1.1.7 Ecology


Namoi environments have been considerably altered since European settlement due to expansion of agriculture. Agriculture covers 77% of the land and is now the main land use, dominated by grazing and cropping. Forestry, natural landscapes and conservation areas comprise another 19%. Despite these significant land use changes, many ecologically significant habitats still remain in the Namoi. The variation in climate combined with the variety of landforms results in a range of different ecosystems, communities and species residing in forests, woodlands, rangelands, riparian areas and the agricultural production landscape. The river basin also contains a wide range of aquatic habitats including large areas of anabranch and billabong wetlands downstream of Narrabri, including the endangered Darling River ecological community.

The Namoi river basin supports a diversity of landscapes (Table 13) including the Liverpool and Kaputar ranges, the rolling hills of the sedimentary slopes, the floodplains of the Liverpool Plains and Darling Riverine plains in the west of the river basin.

Vegetation in the upper Namoi includes open box woodlands on the slopes and temperate and sub-alpine forests in the ranges. The Liverpool Plains contain endangered native grasslands and the riparian vegetation is dominated by river she-oaks and willows with river red gum communities along the major streams. Approximately 3200 km2 of native woodlands and forests are protected in national parks and nature reserves. East of Tamworth the Warrabah National Park approximates 40 km2 of habitat along the Namoi River. East of Narrabri, the Kaputar National Park protects a range of communities including rainforest patches, semi arid to sub-alpine woodlands and forests and heathlands on the high plateaus and peaks. The Pilliga Nature Reserve in the upper catchment of Bohena Creek is the largest reserve in the region. The Pilliga state forest is the largest remaining area of dry sclerophyll forest west of the Great Diving Range in New South Wales and its size and connection to adjacent forests makes it an important habitat for a range of threatened species including the endemic Pilliga mouse.

There are 152 entities listed under the New South Wales Threatened Species Conservation Act 1995 plus four species listed on the Commonwealth’s Environmental Protection, Biodiversity and Conservation Act 1999 in the Namoi river basin. Of these entities, 86 species are vulnerable, 27 species endangered and four species are critically endangered (see Table 15, Table 16 and Table 17).

There are approximately 2770 wetlands totalling 46,398 ha in the Namoi river basin. Lake Goran, a wetland of national importance, is a large internal drainage basin south of Gunnedah, covering more than 60 km2. While ephemeral in nature, agricultural activities and structural works have resulted in the deepest parts of the lake being more frequently inundated. During dry periods, the lakebed is intensively cropped, but when flooded the lake provides extensive habitat for large numbers of water birds. Gulligal Lagoon near Gunnedah is a semi-permanent wetland that is connected to the Namoi River and is filled during flooding events and from river surface flows (Eco Logical Australia, 2008).

There are a number of groundwater-dependent ecosystems (GDEs) that occur in the Namoi river basin. However, there are significant knowledge gaps in relation to the location, condition and water requirements of these GDEs.

The Namoi Catchment Action Plan is a recent document dealing with the future management of the catchment’s natural resources. It takes an integrated view of ecology, society and natural resource use with a resilience focus, and lists a range of assets and strategies for monitoring and improving the environmental integrity of these assets (see Table 19, Table 20 and Table 21).

Last updated:
5 January 2018