Seedling recruitment in the invasive clonal shrub, Mahonia aquifolium Pursh (Nutt.) |
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Authors: | Harald Auge Roland Brandl |
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Institution: | UFZ Centre for Environmental Research Leipzig-Halle, Department of Community Ecology, Hallesche Strasse 44, D-06246 Bad Lauchst?dt, Germany fax: ++49(34635)73-237; e-mail: aug@oesa.ufz.de, DE UFZ Centre for Environmental Research Leipzig-Halle, Department of Community Ecology and Department of Ecological Modelling, Permoserstrasse 15, D-04318 Leipzig Germany, DE
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Abstract: | The clonal shrub, Mahonia aquifolium, is an aggressive invader of some forests in central Germany. We analysed the importance of seedling recruitment for the
local dynamics of these invasive populations. In contrast to many other clonal plants, repeated seedling recruitment takes
place in M. aquifolium, contributing to the colonization of available space within populations. Thus, sexual reproduction is not only important
for dispersal to new sites but also for the local invasion␣process. In situations with grass competition (Calamagrostis epigejos) the number of successful recruits is reduced, and clonal growth is the predominant mode of reproduction. Since seedling
recruitment results in an increasing number of genets as well as ramets, the investigated populations are still below their
carrying capacities. Seedling densities are higher beneath the canopy of adults than outside adult patches, and increase with
increasing cover of adult ramets. The spatially clumped pattern of seedling emergence results in density-dependent mortality
especially in the most crowded seedling clusters. However, adult neighbourhood imposes a much higher mortality. Therefore,
we expect that the importance of seedling recruitment for the dynamics of local M. aquifolium populations will decline as the invasion process continues.
Received: 15 January 1996 / Accepted: 28 September 1996 |
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Keywords: | Biological invasion Clonal growth Density dependence Mahonia aquifolium Seedling recruitment |
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