Remove vegetation that could compete with planted non-woody plants: brackish/saline wetlands
Overall effectiveness category Unknown effectiveness (limited evidence)
Number of studies: 1
Background information and definitions
Removing other plants before or after planting desirable marsh or swamp plants could reduce competition for space, light and nutrients. Survival and growth of planted vegetation may be improved. Note that abundant competitors, and/or the absence of the vegetation to be introduced, could be symptoms of inappropriate physical conditions that may also need to be managed. Also note that existing vegetation may help to protect planted vegetation from extreme temperatures and sunlight, and protect the wetland surface from erosion.
To be clear, this action includes various specific actions that remove undesirable plants (e.g. physical removal, mowing, herbicide application) or kill undesirable seeds (e.g. burning, covering the soil with black plastic) in areas planted with desirable marsh or swamp plants. Management might be one-off or continuous. Evidence summarized for this action focuses on responses of the planted vegetation; studies that report responses of other vegetation are included in separate interventions elsewhere on this site.
Related actions: Introduce nurse plants before/after planting target marsh or swamp vegetation.
Supporting evidence from individual studies
A replicated, randomized, paired, controlled study in 2006 in an estuarine salt marsh in California, USA (Varty & Zedler 2008) found that thinning dominant pickleweed Salicornia virginica before sowing/planting dwarf saltwort Salicornia bigelovii did not significantly affect the density of saltwort seedlings, but did increase survival of planted saltwort. Two months after sowing/planting, the total density of saltwort seedlings did not significantly differ between thinned and unthinned plots (data not reported). However, after six months, the survival rate of planted saltwort seedlings was 2.4 times greater in thinned than unthinned plots (further data not reported). Methods: In March 2006, dwarf saltwort was planted and sown into seventy-two 0.25-m2 plots (three sets of 24) on a pickleweed-dominated salt marsh. Four seedlings and 1.25 ml of seed were added to each plot. In 36 plots (12 random plots/set), pickleweed had been thinned (stems cut and removed) to leave roughly 50% cover. The other plots were left unthinned (>75% pickleweed cover). Pickleweed cover remained lower in thinned than unthinned plots throughout the growing season. Half of the plots had also been lowered slightly (5–10 cm). Vegetation was surveyed between May and September 2006.Study and other actions tested