Differential effects of increasing salinity on germination and seedling growth of native and exotic invasive cordgrasses

Authors: INFANTE-IZQUIERDO, MARIA - Universidad De Huelva; CASTILLO, JESUS - University Of Seville; Grewell, Brenda; NIEVA, F. JAVIER - Universidad De Huelva; MUNOZ-RODRIGUEZ, ADOLFO - Universidad De Huelva

Submitted to: Plants
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/22/2019
Publication Date: 9/25/2019
Citation: Infante-Izquierdo, M.D., Castillo, J.M., Grewell, B.J., Nieva, F.J., Munoz-Rodriguez, A.F. 2019. Differential effects of increasing salinity on germination and seedling growth of native and exotic invasive cordgrasses. Plants. 8(10):372. https://doi.org/10.3390/plants8100372.
DOI: https://doi.org/10.3390/plants8100372

Interpretive Summary: Biological invasions have continued to increase in coastal salt marshes. Spartina cordgrass species have successfully invaded coastal wetlands of several continents, including the western US and Europe, where they have displaced native vegetation, and negatively altered ecosystem processes and services provided by native vegetation. Tidal wetlands are highly stressful environments where halophytes are subjected to high mortality risk. These environments are also undergoing changes in inundation and salinity regimes due to sea level rise. Under these changing environmental forces, it is important to understand recruitment effects of invasive plant species. Soil salinity is a key environmental factor influencing germination and seedling establishment in salt marshes. Global warming and sea level rise are changing estuarine salinity, and may modify the colonization ability of halophytes. We evaluated the effects of increasing salinity on germination and seedling growth of native Spartina maritima and invasive S. densiflora from wetlands of the Odiel-Tinto Estuary. Responses were assessed following salinity exposure from fresh water to hypersaline conditions. The germination of both species was inhibited and delayed at high salinities, and pre-exposure to salinity accelerated the speed of germination. S. densiflora was more tolerant of salinity at germination than S. maritima. S. densiflora was able to germinate at hypersalinity and its germination percentage decreased at higher salinities compared to S. maritima. In contrast, S. maritima showed higher salinity tolerance in relation to seedling growth. Contrasting results were observed with differences in the tidal elevation of populations. Our results suggest S. maritima is a specialist species with respect to salinity, while S. densiflora is a generalist capable of germination of growth under suboptimal conditions. Invasive S. densiflora has greater capacity than native S. maritima to establish from seed with continued climate change and sea level rise.

Technical Abstract: Soil salinity is a key environmental factor influencing germination and seedling establishment in salt marshes. Global warming and sea level rise are changing estuarine salinity, and may modify the colonization ability of halophytes. We evaluated the effects of increasing salinity on germination and seedling growth of native Spartina maritima and invasive S. densiflora from wetlands of the Odiel-Tinto Estuary. Responses were assessed following salinity exposure from fresh water to hypersaline conditions. The germination of both species was inhibited and delayed at high salinities, and pre-exposure to salinity accelerated the speed of germination. S. densiflora was more tolerant of salinity at germination than S. maritima. S. densiflora was able to germinate at hypersalinity and its germination percentage decreased at higher salinities compared to S. maritima. In contrast, S. maritima showed higher salinity tolerance in relation to seedling growth. Contrasting results were observed with differences in the tidal elevation of populations. Our results suggest S. maritima is a specialist species with respect to salinity, while S. densiflora is a generalist capable of germination of growth under suboptimal conditions. Invasive S. densiflora has greater capacity than native S. maritima to establish from seed with continued climate change and sea level rise.