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1

Cluster-based approach for identifying avian life-history groups for use in ecological monitoring

100%
Tworek S.
Polish Journal of Ecology
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2007
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tom 55
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nr 1
Almost ‘since ever’ ecologists have made attempts at the generalization of various site-specific, species-specific and timespecific situations, including different classifications of species, based on different principles and prepared for different purposes. This paper, presenting a conceptual model for selecting species of similar life-history pattern to other species and providing an example using birds as a model system, represents that current in the ecology. All bird species regarded as nesting in a given area of the mosaic landscape in southern Poland were described with respect to nine variables (nest type, nest location, food habits, place and way of foraging, migration status, number of broods, clutch size, incubation and fledging periods), grouped into 43 categories. Cluster analysis was then used to distinguish objectively species displaying similar life history traits and environmental adaptations into unique life-history ‘strategies’. The results of an exemplary analysis of variability in the density, domination, number of species and turnover rate in particular strategies, depending on the size of study plots, their structure, degree of isolation and the characteristic features of their surroundings, using regression and canonical correlation techniques, indicate the suitability of this approach to testing detailed hypotheses connected e.g. with studies on the response of species to different habitat conditions. The methods applied allow one to distinguish, in an objective way, the groups of species displaying similarities with respect to life history traits and environmental adaptations, in spite of the fact that the method of describing variables in cluster analysis may determine a different allocation of species to groups. A model, as described, could allow conservation principles to be developed for species of similar distribution, ecological feature or life history; especially for those species which face with population declines and for which no previous patterns have been established.
2
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Ecological features of Ambrosia artemisiifolia L. flowers and characteristics of Ambrosia L. pollen seasons in the condition of Lublin (Poland) in the years 2001-2008

84%
Weryszko-Chmielewska E., Piotrowska K.
Acta Agrobotanica
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2008
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tom 61
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nr 2
In the study, the biology of fl owering of Ambrosia artemisiifolia L. was investigated and the pattern of the Ambrosia pollen seasons in Lublin in the years 2001-2008 was characterised. The structure of male and female A. artemisiifolia fl owers was observed in cultivated plants under controlled conditions in the 2000 vegetative season. The number of pollen grains produced by the stamen, fl ower, infl orescence and plant was determined. It was shown that in A. artemisiifolia fl owers nonfunctional pistils occurred with a reduced ovary, performing the role of a pollen presenter. The pistils found in female fl owers differed signifi cantly in their morphological features from the pistils in male fl owers. It was calculated that one stamrn produced an average of 3 375 pollen grains, whereas one fl ower 16 875. A plant which produces 20 racemes may release over 420 million pollen grains into the atmosphere. The Ambrosia pollen seasons in particular years had different patterns. In some years, the days of maximum concentration were in the second half of August, in other years in the fi rst half of September. Over the 8-year period, the maximum daily concentration had a mean value of 116 pollen grains in m3 (31-311). Annual total concentrations of Ambrosia pollen grains ranged between 194 and 1200 grains, and it was 523 grains on the average. The pollen seasons were characterised by the occurrence of several-day-long interruptions in the presence of airborne pollen in the atmosphere of Lublin, which may indicate the long-distance transport of Ambrosia pollen.
3
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The structure of septal nectaries and nectar presentation in the flowers of Allium aflatunense B. Fedtsch.

84%
Zuraw B., Weryszko-Chmielewska E., Laskowska H., Pogroszewska E.
Acta Agrobotanica
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2009
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tom 62
|
nr 2
The location and structure of the septal nectaries in the flowers of Allium aflatunense B. Fedtsch. were studied. Light and scanning electron microscopy were used for examination. It has been shown that the septal nectaries are located in the lower part of the ovary and in the gynophore on which the ovary is borne. Nectar is secreted through the single-layered epidermis surrounding three nectary slits and nectar release occurs through three openings located at the base of the gynophore, which are the outlets of the ducts connected to the nectary slits. The expanded and fused bases of the stamen filaments and the tepals participate in secondary nectar presentation. In the flowers of Allium aflatunense, numerous purple elements: tepals, filaments, style and pedicle, perform the role of a colour attractant. On the intensely green ovary, there occur glistening conical outgrowths of epidermal cells, which may also function as signal attractants.
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