RESUMO
Increased frequency and new types of disturbances caused by global change calls for deepened insights into possible alterations of successional pathways. Despite current interest in disturbance interactions there is a striking lack of studies focusing on the implication of decreasing times between disturbances. We surveyed forest-floor vegetation (vascular plants and bryophytes) in a Pinus sylvestris-dominated, even-aged production forest landscape, unique because of the presence of stands under a precisely dated disturbance interval gradient, ranging from 0 to 123 yr between clearcutting and a subsequent megafire. Despite a dominance of early-successional species in all burned stands 5 yr after fire, progression of succession was linked to time since the preceding clearcutting disturbance. This was most clearly seen in increased frequency with time since clearcutting of the dominant, late-successional dwarf shrub Vaccinium myrtillus, with surviving rhizomes as an important mechanism for postfire recovery. Our results demonstrate the role of legacy species as significant drivers of succession. We conclude that the starting point for succession is modulated by disturbance interval, so that shortened intervals risk reducing development towards late-successional stages. We suggest that a decrease in long successional sequences caused by more frequent disturbances may represent a general pattern, relevant also for other forest types and ecosystems.
Assuntos
Ecossistema , Florestas , Dinâmica Populacional , Conservação dos Recursos Naturais , Especificidade da EspécieRESUMO
El bicentenario de la Independencia ha revivido la discusión en torno a la vigencia del pensamiento de Bolívar. Sobre éste, se ha señalado que en su ideario hubo un "pensamiento ecológico", que debería considerarse en estos tiempos. Otros, en cambio, le critican su soberbia antropocentrista al referirse de manera arrogante a los asuntos de la naturaleza. ¿Podría decirnos 'el Libertador' algo sobre la crisis ambiental que experimenta el planeta hoy? El asunto de este texto es valorar este legado. Para ello, se han examinado los decretos y resoluciones relacionados con la conservación de la fauna, la flora, el fomento de la agricultura, la repartición de la tierra, entre otros. De ellos, se deduce que Bolívar no es un conservacionista, ni un ambientalista biocentrista, tampoco un antiecologista, como han dicho algunos. Su ideario político, social y ambiental se ubica en una corriente amplia de la Ecología Política, que cuestiona el intercambio ecológico desigual, entre las metrópolis y los países del Sur, los ricos y los pobres, las multinacionales y los productores locales. Un ambientalismo de la equidad y la justicia, donde impere la armonía entre los seres humanos y de estos con otros seres de la naturaleza y el planeta.
The Independence Bicentennial Celebration has revived the discussion around the validity of Bolivar's thoughts. It has been pointed out that his ideology included an "ecological thought" which should be put into consideration nowadays. Others, however, criticize his haughty anthropocentrism when referring in an arrogant way to nature issues. Could "the Liberator" tell us something about the environmental crisis the planet faces today? The subject of this text is to value such legacy. In order to do this, the decrees and resolutions related with the conservation of fauna and flora, promotion of agriculture, and land distribution, among others, have been examined. From them it has been concluded that Bolivar is neither a conservationist, nor an environmentalist or an anti-ecologist as many have argued. His political, social and environmental ideology is located in a wide stream of Political Ecology which questions unequal ecological exchange between the metropolis and the countries in the South, the rich and the poor, the multinationals and the local producers. An environmentalism of equity and justice where harmony among human beings and between them and other beings in nature and the planet must prevail.