The Barmah Forest is an internationally significant Ramsar Wetland that once supported the most extensive Moira Grass (Pseudoraphis spinescens) dominated floodplains in the Murray-Darling Basin. Moira Grass is highly palatable and provides habitat and food for fauna, while also supporting ecosystem functions such as nutrient cycling and primary production. Its extent has undergone a major decline in Barmah NP since the 1930s, largely due to altered flooding regimes and grazing by large, introduced herbivores.
In 2020, exclosure fences were constructed to assess how Moira Grass wetlands responded once feral animal grazing was excluded. This study reports on five years of ecological monitoring documenting changes in vegetation and wetland condition. Paired vegetation quadrats inside and outside exclosures were assessed annually for species cover, bare ground, soil disturbance, hydrological phase and biomass during similar seasonal periods. Analyses incorporated generalised linear models and linear mixed effects models to account for strong site level variation.
Excluding feral horses and other herbivores led to lower bare ground, higher biomass and increased Moira Grass cover inside exclosures. Vegetation outside fences also improved after horse numbers declined from 2022-23, with gains in Moira Grass and other native species. However, the magnitude and speed of recovery varied between wetlands, reflecting differences in hydrology and ecological condition.
The results show that reducing grazing pressure improves wetland condition and supports the recovery of key species. Long term monitoring remains essential for guiding management and maintaining the ecological character and Ramsar status of the Barmah Forest.