Gunbower Forest is one of a series of river red gum forests on the Murray River floodplain in northern Victoria. Together with the adjoining Koondrook-Perricoota component of the NSW Central Murray Forests Ramsar site, Gunbower Forest comprises the second largest river red gum forest in Australia. It is also an Icon Site in the Living Murray program. The river red gums rely on regular flooding in late winter or early spring to survive. River red gums inhabit the low-lying, more frequently flooded areas of Gunbower Forest. Infrequently flooded areas support woodlands dominated by black box, while grey box is found in areas not subject to inundation. River red gum has understoreys of wallaby grass, kangaroo grass, river swamp wallaby grass, and Warrego summer grass. Black box and grey box are associated with terrestrial grasses and shrubs for their understoreys. The Ramsar site supports several species of waterbirds, including the only breeding colony of intermediate egret in Victoria. Other waterbird species that breed in Gunbower Forest are the Australian white ibis, Nankeen night heron, eastern great egret, and cormorants. Several species of fish are recorded in the Ramsar wetland including golden perch, Murray cod and silver perch. Gunbower Forest is an important indigenous cultural heritage area, featuring shell deposits, mounds, scar trees, burial sites, heaths and sacred sites. The Ramsar site is currently subject to multiple land uses including timber harvesting, firewood collection, and conservation. Recreational pursuits include fishing, camping, bushwalking, and bird watching.
Gunbower Forest
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Government evidence of impact of climate change:
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Australian Government, Gunbower Forest Ramsar Site, Ecological Character Description
It is ix likely due to a combination of factors including water resource development; climate change and shorter term climatic cycles.
Climate change (increased temperatures and decreased rainfall) which exacerbate effects of water resource development and altered fire regimes.
The three aspects of climate that most directly affect wetland ecology are rainfall (both local and in the catchment); temperature; and (to a lesser extent in temperate systems) relative humidity.
Note that the climate as described here is relevant to the time of listing the issue of climate change is dealt with under threats (see Section 7).
Climate Change (decreased rainfall) Threat Water Resource Development Altered fire regimes Biological Resource Use (forestry) Human Disturbance (recreation) Invasive species Stressor Decreased frequency and duration of inundation Increased frequency intensity of fires Direct vegetation (removal (e.g. large hollow bearing trees) Physical disturbance increased erosion Weeds and introduced fish Altered seasonality of inundation Ecological Effects Increased competition from invasive species Altered vegetation community composition Decreased vegetation health Increased likelihood of blackwater events Disruption to breeding Critical Component Process Service Component Vegetation (floodplain forests) Service Significant wetland types physical habitat Component Vegetation floodplain marshes) Service Significant wetland types physical habitat Component Native fish Service Threatened species; ecological connectivity Component Wetland birds Service Physical habitat for feeding breeding threatened species Figure 33 Stressor model of the Gunbower Forest Ramsar site (after Gross 2003 and Davis and Brock 2008). 6.1 Water resource use Water resource use in the Murray Darling Basin involves large scale water interception; delivery and extraction which has resulted in major changes to the hydrology of the Murray River (Gippel and Blackham 2002 MDBC; 2008) and floodplain wetlands (MDBC; 2007).
Particular effects to identified critical components; process and services in the Ramsar site include . decreased condition of river red gums as a result of decreased frequency and duration of inundation (Bren 1988 Cunningham et al. 2009) . an increased number of exotic flora species; due to decreased floodplain inundation frequency (Stokes et al. 2010). . decreases in breeding numbers and successful fledging events of colonial nesting waterbirds due to a decrease in frequency and extent of moderate floods . impacts to native fish populations with low flow conditions having a negative effect on the spawning and recruitment of native fish; including the reduction in the recruitment of carp gudgeons (Hypseleotris sp.); southern pygmy perch (Nannoperca australis) and golden perch (Macquaria ambigua) but a favourable effect on the spawning and recruitment of pest species such as common carp (Cyprinus carpio) (MDBC 2008) and increased incidence and intensity of blackwater events due to reduced frequency of inundation; coupled with unseasonal inundation (during warmer months) resulting in very low dissolved oxygen concentrations and fish deaths. 6.2 Climate change The CSIRO Murray Darling Basin Sustainable Yields Project (CSIRO 2008 Chiew et al. 2008) has modelled the effect of climate change and related factors on the water resources in the Murray Darling Basin; including predictions for the icon sites.
Under the future climate models; there was a range of potential climate estimates ranging from extreme wet to extreme dry.
It is likely due to a combination of a number of factors that include water resource development; climate change and shorter term climatic cycles.
It is ix likely due to a combination of factors including water resource development; climate change and shorter term climatic cycles.
Climate change (increased temperatures and decreased rainfall) which exacerbate effects of water resource development and altered fire regimes.
The three aspects of climate that most directly affect wetland ecology are rainfall (both local and in the catchment); temperature; and (to a lesser extent in temperate systems) relative humidity.
Under the future climate models; there was a range of potential climate estimates ranging from extreme wet to extreme dry.
It is likely due to a combination of a number of factors that include water resource development; climate change and shorter term climatic cycles.
Altered fire regimes (increased frequency and intensity of fires); leading to Death of mature river red gums Adverse changes to forest structure and The loss or degradation of habitat.
Invasive species (weeds; introduced fish); which cause Increased predation or competition with native flora and fauna and Increased risk of destructive wildfire through increased understorey biomass.
However; with decreased inundation; fuel loads in the understorey can increase and result in intensive fires if ignited. 6.5 Invasive species There are a large number of species of introduced flora within the Gunbower Forest Ramsar site and weed cover has been described as extensive (DSE 2003).
Exacerbate effects of water resource development and altered fire regimes.
Certain (short and medium term effects) Medium (long term effects) Current Altered fire regimes (increased frequency and intensity of fires) Death of mature river red gums.
Increased risk of destructive wildfire through increased understorey biomass.
Altered fire regimes (increased frequency and intensity of fires); leading to Death of mature river red gums Adverse changes to forest structure and The loss or degradation of habitat.
Invasive species (weeds; introduced fish); which cause Increased predation or competition with native flora and fauna and Increased risk of destructive wildfire through increased understorey biomass.
However; with decreased inundation; fuel loads in the understorey can increase and result in intensive fires if ignited. 6.5 Invasive species There are a large number of species of introduced flora within the Gunbower Forest Ramsar site and weed cover has been described as extensive (DSE 2003).
Exacerbate effects of water resource development and altered fire regimes.
Certain (short and medium term effects) Medium (long term effects) Current Altered fire regimes (increased frequency and intensity of fires) Death of mature river red gums.
Increased risk of destructive wildfire through increased understorey biomass.
This critical service is linked to changes in the frequency and duration of wetland wetting and drying as well as changes in extent and condition of wetland vegetation.
This critical service is linked to changes in the frequency and duration of wetland wetting and drying as well as changes in extent and condition of wetland vegetation.
Not applicable Physical habitat This critical service is linked to changes in the frequency and duration of wetland wetting and drying as well as changes in extent and condition of wetland vegetation.
There is evidence that the hydrology of the site has changed in recent years and the LAC for small flood frequencies has been exceeded (Table 24).
This critical service is linked to changes in the frequency and duration of wetland wetting and drying as well as changes in extent and condition of wetland vegetation.
This critical service is linked to changes in the frequency and duration of wetland wetting and drying as well as changes in extent and condition of wetland vegetation.
There is evidence that the hydrology of the site has changed in recent years and the LAC for small flood frequencies has been exceeded (Table 24).
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