Recolonization dynamics in a mixed seagrass meadow: The role of clonal versus sexual processes |
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Authors: | Email author" target="_blank">B?OlesenEmail author N?Marba C?M?Duarte R?S?Savela M?D?Fortes |
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Institution: | (1) Ocean Research Institute, The University of Tokyo, 1-15-1 Minamidai, Nakano-ku, Tokyo 164-8639, Japan;(2) Department of Earth and Planetary Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan |
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Abstract: | Recolonization dynamics from disturbance on a Philippine mixed seagrass meadow, containing species spanning more than 10-fold
in rhizome elongation rates and reproductive effort, was examined by following the recovery of a 1,200 m2 gap over 2.5 yr. The objective was to assess the contribution of contrasting species to the recovery process and to evaluate
the importance of sexual versus vegetative colonization. Large, slow-growing species,Thalassia hemprichii andEnhalus acoroides, that produce large, broadly-dispersed seeds dominated sexual colonization with a total of 2,643 and 210 seedlings, respectively,
recruiting to the area. Despite very rapid turnover of sexual recruits, the high frequency of seedling establishment ensured
successful development of new patches in areas devoid of vegetation, leading to a scattered and evenly distributed presence
of vegetation inside the gap. The small seagrass speciesCymodocea rotundata andHalodule uninervis, characterized by fast rhizome elongation rates but low reproductive output and limited seed dispersal, were the major contributors
to the overall 450 m2 increase in vegetation cover through fast lateral extension (144±6 cm yr−1) from meadow edge and surviving patches, forming a compact vegetation cover in one edge of the denuded area. We conclude
that contrasting recruitment strategies in the mixed-species seagrass community examined have implications for colonization
potential at different spatial scales. Fast clonal growth is only an efficient mechanism for colonization of disturbances
within established meadows (small gaps), whereas the large species, which combined high reproductive output with high seed
dispersal capacity, may act to accelerate the colonization process in large gaps or distant from established meadows. |
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