Home About us Contact
|
Home About us Contact | ||
|
|
||
Species-specific Traits (species-specific + trait)
Selected AbstractsInterspecific differences in population trends of Spanish birds are related to habitat and climatic preferencesGLOBAL ECOLOGY, Issue 1 2008Javier Seoane ABSTRACT Aim, Animal monitoring programmes have allowed analyses of population trends, most of which now comment on the possible effect of global climate change. However, the relationship between the interspecific variation in population trends and species traits, such as habitat preferences, niche breadth or distribution patterns, has received little attention, in spite of its usefulness in the construction of ecological generalizations. The objectives of this study were: (1) to determine whether there are characteristics shared among species with upwards or downwards trends, and (2) to assess whether population changes agree with what could be expected under global warming (a decrease in species typical of cooler environments). Location, The Spanish part of the Iberian Peninsula (c. 500,000 km2) in the south-western part of the Mediterranean Basin. Methods, We modelled recent breeding population changes (1996,2004), in areas without apparent land use changes, for 57 common passerine birds with species-specific ecological and distributional patterns as explanatory variables. Results, One-half of these species have shown a generalized pattern towards the increase of their populations, while only one-tenth showed a significant decrease. One half (54%) of the interspecific variability in yearly population trends is explained considering species-specific traits. Species showing more marked increases preferred wooded habitats, were habitat generalists and occupied warmer and wetter areas, while moderate decreases were found for open country habitats in drier areas. Main conclusions, The coherent pattern in population trends we found disagrees with the proposed detrimental effect of global warming on bird populations of western Europe, which is expected to be more intense in bird species inhabiting cooler areas and habitats. Such a pattern suggests that factors other than the increase in temperature may be brought to discussions on global change as relevant components to explain recent changes in biodiversity. [source] Oilseed rape crops distort plant,pollinator interactionsJOURNAL OF APPLIED ECOLOGY, Issue 1 2010Tim Diekötter Summary 1. New incentives at the national and international level frequently lead to substantial structural changes in agricultural landscapes. Subsidizing energy crops, for example, recently fostered a strong increase in the area cultivated with oilseed rape Brassica napus across the EU. These changes in landscape structure affect biodiversity and associated ecosystem services. 2. Mass-flowering oilseed rape has been shown to positively affect colony growth and densities of bumblebees, which may enhance pollination services in agroecosystems. Not considered, however, have been species-specific traits of pollinators resulting in disproportionate benefits from these recurrent resource pulses. A subsequent community shift towards the subsidized species potentially distorts plant,pollinator interactions in the surrounding landscape. 3. We analysed the effects of mass-flowering crops on the abundance of legitimate long-tongued bumblebee pollinators, nectar robbing by illegitimate short-tongued bumblebees and seed set in the long-tubed flowers of red clover Trifolium pratense in 12 landscape sectors with differing amounts of oilseed rape. 4. Densities of long-tongued bumblebees visiting long-tubed plants decreased with increasing amounts of oilseed rape. The simultaneous increase of nectar robbing suggests that resource depletion is a likely explanation for this decline which may lead to a distortion in plant,pollinator interactions. The decline in long-tongued bumblebees, however, did not result in an immediate effect on seed set. In contrast, seed set increased with increasing amounts of semi-natural habitats, indicating the positive effects of these habitats on the legitimate long-tongued pollinators. 5.Synthesis and applications. Accounting for species-specific traits is essential in evaluating the ecological impacts of land-use change. The disproportional trait-specific benefits of increasing oilseed rape to short-tongued bumblebees may abet an increasingly pollinator-dependent agriculture but simultaneously threaten the more specialized and rare long-tongued species and their functions. Semi-natural habitats were found to positively affect seed set in long-tubed plants indicating that they can counteract the potentially distorting effects of transient mass-flowering crops on plant,pollinator interactions in agroecosystems. Future agri-environmental schemes should aim to provide diverse and continuous resources matching trait-specific requirements of various pollinators in order to avoid resource competition. Thereby they harmonize the economic interest in abundant pollinators and the conservation interest in protecting rare species. [source] Phenotypic plasticity , contrasting species-specific traits induced by identical environmental constraintsNEW PHYTOLOGIST, Issue 3 2004John A. Strand No abstract is available for this article. [source] Light use efficiency of dry matter gain in five macro-lichens: relative impact of microclimate conditions and species-specific traitsPLANT CELL & ENVIRONMENT, Issue 1 2000K. Palmqvist ABSTRACT Relations between irradiance (I) and lichen growth were investigated for five macro-lichens growing at two sites in Sweden. The lichens represented different mycobiont,photobiont associations, two morphologies (foliose, fruticose) and two life forms (epiphytic, terricolous). The lichens were transplanted at two geographically distant sites in Sweden (1000 km apart) from Sept 1995 to Sept 1996 in their typical microhabitats, where microclimate and growth were followed. Between April/May and Sept 96, the terricolous species had a dry matter gain of 0ˇ2 to 0ˇ4 g (g DW),1 and the epiphytes 0ˇ01 to 0ˇ02 g (g DW),1. When related to area, growth amounted to 30 to 70 g m,2 for the terricolous species and to 1 to 4 g m,2 for the epiphytes. There was a strong correlation between growth and intercepted irradiance when the lichens were wet (Iwet), with 0ˇ2 to 1ˇ1 g lichen dry matter being produced per MJ solar energy. Across the 10 sets of transplants, light use efficiencies of dry matter yield (e) ranged between 0ˇ5 and 2%, using an energy equivalent of 17ˇ5 kJ g,1 of lichen dry matter. The higher productivity of the terricolous species was due to longer periods with thallus water contents sufficient for metabolic activity and because of the higher mean photon flux densities of their microhabitat. A four-fold difference in photosynthetic capacity among the species was also important. It is concluded that lichen dry matter gain was primarily related to net carbon gain during metabolically active periods, which was determined by light duration, photon flux density and photosynthetic capacity. [source] | ||||||||||