Home‎ > ‎

Gondwana Rainforests of Australia




The Gondwana Rainforests of Australia, formerly known as the Central Eastern Rainforest Reserves, stretch from Queensland to New South Wales. The reserve includes the most extensive areas of subtropical rainforest in the world, large areas of warm temperate rainforest and nearly all of the Antarctic beech cool temperate rainforest. It was first included in the World Heritage List on May 21, 2007. The rainforest reserves have an extremely high conservation value, with more than 200 rare or threatened plant and animal species; in Australia today there is a concentration of primitive plant families that are directly linked to flowering plants that existed over 100 million years ago, as well as some of the oldest of the world's ferns and conifers.[1]



Background



Gondwanaland appeared about 200-180 million years ago, during the breakup of the supercontinent Pangea. After the split, the supercontinent Laurasia drifted north while Gondwana drifted south. Gondwana included most of the landmasses in today's Southern Hemisphere, including Antarctica, South America, Africa, Madagascar, and the Australian continent, as well as the Arabian Peninsula and the Indian subcontinent, which have since moved into the Northern Hemisphere. [2]



Temperature, Moisture, & Wind

Temperature

Annual Temperature Range:
  • Average annual high: 72.7°F
  • Average annual low: 52.5°F
  • Annual average: 62.9°F

Precipitation
  • The Gondwana Rainforests contain 5 different types of rainforests, including subtropical, littoral, dry, warm temperate, and cool temperate, each receiving different amounts of rain.
  • The subtropical rainforests receive around 50 inches of rain each year. The dry rainforests receive between 21-43 inches of rain annually. The littoral rainforests receive rainfall amounts between that of the subtropical and dry. The warm temperate rainforests receive slightly more than the subtropical rainforests at amounts slightly above 50 inches. Lastly, the cool temperate rainforests receive the most rain, somewhere between 70- 118 inches.
  • The precipitation consists mainly of rainfall seeing as the temperature very rarely dips below freezing.
  • Precipitation is highest during the summer months of December, January, and February

The following chart shows the precipitation patterns of an area located in the dry rainforest:


[3]


Humidity and Fog




Wind Speed and Direction

The predominant annual wind direction displays that the strongest wind blows NE in our area.

Below is a graph of the speed of wind throughout the hours of the day. It also gives the direction [5] to which the wind blows and as you can see it varies throughout the day. However, the predominant wind direction appears to be N to NW.



Furthermore, the chart below gives the predominant wind direction [6] within each month along with the average wind speed, wind probability and average air temperature (in Celsius). These are all factors that impact the climate of the Gondwana Rainforests of Australia.



Global Wind Patterns




The Gondwandan Rainforests lie mostly on the subtropical high pressure belt. This means that the air is stable, and there is usually little rainfall. However, the Indian Ocean Dipole, an irregular cycle of warming and cooling of ocean water, can have an effect on the air traveling across Australia. 

    The Indian Ocean Dipole 


When the Indian Ocean Dipole is in its negative phase, the Indian Ocean water west of Australia cools and Timor Sea water to the north warms. This generates winds that pick up moisture from the ocean and then sweep down towards southern Australia to deliver wet conditions. In its positive phase, the pattern of ocean temperatures is reversed, weakening the winds and reducing the amount of moisture picked up and transported across Australia, so the south east misses out on its usual quota of rain. [7]




Weather & Climate


Air masses




According to this map, the air masses that most affect the Gondwana rainforest during the summer are the Tropical maritime from the Pacific Ocean and the Subtropical continental from inland Australia.



According to this map, the air mass that has the largest impact on the Gondwana Rainforest during the winter is the Southern maritime air mass. Additionally, the Tropical maritime has some impact, originating from the Pacific Ocean. [8]



Severe Weather
  • Massive flooding is the main source of severe weather. This flooding is due to heavy rains during summer months such as December, January, and February. [9]


  • Severe weather also includes dangerous thunderstorms which may produce damaging winds, very heavy rainfall, flash flooding and large hailstones. [10]

Temperature and Precipitation Regime



Based on the climograph above, it is observed that the during the high sun season, rainfall is at its highest in accordance with the temperature. During each season, the average amount of precipitation remains constant. [11]




