Melanie Köbel

Aridity alters soil carbon (C), nitrogen (N) and phosphorus (P) stoichiometry, yet the implications of these processes for soil microbial functional traits and potentials at the genomic level remain poorly synthesized. Here we combine measurements of soil C, N and P pools and ratios with shotgun metagenomes from 200 natural ecosystems spanning major biomes worldwide. Across sites, increased aridity is associated with lower soil C:N and N:P (and C:P) ratios and with a coordinated shift in microbial functional potential. Genes linked to catabolic resource acquisition—including carbohydrate-active enzymes and pathways for degradation of plant litter and organophosphorus compounds—are declined as C becomes relatively scarce. In contrast, genes supporting anabolic investment in growth and drought resistance, such as RNA transcription, protein synthesis and intracellular transport, are increased. These patterns indicate that aridity-related change in soil elemental ratios is coupled to a broad shift from catabolic to anabolic strategies in soil microbiomes. By linking soil elemental ratios to microbial functional traits across biomes, our study provides a framework for anticipating how climate-driven drying may reorganize microbial metabolism with consequences for carbon and nutrient cycling.

Microbes, as the planet's most abundant and diverse organisms, drive soil functions globally and are vulnerable to environmental stressors triggered by global change. Yet, knowledge regarding the impacts of multiple environmental stressors on their functional profiles as well as the consequences for soil functionality largely remains unknown. Here, we analyze two global-scale datasets including information on soil metagenomics and multiple environmental stressors. We find that across terrestrial ecosystems worldwide, up to 60% of all functional genes significantly shift when soil microbes experience the high-level of concurrent stressors. In this regard, the relative abundances of genes involved in microbial growth are negatively linked to the increasing number of stressors. Conversely, those genes linked to stress resistance and energy production exhibit positive responses. Taken together, our findings highlight a significant restructuring of global soil functional microbiomes in response to multiple environmental stressors. Consequently, such restructuring drives community-level shifts in matter and energy reallocations, thereby impacting the maintenance of soil functionality under the projected global change.

Ecosystem restoration is crucial for halting biodiversity loss and reversing environmental degradation, playing a key role in addressing the climate crisis and ensuring global human well-being and security. The long-term success and cost-effectiveness of restoration efforts depend on continuous monitoring and management. Here, we explore the main challenges in ecological restoration project implementation, scientific monitoring, and present preliminary findings on changes in plant community composition and diversity. These changes are assessed in response to both short- and long-term climatic conditions, as well as the effects of passive and assisted restoration techniques in Portugal. The projects focus on three distinct contexts: the restoration of a coastal dune system, the rehabilitation of a limestone quarry, and the recovery of agroforestry systems in dryland regions. The ecological restoration of the dunes in S. João da Caparica began in 2014. Scientific monitoring since then has demonstrated the successful establishment of vegetation and faunal communities, alongside positive geomorphological evolution. These results confirm that dune restoration is an effective strategy for protecting coastal ecosystems. The restoration of a quarry site in Arrábida Natural Park started in 1983 and has been under continuous scientific monitoring. After 30 years, the restored vegetation has low similarity to the natural reference and shows a stabilization trend in some recovery indicators, primarily influenced by soil characteristics and the type of restoration intervention (plantations or hydroseeding).Our findings have helped evaluate recovery progress, identify limiting factors, and propose adaptive management strategies to enhance restoration outcomes. Agroforestry systems of oak woodlands (montado) dominating in Portuguese drylands are in decline due to complex environmental pressures, including climate change and unsustainable land use. Over the past decades, several restoration projects have been implemented to enhance their resilience and adaptability to climate change conditions. Its scientific monitoring over the years has provided valuable insights into climate change impacts, guiding land management strategies and informing decision-making to combat desertification and improve the sustainability of these vital dryland agroforestry systems.

