Different geographical areas have different climates and therefore have different plant communities. Plant species only grows in areas where the climate favors their survival. This will result into different plant species in different geographical areas. If a species is not favored with the climate in a particular area, then it will be wiped out and only those species favored by the climate will thrive. This has resulted into different plant communities between eastern and western sierra.
During the late Pleistocene and early Holocene, the eastern sierra appeared to be moistured whereas the western was drier (Davis et al, 1985). Mesic pine forest were found in the eastern sierra because this plant species could only thrive in moistured areas while in the west there was Artemisia pollen which means the drier conditions favored its growth.
East of Sierra Nevada in the Mojave Desert, the climate was wetter at the end of the last glaciation. (Wells et al, 1987). This elevated the population of mesic shrubs and succulents, indicating increased summer precipitation.
West of Sierra Nevada majorly contains two vegetational types that is grass and woodland grass. (Talbot and Sampson, 1948). The climate here is the mediterrean type, characterized by wet, mild winters and long and hot dry summers. It is being affected by the coast Range Mountains that influence the air and cloud movements and the Pacific Ocean which has a moderating effect on certain areas. During dry summers, the days are usually clear with maximum temperatures and relative humidity often between 10-15 percent and sometimes lower.
Great basin sage is an aromatic shrub that grows in arid and semi-arid conditions, through a range of cold desert and mountains habitats in the intermountain west of North America. They are dominant across a large portions of the great basin. The range extends northward through the British Columbia’s southern interior, south into Baja California, and east into the western great plains of the New Mexico, Colorado, Nebraska and the Dakotas. It provide food and habitat for a variety of species like sage grouse and pronghorn antelope (Mackay, 2013).
Great basin sage is used as an herbal medicine by Native Americans, mostly as a smudging herb. It is also used to prevent infections on wounds and stop internal bleeding. It is used to treat headaches and colds. It is placed in shoes to treat athletes’ foot. (Rogosic et al, 2011).
Pinyon pine grows in southwestern United States, especially in New Mexico, Arizona and Utah. The trees yield edible nuts, which is a staple food for Native Americans. It is widely eaten as a snack and used as an ingredient in the New Mexican cussine. The trees are also known to influence the soil on which they grow by increasing the concentration of macronutrients and micronutrients. It relates with other wildlife like the pinyon jay which takes its name from the tree and the pinyon nuts forms the major part of its diet. It plays an important role in the regeneration of the pinyon trees because it stores a large number of the seeds in the ground for later use and the seeds might grow into trees again. The Mexican jay is important in the dispersal of some pinyon species. (William & ruby, 2006).
Chickadees are a group of North American birds. Species found in North America are called chickadees while the other species in the genus are called tits. They are small sized birds having the crown of the head and the throat patch darker than the rest of the body. They are about 6-14 centimeters in size. Their name comes from the call they make “chick-a-dee-dee-dee”. The number of “dees” depends on the number of predators. Chickadee is the official bird for the state of Massachusetts. It is well known for its ability to lower its body temperature during the cold winter nights. It is bold near humans to an extent that it is able to feed from the human hands. It has a good spatial memory that enables it to remember the caches where it stores its food. Insects especially caterpillars form the major part of their diet. (Webster, 1991).
Rabbit brush is a North American shrub in the family of sunflower. It grows in the arid regions of western United States, northern Mexico and western Canada. The shrub reproduces from seeds and root sprouts. It produces pungent smelling, golden yellow flowers. The flower heads are made up of five small tubular disk flowers and occur in an umbrella shape. It is popular in areas where water conservation is important. It thrives well in alkaline soils found mostly in desert regions. It is a major source of food for browsing wildlife in the winter ranges. Its blossoms are used to make yellow dye and the stems are used to baskets. It was considered as a source of rubber as early as 1904. It is also a source of hypoallergenic rubber for use in products designed for people with latex allergies. They exhibit a concentration of radioactive strontium much higher a normal plant (Roberts & Urbatsch, 2003).
Jeffrey pine is a North American pine tree. It is mostly found in California, western Nevada, south western Oregon and northern Baja. It is named in the honor of its botanist documenter john Jeffrey. It is a large coniferous evergreen tree, 25-40m tall. The leaves are needle like and in bundles of three. Its scent is described as a reminiscent of vanilla, apple, lemon, and pineapple and quite commonly butterscotch. The largest Jeffrey pine tree by trunk volume is the eureka valley giant found in the Stanislaus national forest. Its trunk contains 4560 cubic feet of wood, is 192 feet tall and with a diameter of 8.1 feet. It is stress tolerant and can survive in colder and drier climates. It is tolerant serpentine soil and is dominant in these conditions even in fairly low altitudes. The purity of n- heptane distilled from Jeffrey pine is used as a zero point on the octane rating scale of petrol (Farjon, 2013).
Stellars jay is native to western North America. It is a more slender bills and longer legs. The head blackish brown with lighter streaks on the forehead. The dark coloring gives away from the shoulders and lower breast to silver blue. It occurs mostly in the forested areas in the rocky mountains of southern Alaska. They are omnivores, there is about two-third plant matter and one-third animal matter. The nest is usually in a conifer but sometimes is built in a hollow in a tree. It lays between two to six eggs during the breeding season. The eggs are oval in shape with a glossy surface and the shells are pale in color. The clutch is usually incubated entirely by the females for about sixteen days. The males feeds the female during this time. Though they are to be loud, they tend to be quiet during nesting not to attract attention. They have numerous and variable vocalizations, but mostly one similar to the sound of an old fashioned pump handle (Halpern & Daniel, 1986).
Aspen is deciduous tree native to cooler areas of North America. The trees have tall trunks up to 25 meters tall with smooth pale bark. They have glossy green leaves that turn golden yellow in autumn. The species often propagates through its roots to form large clonal groves originating from the shared root system. It is being found from Canada to central Mexico. It contains a substance that was extracted by the indigenous North Americans and was used as a quinine substitute. They are used as wood fuel though they are poor because they dry slowly, rot quickly and do not give much heat. Its leaves serves as food to caterpillars of various moths and butterflies. In Canada the wood is used in pulp products such as books and newsprints. It is good for panel products like oriented strand board and wafer board. It is light in weight and used in furniture, wall panels, boxes and crates (Perala, 1990).
Lodgepole is also known as twisted pine. It is a common tree in western North America. It is common near ocean shore and in dry montane forests but rare in lowland rainforest.it is an evergreen conifer. The formation of twin trees is common in some population in British Columbia. It is fire-dependent species and requires wildfires in order to maintain healthy population of diverse ages. The bark of the tree is fairly thin, minimizing its defense to fire. The heat of the fire opens the cones to release the seeds. This enables this species to regenerate and maintain its place in the forest habitat. This species is attacked by blue stain fungus distributed by the mountain pine beetle from its mouth. It is used as a structural pole in the native North Americans tipi shelter (Sullivan & Steven, 2015).
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