Individual study: A systematic review of the effectiveness of management techniques used in the control of invasive esturine cordgrass Spartina species
Roberts P.D. & Pullin A.S. (2006) The effectiveness of management options used for the control of Spartina species. Systematic Review No. 22. Centre for Evidence-Based Conservation
Several cordgrass Spartina spp. have been introduced to coastal estuaries around Europe, USA, Australia, New Zealand and Asia either deliberately to stabilize mud banks, or through accidental introduction. These non-native Spartina species and hybrids may be highly invasive, frequently becoming the dominant plant and displacing native flora and fauna. This review summarises the effectiveness of management techniques used in Spartina control.
A systematic review (see: www.cebc.bangor.ac.uk for methodology) was undertaken to investigate the effectiveness of management aimed at controlling or eradicating invasive cordgrasses Spartina species (and hybrids). It also aimed to analyse, when possible, the effects of habitat variables (e.g. substrate type) on treatment effectiveness.
The available evidence suggests that to achieve successful Spartina control, management should be species (or hybrid) specific e.g. bio-control was found to be highly effective (92.5%) against S.anglica, but much less so for S.alterniflora (18.4%).
Herbicide control: Imazapyr and Glyphosate herbicide application were by far the most commonly used management interventions. Imazapyr achieved 85.1% S.alterniflora density reduction but was not assessed against S.anglica. Glyphosate achieved 57.9% S.alterniflora density reduction and 42.8% against S.anglica. The addition of a surfactant/ wetting agent increased the effectiveness of both herbicides by an additional 8-12%. Of these two herbicides, Imazapyr provides greater control of S.alterniflora at lower concentrations with a shorter drying time required than Glyphosate. The most effective herbicides against S.anglica were fenuron (88.2%) and aminote-T (75.8%), but both had small datasets and require further trials.
Cutting: Cutting alone is not effective in controlling S.anglica, and produced an overall increase in stem density of 42.8%. However when cutting is combined with a smothering element, e.g. industrial black plastic sheeting, this was highly efficient, achieving declines of on average 98%. In addition cutting and smothering was reported as also the only management intervention which caused a decline in dry root weight. For the control of S.alterniflora both cutting only and cutting with glyphosate reduced densities by 68% and 91% respectively.
Grazing: Grazing of Spartina by ungulates (e.g. horses/cattle/deer) has been carried out for decades with little or no apparent impact.
Biological control: The use of a species such as Prokelisia marginata (a planthopper) as a control agent is still in its infancy and further trials are required.
Confounding variables: The majority of experiments had an insufficient replicates to robustly assess the impact of numerous confounding variables.
Reseach implications: Further experimental evidence is required to fully establish the efficacy of a number of control techniques, including: herbicide use (e.g. paraquat, 2,2-DPA, aminote-T, fenuron, and diuron); cut and glyphosate; cut and smother; and biological control agents e.g. Prokelisia spp. Experiments investigating S.townsendi and S.patens control were few, further research is thus required. In addition, the authors highlight that basic reporting of site characteristics and experimental trial methodologies should be improved.
Note: If using or referring to this published study, please read and quote the original paper, this can be viewed at: http://www.cebc.bham.ac.uk/Documents/CEBC%20SR22%20Spartina%20control.pdf