Combined effects of fire and cattle in shrublands and forests of northwest Patagonia

En el noroeste patagónico, dos de los disturbios de mayor influencia sobre los paisajes y comunidades son el fuego y la herbivoría de ungulados introducidos. Existe una larga historia regional del fuego, pero la reiteración de incendios seguidos de intenso pastoreo constituye un nuevo tipo de régimen de disturbio en este paisaje. Nuestro objetivo fue analizar distintas condiciones micro-ambientales y parámetros de la vegetación en sitios afectados por la combinación de ambos disturbios. Dentro del Parque Nacional Nahuel Huapi, estudiamos 17 sitios bajo la influencia del fuego y el ganado vacuno: sitios no quemados (>50 años) o recientemente quemados (50 years) or recently burned (<15 years); and free of livestock or alternatively under heavy browsing. We found a strong effect of time since fire and a slighter effect of cattle. The combination of both disturbances only had a synergistic effect on humidity (during hours of higher temperature occurrence) and on solar radiation, and consequently an increase in adverse environmental conditions was observed at recently burned sites and with cattle present. Additionally, total cover of woody and semi-woody species decreased at sites affected by both disturbances. Maytenus chubutensis and Rosa rubiginosa characterized unburned sites; and indicator species at sites without cattle and with cattle were Ribes magellanicum and Berberis darwinii, respectively. Through different mechanisms, fire and cattle modify community characteristics, and when both disturbances co-occur, in some cases they can synergistically affect the plant communities, exacerbating xeric conditions which may accelerate land degradation. By increasing knowledge of indicator species and their associated site conditions, we can provide basic information for restoration guidelines, conservation, and sustainable management of Patagonian forests and shrublands.Fil: Blackhall, Melisa. Universidad Nacional del Comahue. Centro Regional Universitario Bariloche. Laboratorio de Ecotono; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Patagonia Norte. Instituto de Investigación en Biodiversidad y Medioambiente; ArgentinaFil: Raffaele, Estela. Universidad Nacional del Comahue. Centro Regional Universitario Bariloche. Laboratorio de Ecotono; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Patagonia Norte. Instituto de Investigación en Biodiversidad y Medioambiente; ArgentinaFil: Veblen, Thomas T.. University of Colorado. Department of Geography; Estados Unido

Habitat distribution modeling reveals vegetation flammability and land use as drivers of wildfire in SW Patagonia

Despite important recent advances in modeling current and future global fire activity in relation to biophysical predictors there remain important uncertainties about finer-scale spatial heterogeneity of fire and especially about human influences which are typically assessed at coarse-spatial resolutions. The purpose of the current study is to quantify the influence of biophysical and anthropogenic variables on the spatial distribution of wildfire activity between 1984 and 2010 over an extensive southern Patagonian-Andean region from ca. 43° to 53° S extending from coastal rainforests to xeric woodland and steppe. We used satellite imagery to map all detectable fires > 5 ha from 1984 to 2010 in four study areas (each of 13,100 to 36,635 km2) and field checked 65 of these burns for accuracy of burned vegetation class and fire perimeters. Then, we used the MaxEnt modeling technique to assess the relationships of wildfire distributions to biophysical and human environmental variables in each of the four regions. The 232 fires > 5 ha mapped in the four study areas accounted for an area of 1,314 km2 indicating that at least 1.8% of the total area burned between 1984 and 2010. In general, areas with intermediate productivity levels (e.g. shrublands) have higher fire probability compared with areas of low and high productivity levels, such as steppe and wet forests, respectively. There is a marked contrast in the flammability of broad vegetation classes in determining fire activity at a regional scale, as well as a strong spatial relationship of wildfires to anthropogenic variables. The juxtaposition of fire-resistant tall forests with fire-prone shrublands and woodlands creates the potential for positive feedbacks from human-set fires to gradually increase the flammability of extensive landscapes through repeated burning. Distance to roads and settlements were also strong predictors, suggesting that fire in all regions is ignition-limited. However, these anthropogenic predictors influenced probability of fire differently among study regions depending on their main land-use practices and their past and present socioeconomic contexts.Fil: Paritsis, Juan. State University Of Colorado-boulder; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Patagonia Norte. Instituto de Investigación en Biodiversidad y Medioambiente; ArgentinaFil: Holz, Andrés. State University Of Colorado-boulder; Estados UnidosFil: Veblen, Thomas T.. State University Of Colorado-boulder; Estados UnidosFil: Kitzberger, Thomas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Patagonia Norte. Instituto de Investigación en Biodiversidad y Medioambiente; Argentin

