The vegetation on either side of fire boundaries in the alpine zone of Mount Wellington, Tasmania, was surveyed in 1978 and 1998. This combination of spatial and temporal sampling gave data for 16, 31, 36 and 51 years since burning. These data were used to test for convergence in vegetation characteristics through time between the areas burned in 1947 and those burned in 1962 and to determine whether lifeform is a reasonable predictor of the successional dynamics of species. While convergence largely prevailed, some lifeforms and species diverged and lifeform was generally a poor predictor of species responses. For example, size class analyses of the larger shrub species indicated a wide variety of successional responses to fire. The tall shrubs on Mt Wellington have higher percentages of tolerators and species relying on the soil seed store for postfire regeneration than physiognomically similar vegetation in more fire-prone environments. Fifty-one years after fire, there is evidence of continuing floristic and structural change in the alpine vegetation that may be partly related to recent climatic warming.
-Standard ecological methods (pitfall traps, trunk eclectors and soil cores) were used to evaluate collembolan community responses to different flooding intensities. Three sites of a floodplain habitat near Mainz, Germany, with different flooding regimes were investigated. The structures of collembolan communities are markedly different depending on flooding intensity. Sites more affected by flooding are dominated by hygrophilic and hygrotolerant species, whereas the hardwood floodplain is dominated by mesophilic species. The survival strategies of the hygrophilic and hygrotolerant species include egg diapause and passive drifting. The physiological adaptations to hypoxic conditions of several collembolan species were analyzed using a microcalorimeter. The activities were tested under normoxic and hypoxic/anoxic conditions as well as during post-hypoxic recovery. Lactate was increased after hypoxic intervals in the species studied, suggesting that, in addition to a massive decrease in metabolic rate, a modest glycolytic activity may be involved in the tolerance to hypoxia.Index terms: behavioral adaptation, ecological adaptation, egg diapause, inundation, morphological adaptation, physiological adaptation. Respostas e adaptações de comunidades de colêmbolos (Hexapoda: Collembola) a condições de inundação e hipoxiaResumo -Foram utilizados os métodos ecológicos padrão (armadilhas "pitfall", armadilhas de tronco e amostras de solo) para avaliar as respostas de comunidade de colêmbolos a diferentes intensidades de inundação. Foram investigados três locais de um habitat de leitos de inundação perto de Mainz, Alemanha, com diferentes regimes de inundação. As estruturas das comunidades de colêmbolos foram nitidamente diferentes conforme a intensidade das inundações. Nos locais mais afetados por inundações, as espécies higrofílicas e higrotolerantes dominaram, ao passo que as espécies mesofílicas foram dominantes nos locais de leitos de inundação com angiospermas. As estratégias de sobrevivência das espécies higrofílicas e higrotolerantes incluem a diapausa dos ovos e o deslocamento passivo. Foi testada a adaptação fisiológica a condições hipóxicas de espécies selecionadas de colêmbolos através de análises por microcalorimetria. A atividade das espécies foi testada em condições normóxicas e hipóxicas/anóxicas e durante a recuperação pós-hipoxia. Verificou-se que o lactato aumentava após condições hipóxicas nas espécies avaliadas, o que sugere que, além de um decréscimo massivo na atividade metabólica, deve haver também certa atividade glicolítica associada à tolerância à hipoxia.Termos para indexação: adaptação comportamental, adaptação ecológica, diapausa dos ovos, inundação, adaptação morfológica, adaptação fisiológica.
Analyses are given for zirconium in 12 soil profiles formed from granite in Sew South Wales and Queensland. On the basis that on rock weathering there is no change of volume, it is shown that a loss of zirconium is general in the lower horizons of the profiles and amounts to 20–50% of the rock zirconium. The high losses imply loss of zirconium from grains of zircon. In view of the use of zircon ns an index mineral in soil studies, it is important that the size of zircon grains which are affected should be further investigated.
-Micro, macro and mesofauna in the soil often respond to fl uctuating environmental conditions, resulting in changes of abundance and community structure. Effects of changing soil parameters are normally determined with samples taken in the fi eld and brought to the laboratory, i.e. where natural environmental conditions may not apply. We devised a method (STAFD -soil tubes for artifi cial fl ood and drought), which simulates the hydrological state of soil in situ using implanted cores. Control tubes were compared with treatment tubes in which fl oods of 15, 30, 60 and 90 days, and droughts of 60, 90 and 120 days were simulated in the fi eld. Flooding and drought were found to reduce number of individuals in all soil faunal groups, but the response to drought was slower and not in proportion to the expected decrease of the water content. The results of the simulated fl oods in particular show the value of the STAFD method for the investigation of such extreme events in natural habitats.Index terms: climate change, drought, fl ooding, soil invertebrates, soil tubes, STAFD method. Um novo método para simular o estado hidrológico do solo em condições naturaisResumo -As micro, macro e mesofaunas no solo respondem frequentemente à variação das condições ambientais, o que resulta em alterações na abundância e na estrutura da comunidade. Os efeitos das alterações nos parâmetros do solo são normalmente determinados com amostras recolhidas no campo e trazidas ao laboratório, ou seja, onde as condições ambientais naturais podem não ser aplicáveis. Criamos um método (STAFD -tubos de amostra de solo para inundações e secas artifi ciais), que simula o estado hidrológico do solo in situ com núcleos implantados. As amostras de controle foram comparadas com amostras de tratamentos em que foram simuladas inundações de 15, 30, 60 e 90 dias e secas de 60, 90 e 120 dias no campo. Verifi couse que as inundações e a seca reduziram a quantidade de individuos em todos os grupos de fauna de solo, mas a resposta à seca foi mais lenta e não proporcional à redução prevista no teor de água. Os resultados das inundações simuladas demonstram, em especial, o valor do método STAFD para a investigação desse tipo de eventos extremos nos habitats naturais.Termos para indexação: alteração climática, seca, inundação, invertebrados do solo, tubos de amostra de solo, método STAFD.
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