Vegetation and water-table relationships in a hydrologically restored riparian meadow

Published source details Hammersmark C.T., Rains M.C., Wickland A.C. & Mount J.F. (2009) Vegetation and water-table relationships in a hydrologically restored riparian meadow. Wetlands, 29, 785-797.
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This study is summarised as evidence for the following.

	Action	Category
	Raise water level to restore/create freshwater marshes from other land uses Action Link

Raise water level to restore/create freshwater marshes from other land uses

A study in 2005 of meadows next to an ephemeral stream in California, USA (Hammersmark et al. 2009) reported that after diverting the incised stream into a new shallower channel, some wetland plant communities developed. Six years after intervention, three communities dominated by wetland-characteristic plant species had developed close to the stream where the water table was highest (flooded for >24 days in the growing season, on average). The most abundant species in each community were Nebraska sedge Carex nebracensis (16% cover), Bach’s calicoflower Downingia bacigalupii (16% cover) and pale spikerush Eleocharis macrostachya (39% cover). The communities contained 8–18 plant species/4 m² and had 56–83% vegetation cover. Areas with a lower water table (flooded for <10 days in the growing season, on average) retained plant communities dominated by the non-native common meadowgrass Poa pratensis and Japanese brome Bromus japonica – which were also abundant before intervention (not quantified). Methods: In summer 2005, vascular plant species and their cover were recorded in 128 plots, each 4 m², across a floodplain. In 1999, the floodplain water table had been raised by plugging the old channelized and incised stream (creating a series of ponds) and diverting the stream along a new, shallower course.

(Summarised by: Nigel Taylor)