Question How does the vegetation of northwestern Patagonia grasslands respond to climate fluctuations and disturbances?Location Northwestern Patagonia, Argentina.Methods Our study was carried out in livestock- grazed grasslands affected by drought (1998), wildfire (1999), and volcanic ash deposition (2011). We analyzed annual precipitation trends, rainfall-use efficiency, and the relationship between ENSO events and seasonal climate. Before a severe drought, we monitored vegetation at three sites over 18 years (1999-2017). Only the North and South sites were affected by fire, while the unburned Control site was impacted by grazing and volcanic ash deposition. We used linear mixed-effects models to assess the relationships between vegetation cover and species richness with precipitation, temperature, and disturbances. We calculated species turnover, diversity, evenness, and similarity, and constructed a native reference community.Results Precipitation showed a negative trend from 1991 to 2018. Rainfall-use efficiency was low in 2006 and high in 2016. ENSO signals were stronger in spring than in winter. Spring precipitation and temperature enhanced both cover and richness. Annual species responded positively to annual and spring precipitation. In the Control site, plant cover recovered faster post-drought than post-eruption, whereas species richness showed the opposite pattern. Grassland recovers fast after fire compared to other disturbances. Species turnover was lowest 8 years post-drought and 6 years post-eruption. Diversity and evenness increased over time, and were higher in burned sites compared to the Control. The community most similar to the native reference community was the recently burned grassland.Conclusions Our long-term study shows that seasonal climate and disturbances shape grassland dynamics, which can be interpreted within the framework of Mediterranean-climate grassland ecology. Grassland managers in northwestern Patagonia could benefit from our findings by adapting livestock management practices to enhance grassland post-disturbance recovery and reduce the invasion of opportunistic species.

Plant fire ephemerals are well-adapted to fire-prone environments, with germination strategies linked to fire-related cues like smoke. Germination requirements linked to fire cues in Patagonian fire ephemerals are poorly studied, with no research on the effects of smoke water (SW) and smoke isolated karrikinolide (KAR) on their germination. We assessed the germination responses of two native ephemeral herbs, Boopis gracilis, and Nicotiana linearis, to SW and KAR1 at three concentrations (1/100, 1/1000, and 1/10000) and a Control (no SW or KAR1). Seeds collected on different harvest dates were incubated in a germination chamber, and germination responses were analyzed using Generalized Linear Models and Kaplan-Meier survival curves. KAR1 significantly enhanced and accelerated germination in both species, with the strongest effect at the highest concentration (1/100). In contrast, SW did not stimulate germination and inhibited germination in N. linearis at the highest concentration. This inhibitory effect decreased with storage time, suggesting that toxic compounds in SW degrade over time. Additionally, N. linearis seeds exhibited variable germination across harvest years, likely due to after-ripening requirements. Our findings highlight the contrasting effects of SW and KAR1 on seed germination; KAR1 being a reliable germination stimulant. The chemical complexity of smoke water (heterogeneous composition and uncertain concentration) and the time elapsed since its production likely limit its efficacy in promoting germination. These results provide valuable insights into post-fire seedling dynamics in Patagonian grasslands for the conservation in fire-affected ecosystems.

Biological invasions are major threats to global biodiversity, and mapping their distribution is essential to prioritizing management efforts. The Pinaceae family (hereafter pines) includes invasive trees, particularly in Southern Hemisphere regions where they are non-native. These invasions can increase the severity of fires in wildland–urban interfaces (WUIs). We mapped pine invasion in the Bariloche WUI (≈150,000 ha, northwest Patagonia, Argentina) using supervised land cover classification of Sentinel-2 imagery with a Random Forest algorithm on Google Earth Engine, achieving 90% overall accuracy but underestimating the pine invasion area by about 25%. We then assessed in which main vegetation context pine invasions occurred relying on major vegetation units across the precipitation gradient of our study area. Invasions cover 2% of the study area, mainly in forests (61%), steppes (25.4%), and shrublands (13.4%). Most invaded areas (89.1%) are on private land; nearly 70% are on large properties (>10 ha), where state financial incentives could support removal. Another 13.5% occur on many small properties (<1 ha), where awareness campaigns could enable decentralized, low-effort control. Our land cover map can be developed further to integrate invasion dynamics, inform fire risk and behavior models, optimize management actions, and guide territorial planning. Overall, it provides a valuable tool for targeted, scale-appropriate strategies to mitigate ecological and fire-related impacts of invasive pines.

