Los Incendios Forestales en Tierra del Fuego

Cuando uno piensa en los incendios forestales de Argentina,Tierra del Fuego no es el lugar que se nos suele venir a la mente.No obstante, todos los que pasamos tiempo en los bosques de la islahemos visto el poder destructivo de los incendios en esta zona.Fil: Ruggirello, Matthew Joseph. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentin

Los Incendios Forestales en Tierra del Fuego

Cuando uno piensa en los incendios forestales de Argentina,Tierra del Fuego no es el lugar que se nos suele venir a la mente.No obstante, todos los que pasamos tiempo en los bosques de la islahemos visto el poder destructivo de los incendios en esta zona.Fil: Ruggirello, Matthew Joseph. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentin

Drivers of post-fire Nothofagus antarctica forest recovery in Tierra del Fuego, Argentina

Introduction: Large wildfires were historically absent in the forests of Tierra del Fuego, southern Argentina. This has changed in recent decades as humans have increased ignition sources, and warmer, drier periods have fueled large, severe wildfires. As a result of its location at an extreme southern latitude, Tierra del Fuego has very low tree species diversity. One of the region's dominant tree species, Nothofagus antarctica, is believed to have traits that may make it resilient to wildfire (e.g., the ability to resprout prolifically). Methods: This study examined post-fire N. antarctica regeneration across an environmental and time-since-fire gradient. Plots were established in burned areas (n = 160) and unburned controls (n = 32) in and around two wildfires that occurred circa 1940 and in 2019. Seedling/resprout and sapling regeneration densities, as well as site characteristics (e.g., slope) and fire-impacted variables (e.g., distance to mature live trees), were measured. Results: Seedling and resprout densities were lower in burned plots than in controls, with this trend being exacerbated in the 2019 fire with increasing distance from mature live trees. Regeneration generally occurs in clumps and principally through sprouting from live and top-killed trees, with not all top-killed trees having resprouted. Seedling and resprout densities were most strongly impacted by time since fire, distance to mature live trees and post-fire canopy cover. Sapling densities were modulated by slope, time since fire, and distance to mature live trees. Discussion: Despite lower regeneration densities in recently burned plots and less live basal area and canopy cover in older burned plots compared to unburned controls, burned stands may be on a trajectory to recover pre-fire characteristics, although this recovery is spatially variable. However, full recovery has not occurred 80 years after the 1940's fire. Currently, these burned areas resemble grasslands or savannas. They do not provide the habitat or ecosystem services that denser forests do and may require active restoration to fully recover their pre-fire characteristics.Fil: Ruggirello, Matthew. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: Bustamante, Gimena Noemi. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: Fulé, Peter Z.. Northern Arizona University.; Estados UnidosFil: Soler Esteban, Rosina Matilde. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentin

Nothofagus pumilio regeneration failure following wildfire in the sub-Antarctic forests of Tierra del Fuego, Argentina

Wildfires on the island of Tierra del Fuego in southern Argentina are not considered to have been a historic driver of forest dynamics. However, dramatic increases in the human population of the island over the last half-century have greatly increased fire ignition sources and thus the frequency of wildfires in the region. Lenga (Nothofagus pumilio (Poep. et Endl.) Krasser) forests support diverse ecosystem services by providing habitat for endemic f lora and fauna and also represent a valuable timber resource for the forest industry of Tierra del Fuego. Evaluating the impact of forest fires on lenga regeneration is important not only because lenga is a native, slow-growing species that seems to lack adaptations that would allow it to recover rapidly after fire, but also because low tree species diversity on the island of Tierra del Fuego means lenga post-fire regeneration failure may lead to ecosystem state shifts. To determine how site characteristics and fire-impacted variables modulate post-fire regeneration densities and spatial patterns in lenga forests, we installed 192 plots (160 burned, 32 unburned) in which we measured site-characteristic (e.g. aspect, elevation) and fire-impacted (e.g. basal area, canopy cover) variables and tallied seedlings and saplings. Regeneration densities were significantly lower in burned than unburned plots. This was exacerbated with increasing distance from the unburned forest edge. Increasing distance to live trees that either survived fire or were outside the burned area negatively impacted regeneration as well. Time since fire negatively affected sapling, but not seedling counts. We concluded that lenga regeneration in the interior of burned areas is largely absent, delaying and potentially preventing forest recovery. These interior areas of burned lenga forests are unlikely to regenerate closed-canopy tree cover through passive restoration alone. Active restoration may be needed in these critical areas where live legacy trees are not present.Fil: Ruggirello, Matthew. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: Bustamante, Gimena Noemi. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: Soler Esteban, Rosina Matilde. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentin

