Sofía Laura Gonzalez

Forest fires are among the most destructive natural disturbances, posing significant threats to ecosystem biodiversity, human lives, and property

Wildfire plays a key role in maintaining and enhancing biodiversity in ecosystems worldwide (Keeley and Pausas, 2022). Post-fire vegetation patterns typically feature the resprouting of fire-tolerant species and the widespread recruitment of fire-ephemeral plants (Ghermandi et al., 2004). The release of resources such as space and light following fire promote vegetation resprouting and seed germination (He et al., 2019) Moreover, fire-related cues, such as heat and smoke can stimulate germination from the soil seed bank, thereby promoting plant diversity (Moreira et al., 2010;Keeley and Pausas, 2018). Understanding the mechanisms behind these post-fire diversity patterns is essential for improving conservation, restoration, and sustainable land management. This Research Topic comprises studies that identify post-fire patterns that enhance the native plant diversity and the mechanisms that explain these patterns. It addresses how fire affects plant diversity across multiple ecological scales, from vegetation recovery at community level to the ecological mechanisms that determine species persistence and regeneration. The collection includes six articles by 30 authors, providing a comprehensive overview of current advances in this field. Several contributions were conducted in Mediterranean type-climate ecosystems, including northwestern Patagonia in Argentina, central Chile, southern California, and the sub-Mediterranean region of southwestern Slovenia. These ecosystems are strongly shaped by fire and are experiencing increasing wildfire frequency and intensity under ongoing climate change, highlighting the importance of understanding how native plant communities and species respond to changing fire regimes (Keeley et al., 2012).Two studies focused on vegetation response to fire. At the community level, the study by Carni et al. documented post-fire succession in sub-mediterranean forest vegetation on the Kras Plateau in southwestern Slovenia over a three-year period. Because fire has historically been uncommon in this region, the vegetation is considered poorly adapted to this disturbance. Despite this, the authors found that the community showed high resilience to wildfire, characterized by early dominance of ephemeral and ruderal species, which rapidly declined as the abundance of resprouting species increased. This study highlighted that enhanced autogenic succession, combined with favorable postfire moisture conditions, can facilitate rapid ecosystem recovery, potentially reducing the risk of long-term degradation or the establishment of persistent post-fire shrublands.

Drivers of non-native plant success in drylands are poorly understood. Here we identify functional differences between dryland native and non-native perennial plants and assess how biotic, abiotic and anthropogenic factors shape the success of the latter. On the basis of plant community and functional trait data from 98 sites across 25 countries, we report a total of 41 non-native plant species at 31 sites. Non-natives tend towards faster growth strategies than natives. Non-native plant richness is higher at sites with greater grazing pressure and under environmental conditions associated with higher soil fertility, decomposition and fungal richness—conditions that tend to occur in less arid regions—and lower where native plant and herbivore richness are greater. Non-native plant cover correlates positively with grazing pressure and negatively with native plant richness. Taken together, our results suggest that non-native plant success in drylands is facilitated when high grazing pressure coincides with elevated resource availability. Such context-dependence of non-native plant success and linkages with native plant and herbivore diversity highlight the need for managing grazing and conserving biodiversity across the world’s drylands.

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.

The invasion of exotic plants threatens biodiversity, affecting ecosystem services and ecological processes in native ecosystems. Road construction creates new environments and contributes to the introduction and spread of exotic and invasive plants. This study aimed to evaluate the representation of different functional groups (annual/biannual herbs and grasses, perennial herbs and grasses, shrubs, trees) in the invasion of exotic species within the assemblage on roadside slopes in the Austrocedrus chilensis forest in northwest Andean Patagonia, Argentina. Roadside slopes (RS) and nearby reference areas (RA) were selected, and the cover of native, exotic, and invasive species from the functional groups was evaluated in 1 m² plots using the Braun-Blanquet method. It was found that invasive perennial herbs and grasses predominated on RS, with a cover (19.6 ± 3.0%) higher than that of RA (8.9 ± 1.5%). Agrostis capillaris and Rumex acetosella were the most abundant invasive species. Native shrubs and perennial herbs and grasses were predominant on RS, with Baccharis rhomboidalis and Acaena pinnatifida being the most abundant. This study demonstrates that the roadside slopes of the Austrocedrus chilensis forest harbor invasive exotic species that can invade nearby natural areas. Early detection of these species is important for proper management and control, thus promoting the conservation of biodiversity in forest environments.

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.

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.

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.