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The Ecotone Between Spartina Foliosa Trin. and Salicornia Virginica L. in Salt Marshes of Northern San Francisco Bay: III. Soil Aeration and Tidal Immersion
Bruce E. Mahall and Roderic B. Park
Journal of Ecology
Vol. 64, No. 3 (Nov., 1976), pp. 811-819
Published by: British Ecological Society
Stable URL: http://www.jstor.org/stable/2258810
Page Count: 9
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Measurements of soil oxygen diffusion rates along transects crossing the ecotone between Spartina and Salicornia were made during the summer. They indicated slight decreases with increasing depth, but there were no significant differences between readings taken in the Spartina zone and those in the Salicornia zone. These results, together with the observation of iron oxides surrounding Salicornia roots in the marsh soil, indicate that soil aeration is not an important factor affecting the distribution of Spartina and Salicornia about the MHW ecotone. Experiments in which Salicornia and Spartina plants were exposed to artificial tides of different heights indicated that the growth of Salicornia seedlings and older plants is reduced by 30-40% by `tides' only 8 cm higher than in the control and lasting only 1/12 of the daylight period. The higher `tides' also inhibited re-rooting and the production of new branches. Growth of Spartina plants was not significantly affected. In the light of measured differences in ground level between the Spartina and Salicornia zones, this indicates that inhibition of growth resulting from tidal immersion may be an important factor checking the seaward advance of Salicornia and tending to exclude it from the Spartina zone.
Journal of Ecology © 1976 British Ecological Society