Germany
Spatio-temporal flowering patterns of insect - pollinated plant species: A xerothermic vegetation complex as an example
Fig. 1 Xerothermic vegetatation complex with flowering Anthericum liliago and Carduus defloratus
Abstract poster, 10 -14 July 2000 Mosonmagyarovar, Hungary, 8th International Pollination Symposium of the ICPBR, Martina Stang & Bodo Schick
The aim of the study was to detect a pattern to the spatio-temporal structure of a vegetation complex in relation to pollination. Therefore all of the insect-pollinated plant species were studied in regard to their spatial distribution, flowering phenology and floral morphology. The chosen xerothermic vegetation complex on calcareous rocky soil is located in the middle of Germany. It consists of grasslands, warm forest fringes and bushes (1500 m²) altogether surrounded by different forest types. Despite the small size of the complex a large number of insect-pollinated plants come into bloom. This species abundance in addition to a small human impact seems to be a good precondition to detect natural niche relationships in relation to pollination.
The flowering phenologies of in total 91 insect-pollinated species in the whole sample area (2700 m² inclusive forest types) were recorded during a period of 4 years. Different weather conditions lead to variable peak flowering times, durations of flowering and numbers of flowering individuals but the sequence of flowering remained nearly the same. The same holds for the flowering peaks of the different communities which show a characteristic sequence.
The studied vegetation complex is composed of nearly all morphological flower types which exist in Central Europe. It comprises typical portions of unspecialised and specialised flowers. The major group among the specialised flowers is adapted to pollination by bees. Bumblebees are particularly important pollinators in the studied area. A continuous reward sequence for this pollinator group is only provided if all plants of the different communities are considered as a whole. Plant species with great overlap in spatial distribution and flowering time show more morphological niche partitioning, which is mainly expressed by differences in accessibility of rewards and position of pollen deposition, than species with a small spatio-temporal overlap. Flower colours are rather typical for different accessibility types of floral rewards and contribute rarely to niche partitioning of species with the same morphological flower type.