Aim: Plant functional traits can influence interaction outcomes between nurse and target plants through a "functional trait match", which occurs when the traits of nurse plants ameliorate their environment, and target plants possess traits that allow them to benefit from this ameliorated environment. We investigated how the traits of putative nurse species affect interaction outcomes across global drylands and determined the functional match that promotes facilitation. We also investigated how grazing pressure and global climatic and edaphic gradients affected this trait match. Location: Global drylands. Time Period: 2016-2019. Major Taxa Studied: Vascular plants. Methods: We used a collaborative survey conducted across 29 sites from five continents, where we gathered in situ co-occurrences of dominant species ('nurses') and other vascular plant species, as well as their functional traits [plant height and leaf dry matter content (LDMC)]. Climate, edaphic variables and grazing pressure were measured in situ or extracted from databases. We used a model building approach to determine the effect of dominant plant traits on interaction outcomes, and how the functional trait match between nurse and target species is affected by environmental variables. Results: Tall dominant plants with conservative leaves generally had a greater positive effect on species richness and cover beneath their canopies, but these effects were strongly modulated by grazing pressure and soil pH. Target plants that were significantly associated with dominant plants tended to be shorter, and have more acquisitive leaves than dominant plants, regardless of environmental conditions. However, the difference in height and LDMC between dominant plants and negatively associated target plants was strongly affected by environmental conditions. Main Conclusions: Functional traits play a significant role in determining interaction outcomes between dryland plants. Facilitation in drylands is driven by a conservative-acquisitive trait match, a pattern observed regardless of grazing pressure, climate and soil conditions.

Earth harbours an extraordinary plant phenotypic diversity(1) that is at risk from ongoing global changes(2,3). However, it remains unknown how increasing aridity and livestock grazing pressure-two major drivers of global change(4-6)-shape the trait covariation that underlies plant phenotypic diversity(1,7). Here we assessed how covariation among 20 chemical and morphological traits responds to aridity and grazing pressure within global drylands. Our analysis involved 133,769 trait measurements spanning 1,347 observations of 301 perennial plant species surveyed across 326 plots from 6 continents. Crossing an aridity threshold of approximately 0.7 (close to the transition between semi-arid and arid zones) led to an unexpected 88% increase in trait diversity. This threshold appeared in the presence of grazers, and moved toward lower aridity levels with increasing grazing pressure. Moreover, 57% of observed trait diversity occurred only in the most arid and grazed drylands, highlighting the phenotypic uniqueness of these extreme environments. Our work indicates that drylands act as a global reservoir of plant phenotypic diversity and challenge the pervasive view that harsh environmental conditions reduce plant trait diversity(8-10). They also highlight that many alternative strategies may enable plants to cope with increases in environmental stress induced by climate change and land-use intensification.

In arid and semi-arid environments, demographic processes of shrubs are affected by fire and precipitation. Understanding the impact on the demographic processes of the population is crucial for ecosystem conservation and management. Our aim was to assess the population dynamics of the native shrub Senecio bracteolatus and its relation to fire frequency and precipitation in northwestern Patagonia. We constructed a stochastic matrix model and we conducted numerical simulations to evaluate scenarios varying fire frequency and precipitation. To parameterize the model, we conducted greenhouse and common garden experiments and collected previous field and precipitation data. We divided the S. bracteolatus life cycle into four classes (current year seedlings, previous year seedlings, juvenile, and adult plants) and two recruitment microsites (under tussock canopy and gaps between tussocks). The climate was included in the model as accumulated spring and summer precipitation. The former affects seedling germination, while the latter affects fire regimes. The model predicts that frequent fires (every four years) increase the population of S. bracteolatus, but if fires are infrequent (more than 16 years), the population increase with an annual rate of growth of around 8.5 %. However, for annual and biannual fire frequencies, the population experiences a decline, and with a three-year fire return interval, it stabilizes. High fire frequencies lead to population decrease, attributed to the reduction of the protective canopy of tussock grasses, essential for the recruitment of the shrub. The population growth rate of S. bracteolatus increases significantly more when spring precipitation is above historical averages, and fire frequency increases when summers are dry. Our study contributes to understanding the influence of fire and precipitation on shrub demographic processes in the context of climate change, providing useful information for fire management to improve the sustainable use of grasslands.

