Leonardo Almonacid

Aim: Dominant trees govern the structure and functioning of temperate forests, and their decline following disturbance often signals reduced resilience and diminished capacity for ecosystem recovery. Disturbances affecting these species have been widely documented in isolation, yet their combined and interacting effects remain poorly synthesized, particularly outside the Northern Hemisphere. Location: Southern cone of South America. Taxon: Nothofagus pumilio (Poepp. & Endl.) Krasser (Magnoliopsida: Nothoafaceae). Methods: We review the effects of individual and combined disturbances on dominant tree species of temperate forests, with a particular focus on Nothofagus pumilio , the dominant tree species of southern South American temperate forests. Using a two‐scale literature review, we first conducted a restricted global search to identify disturbance categories documented in temperate forests and their reported effects on dominant tree species. This served as a framework for a subsequent in‐depth analysis of how those disturbances affect N. pumilio forests across their distribution. We searched Web of Science and Scopus for empirical studies explicitly addressing disturbance impacts on dominant tree species and classified articles by disturbance type. Results: Climatic disturbances, wildfires, biological disturbances, and logging are recurrently documented in temperate forests, and strongly affect N. pumilio throughout its range. Interactions among multiple disturbances represent an increasingly important driver of N. pumilio forest degradation. Climate change amplifies fire activity, triggering cascading effects when combined with pressures such as grazing and biological invasions. N. pumilio exhibits variable and sometimes contrasting responses to the same disturbance depending on local conditions. Main Conclusions: We conclude that multiple, interacting disturbances can jeopardize the persistence of even dominant, plastic species. Forest dynamics models and management strategies should integrate these complex interactions to better anticipate the feedbacks and thresholds that may endanger tree populations and to guide effective mitigation measures. Promoting mixed‐species stands through active restoration, reducing anthropogenic pressures, and controlling invasive species are essential strategies for maintaining ecosystem resilience under global change.

Wildfires are increasing in frequency and severity worldwide, with long-lasting effects on forest vegetation and fungal communities essential for seedling establishment and forest resilience. Nothofagus pumilio, the dominant tree of South American temperate forests, forms key fungal symbioses but shows limited post-fire regeneration. Root-fungal community responses in seedlings under long-term post-fire conditions remain unknown. We characterized root-associated fungal communities in N. pumilio seedlings growing in burned (eight years post-fire) and unburned forest of the southern Andes, using ITS1 metabarcoding. We assessed diversity, composition, and abundance of root-associated fungi, including ectomycorrhizal fungi and dark septate endophytes. Diversity and evenness were significantly lower in burned than in unburned forest, with no significant differences in richness or composition. The ectomycorrhizal genus Cortinarius was less abundant in burned-forest seedlings. In seedlings from burned forest, the dark septate endophyte Cadophora was significantly more abundant, whereas Exophiala and Cladophialophora were less abundant than in unburned forest. Despite these shifts, burned areas retained root-associated fungal taxa linked to plant-beneficial functions and shared most OTUs with unburned forest, indicating an incomplete but ongoing recovery. Further research should evaluate how these shifts affect early seedling performance, and assess the role of persistent beneficial taxa for restoration after wildfires.

This study evaluated the technological and sensory effects of incorporating oyster mushroom (Pleurotus ostreatus) powder and sylvinite as strategies to reduce salt content in beef patties while maintaining product quality. A 4 × 4 full factorial design was implemented to develop sixteen distinct formulations, evaluating the interaction between four levels of mushroom powder (0, 3, 5, and 10% w/w) as a partial meat replacer and four levels of sylvinite (0, 0.5, 1, and 2% w/w) as a NaCl substitute. To establish a baseline for comparison, control samples were prepared without sylvinite, with a fixed concentration of 1% NaCl. Patties were produced with low-fat content (6%), formed into 100 g portions, and evaluated in raw and cooked states. Physicochemical analyses included color (CIE L*, a*, b*), cooking yield, shrinkage, and texture profile analysis, while sensory quality was assessed by an expert panel and complemented with consumer discriminative tests, specifically a triangle test. Multivariate analysis revealed that mushroom powder significantly influenced color parameters, increasing redness and yellowness, whereas sylvinite tended to reduce color intensity; however, their interaction mitigated these effects at intermediate inclusion levels. Mushroom incorporation improved cooking yield and reduced hardness, particularly at 3–5% inclusion, enhancing elasticity and cohesiveness. Sensory results indicated that formulations containing 3–5% mushroom powder and up to 2% sylvinite achieved high overall acceptability. Consumer tests confirmed that these formulations effectively modulated saltiness and texture perception. Overall, the combined use of oyster mushroom powder and sylvinite represents a viable approach for developing reduced-sodium beef patties with acceptable technological and sensory properties.

