| 1. |
- Birkhofer, Klaus, et al.
(författare)
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Land-use type and intensity differentially filter traits in above- and below-ground arthropod communities
- 2017
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Ingår i: Journal of Animal Ecology. - : Wiley. - 0021-8790 .- 1365-2656. ; 86:3, s. 511-520
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Tidskriftsartikel (refereegranskat)abstract
- Along with the global decline of species richness goes a loss of ecological traits. Associated biotic homogenization of animal communities and narrowing of trait diversity threaten ecosystem functioning and human well-being. High management intensity is regarded as an important ecological filter, eliminating species that lack suitable adaptations. Below-ground arthropods are assumed to be less sensitive to such effects than above-ground arthropods. Here, we compared the impact of management intensity between (grassland vs. forest) and within land-use types (local management intensity) on the trait diversity and composition in below- and above-ground arthropod communities. We used data on 722 arthropod species living above-ground (Auchenorrhyncha and Heteroptera), primarily in soil (Chilopoda and Oribatida) or at the interface (Araneae and Carabidae). Our results show that trait diversity of arthropod communities is not primarily reduced by intense local land use, but is rather affected by differences between land-use types. Communities of Auchenorrhyncha and Chilopoda had significantly lower trait diversity in grassland habitats as compared to forests. Carabidae showed the opposite pattern with higher trait diversity in grasslands. Grasslands had a lower proportion of large Auchenorrhyncha and Carabidae individuals, whereas Chilopoda and Heteroptera individuals were larger in grasslands. Body size decreased with land-use intensity across taxa, but only in grasslands. The proportion of individuals with low mobility declined with land-use intensity in Araneae and Auchenorrhyncha, but increased in Chilopoda and grassland Heteroptera. The proportion of carnivorous individuals increased with land-use intensity in Heteroptera in forests and in Oribatida and Carabidae in grasslands. Our results suggest that gradients in management intensity across land-use types will not generally reduce trait diversity in multiple taxa, but will exert strong trait filtering within individual taxa. The observed patterns for trait filtering in individual taxa are not related to major classifications into above- and below-ground species. Instead, ecologically different taxa resembled each other in their trait diversity and compositional responses to land-use differences. These previously undescribed patterns offer an opportunity to develop management strategies for the conservation of trait diversity across taxonomic groups in permanent grassland and forest habitats.
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| 2. |
- Nilsson, Jan-Åke, et al.
(författare)
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Effects of Dispersal Date on Winter Flock Establishment and Social Dominance in Marsh Tits Parus palustris
- 1988
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Ingår i: Journal of Animal Ecology. - : JSTOR. - 1365-2656 .- 0021-8790. ; 57:3, s. 917-928
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Tidskriftsartikel (refereegranskat)abstract
- (1) We studied the effect of sex, size, age and prior occupancy on social dominance winter flock establishment in a population of marsh tits Parus palustris L. (2) When sex was accounted for, time of establishment in the winter flock-prior occupancy, was critical for the outcome of later aggressive interactions juveniles within flocks. Residents won all interactions with intruders irrespective controlling for sex. (3) Success in, and timing of, establishment were closely linked with hatching lower proportion of late-hatched than early-hatched juveniles became established winter flocks; they also became established later. Even small differences in hatching greatly influenced dominance and the probability of becoming established flock. (4) Since early establishment depends on early hatching, dominance and survival juveniles are determined by how early their parents start breeding. Furthermore, will be strong selection for quick establishment after
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| 3. |
- Smith, Henrik G., et al.
(författare)
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The trade-off between offspring number and quality in the great tit Parus major
- 1989
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Ingår i: Journal of Animal Ecology. - : JSTOR. - 1365-2656 .- 0021-8790. ; 58, s. 383-401
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Tidskriftsartikel (refereegranskat)abstract
- (1) Trade-offs between brood size and offspring growth and survival were manipulating the size of 221 great tit Parus major L. broods between 1983 (2) Nestling mass, wing length and tarsus length were inversely related to Hatching date also affected nestling growth, but its effect differed between Intrabrood variability in nestling size increased with brood size. (3) Nestling survival was inversely related to brood size. Small nestlings suffered mortality than large ones. The difference in nestling survival rate between categories was too small to equalize their productivity. (4) Fledgling survival to the autumn and to the following breeding season inversely related to brood size; fledglings from reduced broods survived better from control broods, which in turn survived better than fledglings from enlarged This resulted in the most productive category being the control broods. The fledglings increased with their size as nestlings and decreased with their hatching (5) The sex-ratio among independent fledglings was affected by brood size tion; proportionally more males survived in enlarged than in reduced broods. (6) Dispersal distance of juveniles was not affected by brood size, size hatching date, whereas it was affected by sex. The effects of starvation competition on fledgling survival and dispersal
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