In recent decades, the risk of Wildland-Urban Interface (WUI) fires has increased due to urban growth, particularly in regions with a Mediterranean climate. The identification of the WUI is crucial for formulating fire prevention and management measures. However, there is no unified methodology for defining the WUI and it is not clear if proposals that emerge from scientific research are implemented by fire management agencies. Our objectives were to identify, describe, and compare the methods and criteria used by land and fire management agencies to define the WUI in Mediterranean-climate countries. We conducted a review of laws and fire prevention and management plans and protocols on the official websites of administrative bodies and agencies of the USA, Spain, Portugal, France, Italy, Greece, South Africa, Australia, Chile, and Argentina. Each document was read and analyzed and we conducted searches for the terminology used to name the WUI, the methodology and criteria used for defining the WUI, the fire prevention and management actions implemented in the WUI, the level of territorial organization and the responsible agencies for implementing the actions, and the presence of a methodology and a map at national scale. We found no consensus on the terminology for the WUI, the most common terms used being: wildland-urban interface, urban-rural interface, and urban-forest interface. With the exception of the USA and Portugal, there is no unified methodology at the national scale. We identified three general methods for defining the WUI: considering buffer distance for urban and vegetation areas (USA, Italy, Chile, South Africa), employing networks of strips (Spain, Portugal), and delineating risk-prone zones (Australia, France). All countries undertake fire prevention actions (e.g., fuel reduction and firebreak creation) often implemented at the municipal level. There is almost no interaction between academia and fire management agencies. Our review addresses the gap in the methods to define the WUI effectively implemented by fire management agencies. We highlight the need to implement actions aimed at enhancing the interaction between fire scientists and fire managers, which is essential for formulating and implementing effective strategies for fire prevention and optimizing resources.

El conocimiento de la ecofisiología de la germinación de semillas de especies colonizadoras es útil para su propagación y uso en revegetación. El objetivo fue evaluar los requerimientos de germinación y el tipo de dormición de semillas de especies nativas de estepa y de bosque colonizadoras de taludes en el noroeste patagónico. La hipótesis postulada fue que las semillas presentan dormición asociada a su ambiente de origen: dormición fisiológica o morfológica en ambientes húmedos y dormición física en ambientes secos. Se aplicaron dos tratamientos pre-germinativos luego de un almacenamiento por seis meses en frío seco: estratificación húmeda-fría (5 °C, 45 días) o escarificación mecánica con bisturí, más un grupo control. Las semillas se colocaron a germinar en condiciones de temperatura y fotoperíodo controlados (10/20 °C, 12/12 h). Se calculó el porcentaje, el inicio y el tiempo medio de germinación. Se compararon los dos tratamientos y el control de cada especie y se realizó un análisis de componentes principales. Post-ensayo, se calculó el porcentaje de semillas viables no germinadas, vanas y con presencia de hongos o daños por insectos. La dormición de las semillas no estuvo asociada a su ambiente de origen; otros factores (e.g., estacionalidad climática, similitud filogenética), sin embargo, podrían relacionarse con mecanismos que regulan la dormición. Las semillas de Acaena ovalifolia y Baccharis linearis no presentaron dormición, obteniendo porcentajes de germinación >80% en el control. Las semillas de Anemone multifida presentaron dormición física, incrementando significativamente la germinación con el tratamiento de escarificación mecánica. Ambos pre-tratamientos adelantaron y aceleraron la germinación en Acaena magellanica y A. splendens. No se pudo determinar el tipo de dormición de las otras especies. Este estudio aporta información valiosa sobre las condiciones ecofisiológicas de germinación de especies nativas para incorporar en protocolos de propagación ex situ e in situ para restaurar áreas degradadas.

