hase, during which population growth decelerates as N approaches K. All species have a well-defined life history that involves a beginning of life, a juvenile and reproductive phase and death. There are two important parameters of a population: survivorship (how long one live) and fecundity (how many offspring one leaves). Survivorship is the number still living at the beginning of each age interval. The number of deaths determines the death rate during a given period of time divided by the number still living at the beginning of the time period. COMMUNITIES A community is an assemblage of populations that interact with one another and the effects that they have on each other often greatly influence their ability to survive and reproduce. Because they are assemblages of different species, communities have properties that make them unique from individual organisms and populations. Some communities simply blend gradually into others and for this reason are called open comments, forest communities are like that, as different vegetable types blend together. Conversely, closed communities have more definite borders; few organisms pass from one community to another. In these types of communities, fewer organisms move in and out, so they are more isolated in terms of energy and nutrients. Despite the fact that communities can sometimes be difficult to define, ecologists have been able to identify a lot of attributes by which communities can be described and analyzed. These include - Species composition which is the most fundamental attribute of a community. It's simply a list of species of which the community is comprised. Communities vary tremendously in their composition. - Frequency is a measure of how often we find a species in a community. - Distribution, or how species are arranged in a community - Diversity is a measure of the variation in a community, has two components. The first is richness, which is the number of species in the comm...
