Wyniki wyszukiwania

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The relationships between aboveground biomass and Voronoi area of coexisting species in an old-field community

100%

Du F., Xu X., Zhang X. C., Sui Y., Shao M., Hu L., Shan L.

Polish Journal of Ecology

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2012

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tom 60

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nr 3

Voronoi area of coexisting species in a community has an important role in determining their performances as it is related with the available resources around individuals. Biomass formed within certain Voronoi area probably can be a mark of species that characterised resource competition ability of coexisting species in natural community. In this article, we tried to probe the subject in the following three aspects: 1) what is the apparent relationship between individuals’ aboveground biomass and their available Voronoi area for species in natural community? 2)what is the possible theoretic relationship between them? 3) additionally, whether there are any possible indices that can be elicited from species’ occupied Voronoi area to reflect species’ competitive ability. Using individual-based investigation of aboveground biomass and their corresponding positions, Voronoi area of all individuals of coexisting species in an old field community were computed. The growth of an individual could be regard as a process to compete for resources that is limited by the available area or volume encompassed by the neighborhood individuals. We extended logistic growth model to describe the relationship between Voronoi area and aboveground biomass of coexisting species by relating limiting rhizospheral resource with the Voronoi area around an individual. Theoretically, the individual’s aboveground biomass is also controlled by factor-ceiling effects of Voronoi area. So the extended model was fitted with boundary analysis method. And also, their linear relationship was fitted. Under the prediction that competive ability is one of the main driving factors of community succession, two parameters as the Voronoi area of coexisting species and the Voronoi area per unit of aboveground biomass were used to check whether they can designate species’ competitive abilities and competitive hierarchies. This was presented by fitting the two parameters with the successional niche positions that was represented by the ordination values along abandonment ages of old field communities in the local area. The results showed that: 1) For most species, the linear regression demonstrated that Voronoi area of an individual that occupied larger Voronoi area tended to have greater aboveground biomass. The nonlinear regression of showed that the relationship might depend upon species’ growth characteristics, like shade tolerance and root proliferation. Generally, the relationship could be better fitted by the extended logistic growth model using boundary analysis method than by the linear regression, except for some shade-preferring or clone species. If factor-ceiling effects were considered, at the highest, about 48% of the variation of aboveground biomass could be interpreted by Voronoi area. For some other species with light preference or clone proliferation, the determination coefficient was around zero. 2) Species’ averaged Voronoi area had significant and positive Kendall’s tau-b and Spearman correlations with successional niches, and species’ per-unit aboveground biomass positions of Voronoi area has significantly negative rank correlation with successional niche positions. These indicate that both of them can reflect species’ competitive ability and hierarchy to some extent.

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Topographic differences play a limited role on species distribution in a sub-tropical forest in South China

100%

Gong G.-Q., Huang Z.-L., Ye W.-H., Cao H.-L., lian J.-Y., Lin G.-J., Wei S.-G., Li L., Bin Y., Kong B., Li B.-W.

Polish Journal of Ecology

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2013

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tom 61

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nr 3

Habitat association test has been regarded as an effective way to evaluate the relative role of niche differentiation in a community. Topographical attributes are often selected as surrogates of niche processes. However, the inference for relative role of niche differentiation is likely problematic if the spatial dependence of plant community on underlying spatiallystructured topographic variables is not accounted for. In this study, we used the torus shift and principal component analysis (PCA) to resolve this problem, and tested the habitat associations by adjusted-SD test in a sub-tropical evergreen broad-leaved forest in south China. The result revealed that minority of 100 common species were specialist, among which 8 species associated with first two PC axes (accounted for 98% of total eigenvalue and contributed mainly by mean elevation and aspect) and 22 species associated with last two PC axes (contributed by slope and convexity). In conclusion, we found the niche processes represented by topographical attributes play a limited role in the Dinghushan sub-tropical evergreen broad-leaved forest plot. Further study should include more habitat variables to examine the habitat associations.

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Circadian rhythms of ground living spiders: mechanisms of coexistence strategy based on the body size

100%

Krumpalova Z., Tuf I. H.