La construcción de caminos genera impactos ambientales en los ecosistemas que atraviesan, al fragmentar y transformar los hábitats. Esto afecta el ensamble de especies en áreas degradadas y contribuye a la introducción y al aumento de especies de plantas exóticas e invasoras. La introducción de especies invasoras cambia la abundancia y la composición de especies nativas, representando una amenaza para la biodiversidad a nivel global. El objetivo de este trabajo fue analizar el ensamble de la vegetación en pie y el banco de semillas, e identificar las especies invasoras en taludes de desmonte en bordes de camino de matorrales de Nothofagus antarctica en el noroeste patagónico. Se analizó la composición, la riqueza, la diversidad y la abundancia de especies exóticas y nativas, y de grupos funcionales de la vegetación en pie y en el banco de semillas en taludes y áreas de referencia cercanas. Los taludes presentaron diferente composición florística, con menor cobertura de la vegetación y densidad de semillas de especies totales, menor riqueza y cobertura de especies nativas, y menor densidad de semillas de especies exóticas que las áreas de referencia. La similitud entre la vegetación en pie y el banco fue alta para las especies exóticas. En la vegetación de los taludes predominaron las hierbas, las gramíneas anuales/bianuales y las perennes exóticas invasoras, y las hierbas, las gramíneas perennes y los arbustos nativos; no se encontraron semillas de arbustos. La presencia de especies exóticas en los taludes puede deberse a las condiciones de los micrositios y a los rasgos de las especies que los colonizan, como a la capacidad de formar banco de semillas, la alta producción de semillas y la forma y el ciclo de vida. Este trabajo en matorrales del noroeste patagónico mostró que los bordes de camino y sus áreas cercanas albergan especies exóticas potencialmente invasoras, y que es importante identificarlas tempranamente para controlarlas.

Introducción: En el proceso de urbanización, la fragmentación de ambientes conlleva a la pérdida de hábitats y diversidad de especies nativas. El rescate de plantas para su conservación ex situ puede ser una medida de intervención temprana luego de la perturbación. Objetivo: Se analizó el efecto de la remoción de suelo sobre la población de la geófita bulbosa Zephyranthes gilliesiana (Herb.) Nic. García (Amaryllidaceae) y se evaluó el éxito del rescate de ejemplares para su conservación ex situ. M&M: En un sector de reciente urbanización inmerso en la estepa al este de la ciudad de Bariloche (Río Negro, Argentina), se calculó la frecuencia y se estimó la cobertura y densidad de Z. gillesiana en áreas degradadas por el movimiento de suelo y áreas de referencia no disturbadas. Se rescataron 60 plantas de Z. gilliesiana, se registró la profundidad de ubicación del bulbo, y se evaluó la relación entre el peso del bulbo y la supervivencia temprana (60 días del trasplante). Resultados: La riqueza de especies y la cobertura de la vegetación fueron menores en el área degradada que en la referencia. La frecuencia, cobertura y densidad de Z. gilliesiana fue mayor en el área degradada. La supervivencia fue del 47% en plantas con bulbos de mayor peso (25% desarrolló estructuras reproductivas). Conclusiones: Consideramos que el rescate de Z. gilliesiana fue exitoso y su documentación junto al estudio de la propagación agámica y sexual contribuirían a generar planes de conservación de esta especie.

Introduction and aims: In the process of urbanization, fragmentation of environments leads to the loss of habitats and native species diversity. Rescue of plants for ex situ conservation can be an early intervention measure after disturbance. We analyzed the effect of soil removal on the population of the bulbous geophyte Zephyranthes gilliesiana (Herb.) Nic. Garcia (Amaryllidaceae) and assessed the success of rescuing specimens for ex situ conservation.M&M: In a recently urbanized sector immersed in the steppe east of Bariloche city (Rio Negro, Argentina), the frequency, cover, and density of Z. gillesiana plants were calculated and estimated in degraded and undisturbed reference areas. Sixty Z. gilliesiana plants were rescued, the depth localization of the bulb was recorded, and the relationship between bulb weight and early survival (60 days after transplanting) was evaluated.Results: Species richness and vegetation cover were lower in the degraded area than in the reference area. The frequency, cover and density of Z. gilliesiana were higher in the degraded area. Survival was 47% in plants with heavier bulbs (25% developed reproductive structures).Conclusions: We consider that the rescue of Z. gilliesiana was successful and its documentation together with the study of agamic and sexual propagation would contribute to generate conservation plans for this species.

