定義： A linear shoaling landform feature within a body of water. Bars tend to be long and narrow (linear) and develop where a current (or waves) promote deposition of granular material, resulting in localized shallowing (shoaling) of the water. Bars can appear in the sea, in a lake, or in a river. They are typically composed of sand, although could be of any granular matter that the moving water has access to and is capable of shifting around (for example, soil, silt, gravel, cobble, shingle, or even boulders). The grain size of the material comprising a bar is related: to the size of the waves or the strength of the currents moving the material, but the availability of material to be worked by waves and currents is also important.
定義： Description of the relationships among individuals within a population of organisms, including reproductive relationships (mating system), relationships within each sex, adult – young interactions, helpers and cooperation (group living).
定義： A group of species that exploit the same food resources, and/or use the same feeding or foraging methods. http://en.wikipedia.org/wiki/Guild_(ecology)
