Water is also needed for enzyme activity, transport, photosynthesis and support. Water allows osmotic balance between the outside and inside the cells of plants. Water is also needed for support for non woody plants and determines its turgidity. Too little water will cause the cells to flaccid, plasmolysis will occur and plant will wilt and eventually die if there’s no water available. Water is also a habitat for aquatic plants such as duckweeds. Therefore the distribution of duckweeds would be concentrated in areas where there is water available such as ponds in tropical rain forest. Desert scrubs vegetation is found in Mojave Desert in North America, a region frequently experiences thirty weeks or more without any measurable rain.
Light is also an important factor that influences the distribution of plants. Light intensity, photo period determine the closing and opening of stomata, hence the effectiveness of photosynthesis. Light also triggers flowering and seed germination. Shrubs inside Sunset Crater, AZ have whitish leaves that help maintain energy balance in a hot, sunny environment.
Soil pH is an important chemical property because it affects the availability of nutrients to plants. If the soil is acidic, desertification can occur. Different species of plants are adapted to certain ranges of acidity. Plants like firs and huckleberries are able to survive in acidic soil and alkaline soil such as salt bush. Plants that cannot withstand alkaline soil the leaves will have brown or black margins on them before they lose their leaves.
The availability of mineral and nutrients in soil is affects distribution of plants. For example, plants that require a large amount of K+ will not survive if there’s not enough potassium available.
Salinity has an affect on the absorption through osmosis. High salinity causes plants to lose water through osmosis. Halopohytes live in high salinity. Salinity reduces achene germination and corm sprouting in Scirpus maritimus and S. robustus. High salinity also reduces overall growth rate, height and diameter, root development, number of leaves, and other growth measures Mangrove trees are distributed in high salinity area such as coastal areas and able to survive due to its ability to get rid of excess salts.
Wind influences the rate of transpiration, or pull of water and minerals as well as seed and pollen dispersal. For example Bog Labrador tea is distributed throughout Alaska, Canada, and Greenland areas of strong cold winds. Leaves which are smooth on the upper side, with rusty hairs underneath enables the plant to limit transpiration rate.
The distribution of plants would be influence by animal in terms of seed and pollen dispersal. Animals like bees are attracted to the colour and smell of the flowers, in turn carry the pollen with it and land at another flower.
Herbivory can be, like competition, an interaction with another factor, reducing a species ability to survive until it cannot cope with herbivory. Remove this or competitors and most ranges would shift outwards a fair bit. A mountain Herb of the Alps, Arnica montana, is restricted to higher altitudes by slug herbivory. On lower slopes the new shoots of the plant coincide with peak slug activity.
The distribution of animal species is also affected by many factors
Animal species are specially adapted to suit different environment. For example, High animal distribution according to temperature is found in the tropical rain forest due to the suitability of temperature and high availability of producers as starters of food chains and webs. Cold blooded animal such as Central Texas Whip Snake (Masticophis taeniatus girardi) depend on sunlight to warm up their body temperature during the day time for its enzymes to work at an optimum level. Atlantic white-sided dolphins are found only in the North Atlantic, generally from waters just south of New England north to Norway. Atlantic white-sided dolphins are members of the genus Lagenorhynchus, which are typically adapted to colder water.
Water is needed for vital functions, so there is low animal distribution is deserts. Population of camel can be found throughout the deserts due to its characteristic of able to store water. In comparison frogs in tropical Queensland, Australia would not be found in the Sahara desert because frogs depend on high humidity as it breathes through its skin.
Breeding sites are needed for growth and protection of young. High animal diversity is found in areas with varied topographical nature. For example, the breeding site for humpback whales is concentrated in the northern hemisphere. However when is it not in the breeding season Humpback whales are distributed world-wide, with three major distinct populations: the North Atlantic, North Pacific, and southern oceans
Food supply is important for survival since animals are heterotrophs. High animal diversity is once again found in the rain forest. Animal such Black-billed and Yellow-billed Cuckoos are found in areas where there is a large population of gypsy moths.
Some animals are territorial and need large areas for feeding, mating, and protecting their young. Some are territorial during breeding season and occupy areas to prevent others from approaching them. There is high animal distribution where there is room to occupy territory and defend against other members of the species. For example, male mudskippers occupy mud ponds to attract mating partners and would be in competition with another male mudskipper if it invades its territory.
Predators would also influence the distribution of species. For example, if there’s a high number of a population of tigers in an area, there would be less distribution of deer in the same area.
Competition is also another factor that affects the distribution of animal species. Interspecific competition occurs when two or more species are competing for the same resource. The outcome might force one species to migrate to another area.
David Ellsworth http://www-personal.umich.edu/~ellswor/About_Phys-Ecol.html
Communication and Educational Technology Services, University of Minnesota Extension Service.
Harold A. Kantrud National Biological Service, Northern Prairie Science Center
http://www.whalecenter.org/species.htm