The first annual Flow-MER Macquarie Marshes wetland vegetation survey was conducted at 36 new Flow-MER monitoring sites and the 43 long-term NSW Government sites over four weeks from 3 March to 2 May 2025. Vegetation was in relatively good condition after responding to local rainfall events and previous floods.

The Flow-MER team is using existing NSW Department of Climate Change, Energy, the Environment and Water (NSW DCCEEW) monitoring, evaluation, and reporting (MER) sites and methods in order to add value to and capitalise on historic data. This is in addition to new sites, selected in collaboration with NSW DCCEEW and Aboriginal partners, to broaden the understanding of other vegetation communities and inundation regimes. 

The team spent the first two weeks surveying existing NSW DCCEEW MER sites, and the second two weeks establishing and surveying new plots.

Native species were dominant relative to non-native species at all sites. Flow-dependent native species formed the dominant understorey cover class at most sites.

There was evidence of new recruitment at many sites with a woodland or forest overstorey. Half (50 per cent) of the river red gum (Eucalyptus camaldulensis) and black box (Eucalyptus largiflorens) overstorey plots had showed recent seedling establishment, while 40 per cent of coolabah (Eucalyptus coolabah) plots had new recruits.

As flooding events are essential for seed dispersal and germination, particularly for species like river red gum, black box, and lignum (Duma florulenta), vegetation surveys also involve observations of water inundation.

There was evidence of water flowing into some of the vegetation survey sites in the northern parts of the Marshes.

At the time of the survey, 66 plots were dry, 11 were flooded, and two remained wet from recent inundation. The flooded sites were predominantly non woody wetland communities (water couch (Paspalum distichum) or sedgeland communities), with one river red gum site.

The establishment and surveys of the new Flow-MER sites were conducted by NSW DCCEEW Regional and Science staff and volunteers on behalf of the University of New South Wales (UNSW).

With the first year of field data collected, the Flow-MER team will analyse the data together with satellite imagery and drone imagery. The findings will help inform future environmental water management.