The water quality of the lagoon may change rapidly depending on the influence of climatic conditions (C) or physical modifications at the site (e.g. from fresh to saline conditions following breaching of the sand bar at the lagoon entrance).
Each of the services meet the DEWHA (2008a) indicative criteria for identifying critical components; processes and services; as they are important in determining the site’s unique character are important in supporting criteria under which the site was listed are reasonably likely to change in the next 100 years and changes to them could cause significant negative consequences. (P) Modification of landscape by wind and precipitation Climate (C P) .
Mean daily understanding of the impact of climatic temperatures are projected to be warmer processes on other critical components; (both minimum and maximum temperatures) processes and services; such as; with increased solar radiation; relative hydrology; geomorphology; flora and humidity in summer; and increased fauna. evaporation (ACE CRC 2010).
Climate change Climate change is considered a threat to the ecological character of the site; with estuaries and wetlands identified as one of the coastal ecosystem types most at risk from the effects of climate change (DCC 2009).
Changes associated with such a climate may potentially impact the hydrology; geomorphology; vegetation; habitat and species at Logan Lagoon.
For plant and animal species; variation in climate ca stress; affect their behaviour and phenology (i.e. response to temperature); and provide opportunities for weeds and invasive species to fill niche gaps previously held by stressed species (DCC 2009).
For coastal settings of this type; sea level rise and a higher frequency of extreme high tide events; associated with climate change; could potentially result in major geomorphic and hydrological changes.
According to Bowling and Tyler; the water sample was collected in May at the end of an extremely dry summer’; which is consistent with climate data (Figure 7) and the 1982 83 drought that occurred in southeast Australia.
Climate change via changed rainfall patterns; changed temperature and wind regimes; more frequent and severe weather events; sea level rise and or coastal retreat Changes associated with such a climate may potentially impact the hydrology; geomorphology; vegetation; habitat and species at Logan Lagoon.
The water quality of the lagoon may change rapidly depending on the influence of climatic conditions (C) or physical modifications at the site (e.g. from fresh to saline conditions following breaching of the sand bar at the lagoon entrance).
The four aspects of climate that are most likely to affect the wetland ecology of Logan Lagoon are rainfall; temperature; wind and evaporation.
The implications of climate change on the site are a threat but are poorly understood however; climate change predictions for south eastern Australia suggest a generally warmer climate with less rainfall and rising sea levels (DCC 2009).
Changes associated with such a climate may potentially impact the hydrology; geomorphology; vegetation; habitat and species at Logan Lagoon (see threats Section 8.7). 4.3.2.
Mean daily temperatures No LAC can be determined due to a are projected to be warmer (both minimum and lack of understanding of the impact of maximum temperatures) with increased solar climatic processes on other critical radiation; relative humidity in summer; and components; processes and services; increased evaporation (ACE CRC 2010). such as hydrology; geomorphology; flora and fauna.
Likelihood Threat to ecological character Potential impacts to wetland components; processes and or services Timing of threat Inappropriate fire regime Certain Immediate Altered vegetation communities Loss of threatened communities Increased susceptibility of dune systems to erosion Disturbance to resident and migratory fauna Certain Immediate Inappropriate use of recreational vehicles at the site Erosion of shoreline vegetation and alteration of dune structure Damage of soils and vegetation potential for activation of acid sulphate soils Disturbance of coastal breeding birds and or destruction of their eggs Likelihood Threat to ecological character Potential impacts to wetland components; processes and or services Timing of threat Medium Changes to the hydrological regime Unnatural water quality conditions Reduced water depth leading to reduced habitat for some species Immediate Medium term (5 years) Alteration to drainage regime Artificial opening of the agoon mouth Modifications of the natural flow into the lagoon Introduction of animal and plant pests diseases Feral pigs and cats Certain Immediate Reduction of habitat and changes in vegetation structure Competition with native flora and fauna Introduction of disease (e.g.
Similarly; in the southern part of the Ramsar site; there is mainly E. nitida dominated scrub with a heath understorey which in many places has been converted to a predominantly bracken understorey by the high fire frequency.
Fire frequency at Logan Lagoon (Figure 22) may have varying degrees of impact on the different vegetation communities; as some communities are more susceptible to changes in fire regime than others.
The dense vegetation is often perceived as a safety risk due to potential wildfire and often results in legal and illegal fuel reduction burning.
Aerial photograph of the northern area of Logan Lagoon Ramsar site illustrating the change in vegetation structure between areas with low (A) and high (B) fire frequency (Photograph Luke Finley; Elgin Associates; July 2009).
Callitris rhomboidea is fire sensitive; generally confined to infrequently burned vegetation in eastern Tasmania and although it will regenerate well after fire; frequent fires will eliminate it (DPIWE 2007).
Other vegetation communities that occur throughout the Ramsar site re also vulnerable to changes in fire frequency and rely on appropriate fire regimes to maintain the species composition of the communities.
Although the maintenance of specific conservation values often depends upon periodic low intensity fires (Parks and Wildlife Service 2007); the recent high frequency of fires at the site is unsustainable and it is argued that fire should be prevented (where possible); particularly on the eastern side of the lagoon. 8.2.
The impact of fire on the current extent and condition of vegetation types is unknown.
Threats There are several threats which could adversely impact on the ecological character of the Logan Lagoon Ramsar site; comprising Inappropriate fire regime frequent and extensive firing has dramatically altered some of the vegetation within the Logan Lagoon Ramsar site.
North of Logan Lagoon there is forest and scrub which experiences a higher fire frequency than the vegetation on the leeward side the prevailing wind direction is from the west and north west.
On the windward side of Logan Lagoon; and in the southern part of the conservation area; Western peppermint (E. nitida) and Allocasuarina spp. scrub is dominant with a heath understorey; which in many places has been converted to a predominantly bracken understorey by the high fire frequency (Section 8.1 Figure 23).
A buffer of native or riparian vegetation along streams leading into coastal lagoons can help to reduce the impact of frequent flooding; particularly if salt and flood tolerant species are planted in the expected zone of flooding (Parks and Wildlife Service 2007).
Changed weather patterns and rising sea levels have the potential to cause wide ranging impacts at the site that could result in fundamental changes to its structure and ecology.
Surrounding farmers should be educated in ways to reduce the risk of flooding; such as ensuring that drains on their properties are cleared of vegetation and properly maintained; and plant salt and flood tolerant species in the expected zone of flooding on adjacent land (Parks and Wildlife Service 2007). 13.
The persistent winds; elevated summer water temperatures and shallow waters at Logan Lagoon are likely to contribute to a higher evaporation rate than those estimated from the weather station. 180. 160. 140. 120. 100. 80.
Acidification of soils through disturbance of potential acid sulphate soils or via dryland salinity can have detrimental impacts on soil pH and structure; affecting its ability to support vegetation and increasing the potential for soil erosion. 5.1.3.

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