Notes

Biologist consider it is important to study islands because it is one of the important ecosystem in the world and they also contribute to the balance of ecosystems. As these have isolated and limited geographical area, it is easy to study the species diversity and other environment factors persisting there. Existence of comparable conditions present in an island also adds to the benefits. And these are regions with changing species diversity and factors affecting this can also be studied by studying islands. Extinction of species is a big problem faced by islands. Many endemic species of plants and animals may be present there. This need to be studied and solutions have to be made inorder to protect the biodiversity in islands.

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Organisms living on an island are more likely to go extiction because of the limited or less geographical area. Hence the species are only limited to a small region. Because of this the resources for survival available to them will be very less and this may also lead to competition between them. Also natural factors and disasters like forest fire, flood, disease and population fluctations can easily affect the population numbers because of the limited area.

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Mostly islands will be colonized by the species from the mainland via migration. As islands are surrounded by water, mostly species have to travel via air/wind or water to reach and colonize in an island. So, mostly birds and plants will colonize an island. But in some cases some mammals and other animals which can swim can also reach the island. Another way is that they can get washed away from the mainland and reach the island.

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Colonization depends on the distance of the island from the mainland. If the distance is less colonization by the species will be more and vice versa. This is because if the distance is very large, then organisms find it difficult to migrate to the island. Hence the immigration rate decreases in the island if the distance is more.

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Size of the island affects the extinction rates in an island. When the geographical size of an island is very less, then the extiction rates increases and vice versa. This is because a larger area means more resources and habitats, and hence more biodiversity. In a small area availability of less resources can affect the survival rate of the organism. Also, small area will affect the population more in case of a natural disaster.

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Primary productivity refers to rate at which organic compound/biomass is produced in an ecosystem, by plants and other autotrophs. This is maily achieved by photosynthesis, but it can also occur via chemosynthesis. Primary production is very important component of an ecosystem because all the organism depends on it directly or indirectly. Primary producers which photosynthetic organisms ( like green plants, algae and phytoplanktons) are responsible for the primary production, and they form the base/foundation of a food chain and food webs, which is then continued by secondary producers, tertiary producers and so on. Hence, primary productivity is very important part of our ecosystem.

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Productivity depends on several factors like availability of light energy, temperature, moisture, nutrient availability, Carbon dioxide levels and also the interaction between communities. As photosynthesis is the main process involved in primary production, factors which promote photosynthesis can also improve productivity. Temperature (by Q10 effect) and moisture level increases photosynthesis, As sunlight is main source of energy for photosynthesis, it also increases productivity. High CO2 levels and high nutrient availabilty are other factors which promote photosynthesis and productivity.

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It is said that biodiversity increases the productivity. Biodiversity simply refers to species richness in a particular area. These species interact in an ecosystem for their survival and to maintain a balanced ecosystem. So, as it is said productivity refers to rate of biomass production in an ecosystem. Hence, when the biodiversity is more there will be increased biomass production because of higher organic matter and organisms. So, this means increased productivity.

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Main factors which determine the migration of a species from mainland to island are the size of the island and the distance of the island from the mainland. This is because larger geographical area (larger island) means the resources available in the region will be more and also there will be less competition. Affect of calamities will be also less. In the case of distance, if the distance of the island from the mainland is very large, organisms find it difficult to reach there as the island will be surrounded by water. So, these factors affect the migration likelihood of species in an island from the mainland.