Field-validated burn-severity mapping in North Patagonian forests

Burn severity, which can be reliably estimated by validated spectral indices, is a key element for understanding ecosystem dynamics and informing management strategies. However, in North Patagonian forests, where wildfires are a major disturbance agent, studies aimed at the field validation of spectral indices of burn severity are scarce. The aim of this work was to develop a field validated methodology for burn-severity mapping by studying two large fires that burned in the summer of 2013-2014 in forests of Araucaria araucana and other tree species. We explored the relation between widely used spectral indices and a field burn-severity index, and we evaluated index performance by examining index sensitivity in discriminating burn-severity classes in different vegetation types. For those indices that proved to be suitable, we adjusted the class thresholds and constructed confusion matrices to assess their accuracy. Burn severity maps of the studied fires were generated using the two most accurate methods and were compared to evaluate their level of agreement. Our results confirm that reliable burn severity estimates can be derived from spectral indices for these forests. Two severity indices, the delta normalized burn ratio (dNBR) and delta normalized difference vegetation index (dNDVI), were highly related to the fire-induced changes observed in the field, but the strength of these associations varied across the five different vegetation types defined by tree heights and tree and tall shrub species regeneration strategies. The thresholds proposed in this study for these indices generated classifications with global accuracies of 82% and Kappa indices of 70%. Both the dNBR and dNDVI classification approaches were more accurate in detecting high severity, but to a lesser degree for detecting low severity burns. Moderate severity was poorly classified, with producer and user errors reaching 50%. These constraints, along with detected differences in separability, need to be considered when interpreting burn severity maps generated using these methods.Fil: Franco, María Guadalupe. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Mundo, Ignacio Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Veblen, Thomas T.. University of Colorado; Estados Unido

wildfire activity and land use drove 20th century changes in forest cover in the colorado front range

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Effects of prescribed fires on young valley oak trees at a research restoration site in the Central Valley of California

Woodland restoration sites planted with Quercus lobata (valley oak) often have serious invasions of nonnative annual grasses and thistles. Although prescribed fire can effectively control these exotics, restoration managers may be reluctant to use fire if it causes substantial mortality of recently planted saplings. We studied the effects of prescribed fires on the survival and subsequent growth of 5- and 6-year-old valley oak saplings at a research field near Davis, California. One set of blocks was burned in summer 2003 at a time that would control yellow star thistle, a second set of blocks was burned in spring 2004 at a time that would control annual grasses, and a third set was left unburned. Very few oaks died as a result of either fire (3–4%). Although a large proportion was top-killed (66–72%), virtually all these were coppiced and most saplings over 300 cm tall escaped top-kill. Tree height, fire temperature, and understory biomass were all predictive of the severity of sapling response to fire. Although the mean sapling height was initially reduced by the fires, the growth rates of burned saplings significantly exceeded the growth rates of unburned control trees for 2 years following the fires. By 2–3 years after the fires, the mean height of spring- and summer-burned saplings was similar to that of the unburned control saplings. The presence of valley oak saplings does not appear to preclude the use of a single prescribed burn to control understory invasives, particularly if saplings are over 300 cm tall

Earth incorporated: centralization and variegation in the global company network

Over the past 20 years, a widening gulf has appeared between the increasingly internationalized financing arrangements of the world’s leading corporations, and the persistence of nationally compartmentalized approaches to the study of corporate control. In lieu of direct empirical evidence on corporate control at the global level, the most widespread assumption is that the globalization of ownership has taken the form of an expansion of arms-length, market-based arrangements traditionally prevailing in the Anglo-American economies. Here, however, we challenge this assumption, both empirically and conceptually. Empirically, we show that three quarters of the world’s 205 largest firms by sales are linked to a single global company network of concentrated (5%) ownership ties. This network has a hierarchically centralized organization, with a dominant “global network core” of US fund managers ringed by a more geographically diverse “state capitalist periphery.” Conceptually, we argue that the this architecture can be broadly explained through a Polanyian “variegated capitalist” model of contradictory market institutionalization, with the formation of the global company network actually a counterintuitive product of global financial marketization. In order to understand this process of network formation, however, it is necessary to extend Polanyi’s model of a double movement mediated through political interventions in the market, to incorporate Veblenian processes of evolutionary institutional change mediated through the market

Visible inequality breeds more inequality

Experiments suggest that when people can see wealth inequality in their social network, this propels further inequality through reduced cooperation and reduced social connectivity. News & Views comment on Nishi et al, Nature 526, 2015, p. 426-429

Learning From Early Attempts to Generalize Darwinian Principles to Social Evolution

Copyright University of Hertfordshire &amp; author.Evolutionary psychology places the human psyche in the context of evolution, and addresses the Darwinian processes involved, particularly at the level of genetic evolution. A logically separate and potentially complementary argument is to consider the application of Darwinian principles not only to genes but also to social entities and processes. This idea of extending Darwinian principles was suggested by Darwin himself. Attempts to do this appeared as early as the 1870s and proliferated until the early twentieth century. But such ideas remained dormant in the social sciences from the 1920s until after the Second World War. Some lessons can be learned from this earlier period, particularly concerning the problem of specifying the social units of selection or replication

Neighbors' income, public goods, and well‐being

How does neighbors' income affect individual well‐being? Our analysis is based on rich U.S. local data from the Behavioral Risk Factor Surveillance System, which contains information on where respondents live and their self‐reported well‐being. We find that the effect of neighbors' income on individuals' self‐reported well‐being varies with the size of the neighborhood included. In smaller areas such as ZIP codes, we find a positive relationship between median income and individuals' life satisfaction, whereas it is the opposite at the county, MSA, and state levels. We provide evidence that local public goods and local area characteristics such as unemployment, criminality, and poverty rates drive the association between satisfaction and neighbors' income at the ZIP code level. The neighbors' income effects are mainly concentrated among poorer individuals and are as large as one quarter of the effect of own income on self‐reported well‐being