Growth strategies of four salt marsh plants on Mankyung River estuary in Korea

The emergence of seedlings, the length of roots and shoots, and the biomass of four dominant plant species and shore height were measured to investigate the growth strategy of these plants on the salt marsh of Mankyung River estuary. Four salt marsh plants showed a distinctive zonation, for example, Suaeda japonica was predominantly spread around the low salt marsh, Atriplex gmelini and Aster tripolium were in the middle, and S. asparagoides was in the upper part of the marsh. In terms of emergence of seedlings, S. japonica appeared first followed by A. gmelini, S. asparagoides, and A. tripolium. The growth strategies of halophytes were as follows: S. japonica germinated earlier than the other halophytes so that its root grew rapidly and extensively at the beginning of growth. This species adopted a continuous germination strategy, allowing growth whenever favorable conditions were provided. A. gmelini germinated later than S. japonica, as a quasi-simultaneous germination type, it showed the highest germination rate within the shortest time. Aster tripolium germinated later than any other halophyte. Since this species exhibited characteristics between the continuous germination type and the quasi-simultaneous germination type, it did not show a very high germination rate. Instead, it showed continuous germination and consistent growth of both above-ground and underground parts. Suaeda asparagoides showed an especially high emergence rate at the beginning of its growth. However, the high density retarded its growth until the middle stage. Its roots extended longer than the other halophytes, allowing it to grow well in the dry conditions of the upper marsh.