Control problematic plants (specific intervention unclear): freshwater marshes or swamps
Overall effectiveness category Unknown effectiveness (limited evidence)
Number of studies: 1
Background information and definitions
This section considers studies that have controlled problematic plants, but which do not clearly report the specific intervention(s) used for control so the study cannot be summarized elsewhere in this chapter.
For this section, “vegetation” refers to overall or non-target vegetation. Studies that only report responses of target problematic plants have not been summarized.
Supporting evidence from individual studies
A replicated, site comparison study in 2011 of 26 freshwater marshes in Oregon, USA (Rowe et al. 2014) found that marshes in which non-native plants were actively controlled had higher overall plant richness and diversity than marshes where non-native plants were not controlled, but similar overall vegetation cover. Controlled marshes contained more plant taxa (13 taxa/30 m2; 87 taxa across 18 marshes) than uncontrolled marshes (9 taxa/30 m2; 42 taxa across eight marshes). The same was true for plant diversity (data reported as a diversity index). Controlled marshes had statistically similar overall vegetation cover to uncontrolled marshes but lower cover of plants not native to Oregon (reported as statistical model results). The study also reported data on cover of individual plant species. For example, native spikerush Eleocharis sp. had greater cover in controlled marshes (13%, vs uncontrolled: 7%), whereas invasive reed canarygrass Phalaris arundinacea had lower cover in controlled marshes (8%, vs uncontrolled: 33%). Methods: In summer 2011, emergent vegetation was surveyed in 26 permanent and ephemeral marshes (0.08–14.7 ha). In each marsh, plant species and cover were recorded in thirty 1-m2 quadrats along transects from the shore to shallow water. Non-native plants had been actively controlled in 18 marshes (“intensive management” applied to >50% of the marsh at least twice in the past three years; no further details reported) but not in the other eight marshes (where the only management, if any, involved “minimal” control of the water level).Study and other actions tested