Introduction and aims: In the process of urbanization, fragmentation of environments leads to the loss of habitats and native species diversity. Rescue of plants for ex situ conservation can be an early intervention measure after disturbance. We analyzed the effect of soil removal on the population of the bulbous geophyte Zephyranthes gilliesiana (Herb.) Nic. Garcia (Amaryllidaceae) and assessed the success of rescuing specimens for ex situ conservation. M&M: In a recently urbanized sector immersed in the steppe east of Bariloche city (Rio Negro, Argentina), the frequency, cover, and density of Z. gillesiana plants were calculated and estimated in degraded and undisturbed reference areas. Sixty Z. gilliesiana plants were rescued, the depth localization of the bulb was recorded, and the relationship between bulb weight and early survival (60 days after transplanting) was evaluated. Results: Species richness and vegetation cover were lower in the degraded area than in the reference area. The frequency, cover and density of Z. gilliesiana were higher in the degraded area. Survival was 47% in plants with heavier bulbs (25% developed reproductive structures). Conclusions: We consider that the rescue of Z. gilliesiana was successful and its documentation together with the study of agamic and sexual propagation would contribute to generate conservation plans for this species.

There are many reports on anatomical variations of the vertebral arteries, which may be related to origin, trajectory, caliber, and side. Bilateral variations are less frequent, however, and less common are bilateral variants that differ from each other. The aim of this work was to report the presence of a bilateral variation of the vertebral artery and its functional and clinical implications. Dissection of a female cadaver, fixed in 10 % buffered formaldehyde, which had not undergone any previous surgeries in the study area and had anatomical variations in both vertebral arteries. In each one, follow-up was done from its origin to its end, determining its trajectory, diameters, branching, and anatomical relations. A left vertebral artery was found, starting in the aortic arch and making a sinuous trajectory of 4 curvatures to enter the transverse foramen of C4. The right vertebral artery began as the first branch of the subclavian artery. Its initial trajectory was rectilinear, followed by a right concave curve, a 360 & DEG; loop that included a second ascending curve, and ended straight before entering the transverse foramen of C6. The coexistence of bilateral variations in the vertebral arteries is possible. This atypical situation can potentially generate vascular and neurological pathologies, but with different symptoms and causes. Knowing these variations and deliberately searching for them will enable the specialist to make a suitable differential diagnosis.

Wildland-urban interface (WUI) fires have increased in the last decades, putting lives and homes at risk, and fire hazard assessment is a useful tool to develop plans for prevention and fire management. In northwestern Patagonia, the WUI areas are principally located around the urbanized zones that are not only cities or towns but settlements surrounded by the natural environment. In Patagonia, there are the largest and most ancient national parks of Argentina with areas where former settlers develop their livestock activities. We assessed the fire hazard in the Laguna Blanca National Park (LBNP) located in Neuquén province (Patagonia, Argentina) dominated by steppe vegetation. We performed the study at two scales: community and species. Community scale comprised the variables vegetation cover, slope, and rock fragments, whereas species scale included flammability variables of dominant species (tussock grasses and shrubs) at leaf- and plant-level. We integrated all variables at different scales and grouped the vegetation units into three classes using multivariate analysis. Finally, we established three fire hazard categories for each vegetation unit: low, moderate, and high, to elaborate a fire hazard map. Three vegetation units, which represented 37% of the area of the park, were categorized with high fire hazard because of the high cover and horizontal continuity of dominant vegetation. The tussock grass Pappostipa speciosa and the shrubs Mulinum spinosum, Nassauvia axillaris, and Anarthorphyllum rigidum were the most flammable species and the most frequent species in the park. Land uses in the park (i.e., transhumance and tourism) would be regulated with the collaboration of settlers because increase the vulnerability to wildfires. Our fire hazard map constitutes a valuable tool because it identified the most vulnerable WUI in the LBNP. This study emphasizes the need to include flammability and fuel load studies in fire management plans to better protect human lives and natural resources in protected areas.

Urbanization of forested areas increases the surface of wildland–urban interface (WUI), where fire is the primary hazard for humans and ecosystems. We determined the WUI using a novel approach in NW Patagonia, Argentina and evaluated its relationship with the fire ignition points. The WUI expands a greater distance on upslopes, where the rate of fire spread is highest. The WUI reaches the maximum distance under the most hazardous conditions: houses surrounded by fuel with steep slopes towards them. In the Bariloche district in 2021, the WUI included 81% of the houses and occupied 37% (11,006 ha) of the total study area. Between 2015 and 2021, 77% of fire ignitions occurred in the WUI, highlighting the relevance of urban growth planning and the management of fuel load in order to reduce wildfire risk.