In recent years, the need to adopt materials that are partially or fully recyclable or biodegradable has grown significantly. This paper presents a study aiming to develop a physical and thermal characterization of post-harvest blocks (spent mushroom substrate) used in the production of the edible mushroom Pleurotus ostreatus in order to test its feasibility as an insulation material. For this purpose, culture blocks based on wheat straw residues were prepared using a wild strain of the fungus. After the mushroom harvest, the post-harvest blocks were evaluated for stability, thermal conductivity, moisture content, fire behavior, and surface analysis. The results showed that the post-harvest blocks had an average thermal conductivity of 0.032 W/mK, a density of 56.63 kg/m³, and a moisture content of 5.96%. They also exhibited high fire resistance. The culture blocks showed stable dimensional properties, reasonable productivity, low moisture, high density, and fire resistance. Therefore, results suggest that this material could be used as insulation in construction.

Background and Aims: Wildfires can dramatically alter forests, their biodiversity and goods they provide to society. In the Andes Cordillera, Nothofagus pumilio is a native, fire-sensitive tree that is completely excluded from severely burned areas. Therefore, it is of interest to evaluate whether there are differences in the microbial soil communities that could contribute to an improvement in the recruitment of N. pumilio after a fire. We aimed at determining the diversity of soil bacteria and fungi associated with the native tree Nothofagus pumilioin old-growth forests affected by a severe fire in the Andes Cordillera of south-central Chile in 2015. Methods: Rhizosphere soil samples were collected from selected N. pumiliotrees and bulk soil in fire-affected areas and compared with those from unburned areas using a metabarcoding approach. Results: We found that beneficial microorganisms such as saprophytic, ectomycorrhizal fungi, ericoid mycorrhizal taxa and N-fixing bacteria were present in the burned area. The most abundant bacterial genera were Mycobacterium, Rhodoplanes and Bryobacter. While Cortinarius and Penicillium were the most common fungal genera identified in burned and unburned sites. Conclusions: In the burned forest, eight years after the fire, there is little disparity observed in the bacterial and fungal species associated with N. pumilio, when compared to the unburned forest, which could be determinant to N. pumilio establishment and survival after fire. Identifying the microbial diversity associated with native trees is essential to know beneficial microorganisms supporting the recovery of plant species and the restoration of forest ecosystems in fire-affected forests.

Chilean native forests have been subjected to several types of disturbances, with one of them being the replacement by exotic species. Pinus radiata D. Don is a widespread exotic tree that forms extensive plantations in southern Chile. It covers extended areas, affecting the landscape, biodiversity, and ecosystem services associated with native forest ecosystems. Although advances in assessing the impact of exotic plant species have been conducted, few studies have focused on the alteration of soil microorganisms. This study aimed to characterize the rhizosphere bacterial and fungal communities associated with the tree species Nothofagus obliqua inside a native forest stand and within a P. radiata plantation growing nearby. We used a 16S rRNA gene and ITS region metabarcoding approach. Using bioinformatics, diversity indices, relative abundance, preferential taxa, and predicted functions and guilds were estimated. The β-diversity analysis showed that both factors, the type of soil (rhizosphere or bulk soil) and the type of site (native forest or P. radiata plantation), were significant, with the site explaining most of the variation among bacterial and fungal communities. Proteobacteria and Basidiomycota were the most abundant bacterial and fungal phyla in both types of soil and sites. Similarly, bacteria showed similar abundant taxa at the family level, independent of the soil type or the site. The main fungal taxa associated with native forests were Tricholomataceae and Cantharellales, whereas in P. radiata plantations, Russulaceae and Hyaloscyphaceae were the most abundant families. The main bacteria functional groups were chemoheterotrophy and aerobic chemoheterotrophy, without significant differences between the type of soil or sites. Overall, these results demonstrate that the composition and diversity of bacterial and fungal communities associated with native N. obliqua forest are influenced by the surrounding forest, and mainly depend on the site’s characteristics, such as the lignin-rich wood source. These results improve our understanding of the impact of native forest replacement on soil microbial communities, which can alter microbial-related soil ecosystem services.

Forest fires can alter essential ecosystem processes, including soil nutrient cycling, potentially cascading into permanent vegetation changes. This is key to elucidate in ecosystems where fires are infrequent. We assessed the effects of fire severity on the spatio-temporal response of soil nutrients and plant diversity in old-growth forests of south-central Chile, 1, 2, and 3 years after a fire that occurred in 2015. Within ancient, old-growth Araucaria araucana (Mol.) K. Koch and Nothofagus pumilio (Poepp. and Endl.) Krasser forests, ranging from areas burned with fire of high severity to unburned forests, we evaluated nitrogen (N), phosphorus (P), potassium (K), and soil organic matter (SOM) content using spatial interpolation to predict their spatial distribution and assessed their availability over time. We also assessed plant species richness and abundance following the fire. The availability of N noticeably increased during the first year after fire but rapidly decreased in the following years, especially in areas of high fire severity. P, K, and SOM were less affected by the fire, remaining more constant over time. In the short term, plant species richness and diversity significantly decreased in severely burned areas, but over time, they became more similar to those of the unburned forests. The time since a fire and its severity determine a heterogeneous distribution of soil nutrients, with N shifting to a significantly lower availability after fire, which was more notable in areas of high fire severity. Here, vegetation exhibited a decrease in plant diversity and the establishment of exotic species, likely producing cascading effects at the community level.