THE COMMUNITIES

Do u know about community in the living world

That part of an ecosystem that is living, all the animals and plants and other organisms that live together in an area, is called a community. The countless number of species that inhabit a rain forest or the sparse number of species that live in the boiling waters of a hot spring make up a community. Indeed, every inhabited place on earth supports its own particular array of organisms. Over time,
the different species have made many complex adjustments to community living, evolving together and forging relationships that give the community character and stability. Both competition and cooperation have played key roles in molding these communities. The magnificent redwood forest, shown  that extends along the coast of central and northern California and into the southwestern corner of Oregon is an example of a community. Within it, the most obvious organisms are the redwood trees, Sequoia sempervirens. These trees are the sole survivors of a genus that was once distributed through-out much of the Northern Hemisphere. A number of other plants, like the redwood sorrel flower  and the sword fern and animals, like the ground beetle feeding on a slugare regularly associated with redwood trees. Their coexistence is in part made possible by the special conditions the redwood trees themselves create, providing shade, water (dripping from the branches), and relatively cool temperatures. This particular distinctive assemblage of organisms is called the redwood community. The organisms characteristic of this community have each had a complex and unique evolutionary history. They evolved at different times in the past and then came to be associated with the redwoods.

We recognize this community mainly because of the redwood trees, and its boundaries are determined by the redwood's distribution. The distributions of the other organisms in the redwood community may differ a good deal. Some organisms may not be distributed as widely as the redwoods, and some may be distributed over a broader range. In the redwood community or any other community, the ranges of the different organisms overlap; that is why they occur together. Many communities are very similar in species com-position and appearance over wide areas. For example, the open savanna that stretches across much of Africa includes many plant and animal species that coexist over thousands of square kilometers. Interactions between these organisms occur in a similar manner throughout these grassland communities, and some interactions have evolved over millions of years.