MWRPP 15.3: Proposed Vegetation Condition Monitoring Program for the Cockatoo Swamp.

This document presents a proposed vegetation condition monitoring program to evaluate the effect of the capital works program planned by Melbourne Water (MW) for the Cockatoo Swamp. Cockatoo Swamp refers to wetland areas along sections of the Cockatoo and Macclesfield Creeks. The swamp comprises threatened wetland forest and shrub thickets which provide critical habitat for the critically endangered Helmeted Honeyeater and lowland Leadbeater’s Possum. These wetland forests are currently under threat from dieback of mature woody vegetation and a lack of natural regeneration. An altered water regime, due to stream channelization and levee construction upstream of the swamp, is thought to be driving these threatening processes. Stream channelization led to channel incision, erosion and sediment deposition within low-lying swamp areas impeding drainage, causing prolonged waterlogging and tree dieback. MW plan capital works including a pipeline to aid drainage and partial levee bank removal to reinstate more natural patterns of wetting and drying within the swamp. The proposed vegetation condition monitoring program would adopt a Before-After-ReferenceImpact (BARI) approach with impact sites within both: dieback-affected areas (those predicted to become drier), and floodplain areas behind the levee (those to become wetter). The impact of the water regime changes resulting from the works would be compared against two reference sites: one on Macclesfield Creek, the other on the Cockatoo Creek. Vegetation response variables to be monitored would include: mature tree and stand condition (using The Living Murray Method and hemispherical photography respectively); seed production (using seed traps which have now been monitored for 27 months); seedling germination and recruitment (using 3 permanent 100 m quadrats at each site; these quadrats will also be used to monitor midstorey and understorey vegetation composition). It is expected that the condition and seed production of the woody vegetation (i.e. Eucalyptus camphora and native shrub species), and germination of woody seedlings will increase in the impact sites, to become more similar to those observed in the reference sites. The final vegetation condition monitoring design will be determined in consultation with relevant land management agencies (e.g. Melbourne Water, Parks Victoria) and community groups (e.g. Friends of the Helmeted Honeyeater and Friends of the Leadbeater’s Possum).