What is Community Ecology explain their characterstics?

Community Ecology: In ecological terms, a community consists of an assemblage of all of the populations living and interacting within a given area, making up a living unit. There can be a wide variation of the numbers of species, as well as the kinds of species that form a community, but all of the different plants, animals, fungi, bacteria, and microorganisms can number in the hundreds. Although some communities are distinct from each, often they overlap or grade into each other, blurring the lines between them. The study of communities and the inter-relationships between the species is called synecology. The study of an individual organism or members of a single species is known as autecology.

Characteristics 

Species Distribution :  The organizational level of community possesses its own set of characteristic features, which can be seen in most community assemblages, from tropical rainforests to rocky shores. Species within communities often have a vertical distribution in space, or what ecologists refer to as stratification. For instance, tropical rainforests have various species of trees that form canopy layers that shade the lower growing shrubs and brush plants (called the understory). The canopy also provides habitats for animals and other plants called epiphytes to grow upon.

In fact, a major difference between tropical rainforests and the typical deciduous forests found in places like the northeast of North America is that much of the rainforests biomass, or organic plant material is above the ground. The soil in rainforests is usually only a few centimeters deep, and does not receive as much plant matter for decomposition, and so the soil lacks the rich nutrients that typify deciduous forests.

Vertical stratification can also be seen in aquatic habitats as well. The water column in both fresh water and marine environments filters sunlight so that the more energetic, shorter wavelengths penetrate to greater depths. Different species of algae grow to different depths depending on their ability to absorb the different wavelengths, providing for a distinct vertical distribution of algae. Animals that do not require light are usually found below the algae or plankton, or on the bottom, feeding on the food that rains down from the above water column. There are many other factors at work besides sunlight that determine the vertical stratification of species. For example, on the rocky shores of the Pacific coast, wave force, desiccation (drying out), salinity, temperature, and inter- and intra-specific competition, among other factors, influence distribution as well.

The distribution of species within communities varies widely. Distribution can be thought of in terms of space as well as time. Whether or not plants grow in clumps or are widely spaced can depend on factors such as sunlight, water, nutrients, or temperature. Plant distribution determines to a large extent the distribution of animals that depend on them for food or shelter. Examples of distribution in time are the seasonal migration patterns of elk, birds, butterflies and whales. Migratory patterns are often tied to food availability and mating patterns.

Species Diversity :  The number of species in a community is often used as an indicator of its complexity. Usually a community that is less diverse reflects conditions that are probably not favorable to many species because only those species that have evolved the ability to withstand extreme physical conditions in temperature, rainfall, salinity, nutrients, substrate, or gas availability are able to survive.

Higher numbers of species also means more complex energy relationships are able to develop. More species normally translates into a greater number of trophic, or feeding levels, through which energy flows and nutrients cycle. More resources are utilized by different species in different ways, forming food webs rather than food chains. Complex food webs and nutrient cycles are developed by species that co-evolve together. Clearly, communities represent many very complex interactions between species.

Stability :  The stability of a community refers to its ability to recover and return to its original state from a disturbance such as a fire or infestation that destroys the major species. The ability to recover depends on the species, as some species are more susceptible than others. For example, some species of plants are not only resistant to fire, but require fire to release seeds from cones, such as some species of pine. In these cases, the seedbed is prepared for nurturing the seedlings by burning. These plants resist fire damage with thick bark, underground stems and buds, and shoots that are annuals. Some entire communities in ecosystems are fire-adapted, such as the chaparral. Chaparral can be found in climates with mild, wet winters and dry hot summers. Chaparral occurs in the Mediterranean, along the coasts of Chile, California, and southwestern Australia and Africa.