Biotic FactorsBiotic factors are influences on the ecosystem by living things. An example of a biotic factor in this ecosystem is the keystone species. A keystone species will be explained more in depth in a later section. A keystone species is vital to an ecosystem because its removal could cause a drastic change in the ecosystem. There are many different types of keystone species. Some manipulate the environment whereas others keep populations of species in check. There are many other biotic factors that affect the ecosystem.
(Photo above) http://2.bp.blogspot.com/-Ytjg3Q38Zzo/Tp 5w0OKCYI/AAAAAAAABJ0/bNFVcECXA48/s1600/Starfish5.jpg (Photo Right)http://www.shannontech.com/ParkVision/VirginIslands/VirginIslands5.html#Plants |
Abiotic FactorsAbiotic factors are influences on the ecosystem by non-living things. An abiotic factor in the Virgin Islands National Park is sunlight. Sunlight is important to the ecosystem in the Virgin Islands because it is the main source of energy for all of the plants. Sunlight fuels photosynthesis, allowing plants to convert light energy to chemical energy. Photosynthesis allows the plant to take carbon dioxide in from the atmosphere and after a series of reactions, release it as oxygen and water. Plants in this national park are isolated from the rest of the world due to living on an island. But, living on an island in the Caribbean allows maximum sunlight. Over 65% of the island of St. John is covered by forests. Sunlight is needed for the large variety of trees at this park to thrive. Some trees you can find at the Virgin Islands National Park are mango trees, mangrove trees, and gumbo limbo trees.
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Limiting Factors
Density DependentA density dependent factor is something that affects the population size and growth based on population density. An example of a density dependent factor is population carrying capacity. When a population gets too large competition for food and resources increases and individuals have higher risk for starvation and death. When the population size gets too large, negative frequency selection may take place. Negative frequency selection is when the common (large population) is chosen against in natural selection. A predator will have more food with a large population of prey.
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Density IndependentA density independent factor is something at affects the population regardless of the population density. In other words, it is not reliant on the population density. Examples density independent factors are hurricanes and earthquakes. The population density does not affect the strength of these natural disasters. Individuals are affected by hurricanes and earthquakes regardless of the size of the population.
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