 |
Interpretation:
Over what months of the year does adult vegetation prefer to be inundated with floodwater in order to maintain its condition?
More information:
MFAT Technical Manual [PDF 2.9 MB] |
|
Evidence:
In northern Victoria Giant rush occurs in areas that are flooded in winter-spring, lasting 6-11 months, and can tolerate water depths up to 1.5 m (Ward, 1996; Roberts and Marston, 2000). The preferred timing for inundation of Giant rush is May to November, but floods at other times may also be beneficial.
Confidence level: A
Sources:
Roberts, J. and Marston, F. (2000). Water regime of wetland and floodplain plants in the Murray-Darling Basin - a source book of ecological knowledge. CSIRO Land & Water Technical Report 30/00.
Ward, K. (1996). Flood requirements of vegetation for the rehabilitation of Lake Mokoan. Draft Report. Department of Natural Resources and Environment. |
|
|
Interpretation:
What is the lower limit and upper limit of water depth that is suitable for maintaining the condition of adult vegetation, expressed as a percentage (%) of the maximum mean depth of the wetland?
The 'mean depth' of a wetland is different from the actual depth of water than individual plants at a specific location prefer or tolerate. It is calculated based on a volume-area relationship for the wetland.
More information:
MFAT Technical Manual [PDF 2.9 MB] |
|
Evidence:
This preference curve has been adjusted from the SRP default setting by REG C.
This range of depths represents the preferred conditions for Giant Rush on the Moira Grass plains at Barmah-Millewa Forest.
Confidence level: C
Sources:
Expert knowledge and judgment, Keith Ward (REG C Member).
|
 |
Interpretation:
What is the preferred duration (in days) of continual inundation, within the upper and lower depth limits specified for 'Inundation Depth' (above), for maintenance of adult vegetation?
More information:
MFAT Technical Manual [PDF 2.9 MB] |
|
Evidence:
This preference curve has been adjusted from the SRP default setting by REG C.
Flooding of up to 60 days provides marginal benefit to Giant rush, but flooding of between 4 and 9 months is optimal. The performance of Giant rush is severely reduced if flooding persists for more than one year.
Confidence level: C
Sources:
Expert knowledge and judgment, Keith Ward (REG C Member).
|
 |
Interpretation:
What is the preferred rate of change in water depth in the wetland (in cm per day) for the maintenance of adult vegetation?
More information:
MFAT Technical Manual [PDF 2.9 MB] |
|
Evidence:
Giant rush has a high tolerance to rapid draw-downs. Although adult plants may collapse, the microclimate within a stand is such that desiccation of young shoots would be minimal if completely exposed. The water level is not critical for Giant rush as long as it is covering the roots and is no deeper than 2/3 of the plant for continued respiration.
Confidence level: C
Sources:
Keith Ward (REG B and C Member) and SRP expert opinion and judgment.
|
 |
Interpretation:
What is the preferred timing (in calendar months) of the drying and re-wetting sequence required for the successful recruitment of wetland vegetation?
More information:
MFAT Technical Manual [PDF 2.9 MB] |
|
Evidence:
Giant rush prefers the draw-down and re-wetting sequence (required for recruitment) in spring to summer. This coincides with suitable germination conditions (i.e. wet mud after recession of late winter-spring floods).
Confidence level: C
Sources:
Keith Ward (REG B and C Member), Jane Roberts (REG E Coordinator) and SRP expert knowledge and judgment.
|
 |
Interpretation:
What is the preferred rate of decrease in water depth of the wetland (in cm per day) for the successful recruitment of wetland vegetation?
More information:
MFAT Technical Manual [PDF 2.9 MB] |
|
Evidence:
This preference curve has been adjusted from the SRP default setting by REG C.
Confidence level: C
Sources:
Expert knowledge and judgment.
Note: More recent advice suggests that the SRP default curve should be used in place of this curve in future versions of MFAT. |
 |
Interpretation:
What is the preferred rate of increase in water depth of the wetland (in cm per day) for the successful recruitment of wetland vegetation?
More information:
MFAT Technical Manual [PDF 2.9 MB] |
|
Evidence:
A rise in water level of 18 cm per day over 5-6 days is equivalent to nearly 1 m, which is too rapid for a seedling. Lower rates of rise are considered more suitable.
Confidence level: C
Sources:
Jane Roberts (REG E Coordinator) and SRP expert knowledge and judgment.
|
 |
Interpretation:
What is the preferred length of time (in days) of the period between draw-down and re-wetting of the wetland for the successful recruitment of wetland vegetation?
Note: The Inter-Period begins as soon as the water level first begins to fall, and ends when the water level begins to increase again during an inflow event.
More information:
MFAT Technical Manual [PDF 2.9 MB] |
|
Evidence:
The preferred duration between floods for Giant rush is 60-80 days. If the intervening period is too long, seedlings may die; if it is too short, seedlings may not achieve sufficient growth. It is estimated that 10 months between germination and re-flooding is too long, and that 1.5 months is too short. High soil moisture levels during 'dry' periods, interspersed with low-level flooding are ideal conditions for germination.
Confidence level: C
Sources:
SRP, Keith Ward (REG B and C Member) and Jane Roberts (REG E Coordinator) expert knowledge and judgment.
|
| |
and links for more explanation.