Burial effects on seed germination and seedling emergence of two halophytes of contrasting seed size

Abstract

ABSTRACT Background Germination and especially emergence can decrease significantly with depth. Aim Our main goal was to examine the effects of sand burial depth on seed germination and seedling establishment of two halophytes, Spartina densiflora and Atriplex portulacoides, with contrasted fruit traits. Methods The effects of sand burial to depths of 0 to 6 cm on seed germination and seedling establishment were studied in a greenhouse experiment. Sediment erosion/accretion dynamics were also recorded at a salt marsh colonised recently by both species. Results Germination percentage for both halophytes was higher at a depth of 1 cm than at the surface, and decreased gradually with increasing depth below 1 cm. Emergence of seedlings was similar between 1 and 3 cm (ca. 20–60 %) for both species. The highest seedling survival rates (ca. 100 %) were recorded for seeds sown at a depth of 2 cm for S. densiflora and between 1 and 3 cm for A. portulacoides. Recorded erosion and accretion rates was large enough to modify germination and establishment patterns in both halophytes. Conclusions Spartina densiflora showed higher germination rates than A. portulacoides at greater depths, which seemed to be related to its growth form.