scarce during certain parts of the year, animals tend to “clump” together
around these crucial resources; e.g., elephants in Africa clumped together
near water holes during the dry season. Individuals might also be clustered
together in an area due to social factors such as family groups, e.g.,
wildebeests. Organisms that usually serve as prey also form clumped
distributions in areas where they can hide and detect predators easily, e.g.,
ducks. Other causes of clumped distributions are the inability of offspring to
independently move from their habitat. This is seen in juvenile animals that
are immobile and strongly dependent upon parental care, e.g., chimpanzees.
Clumped distribution in species also acts as a mechanism against predation
as well as an efficient mechanism to trap or corner prey, e.g., lions.
Threatened or endangered species are also more likely to be clumped in
their distribution.- RANDOM. Little interaction between members of the population leading to
random spacing patterns. Random distribution usually occurs in habitats
where environmental conditions and resources are consistent. This pattern
of dispersion is characterized by the lack of any strong social interactions
between species; e.g., dandelion seeds being dispersed by wind. - UNIFORM. Fairly uniform spacing between individuals. Uniform distributions
are found in populations in which the distance between neighboring
individuals is maximized. The need to maximize the space between
individuals generally arises from competition for a resource such as
moisture or nutrients, or as a result of direct social interactions between
individuals within the population, such as territoriality; e.g., penguins often
exhibit uniform spacing by aggressively defending their territory among
their neighbors or creosote bushes releasing chemicals that inhibit the
growth of other plants around them (allelopathy).
Ecosystem (Community) Characteristics(1) Physical appearance Relative size; stratification; distribution of
populations and species
(2) Species diversity Number of different species
(3) Species abundance Number of individuals of each species
(4) Niche structure Number of ecological niches; how they
resemble or differ from each other; species
interactions