Drylands occupy 47% of the world’s terrestrial area and comprise important biodiversity hotspots such as the Mediterranean Basin, where one can find high levels of plant diversity and endemism. At the same time, they provide resources for human populations, being cattle grazing one of the main activities in dryland ecosystems. Mediterranean woodlands and pastures are currently under threat with increasing aridity due to climate change. Aridity, together with human exploitation, pushes these ecosystems towards land degradation, leading to decreased diversity, ecosystem functioning, and economical value. Understanding how plant communities respond to climate in the long-term, as well as climatic fluctuations, is crucial to anticipate the impacts of climate change in these ecosystems and build a knowledge base to design adaptation and restoration measures and promote their resilience. In the western Mediterranean Basin dryland areas are commonly occupied with oak open woodlands. It is an agro-silvo-pastoral system with a savannah-like structure, dominated by oaks with a species-rich understory of pastures and shrubs. In Portugal, this system is called montado, and due to its socio-economic and ecological importance, it is currently monitored within the LTsER montado platform. The herbaceous layer, dominated by annual species, is a major component of this system’s diversity. While these pastures are adapted to dryland climatic conditions, its annual turnover may make these communities quick responders to environmental changes, providing a good model system to study the effects of climate on diversity and ecosystem functioning. In this work, we aim to assess the effects of long-term climate and yearly climatic fluctuations on plant taxonomic and functional diversity and on pasture productivity, as well as the relationship between diversity and productivity. We sampled the understory plant community of 10 holm-oak open woodlands along a spatial aridity gradient in southern Portugal in multiple years, 5-7 times, between 2012 and 2022. A stratified random selection of sites was made, avoiding as much as possible confounding effects, namely from differences in slope, elevation and fire occurrence. The plant community was sampled in spring, at the peak standing biomass, with the point-intercept method along six 20 m transects per site. Pasture productivity was measured by collecting the aerial herbaceous biomass in three 30 cm squares placed randomly in each site. Functional diversity was calculated using mean trait values per species retrieved from online databases. We fit linear mixed-effects models to assess the relationship between long- and short-term climate variables and taxonomic and functional diversity. We further explored the role of diversity on productivity with structure equation modeling. To assess the patterns of compositional changes along space and time, we determined compositional and functional dissimilarity among sites and among years. Preliminary results show that both productivity and species diversity increase with annual precipitation and winter temperature, while long-term aridity does not seem to be a main driver. On the other hand, species compositional changes between years suggests that more arid sites have higher species turnover, and possibly a higher species richness considering both dry and more wet years, while less arid sites are more stable along time. In this presentation, we will further explore these patterns and assess the role of functional traits and functional diversity as a means by which communities adapt to climatic conditions, and how these influence pasture productivity. These findings may then contribute to a discussion on the projections on future scenarios for these ecosystems and which adaptation and restoration measures may be adopted to promote its sustainability and resilience.

Global biodiversity hotspots, including Mediterranean‐type ecosystems worldwide, are highly threatened by global change that alters biodiversity, ecosystem functions, and services. Some restoration activities enhance ecosystem functions by reintroducing plant species based on known relationships between plant traits and ecosystem processes. Achieving multiple functions across different site conditions, however, requires understanding how abiotic factors like climate and soil, along with plant assemblages, influence ecosystem functions, including their trade‐offs and synergies. We used the ModEST ecosystem simulation model, which integrates carbon, water, and nutrient processes with plant traits, to assess the relationships between restored plant assemblages and ecosystem functions in Mediterranean‐type climates and soils. We investigated whether maximised carbon increment, water use efficiency, and nitrogen use efficiency, along with their trade‐offs and synergies, varied across different abiotic contexts. Further, we asked whether assemblages that maximised functions varied across environments and among these functions. We found that maximised ecosystem carbon increment and nitrogen use efficiency occurred under moist, warm conditions, while water use efficiency peaked under drier conditions. Generally, the assemblage that maximised one function differed from those for other maximised functions. Synergies were rare, except between water and nitrogen use efficiencies in loam soils across most climates. Trade‐offs among maximised functions were common, varying in strength with abiotic context and plant assemblages, and were more pronounced in sandy loam soils compared to clay‐rich soils. Our findings suggest that due to variation in abiotic conditions within and across Mediterranean‐type regions at the global scale, site‐specific plant assemblages are required to maximise ecosystem functions. Thus, lessons from a single site cannot be transferred to another site, even where the same plant functional types are available for restoration. Our simulation results offer valuable insights into potential ecosystem performance under specific abiotic conditions following restoration with particular plant functional types, thereby informing local restoration efforts.

Increases in the abundance of woody species have been reported to affect the provisioning of ecosystem services in drylands worldwide. However, it is virtually unknown how multiple biotic and abiotic drivers, such as climate, grazing, and fire, interact to determine woody dominance across global drylands. We conducted a standardized field survey in 304 plots across 25 countries to assess how climatic features, soil properties, grazing, and fire affect woody dominance in dryland rangelands. Precipitation, temperature, and grazing were key determinants of tree and shrub dominance. The effects of grazing were determined not solely by grazing pressure but also by the dominant livestock species. Interactions between soil, climate, and grazing and differences in responses to these factors between trees and shrubs were key to understanding changes in woody dominance. Our findings suggest that projected changes in climate and grazing pressure may increase woody dominance in drylands, altering their structure and functioning.

Grazing represents the most extensive use of land worldwide. Yet its impacts on ecosystem services remain uncertain because pervasive interactions between grazing pressure, climate, soil properties, and biodiversity may occur but have never been addressed simultaneously. Using a standardized survey at 98 sites across six continents, we show that interactions between grazing pressure, climate, soil, and biodiversity are critical to explain the delivery of fundamental ecosystem services across drylands worldwide. Increasing grazing pressure reduced ecosystem service delivery in warmer and species-poor drylands, whereas positive effects of grazing were observed in colder and species-rich areas. Considering interactions between grazing and local abiotic and biotic factors is key for understanding the fate of dryland ecosystems under climate change and increasing human pressure.