Polish Journal of Ecology

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2013

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tom 61

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nr 3

Circadian rhythms of activity are one of the many cases of the multidimensional mechanisms of species coexistence. Except of others, the mechanisms of coexistence strategy of spiders involve habitat, seasonal occurrence, food offers and body size of spiders. Circadian rhythm of activity of ground living spiders in floodplain forest and clearcut along the Morava River in the Litovelské Pomoraví Protected Landscape Area (Czech Republic, Central Europe) was studied. Activity of whole community was asymmetrical, diurnal activity was more frequent than nocturnal. Abundant species were analysed closely. Patterns of similarity in syntopic spider groups suggested the body size is significant factor influencing their circadian activity. We found out the predominantly small species achieved bimodal pattern of activity, influenced by the different activity of males and females. Generally we can conclude that spiders smaller than 5 mm were active during late night-morning and spiders bigger than 5 mm were active during afternoon and evening. This pattern was associated with changes of temperature of soil surface – big spiders were active during warmer parts of day. The presented data provide evidence of body-size differences among the spiders enable their coexistence in assemblages.

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Community ecology of the terrestrial small mammals of Zakouma National Park, Chad

100%

Granjon L., Houssin C., Lecompte E., Angaya M., Cesar J., Cornette R., Dobigny G., Denys C.

Acta Theriologica

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2004

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tom 49

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nr 2

The terrestrial small mammal community of the Zakouma National Park (Chad) was assessed by live trapping in various habitats during the dry season. Nearly 3000 trap-nights yielded 505 captures of nine rodent and two shrew species, making up a representative small mammal community for the Sudanian savanna biotic zone. Murine rodents of the genus Mastomys dominated, with M. erythroleucus and M. cf. kollman- nspergeri occuring at similar abundances. The former was widespread and especially abundant in habitats with high tree cover. The latter was more localized, predominantly in annually flooded habitats characterized by a clay-rich soil, often with Acacia seyal as the main vegetation. Population structure differed between the two species, suggesting distinct reproductive strategies possibly linked with habitat preferences: the M. erythroleucus population comprised mainly young, immature individuals, whereas M. cf. kollmannspergeri was represented by older individuals, a significant fraction of which had already reproduced. Taterillus congicus and Tatera kempi (gerbilline rodents), togetjier with Lemniscomys zebra, were mainly found in more open habitats with sand-rich soils. Arvicanthis niloticus, Acomys cf. johannis, Mus mattheyi and Xerus erythropus were the other rodents captured, whereas shrews were represented by Crocidura fulvastra and Suncus sp.

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Characterization of two coexisting pathogen populations of Leptosphaeria spp., the cause of stem canker of brassicas

80%

Kaczmarek J., Jedryczka M.

Acta Agrobotanica

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2011

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tom 64

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nr 2

Stem canker of brassicas, also known as blackleg is the most damaging disease of many Brassicaceae. The disease is caused by Leptosphaeria maculans (Desm.) Ces et de Not. and L. biglobosa sp. nov., Shoemaker & Brun, which coexist in plants and resulting in disease symptoms and decreased yield, quantity and quality of cultivated vegetables and oilseed rape. The paper presents taxonomic relationships between these coexisting pathogen species, describes particular stages of their life cycles, summarizes the differences between the species, and reviews methods for their identification.

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Interspecific hybridization in sympatric species of Daphnia inhabiting lakes in Northeastern Poland

80%

Brzezinski T., Fronk J., Trzcinska-Danielewicz J., Dawidowicz P.

Oceanological and Hydrobiological Studies

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2012

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tom 41

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nr 2

Ograniczanie wyników

The relationships between aboveground biomass and Voronoi area of coexisting species in an old-field community

Topographic differences play a limited role on species distribution in a sub-tropical forest in South China

Circadian rhythms of ground living spiders: mechanisms of coexistence strategy based on the body size

Community ecology of the terrestrial small mammals of Zakouma National Park, Chad

Characterization of two coexisting pathogen populations of Leptosphaeria spp., the cause of stem canker of brassicas

Interspecific hybridization in sympatric species of Daphnia inhabiting lakes in Northeastern Poland