Effects of flooding on germination and establishment of the invasive cordgrass Spartina densiflora

Abstract

Flooding has been described as one of the most important environmental factors determining the distribution of salt marsh plants. We studied the impact of five water levels (from well-drained to 8cm deep) on the germination and establishment of the invasive cordgrass Spartina densiflora under controlled glasshouse conditions. The germination rate was ca. 60%, tending to decrease gradually with depth. There was no seedling emergence from deeper than 4cm, because every seedling at 8cm died. Spartina densiflora showed a high physiological plasticity. Seven months after germination, relative water content varied between 69±13% at well-drained conditions and 87±7% at 4cm, without significant differences between treatments. Plants rooted at 4cm presented the highest quantum efficiency of photosystem II (PSII) with slightly lower maximum net photosynthesis rate than other treatments, reflecting high photoprotection levels, together with low nitrogen and pigments contents. Water level depth reduced shoot relative growth rate (RGR). Our results could be useful to fight S. densiflora invasion, because artificial inundation of invaded marshes to a water depth of 8cm would prevent its establishment from the seed bank. © 2012 The Authors. Weed Research © 2012 European Weed Research Society.