Post-fire forest recovery at high latitudes: tree regeneration dominated by fire-adapted, early-seral species increases with latitude

Abstract Key message Above 40° N/S, increasing latitude is linked to greater post-fire tree regeneration. However, species dominance shifts from conifers to short-lived deciduous trees, which may negatively impact flora, fauna, and ecosystem services dependent on coniferous forests. These results were primarily driven by studies from North America, highlighting the need for more research that directly measures post-fire forest recovery in other high-latitude regions. Context As the size and frequency of wildfires increase across many regions, high-latitude forests may be at particular risk for decreases in regeneration and state shifts post-fire. Aims Through this systematic review, we sought to determine the general relationship between post-fire tree regeneration densities and latitude in forests above 40° N/S. We expected regeneration densities post-fire would decrease with increasing latitude, and that forest regeneration would be negatively impacted by high burn severities, forest management, harsh site conditions, and unprotected microsites. We also anticipated that light-demanding species with adaptations to fire would replace shade-tolerant species that lack such adaptations post-fire. Methods We conducted a literature search that returned over 4500 articles. We selected those that directly measured post-fire regeneration at or above 40° N/S and retained 93 articles for analysis. Fire characteristics, pre- and post-fire tree species compositions and regeneration densities, and regeneration predictors were then extracted from the retained articles. We fit linear mixed models to post-fire regeneration density with latitude and species traits as explanatory variables and also explored the significance and magnitude of predictors that informed post-fire tree species response. Results Contrary to our expectations, post-fire regeneration increased significantly with latitude. High burn severities and unprotected microsites had negative impacts on post-fire regeneration; higher elevations and more prolific pre- or post-fire reproduction were positively correlated with post-fire regeneration, while management of any type did not have an impact. Conclusion Although forests are regenerating after wildfires at the most extreme latitudes included in this study (above 55° N), regeneration is often limited to only a handful of genera: aspen (Populus) and birch (Betula), for example. Regeneration was less abundant at the lower range of our study area. Certain lower latitude forests that occupy marginal habitats are under increasing stress from drier, warmer conditions that are exacerbated by wildfires. Results were largely driven by studies from Canada and the USA and may not be applicable to all high-latitude forests

Understory plant dynamics following a wildfire in southern Patagonia

Historically, wildfires have occurred infrequently in the Subantarctic forests on the island of Tierra del Fuego in southern Argentina: wildfires on the landscape are sporadic and exclusively human-caused. As a result of this, post-fire effects on native vegetation are largely unknown. In November of 2008, a wildfire started near a sawmill in the central part of the island. Six pre-established research plots located in Nothofagus antarctica (ñire) dominated forests burned, impacting a long-term study of understory vegetation dynamics. In 2008 (pre-fire), two 10 m long permanent transects were established per plot (n = 12), where we evaluated species richness and plant cover using a point intersection method at 20 cm intervals, resulting in 50 points per transect. After the fire, we continued sampling to evaluate post-fire understory response in burned and unburned plots. The first post-fire sampling occurred in January 2009, and was repeated semi-annually in burned and unburned plots (2010–2014, 2016, 2018, 2020, and 2021). Data were analyzed using GLMMs (Generalized Linear Mixed Models) and multivariate analyses (Nonmetric Multidimensional Scaling, Multi-Response Permutation Procedures). Total species richness and cover decreased the year following the fire, but recovered by 2010, eventually surpassing pre-fire levels. Increases in species diversity were due principally to an increase in exotic species richness (F = 4.73; p < 0.001) and cover (F = 51.59; p < 0.001). For native species, richness followed the same trend as total vegetation, but cover decreased drastically following the fire (F = 19.77; p < 0.001) and had not recovered to pre-fire levels by 2021. MRPP revealed that plant assemblage in burned plots differed from those in unburned plots the season following the fire (p < 0.001) and still differed 7–12 years post-fire (p < 0.001). Wildfire in Tierra del Fuego produces changes in understory dynamics that create non-forest plant assemblages dominated by exotic species; these changes last many years and pose a significant threat to the forests and native plant species of the island. Without active restoration, forests impacted by wildfire may be permanently lost along with the ecosystem services and habitat they provide.Fil: Ruggirello, Matthew Joseph. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: Soler Esteban, Rosina Matilde. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: Bustamante, Gimena Noemi. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: Lencinas, María Vanessa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentin