Natural Ecosystem

Natural Ecosystem• They conserve water by excreting concentrated urine.• Animals and birds usually have long legs to keep the body away from the hotground.• Lizards are mostly insectivorous and can live without drinking water for severaldays.• Herbivorous animals get sufficient water from the seeds which they eat.Camel is known as the ship of the desert as it can travel long distances without drinkingwater for several days.MODULE - 2Ecological Conceptsand IssuesNotes(d) TundraThe word tundra means a “barren land” since they are found in those regions of the worldwhere environmental conditions are very severe. There are two types of tundra- arcticand alpine.• Distribution: Arctic tundra extends as a continuous belt below the polar ice capand above the tree line in the northern hemisphere. It occupies the northern fringe ofCanada, Alaska, European Russia, Siberia and island group of arctic ocean. On thesouth pole Anatarctica tundra in the south pole is very small since most of it iscovered by ocean .Alpine tundra occurs at high mountains above the tree line. Since mountains arefound at all latitudes therefore alpine tundra shows day and night temperature variations.• Flora and fauna: Typical vegetation of arctic tundra is cotton grass, sedges, dwarfheath, willows, birches and lichens. Animals of tundra are reindeer, musk ox, arctichare, caribous, lemmings and squirrel.Most of them have long life e.g. Salix arctica that is arctic willow has a life span of 150 to300 years. They are protected from chill by the presence of thick cuticle and epidermalhair. Mammals of the tundra region have large body size and small tail and ear to avoid theloss of heat from the surface. The body is covered with fur for insulation. Insects haveshort life cycles which are completed during favourable period of the year.INTEXT QUESTIONS 6.21. What are deciduous trees?______________________________________________________________2. Explain two common characteristics of the desert.______________________________________________________________99