Köppen Climate Classification


According to Köppen climate classification, the Gondwana rainforests generally have a humid subtropical climate. This climate, which usually occurs in the interiors of continents or on their east coasts and generally between latitudes 25° and 40° north and south, is characterized by hot, humid summers and mild or cool winters. These characteristics are due in part to unstable tropical air masses or onshore trade winds. [12]

Biogeography


Adaptations of Plants and Animals

  • Hip-pocket frogs

    In order to protect baby tadpoles from predators, the adult male Hip-pocket frog will let the tadpoles stay in small pockets located near his hips until they hatch after two months. This breeding technique also prevents the tadpoles from being carried away by the fast flowing rainforest streams. [13]



    
This map shows the distribution of the Hip-pocket frogs in Australia. [14]
  • Sassafras Tree 

    The sassafras is allelopathic to some species meaning it attempts to steer other plants away from its habitat. For example, the sassafras produces unpleasant chemicals for some species such as American elm. This adaptation gives the sassafras a competitive advantage. [15]


Biome and Ecoregion
According to the following map, the Gondwana Rainforests is located in the Temperate Deciduous Forest biome. [16]


The forest is also located in the Southeast Australian Temperate Forest and the Eastern Australian Temperate Forest ecoregion. This ecoregion is the transitional zone between temperate southeastern Australia and the tropical climate of north and northeast Australia. Within this transitional ecoregion, there are vast types of vegetation due to varied substrates, altitude gradients and micro-climates. [17]


Topography

The Great Dividing Range, the third longest mountain range in the world, separates the central lowlands from the eastern highlands and spans Victoria in the south, through all of New South Wales, and ends in Northern Queensland's Cape York Peninsula. These are the mountains to the right of the map. [18] 

They serve as a rain shield, and cause orographic precipitation on the windward (coastal) side of the mountains, the rainforest areas. Because the range tends to trap moisture from easterly weather fronts originating in the Pacific Ocean, the landscape west of the range is forbidding and the weather hot and dry. [19]


Factors that Influence Vegetation and Wildlife

Rainforests cover only about 0.3% of Australia, but contain about half of all Australian plant families and about a third of Australia's mammal and bird species. [20] Many of these species are endemic, which means they are especially threatened, and currently 20% of Australia's animal and plant species are threatened with extinction. [21]

Factors influencing plant growth can be genetic or environmental. Genetics influence characteristics such as quality, disease resistance, and drought hardiness. Environmental influences include biotic factors such as soil organisms, disease, and weeds, as well as abiotic factors such as temperature, soil quality, and sunlight. [22]

Factors that influence wildlife include the development of suburban/urban centers, livestock production, agriculture, and timber production, among others. Certain species are highly sensitive to habitat fragmentation, such as breeding songbirds exposed to parasitism or elevated nest predation; many forest understory species are also unable to cross deforested areas. [23] Exotic species (invasive and introduced species) can have extensive and significant impacts on native communities. Periodic large-scale disturbance events such as fire also influence development; the loss of a single species can have cascading impacts on forest structure and ecology. [24]


http://www.youtube.com/watch?v=SVw-6m4Ygec

Above is a link that does a quick overview of the Gondwana Rainforests discussing all the National Parks that are found within the rainforest along with the natural wildlife.


Environmental Threats (Invasive species)


  • Weeds affect many parts of the rainforest and can spread extremely quickly. Weeds that are of major concern are mistflower, lantana, camphor laurel and Madeira vine. Currently, the only form of controlling this species is weeding. [25]
*An example of a mistflower. [26]
  • Foxes and feral cats are examples of invasive animal species. These animals can eliminate a large portion of the prey population and have caused the extinction of many native species.
*An example of a fox that is invasive to the Gondwana Rainforests.[27]
  • Pest animals also can negatively effect the forest. They can degrade sites of cultural significance such as Aboriginal rock and can spread diseases to livestock which acts as a major threat to agriculture in the area. [28]

Landforms 

Internal Processes and Landforms

Mount Warning is a 1,156 meter high extinct volcano located in the rainforest. The caldera of the mountain was formed after a major volcanic eruption caused the collapse of the volcano's cone. In addition, the creation of the mountain also contributed to the creation of Tweed Valley, located next to the mountain. [29]

Waterfalls can be found everywhere throughout the forest. The waterfall making process has been occurring for thousands of years but it also continues to occur today.

