Evidence details
angus.webb@unimelb.edu.au on 04 Oct 2021
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Study
- Citation
- GREET, J., WEBB, J. A., & DOWNES, B. J. (2011). Flow variability maintains the structure and composition of in-channel riparian vegetation. Freshwater Biology.
- Study description
- Looked at plant species richness upstream and downstream of three small dams with two other streams acting as control sites.
Response
- Cause term/trajectory
-
Hydrology - surface flow (variability)
(Decrease)
- Cause description
- Small dams cause a decrease in flow variability, removing a lot of the flow fluctuations downstream, although they do not prevent large floods that over-top the structures.
- Effect term/trajectory
-
Plants (riparian) - richness
(Increase)
- Effect description
- There was a greater number of plant species found within the channel (but not looking at aquatic plants) in the sites downstream of dams. This was mostly driven by a greater number of 'dry' life history specialists and greater number of grass taxa.
- Response measure type
- F statistic/ratio
- Response measure error type
- Error not reported
- Statistical significance
- p = 0.036 for the interaction term of interest (Regulation x Upstream/Downstream)
- Documentation
- Table 2, Figure 3
- Response measure description
- Split plot analysis of variance looking to see if species richness changed from upstream to downstream and whether that changed for regulated versus unregulated streams. The term of interest is Regulation x Up/Down interaction. Full response measure information is available in online supplementary material.
Design
- Source data
- Field
- Study type
- Observation
- Study design
- Spatial gradient
- Number of independent control or reference sampling units
- 2
- Number of indendent impact or treatment sampling units
- 3
- Sample size used in analysis
- 10
- Design description
- Upstream and Downstream locations at each of 5 sites. Each location surveyed with 20 quadrats. Design is split plot, but most like an MBACI where upstream / downstream is analogous to Before/After
Context
- Climate
- Temperate
- Country
- Australia
- Habitat
- Stream/river
- Spatial extent
- Drainage basin
- Temporal extent
- Snapshot
- Context description
- Spatial extent - the surveys were done on 5 independent tributaries of a major river within the same river basin (Yarra River).