Long-term population dynamics of two Carex curvula species in the Central Alps on native and alien soils |
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Authors: | B Erschbamer U Buratti J Winkler |
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Institution: | (1) Department of Geobotany, Institute of Botany, University of Innsbruck, Sternwartestrasse 15, A-6020 Innsbruck, Austria Fax +43-512-507-2715; e-mail: Brigitta.Erschbamer@uibk.ac.at, AT |
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Abstract: | The demography of two closely related alpine sedges, Carex curvula subsp. curvula and Carex curvula subsp. rosae (=C. curvula and C. rosae) has been investigated on their typical sites in the Central Alps. Both species proliferate vegetatively and develop dense
tussocks but they show different dominance behaviours in their respective grasslands. It was hypothesized that this may be
caused by different growth abilities. The main aim of the study was to compare the vegetative growth of the species under
field conditions, under competition-free conditions and under changed soil conditions. An attempt was also made to clarify
whether vegetative growth is density dependent. Permanent plots were established in the respective grasslands of the two species
and the ramet density was counted over 3 years. Groups of 10 and of 30 ramets of each species were grown in pots with typical
and with alien substrate and their growth was observed for 5 years at the field site. The grassland populations of both species
were very stable and the overall ramet growth rate (λ) was close to 1.0. Within the pots, both species reached a high ramet
number. Only the group of 30 ramets of C. curvula on alien soil could not recover from the transplantation shock. Within the pots, C. rosae showed a greater ramet turnover and a higher increase in ramets than C. curvula. On their native substrate, both species had a significantly higher ramet increase than on the alien substrate. Ramet growth
was found to be density dependent for both species, the increases recorded for the groups of 10 being significantly greater
than for the groups of 30. Although C. curvula produced fewer ramets than C. rosae, the aboveground dry weight of the former was significantly higher. This may be decisive for its greater competitive success
in closed grasslands.
Received: 12 April 1997 / Accepted: 12 December 1997 |
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Keywords: | Alien substrate Density dependence Population dynamics Ramets Substrate dependence |
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