'Forested wetlands' landscape class Qualitative mathematical model

A qualitative model was developed to describe the forest communities in landscape classes that are in floodplains and wetlands (Figure 24). Drawdown of groundwater by coal mines and coal seam gas (CSG) development in the AE for the Gloucester subregion is predicted to impact the supply of both deep and shallow groundwater (DGW and SGW, respectively in Figure 24) to these forest communities. In some instances, the coal mine footprint will also have a direct impact on the remaining amount of forested wetlands in the AE, which will lead to impacts via forest fragmentation (FF).

The principal ecosystem components, processes and functions attributed to wetland forests were the roles that their canopies offered in providing flower nectar (FN), which is a food resource for bird and mammal consumers such as the swift parrot (SP), regent honeyeater (RHE), arboreal mammals (AM) and grey-headed flying fox (GHFF; Commonwealth of Australia, 2015; Saunders and Tzaros, 2011), as well as insects, and habitat structure, such as tree hollows for nesting (Commonwealth of Australia, 2015; Saunders and Tzaros, 2011), and also in providing habitat for various predatory diurnal and nocturnal raptors (DR and NR, respectively), such as the red goshawk (Erythrotriorchis radiatus). Contiguous unfragmented forest canopies were described as being an especially critical habitat feature for aggressive native honeyeaters (ANHE), such as the noisy miner (Manorina melanocephala), noisy friarbird (Philemon corniculatus) and red wattlebird (Anthochaera carunculata), which exert a strong competitive hierarchy on the community of nectar consumers. Koalas (Koa) also benefit from forest canopies (FWOS) for all aspects of their life history requirements. On the one hand, the supply of deep groundwater was thought to be critical for the survival of forested wetlands, and it was suggested that vegetation accesses these stores through deep root systems. On the other hand, shallow groundwater, along with rainfall (Ppt), was described as being a main factor in the magnitude of flower and nectar production, and shallow groundwater was also critical for the presence of a herbaceous wetland vegetation (HWV). In a recent study of riparian Tamarix, Anderson and Nelson (2013) failed to find any relationship between depth to groundwater and noted: ‘The extent to which a reduction in soil water availability will affect riparian plant floral ecology, riparian pollinators, and plant pollinator interactions is largely unknown, because we lack information on most plant species’ response to shifts in depth to groundwater’.

Figure 24

Figure 24 Signed digraph of the 'Forested wetlands' landscape class in the Gloucester subregion

Variables are: arboreal mammals (AM), aggressive native honeyeaters (ANHE), deep groundwater (DGW), diurnal raptor (DR), forest fragmentation (FF), forest habitats (FH), flowers & nectar (FN), forested wetland overstorey (vegetation)(FWOS), grey-headed flying fox (GHFF), herbaceous wetland vegetation (HWV), koala (Koa), nocturnal raptor (NR), precipitation (Ppt), recruitment (Rec), regent honeyeater (RHE), shallow groundwater (SGW), swift parrot (SP), wetland community (WC).

Data: Bioregional Assessment Programme (Dataset 1)

Surface water and groundwater modelling predict potential impacts of coal mining to both deep and shallow groundwater stores, and a single cumulative impact scenario (C1) was developed based on a simultaneous decrease in both these sources of groundwater (Table 24).

Table 24 Summary of the cumulative impact scenarios for the ‘Forested wetlands’ landscape class in the Gloucester subregion

Cumulative impact scenario

Deep groundwater

Shallow groundwater


Cumulative impact scenarios are determined by combinations of no change (0) or a decrease (–) in the following signed digraph variables: deep groundwater (DGW), shallow groundwater (SGW). Scenario C1 shows the changes to these variables under the coal resource development pathway (CRDP).

Data: Bioregional Assessment Programme (Dataset 1)

Qualitative analysis of the signed digraph model (Figure 24) generally indicates an ambiguous or negative response prediction for biological variables within the forested wetlands community as a consequence of a decrease in available nectar production and quality of forest habitats (Table 25). Ambiguity in the response predictions for swift parrots, diurnal raptors and the regent honeyeater arise from positive effects associated with the potential release from competitive dominance by aggressive native honeyeaters matched by negative effects resulting from reduced nectar production. An ambiguous response prediction for grey-headed flying foxes stems from a potential decrease in nectar resources and a possible decline in the abundance of their nocturnal raptor predators due to habitat loss.

Table 25 Predicted response of the signed digraph variables in the ‘Forested wetlands’ landscape class to cumulative changes in hydrological response variables for the Gloucester subregion

Signed digraph variable

Cumulative impact scenario

Full name

Shortened form


Diurnal raptor



Nocturnal raptor


Aggressive native honeyeaters


Swift parrot



Regent honeyeater



Grey-headed flying fox



Forest habitats


Forest fragmentation



Flowers and nectar







Arboreal mammals


Forested wetland overstorey (vegetation)


Herbaceous wetland vegetation




Wetland community


Qualitative model predictions that are completely determined are shown without parentheses. Predictions that are ambiguous but with a high probability (0.80 or greater) of sign determinancy are shown with parentheses. Predictions with a low probability (less than 0.80) of sign determinancy are denoted by a question mark. Zero denotes completely determined predictions of no change.

Data: Bioregional Assessment Programme (Dataset 1)

Last updated:
7 January 2019