Difference between revisions of "Coastal Zones"

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(Fore Dune and Dune Crest)
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protection to themselves.
protection to themselves.
[[Beach Wattle]]
[[Soap Tree]]
== Beach Scrub and Hind Dunes ==
== Beach Scrub and Hind Dunes ==

Revision as of 00:40, 21 October 2008

The coastal ecosystem is very complex with several very different zones, all of which are interdependent on each other. It is not possible to remove any part of the system without severely impacting on all remaining areas. Plants in this ecosystem are highly specialised, so when they are removed or destroyed there is great impact on surrounding flora, fauna, sand movement, nutrients and oxygen levels.

Coastal Zones 002.jpg

Fore Dune and Dune Crest

The fore dunes are essential barriers against extremely harsh oceanic conditions. They withstand ocean storms, extreme sun, strong winds and powerful waves. There has never been a man made equivalent of the fore dune area that has been effective in the long term. Vegetation in the dune area catches wind blown sand and binds it to the dune. Without plants to trap the sand, the sand is blown away and the dune erodes. Plants in this zone are extremely enduring with special adaptations that allow survival. They provide vital protection for fauna that live in this zone, such as crabs, and for other flora further back in the dunes. The dune crest is also subject to harsh conditions with plants in this zone prone to growing in patches to provide extra protection to themselves.

Beach Wattle Soap Tree

Beach Scrub and Hind Dunes

This area is relatively protected from the elements by the fore dunes and therefore more stable. There is more vegetation in this section, although these plants are still very hardy. Beach scrubs are vine forests growing in sand and often a denser thicket with older and larger trees. They are very valuable communities due to their high biodiversity (or number of different plant and animal species living together). Soil is still loose and sandy, but held together by the trees and shrubs. This zone is rapidly disappearing in many places due to coastal developments. Beach scrub in particular is now an endangered community, with over 70% of the original extent of beach scrub wiped out. Without this defensive hind dune zone, infrastructure has decreased protection from erosion, winds and cyclones.



Threats to Coastal Zone Health

Coastal areas are extremely important and delicate ecosystems with highly specialised flora and fauna. Plants in each part of the coastal zone have specialised adaptations and roles that are essential to the overall health of the ecosystem. Essential roles that these plants perform include:

• Trapping and binding mobile sand

• Providing shelter and food for coastal fauna

• Providing an essential barrier from the particularly harsh ocean environment for terrestrial life

• Preventing erosion and exotic flora and fauna species from destroying the dune.

Planting local species in residential gardens has a two fold positive effect. Firstly it limits the competition of exotic plants or weed species, which upset the delicate plant ecology and out-compete natives. It also increases the spread of local species through birds, insects and other fauna to dunes and surrounding coastal areas. This latter effect is especially important because without these plants, coastal areas are unprotected from natural elements and can become unstable and mobile. Erosion is arguably the biggest problem faced by coastal managers today.

There are many threats to the Burdekin Dry Tropics coastline, from obvious threats such as vehicles driving on dunes and vegetation, to more subtle threats such as the spreading of weeds. Coastal development is a complex coastal issue which is ever on the increase. Industrial, recreational and housing developments change the physical structure of dunes and the interaction with the natural environment. These developments remove vegetation and introduce pollution and effluent to the ecosystem, thus creating erosion and increased nutrient loads.

Climate variability is a contributing factor to rising sea levels. Saltmarsh and fore dunes are particularly effected as the forefront areas of the natural systems can’t evolve quickly enough to survive. With the disappearance of these ecosystems, marine species looses their nurseries and protection for breeding, and terrestrial life loses the natural barrier from the ocean. Increased levels of ultra-violet radiation due to ozone depletion also contribute to plant loss and put pressure on ecosystems. These alterations to the natural environment extend to changing the natural fire regime. Many native plants use fire as a stimulus for germination and fire intensity and timing is crucial to the survival of several local species.

All of these contributing factors are putting untold pressure on our coastline which is becoming more pronounced. Legislation is slowly changing to protect this delicate ecosystem, but without appreciation for these important natural areas and action from the local community, they may become a thing of the past.