Effects of irrigation on seed production and vegetative characteristics of four moist-soil plants on impounded wetlands in California

Published source details Mushet D.M., Euliss N.H. & Harris S.W. (1992) Effects of irrigation on seed production and vegetative characteristics of four moist-soil plants on impounded wetlands in California. Wetlands, 12, 204-207.
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This study is summarised as evidence for the following.

	Action	Category
	Actively manage water level: freshwater marshes Action Link

Actively manage water level: freshwater marshes

A replicated, randomized, controlled study in 1990 in nine ephemeral freshwater marshes in California, USA (Mushet et al. 1992) reported that irrigated marshes and non-irrigated marshes supported a similar relative abundance of common plant species, but that irrigation increased the height of four species and increased the biomass of two. Results summarized for this study are not based on assessments of statistical significance. All marshes were drained in spring. Four months later, the relative abundance of the most common plant species was broadly similar in irrigated and non-irrigated marshes: 49–62% of individual plants were pricklegrass Crypsis niliaca, 30–40% were sprangletop Leptochloa fasicularis, <5% were barnyardgrass Echinochloa crusgalli and <5% were swamp timothy Heleochloa schoenoides. However, all of these species were taller in irrigated marshes (3–29 cm) than in non-irrigated marshes (1–5 cm). Above-ground biomass of sprangletop and barnyardgrass was greater in irrigated marshes (0.1–0.7 g/plant) than non-irrigated marshes (<0.1–0.2 g/plant). Irrigation had little effect on the above-ground biomass of the other two species (irrigated: 0.1–0.2 g/plant; not irrigated: 0.1–0.2 g/plant). Methods: Nine adjacent experimental marshes were drained in April 1990 to simulate management for waterfowl. Six random marshes were irrigated by flooding (for <24 h): three in May only, and three in May and June. The other three marshes were not irrigated. In July–August, plants were counted and identified in five 0.25-m² plots/marsh, and 40 plants/species/marsh were measured, cut, dried and weighed.

(Summarised by: Nigel Taylor)