Action: Crassula helmsii: Alter environmental conditions to control plants
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- No evidence was captured on altering environmental conditions to control Crassula helmsii by using shading, increasing turbidity, re-shaping or re-profiling banks of waterbodies or dredging.
'No evidence' for an action means we have not yet found any studies that directly and quantitatively tested this action during our systematic journal and report searches. Therefore we have been unable to assess whether or not the action is effective or has any harmful impacts. Please get in touch if you know of such a study for this action.
There are several possible methods of changing environmental conditions which could be used to reduce the growth of C. helmsii.
C. helmsii is relatively tolerant of shade, but heavy shade, such as that from overhanging willow trees could potentially reduce its competitive ability.
Increasing turbidity of the water to reduce light penetration and hence restrict plant growth has been suggested as a potential control method for C. helmsii. This could be achieved by releasing bottom-feeding fish, or seeding with nutrients to encourage algal growth (Leach & Dawson 2000).
Physical modification of waterbodies to increase the depth or make the sides steeper, could potentially reduce the area available for colonisation by C. helmsii. There is little evidence that dredging is an effective approach to control C. helmsii, although the total removal of the organic matter layer at the bottom of a pond was reportedly successful in eradicating C. helmsii from one site (Leach & Dawson 2000).
Leach J. & Dawson H. (2000) Is resistance futile? The battle against Crassula helmsii. Journal of Practical Ecology and Conservation, 4, 7-17.