When water starts flowing through the forest, it passes on top of different types of rock, some are hard while others are soft. After thousands of years, the soft rock becomes eroded and the stream cuts the soft rock vertically. However, hard rock does not erode. Because the erosion process is not uniformed, it causes high cliffs of running water and deep pools.

Because the Gondwana rainforest often experiences earthquakes, some of the waterfalls may have been caused by the abrupt tectonic activity. When an earthquake occurs, it can cause a valley to deepen which will increase the speed of water flow in the area, resulting in a waterfall. [30]

Rock Types

What makes the area of Gondwana Rainforests of Australia unique and Australia in general is the diverse rock types that can be found with in certain geographical structures such as volcanoes, fault zones, karst and caves. These geographical structures and trace rock types all the way back to 2.5 billion years ago.

One common type of rock is igneous rock that is found around the Gondwana Rainforest. When igneous rock is present that means that there has been some sort of volcanic activity in the past that has gone through the cooling process right on or near the Earth's surface causing the formation of igneous rock. [31]
Though pretty general this is an image of an igneous that is common amongst the rock types near or around the Gondwana Rainforests.

Sedimentary rock is also a commonly found rock type in Australia but more specifically the sedimentary rock known as Karst. Karst landforms are usually represented through geographical structures such as caves. We can conclude that the history of the formation of Karst includes natural waters coinciding with soluble rocks, which more specifically are limestone or dolomite. [32]
This is an example of Karst that is found within Australia.



Plate Boundaries

Australia is actually sitting on the entire Indo-Australian Plate. This huge plate connects to the Pacific plate and the Indian plate. Where it connects to the Pacific plate is one of the most intense places in the world. It is called the Ring of Fire, where there are 452 volcanoes and is home to 90% of the worlds earthquakes from all of the movement. Because of the movement of the Indo-Australian plate, it has created numerous volcanoes on the eastern part of Australia. These are caused by when the plate gradually moves hotspots find new weak points in the Earth's crust, which cause the magma to go through and volcanoes are created. [33]


Weathering and Erosion

Landforms in the area, including mountains and lakes, are affected by weathering and erosion processes. The Great Dividing Range, known also as the East Australian Cordillera, was formed about 300 million years ago when Australia collided with what is now parts of South America and New Zealand. At the time they were formed, during what is called the Carboniferous Period, the mountains were as high as any mountains today, but in 300 million years they have been almost completely eroded. [34]

In addition, numerous lakes have formed in volcanic craters. One lake formed in this manner is Lake Barrine. It was formed over 17,000 years ago when a large volcano erupted, leaving a crater that over time filled with water to create a lake. The crater, called a maar, was formed as a result of a series of volcanic explosions. These explosions were caused by the hot molten rock coming into contact with groundwater. This caused a build-up of steam, gases, and pressure which blasted the central core from the volcano. This massive explosion left a crater, which filled with rainwater to create Lake Barrine. [35]


Water


Water Impact

 Most of the water in the Gondwana Rainforests of Australia comes from rivers, including the Clarence and Warrego Rivers, which drain to the Murray-Darling Basin. The suptropical region receives an average of 50 inches of rain annually, and snow covers mountains in the Great Dividing Range during the winter months.

Landforms

As we mentioned above, the waterfalls within our area have been impacted by volcanic eruptions and volcanoes have been the only influential causes of the landforms of Gondwana Rainforests of Australia.


Springbrook Waterfall-- This is one of the major waterfalls that has been impacted and shaped by past volcanic eruptions. [36]


The Oxley Wild Rivers National park-- This is a mountainous region containing many different rivers and waterfalls that is located in the Gondwana Rainforest. The Great Dividing Range, once covered by an ancient ocean, was formed as a result of plate tectonic movement and volcanic eruptions. Wind, rain, and storm erosion over millions of years carved out rivers in the plateaus of the region including the Apsley River and the Macleay River. [37]

Glacial Impact

Today, no glaciers remain on main land Australia because it is simply too hot for glaciers to form and stay. Since the Gondwana Rainforests have relatively warm temperatures, glaciers have not had a hugely significant impact on the region.



Comments