The availability of soil-stored seed determines initial plant functional types in post-fire landscapes. We evaluated the post-fire regeneration of Nothofagus pumilio forests, in Patagonia, Argentina, analyzing the soil seed bank (SSB) and the above-ground vegetation (AV). At three sites: La Colisión, Río Turbio and Monte Zeballos, burned in 2008, 1980 and 1941, respectively, we sampled the SSB and AV in two transects from the edge of the remaining forest, up to 90 m within the burned area, and recorded the emergence (198 soil samples) and presence of vascular species. To determine the effect of the distance to the remnant forest on the germinable seed bank, we performed simple linear regression analysis through the use of linear mixed-effect models, and we analyzed the similarity between the composition of SSB and AV with PERMANOVA. The emergence of plant growth forms had different patterns in relation to the distance from the forest in the three sites, which might be associated with the time of fire occurrence, and specific characteristics of each site. The emergence of N. pumilio was registered at more than one distance at the recent burning site. Herbs constituted the main source of cover with 69% of the composition, and native/endemic species represented 71%. This study contributes to the understanding of the relationship between the seed bank and standing vegetation and a better understanding of the resilience of post-fire N. pumilio forests. Our findings suggest that from 15–20 m from the edge, the SSB would be insufficient to ensure the spontaneous recovery of the forest, making active restoration necessary in order to tend to a recovery of the structure and functionality of the original community.

Questions: In terms of biodiversity conservation, forest plantations are often considered problematic because they usually have negative effects on natural ecosystems. Soil seed banks could play an important role in restoring vegetation that was originally present, by recruiting species that have disappeared above‐ground. We addressed this topic in plantations located in the Patagonian steppe by asking the following questions: Are richness, abundance and composition of steppe above‐ground vegetation and soil seed bank affected by plantations? Is species composition of the above‐ground vegetation and soil seed bank similar in plantations and in the steppe?Location: NW of Chubut Province, Patagonia, Argentina.Methods: We selected three plantations located in the steppe, and delimited three sectors: steppe, plantation edge and plantation interior. We compared richness and abundance by species origin and growth form among sectors for the above‐ground vegetation and soil seed bank compartments, using generalized linear mixed models. We compared species composition for each compartment and between them using permutational multivariate analysis of variance and non‐metric multidimensional scaling.Results: In above‐ground vegetation, we found a decrease in richness and abundance, and changes in composition from the steppe to the plantation interior. Richness and abundance of the soil seed bank did not show differences among steppe and the plantation sectors, although composition was different among them. Above‐ground vegetation and soil seed bank species composition were always different; native perennial herbs and shrubs were predominant in the above‐ground vegetation while exotic annual herbs dominated the soil seed bank.Conclusions: Our findings suggest that plant recruitment from the soil seed bank would not be sufficient for restoring depleted species pools in the above‐ground vegetation of plantations. Therefore, actions promoting native species reestablishment and control of exotics should be considered to reach the aim of restoring biodiversity in former plantations.

Background: Severe wildfires in forest ecosystems promote soil erosion and the loss of fertile soil as a scarce natural resource. Our objective was to quantify post-fire ecosystem response in terms of soil accumulation and seed availability through redistribution. Within our study area in Northern Patagonia, Argentina, we chose three study sites at which forest fire events occurred in different years, namely 1 year post-fire (2022), 2 years post-fire (2021), and 8 years post-fire (2015). At each of the sites, we recorded both burned and control slope transects. Along these transects, three accumulation zones were differentiated, at each zone the amount of accumulated soil material as well as the number of seeds in it were determined. Results: We observed significant amounts of accumulated soil material along the slopes with the highest annual rates in the first year after the forest fire. The mean accumulated soil material (± standard deviation) over all slope accumulation zones increased from 9.5 ± 2.6, 15.9 ± 4.6 to 42.9 ± 14.0 kg*m⁻², at the 1 year-old, 2 years-old, and 8 years-old forest fires sites. Despite the generally high spatio-temporal variability of seed dispersal, the transects at the burned forest sites show significantly lower numbers of seeds than control transects. In the investigated burned forest sites, the total number of seeds of the four tree species found was 64, 250, and 252 seeds*m⁻² in the 1 year-old, 2 years-old, and 8 years-old site, respectively. In general, the more recent fire events had lower number of seeds, which increased with accumulated soil material and time. We also observed a greater number of shrub seeds in the burned sites, but these did not show a pattern with time since the wildfire events. Conclusion: Among the 14 species recorded, the tree Austrocedrus chilensis and the shrub Aristotelia chilensis emerge as key players in post-fire recovery, with the highest number of seeds at all study locations. Forest restoration after disturbance is a global challenge, especially in the context of large-scale forest fires. Understanding the risk of soil redistribution and seed availability will assist restoration efforts and ecosystem management.

Las plantaciones de Pinus ponderosa establecidas en la estepa patagónica ponen en riesgo funciones ecosistémicas si no se las maneja apropiadamente. La respuesta de los arbustos ante las variaciones lumínicas que provocan las forestaciones e intervenciones silvícolas puede influir en su rol ecológico. En este trabajo evaluamos la dinámica de la acumulación de biomasa total de calafate (Berberis microphylla) y mamuel choique (Adesmia volckmannii) al 20, 60 y 100% de irradiancia, y su respuesta al aumento lumínico que sucedería luego de intervenciones como el raleo y la corta final. Para cada especie evaluamos 1) la relación entre la biomasa y el diámetro en la base del tallo, 2) la dinámica de la biomasa durante dos estaciones de crecimiento en las tres condiciones de irradiancia, y 3) la respuesta temprana al incremento lumínico en plantas sometidas a irradiancias del 20 y 60%. Además, 4) comparamos los niveles de irradiancia que supondrían los esquemas de manejo forestal propuestos para la región con los aquí evaluados. Para ambas especies, la biomasa y el diámetro se relacionaron linealmente, y la acumulación de biomasa fue menor en irradiancias del 20%. El calafate tendió a acumular más biomasa al 100%, y el mamuel choique, al 60%, aunque ninguna especie presentó diferencias entre dichas irradiancias. Mientras que el calafate proveniente del 20% de irradiancia solo incrementó su biomasa al aumentar la irradiancia al 100%, mamuel choique lo hizo al aumentarla al 60%. Estos resultados sugieren que ambas especies, al menos en la fase juvenil, podrían aclimatarse a la sombra, y que el mamuel choique respondería mejor ante incrementos parciales de luz (e.g., ante un raleo). La respuesta del calafate sugiere que el manejo propuesto, cuyos niveles de irradiancia serían menores que los aquí evaluados, no sería óptimo para su desarrollo.