degradation Neutrality Initiative of the UN Convention to Combat Desertification (UNCCD) en-courages each of the 123 signatory countries to stabilise or reduce their extent of degraded land. Land degradation is assessed using the methods described in the Good Practice Guidance (GPG) document for Sustainable Development Goal (SDG) Indicator 15.3.1 (the proportion of land that is degraded over total land area), using three sub-indicators: land cover change, land productivity and soil organic carbon (SOC) stocks (as a proxy for carbon stocks above and below ground). The GPG identifies degraded areas by aggregating the sub indicator assessments using a one-out-all-out (1OAO) approach, in which an area is identified as degraded if any one or more of the sub-indicators shows degradation i.e. a land cover transition defined as degradation, a reduction in productivity, and/or a reduction in SOC stocks. Under some circumstances, however, the 1OAO method can result in a counterintuitive degradation assessment, such as where the removal of invasive plant species reduces plant biomass, which would normally suggest degradation of net primary production, but which in this circumstance is considered a positive change in the context of land remediation activities. Each country has the opportunity to report areas within its sovereign bounds as an error of 'false positive' or 'false negative' degradation with sufficient justification, however it is vital that this is done in a way that ensures consistency of reporting amongst countries at regional and global scales. This paper describes scenarios in which the 1OAO process can lead to a counterintuitive degradation assessment, focusing on the potential impacts of invasive plants, woody encroachment (i.e. bush encroachment), and land remediation activities on SOC stocks as examples. We present an interpretation matrix to assist with determining how to report degradation in these cases, and help identify the drivers of degradation and potential remediation activities. Increased clarity around degradation labelling and interpretation could improve reporting consistency and transparency, and increase the efficiency and effectiveness of land degradation remediation actions.

Plant-soil interactions are important drivers of plant productivity and community structure. Biocrusts – soil surface-dwelling biotic communities comprised of cyanobacteria, fungi, bryophytes, and/or lichens - are widespread in drylands globally. Biocrusts are described as “mantles of fertility” and have been shown to have facilitative, but species-specific effects on plant productivity. Yet, patterns and mechanisms underlying biocrust facilitation of plant productivity remain unclear. Using mesocosms with bare soil versus biocrust cover we investigated the effects of biocrusts on plant biomass allocation, leaf chemistry and colonization by root-associated fungi. Plant responses to biocrust presence were species-specific. Overall, biocrusts were associated with increased plant biomass and/or leaf N concentrations in Elymus elymoides, Bouteloua gracilis and Zea mays. However, plants grown in biocrusts had lower root-associated fungal colonization compared to bare soils. Biocrusts were associated with increased plant biomass and leaf N. Yet, plant growth responses to biocrusts were not correlated with differences in root-associated fungal colonization between soil mesocosm types. Understanding species-specificity in biocrust facilitation of plant growth may have important implications for understanding plant community structure in dryland ecosystems.