Grasslands are one of the major ecosystem types in drylands. Encroachment of shrubs into grasslands affects the functioning of drylands by altering community structure, with impacts exacerbated under greater intensity of encroachment. Yet, we have a limited understanding of how ecosystem structure responds to the degree of shrub encroachment. Here, we describe a field-based study designed to examine changes in ecosystem structure beneath shrub patches (patch condition) and between patches (spatial distribution pattern of patches) along a gradient in encroachment in a semiarid grassland in Inner Mongolia, China. We found that greater encroachment was associated with wider and taller shrubs with more branches. As shrub encroachment intensified, the area beneath shrubs had more litter and was less exposed to grazing. The landscape was characterized by more discontinuous patches of vegetation and more bare ground as encroachment intensified. Either the patch condition or the patch spatial pattern was shaped mainly by the magnitude of shrub encroachment rather than by the structure of individual shrubs (e.g., height and canopy width). Our study highlights the idiosyncratic response of ecosystem structure (patch condition and patch spatial pattern) to intensifying encroachment, reinforcing the importance of considering the degree of shrub encroachment when managing encroached grasslands.

In the Patagonian drylands, extensive sheep production coexists with guanaco, the most abundant native herbivore. While sheep’s impacts on vegetation are well known, guanaco effects remain poorly understood, limiting effective management. We evaluated the influence of both species on grassland regeneration at two representative sites by comparing areas grazed by sheep or guanaco and applying short-term herbivore exclusions. We analyzed pre- and post-dispersal soil seed banks in vegetated patches and bare soil, and measured seedling emergence and tiller production of dominant perennial grasses. The soil seed bank was dominated by annual species, and vegetated patches showed higher perennial abundance after seed dispersal, but no significant differences emerged between herbivores. Seedling emergence was similar for sheep and guanaco, increasing notably after short-term exclusion. However, perennial grass regeneration through tillering responded differently: guanaco exclusion enhanced tillering of Nassella tenuis and Pappostipa speciosa, whereas sheep exclusion produced no significant effect. Overall, most regeneration mechanisms showed comparable patterns under both herbivores. These findings suggest that, although guanaco and sheep exert similar pressures on seedling dynamics, guanaco grazing may differently affect perennial grass recovery. We emphasize the need for careful monitoring of guanaco stocking rates to ensure sustainable management of Patagonian shrub-steppe ecosystems.

Climate hazards impact pastoral communities due to their dependency on nature for their primary livelihoods. This study analyzes climate risk in ten pastoral livestock farming communities in Patagonia drylands of Argentina. A participatory impact chains (PICs) approach was used as a qualitative and participatory bottom-up methodology allowing for the identification and contextualization of climate hazards, exposure, intermediate impacts and vulnerability dimensions through knowledge co-production with local stakeholders. Results show that, although drought is the predominant climate hazard across the region, its impacts are heterogeneous and mediated by local socio-environmental conditions. The analysis underlines that vulnerability is not evenly distributed but is shaped by specific historical, political and environmental pathways. These findings challenge standardized top-down risk assessments, and highlight the need for adaptation strategies that are context-sensitive, territorially differentiated and that integrate local knowledge. The study also contributes to advancing qualitative participatory methodologies for climate risk assessment in pastoral systems in arid areas of Latin America, showing the regional heterogeneity and social inequalities.

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.

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.

The rapid spread of non-native perennial grasses across South American savannas poses a growing threat to native plant diversity and ecosystem functioning. They disrupt key ecological processes, including fire regimes, nutrient cycling and plant community dynamics, driving the loss of functional diversity and the homogenization of native vegetation. This review compiles current knowledge on the ecological impacts of the nine most invasive perennial grass species in South American savannas and the challenges faced in controlling them, with a particular emphasis on the Brazilian Cerrado. We examine the mechanisms by which they outcompete native species, alter soil–plant interactions and inhibit natural regeneration. Particular attention is given to the ecological traits that confer competitive advantages to these invasive grasses under conditions of disturbance, increased nutrient availability and climate change. We also evaluate the challenges faced in the ecological restoration of invaded areas and discuss integrated strategies for controlling invasions and promoting the recovery of native species. This synthesis underscores the urgent need to address invasions by non-native grasses through coordinated research, new policies and management efforts aimed to safeguard the long-term biodiversity and ecological resilience of South American savannas.