Drylands are increasingly degraded by livestock grazing, mining, recreation, off-road vehicles and wildfire. These disturbances damage biological soil crusts (biocrusts) that stabilize soil, cycle nutrients, and store carbon. Farming biocrust as transplantable “sods” offers a promising restoration approach, but invasive plants colonizing sods risk contaminating restoration areas. Manually removing invasives is labor-intensive and unreliable. To determine the viability of herbicide control of weeds while cultivating biocrust, we tested four herbicide treatments, hand-cutting and untreated controls on biocrust sods seeded with the rapidly invading Oncosiphon pilulifer (stinknet) and, later, native plants. We measured biocrust and stinknet cover, native seedling establishment and treatment costs. Late-successional biocrust (lichens, mosses and dark cyanobacteria) grew best under all herbicide treatments compared to controls. Post-emergent herbicides (aminopyralid and glyphosate) effectively controlled stinknet while allowing later native seedling establishment. Preemergent indaziflam prevented both stinknet and native plant establishment. Preemergent aminopyralid was less effective against stinknet. Post-emergent aminopyralid and preemergent indaziflam were most cost-effective and suitable for promoting or preventing native recruitment, respectively. Herbicide application to biocrust sods represents a significant advancement in making biocrust farming economically viable by reducing manual labor, while providing critical information for combating an emerging invasive species threat.

Compost amendments are a promising tool for building productivity in degraded rangelands, but the effect on biological soil crusts (biocrusts), the surface microbial communities found in drylands, has not been investigated. Biocrusts contribute both carbon uptake and other ecosystem services in drylands. We investigated how 6.3 mm of surface-dressed compost at a Tribal rangeland in central New Mexico, USA, affected temperature, carbon and nitrogen characteristics, the relative abundance of biocrust microbial communities (fungi and bacteria) – specifically cyanobacterial communities – as well as the resulting aggregate stability at the soil surface after 1 year. Surface temperature maxima increased with compost addition in cooler ambient conditions, and the δ13C signatures of the soils from compost addition plots were >1‰ lighter compared to controls, indicating >35% of soil carbon was compost-derived, but organic C, total N percentage and aggregate stability did not differ among compost treatments. Several compost-derived taxa became indicator species in the amended plots, and compost addition decreased cyanobacteria relative abundance up to 58%. While previous results show that compost may benefit plants from a slow-release fertilization effect and soil carbon in deeper soil layers increases, there could be complex impacts on biocrust organic carbon with changing temperature and microbial community.

Biological soil crusts (biocrusts) are key components of dryland ecosystems worldwide, contributing to soil stabilization, nutrient cycling and enhancing ecosystem resilience. Despite their ecological importance, biocrusts in the Arabian Peninsula are largely underexplored, with much of the region’s biocrust diversity and functionality remaining undocumented. This review synthesizes current knowledge on biocrusts across the Arabian Peninsula, focusing on their major taxonomic groups (cyanobacteria, fungi, lichens, mosses and algae), their ecological roles and distribution patterns. It also discusses the potential for biocrust restoration through strategies such as cyanobacterial inoculation and passive protection, which could contribute to land degradation and desertification control in the Arabian Peninsula. Our work identifies significant research gaps in biocrust biodiversity, ecophysiology and their role in ecosystem functioning within this region, and calls for more focused research to integrate biocrusts into land management strategies for the Arabian Peninsula.

Islands of fertility, patches of locally enhanced soil conditions, play a key role in increasing productivity in dryland regions. The fertile island effect (FIE) influences a range of variables including nutrient availability, soil moisture and microbial activity. While most examinations of the FIE focus on islands created by perennial plants at local scales, the effect may vary across spatial scales and under cover types including shrubs, grasses and biological soil crusts (biocrusts). This study explored differences in the FIE between soil depths across landforms and patch types for biogeochemical factors (nutrient availability) and biotic properties (microbial community structure, extracellular enzymatic activity). The FIE differed across landforms and soil depths, suggesting that soil geomorphology may play a major role in predicting soil fertility. Additionally, the FIE of enzymatic activity and available nutrients varied by patch type consistently across landforms, suggesting patch-scale processes influencing nutrient availability and acquisition are independent of landscape-scale differences. We show that biocrusts can have an FIE similar to that of shrubs and grasses, an underexplored control of variability and productivity in drylands. These findings necessitate further work to improve our understanding of how ecosystem processes vary across scales to influence patterns of productivity and soil fertility.