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Ecological Behaviour (ecological + behaviour)
Selected AbstractsShifts in the ecological behaviour of plant species between two distant regions: evidence from the base richness gradient in miresJOURNAL OF BIOGEOGRAPHY, Issue 2 2008Petra Hájková Abstract Aim, Water pH and conductivity are known to be major environmental factors controlling the species composition of nutrient-poor wetlands. Based on the analysis of two large data sets of species co-occurrence, sampled along the entire pH/calcium gradient, we explored whether species exhibit similar or different ecological behaviour in the two regions. Location, West Carpathians (central Europe) and Bulgaria (south-eastern Europe), situated 800 km apart. Bulgaria represents a range margin for many mire species. Methods, The probability of occurrence of the 41 most common species along the pH and conductivity gradients was assessed using logistic regression fitted by means of generalized additive models. The species optimum and amplitude were determined. To check the possible effect of competitive release, we estimated where the potential maximum number of species (maximum overlap in realized niches) occurs along the base richness gradient. Results, Most of the 41 frequently occurring species showed a significant response to water pH and ln-transformed conductivity (approximating total mineral richness) in both regions. Eight species showed a shift in pH optimum greater than one unit, while 12 species showed the same or a larger shift along the conductivity gradient. Nearly all these striking shifts were connected to an extension of species tolerance towards mineral-poor acid habitats in Bulgaria, which causes links between species and measured factors to be conspicuously weaker in Bulgaria than in the West Carpathians. Regarding ecological amplitude, 24 species exhibited a wider tolerance to water conductivity in the West Carpathians, whereas 17 species exhibited a wider tolerance in Bulgaria. Main conclusions, A distinctive variation in the realized niche was observed in a large portion of the species examined. Niche shifts between local populations of the same species were similar to those of closely related vicariant species. Ecotypic adaptation within species is a possible explanation for this pattern. Other possible explanations (competitive release, specific habitat conditions, compensation for climate) seem to be less justified. The local populations of rich-fen species may have adapted to mineral-poor acid conditions in the high crystalline mountains of Bulgaria during dry periods of pleniglacials. Nomenclature,Marhold & Hindák (1998); for Balkan elements not included in this source, Andreev et al. (1992). [source] Fruit dispersal and seed banks in Atriplex sagittata: the role of heterocarpyJOURNAL OF ECOLOGY, Issue 2 2001Bohumil Mandák Summary 1Atriplex sagittata, an arly succesional, annual species of disturbed habitats in Central Europe, produces three types of fruits. We studied the differences in dispersal between the fruit types in order to investigate their ecological roles. 2The typical positive relationship between dispersal ability and germinability is not found in this species. Type A (ebracteate) fruits produced deeply dormant seeds and had the lowest dispersal potential, but of the two fruits with bracts, type B, with dormant seeds, was better dispersed by both water and wind than type C, which produces non-dormant seeds. 3Wind, temperature and precipitation have significant effects on fruit release but their effects differ between fruit types. The release of fruit types with bracts was positively correlated with wind whereas all fruit types tended to be negatively correlated with precipitation and temperature range. 4Type C fruit, which contains non-dormant seed, are absent from the soil in summer and have a Type II transient seed bank. Type A and B fruits, containing dormant seeds, form a persistent seed bank. 5Heterocarpy, where fruit types show distinct ecological behaviour, enables colonizing species such as A. sagittata to survive both major disturbance (by ensuring that some seeds persist) and unfavourable conditions (by spreading germination over a long period). 6In A. sagittata, seed dynamics can be explained by the germination behaviour of seeds produced by the three types of fruit. All fruit types mature in autumn, but few of Type A fall from the mother plant until spring, when germination is probably inhibited because of insufficient stratification. Type C fruit, however, show peak dispersal in winter and the majority of these non-dormant seeds are able to germinate as soon as conditions become more suitable. [source] Seasonality of hydrographic variables in a coastal lagoon: Mar Chiquita, ArgentinaAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 4 2006Jorge Marcovecchio Abstract 1.The concentration and distribution of several hydrographical variables from Mar Chiquita coastal lagoon, Argentina, were measured monthly over a year in order to quantify their seasonal variations. Temperature, salinity, inorganic nutrient concentrations (nitrate, nitrite, phosphate, silicate) in the water column, and photosynthetic pigments (chlorophyll a and phaeopigments) in suspended particulate matter (SPM), were measured using internationally standardized analytical methods. 2.Agricultural use of land surrounding the coastal lagoon has been shown to be the main nutrient source, owing to the use of fertilizers for farming and the consequent leaching of the soils by freshwater runoff. 3.Two different hydrographical areas were identified within the coastal lagoon, one showing marine influence and the other dominated by inland influence (due to catchment and freshwater inputs), both with different characteristics and ecological behaviour. 4.The frequent occurrence of phytoplankton blooms has also been identified within the coastal lagoon. There was significant biological production (in terms of chlorophyll a) within the lagoon throughout the year. The lagoon appears to function as a transitional system, opportunistically benefiting from extra nutrient inputs which, together with other environmental conditions, results in a continuous food supply, useful to both marine and estuarine organisms. Consequently the system is important for numerous fish and shellfish species as a nursery area. Copyright © 2005 John Wiley & Sons, Ltd. [source] Factors affecting corporate environmental strategy in Spanish industrial firmsBUSINESS STRATEGY AND THE ENVIRONMENT, Issue 8 2009Elena Fraj-Andrés Abstract During the last 30 years, environmental issues have become very important for governments, consumers and companies. Firms, aware of their environmental responsibilities, have started to show an important commitment to society and the natural environment, developing environmentally friendly strategies. However, the factors that determine the choice of environmental strategies are still unclear. They range from ethical motivations to social, legislative and competitive factors. This study analyses the main antecedents that influence firms' ecological behaviour, distinguishing between environmental orientation and environmental strategies. The hypotheses proposed in this study are analysed by means of a structural equation model on a sample of 235 industrial firms. The results reveal that competitive motivations and management commitment are the most important factors explaining why firms incorporate environmental issues into their strategic planning process. Moreover, management commitment is a critical factor for firms because managers' perception about customers' ecological concern directly influences firms' environmental behaviour. Copyright © 2008 John Wiley & Sons, Ltd and ERP Environment. [source] Carbon isotope discrimination and wood anatomy variations in mixed stands of Quercus robur and Quercus petraeaPLANT CELL & ENVIRONMENT, Issue 8 2001S. Ponton Abstract The two most common oak species in western Europe, Quercus robur and Quercus petraea, display different ecological behaviours, particularly with respect to their responses to drought. The ecophysiological basis of this niche difference is not understood well. Here we test the hypothesis that these two species present distinct water use efficiencies (WUEs), using the carbon isotope discrimination approach. Leaves and 13 dated ring sequences were sampled in 10 pairs of adult trees growing side by side. Carbon isotope composition was measured on cellulose extracts. In addition, relationships between carbon isotope discrimination and wood anatomy were assessed at the tree level. Quercus robur displayed a 1·0, larger isotopic discrimination than Q. petraea, and therefore a lower intrinsic WUE (,13%). This interspecific difference of isotopic discrimination was quite stable with time and independent of tree radial growth and climate fluctuations. A strong positive correlation was observed between average tree values of earlywood vessel surface area and 13C isotopic discrimination. This correlation was even higher with 13C of the 1976 dry year (r = 0·86). These observations led to the hypothesis that hydraulic properties of xylem could exert a constraint on leaf gas exchange, resulting in a larger WUE for individuals with smaller vessel cross-section area. [source] | |||||||||||||