Fire is a major disturbance affecting ecosystems worldwide. Phylogenetic studies have shown that the evolution of seed persistence (fire resistance) is associated with fire frequency or severity. However, the existence of specific seed traits resulting from natural selection mediated by fire remains a key question in plant evolution. We evaluated the role of fire in the evolution of seed traits from a microevolutionary perspective, using as a study system a native forb from the Chilean matorral, where fire is a novel, anthropogenic disturbance. We show that anthropogenic fires are shaping the evolution of seed traits such as pubescence and shape. Amongpopulation variation in seed pubescence, shape, and pericarp thickness was strongly associated with fire frequency, and within a population, fire selected those plants with more pubescent seeds, thicker pericarps, and less rounded seeds. Seed pubescence and shape were shown to be heritable traits. Our findings provide insights into the understanding of the evolution of seed traits in fireprone environments and demonstrate that human-made fires can be driving evolutionary changes in plant species from ecosystems where fires do not occur naturally.fire ecology | Mediterranean ecosystems | microevolution | seed germination

The Southern Annular Mode (SAM) is the main driver of climate variability at mid to high latitudes in the Southern Hemisphere, affecting wildfire activity, which in turn pollutes the air and contributes to human health problems and mortality, and potentially provides strong feedback to the climate system through emissions and land cover changes. Here we report the largest Southern Hemisphere network of annually resolved tree ring fire histories, consisting of 1,767 fire-scarred trees from 97 sites (from 22°S to 54°S) in southern South America (SAS), to quantify the coupling of SAM and regional wildfire variability using recently created multicentury proxy indices of SAM for the years 1531-2010 AD. We show that at interannual time scales, as well as at multidecadal time scales across 37-54°S, latitudinal gradient elevated wildfire activity is synchronous with positive phases of the SAM over the years . Positive phases of the SAM are associated primarily with warm conditions in these biomass-rich forests, in which widespread fire activity depends on fuel desiccation. Climate modeling studies indicate that greenhouse gases will force SAM into its positive phase even if stratospheric ozone returns to normal levels, so that climate conditions conducive to widespread fire activity in SAS will continue throughout the 21st century.fire scars | climate modes | AAO | synchrony | warming

Historia preliminar de incendios y prácticas (multi) culturales en la cuenca media del río Cachapoal (34º S), Chile centralPreliminary fire history and (multi) cultural practices in the Cachapoal river's middle basin (34º S), Central Chile SUMMARYThis work was developed in the Cachapoal river basin, Andean Mountain, of Central Chile. In this basin the relations between anthropogenic factors and fire frequency in Austrocedrus chilensis forests were explored. Fire history of this area was reconstructed using cypress cross-sections dating, historical revision and local people interviews. Archaeological information reports human occupation of this zone since the Early Holocene. Starting in the XVII century, this area was used by Jesuits mainly for cattle ranching activities. Later, the property was passed to private owners who continued using this area for agricultural and cattle purposes. The tree-ring chronology presents a length of 754 years (1249 -2003). The oldest fire dated occurred in 1389 and the latest fire in 1923. Based on the numbers of dated samples, the main fires during this period occurred in 1484, 1526, 1575, 1800 and 1893. The fire in this region is an important process in the ecosystem functioning and a major landscape modeler. The interviews showed that fire had been an element widely used by rural population for heating and cooking functions, location (smoke signals) and animal hunting. These evidences allow making a close connection between anthropogenic activities and climate in the occurrence and frequency of fires.Key words: Austrocedrus chilensis, anthropogenic influence, Cachapoal basin, Central Chile. RESUMENEste trabajo se desarrolló en la porción media de la cuenca del río Cachapoal, cordillera andina de Chile central (34º S). En esta zona se exploraron las relaciones entre factores antropogénicos y frecuencia de incendios en bosques de Austrocedrus chilensis (ciprés de la cordillera). Se reconstruyó una cronología preliminar de incendios de esta cuenca mediante el fechado de cicatrices de fuego en rodelas de ciprés, revisión histórica y entrevistas a habitantes de la zona. La revisión historiográfica informa de la ocupación humana de esta zona desde el Holoceno temprano. A partir del siglo XVII, el área fue utilizada por la orden jesuita con fines principalmente ganaderos y mineros, para luego ser traspasada a terratenientes y propietarios privados que siguieron utilizando el área extensivamente en actividades agrícola-ganaderas. La cronología de ancho de anillos presentó una longitud de 754 años . El incendio más antiguo fue datado en 1389, y el más reciente en 1923. Los principales incendios durante este periodo ocurrieron en 1484, 1526, 1575, 1800 y 1893. El fuego en esta zona es un proceso importante en el funcionamiento del ecosistema y un claro modelador del paisaje. La información recopilada mediante entrevistas indica que el fuego ha sido un elemento ampliamente usado por la población rural, especialmente para fines de calefacción y preparación de alimentos, ubicación (señales...