Tropical Rainforest A tropical rainforest has a very humid and warm climate year round, and rain is almost constant. The rainforest also consists of many layers. These layers are forest floor, understory, canopy layer, and the emergent layer. Many species can be found in a tropical rainforest.
<ul><li>Elevation: There are two types of rainforests; lowland- found in areas of low elevation. They contain tall trees with high canopies, and they receive intermittent precipitation. Cloud- found in mountainous regions and growth is usually thicker than in lowland forests. They gain moisture through mist, rain, and clouds. </li></ul><ul><li>Average yearly wind speed: The lower levels don’t receive much wind, but the higher the level the more wind there is. </li></ul><ul><li>Topography: The tropical rainforests range from lowland forests with less rainfall and different plant and animal life to cloud forests that are very lush and thick and contain a very different plant and animal population than the lower layers. </li></ul><ul><li>Soil Conditions: Soil in the tropical rainforest is low in </li></ul><ul><li>nutrients. Plants are so lush because they have the ability </li></ul><ul><li>to store the nutrients from plant decay around them. </li></ul><ul><li>The soil is so is so infertile because its 100 million years </li></ul><ul><li>old and has taken a beating from the elements of nature. </li></ul>Rainfall~Temperature~ Abiotic Factors
Food Web Plants Amphibians Insects Mammals Reptiles Birds Decomposers
Nitrogen in Atmosphere (N 2 ) Plants Decomposers (Fungi, bacteria, and plantae) Ammonium (NH 6 ) Nitrates (NO 2 ) Nitrates (NO 3 ) Nitrogen-fixing in root nodules of legumes. Nitrogen Cycle
Mutualism I saw two great examples of 3-way mutualism in Australian tropical forests. There was an arboreal termite nest high up on a tree with a large, conspicuous hole (approximately 4 cm. in diameter). This hole was created by a kookaburra bird. The bird hollows out part of the termite nest to use as its own nest, where it will lay its eggs. The kookaburra lines the bottom of its nest with twigs and mud. The termites benefit from the bird nest because the hole created by the bird helps ventilate and regulate the temperature of the termite nest in this hot, tropical environment. The kookaburra benefits because it has a safe nesting location where predatory animals will not disturb its young when they hatch. The third member of this mutualistic trio is a moth who lays its eggs so they will hatch at the same time as the kookaburra eggs hatch. The moth larvae eat excrement and parasites from the young kookaburra chicks. The moths benefit because they get a plentiful supply of food and a safe living location. The birds benefit because the moths keep their nest and chicks clean and free of excrement and parasites. This is a beneficial association for all three members-termites, kookaburras, and moths.
Commensalism <ul><li>An example is vermiliads (plants living on trees in rainforests) and frogs; the frogs get shelter and water from the vermiliad but the vermiliad is unaffected. Commensalism is a type of symbiosis </li></ul>
Parasitism <ul><li>Strangler fig grows on the branches of a tree and then the strangler fig eventually sprouts aerial roots. Over time, many roots may grow and then will wrap around the tree resulting in death of the tree. </li></ul>
Disaster! <ul><li>A multiple year experiment mimicking drought in an Amazonian rainforest revealed some surprising short-term survival strategies used by trees. For example, during droughts, some tree species use their deep roots to bring water to the surface where fine surface roots absorb it. Other species absorb water through their leaves. The study also indicates that despite such survival strategies, the death rates of trees significantly increase after multiple years of drought. The resulting loss of shade </li></ul><ul><li>promotes the drying of the leaf litter on </li></ul><ul><li>the ground and thereby helps fuel fires. By </li></ul><ul><li>providing such insights, this study </li></ul><ul><li>improved understanding of tree </li></ul><ul><li>physiology, how tree losses and fire </li></ul><ul><li>affect the carbon cycle, and </li></ul><ul><li>the feedbacks between climate and the </li></ul><ul><li>Amazonian rainforest. </li></ul>