Taiga Biome:boreal forests

      Taiga Biome:boreal forests

        

              Taiga is the world's largest land biome, and makes up 29% of the world's forest cover. the largest areas are located in Russia and Canada. The taiga is the terrestrial biome with the lowest annual average temperatures after the tundra and permanent ice caps. Extreme winter minimums in the northern taiga are typically lower than those of the tundra. The lowest reliably recorded temperatures in the Northern Hemisphere were recorded in the taiga of northeastern Russia. 

               The growing season, when the vegetation in the taiga comes alive, is usually slightly longer than the climatic definition of summer as the plants of the boreal biome have a lower threshold to trigger growth. In Canada, Scandinavia and Finland, the growing season is often estimated by using the period of the year when the 24-hr average temperature is 5 °C or more. For the Taiga Plains in Canada, growing season varies from 80 to 150 days, and in the Taiga Shield from 100 to 140 days. Some sources claim 130 days growing season as typical for the taiga.Other sources mention that 50–100 frost-free days are characteristic. Data for locations in southwest Yukon gives 80–120 frost-free days. The closed canopy boreal forest in Kenozyorsky National Park near Plesetsk, Arkhangelsk Province, Russia, on average has 108 frost-free days.The longest growing season is found in the smaller areas with oceanic influences; in coastal areas of Scandinavia and Finland, the growing season of the closed boreal forest can be 145–180 days.

            Animals found in taiga include woodpeckers, hawks, moose, bear, weasel, lynx, fox, wolf, deer, hares, chipmunks, shrews, and bats. Mammals living in the boreal forests have all adapted in various ways to survive the long cold winters. Generally they have heavy fur coats and many hibernate through the winter.

Growthform Adaptations: The main reasons firs, sprucs and pines are the dominant trees in the boreal forest, and thus define the biome is because they are adapted to the extreme conditions brough about by the cold, including the winter-induced drought and the short growing season. The following are some of the main adaptations we found that trees in this zone have:

• Conical shape - promotes shedding of snow and prevents loss of branches.
• Needleleafs - narrow leaves reduce surface area through which water can be lost (transpired), especially in the winter when the frozen ground prevents plants from replenishing their water supply. The needles of boreal conifers also have thick waxy coatings--a waterproof cuticle--in which stomata are sunken and protected from drying winds.
• Evergreen habit - retention of foliage allows plants to photosynthesize as soon as temperatures permit in spring, rather than having to waste time in the short growing season merely growing leaves. [Note: Deciduous larch are dominant in areas underlain by nearly continuous permafrost and having a climate even too dry and cold for the waxy needles of spruce and fir.]
• Dark color - the dark green of spruce and fir needles helps the foliage absorb maximum heat from the sun and begin photosynthesis as early as possible.

Mountain biome

          The mountain biome is harsh. The higher you climb the harsher it becomes due to the thinner atmosphere, high winds, and low temperatures. The type of flora and fauna change from the bottom to the top as the climate changes and the soil thins. The mountain biome has the largest variety of ecosystems and they will vary with the location of the mountain. I.e. the ecosystems of the Alps will not be the same as those of the Andes. The mountain biome is the most difficult to study as a whole because the fauna and flora varies from mountain range to mountain range.

            Mountains are usually found in groups called chains or ranges, although some stand alone. A mountain biome is very cold and windy. The higher the mountain, the colder and windier the environment. There is also less oxygen at high elevations.Several different types of plants and animals found in the mountain biome were left behind with the melting of the ice sheets as they retreated north at the end of the last ice age.

           The animals of this biome have adapted to the cold, the lack of oxygen, and the rugged landscape. They include the mountain goat, ibex (wild goat), sheep, mountain lion, puma, and yak. All of them are excellent climbers, which means they can move freely in the steep, rocky landscape. Types of plants vary depending on geographic location and altitude. Lower elevations are commonly covered by forests, while very high elevations are usually treeless.

               One common trait among the mountain biome fauna is that most of them are plant eaters. Such as the yak, mountain goat, the takin, ibex, chinchillas. Flora that can be found in most mountain biomes includes heather, lichens, coniferous tress, and chaparral.

                Mountains are a common sight on this planet. They make up one-fifth of the world's landscape, and provide homes to at least one-tenth of the world's people. Furthermore, 2 billion people depend on mountain ecosystems for most of their food, hydroelectricity, timber, and minerals. About 80 per cent of our planet's fresh water originates in the mountains. Since about half of the world's people are reliant upon mountains for fresh water, and in this time of increasing water scarcity, it is becoming increasingly important to protect the mountain biome.

                 All mountain ecosystems have one major characteristic in common--rapid changes in altitude, climate, soil, and vegetation over very short distances. Mountain ecosystems sport a high range of biodiversity, and are also a home to many of our planet's ethnic minorities. These cultures are sometimes 'protected' due to the challenging environment to produce a living, but others are not. More and more these indigenous people are being kicked out of their homes due to population and commercial growth, logging, and mining.

                 Rainfall varies greatly across the world's montane (mountain) biomes, ranging from very wet to very dry. However in all the biomes comes swift weather changes. For example, in just a few minutes a thunder storm can roll in when the sky was perfectly clear, and in just a few hours the temperatures can drop from extremely hot temperatures to temperatures that are below freezing.

                The world's mountains provide a home to several thousand different ethnic groups. The mountain people, which mainly consist of indigenous people, ethnic minorities, and refugees, have been able to cope with this harsh environment of the mountain ecosystem. They live as nomads, hunters, foragers, traders, small farmers, loggers, and miners, etc. They have been able to live off the land without widespread destruction and deforestation. Plant and animal species have been preserved by these people.

                The Himalayan Yew, a slow-growing conifer, is currently on the World Wildlife Fund's list of the ten most endangered animals. This plant can be found throughout Bhutan, Afghanistan, India, Nepal, Burma, and maybe China. Taxol, which is promising to be a drug which can help cure cancer, is present in both the Pacific and Himalayan varieties. Found in the world's highest mountain range, the Himalayan Yew is extremely rare because of heavy deforestation and harvesting for Taxol extraction, without replanting.

 Major biomes

Savanna ecosystem

Savanna ecosystem

                A savanna, or savannah, is a grassland ecosystem characterized by the trees being sufficiently small or widely spaced so that the canopy does not close. The open canopy allows sufficient light to reach the ground to support an unbroken herbaceous layer consisting primarily of C4 grasses. Some classification systems also recognize a grassland savanna from which trees are absent.This article deals only with savanna under the common definition of a grassy woodland with a significant woody plant component.

          It is often believed that savannas feature widely spaced, scattered trees. However, in many savannas, tree densities are higher and trees are more regularly spaced than in forest. Savannas are also characterized by seasonal water availability, with the majority of rainfall confined to one season. Savannas are associated with several types of biomes. Savannas are frequently in a transitional zone between forest and desert or prairie. Savanna covers approximately 20% of the earth's land area.

         Many grassy landscapes and mixed communities of trees, shrubs, and grasses were described as savanna before the middle of the 19th century, when the concept of a tropical savanna climate became established. The Köppen climate classification system was strongly influenced by effects of temperature and precipitation upon tree growth, and his over-simplified assumptions resulted in a tropical savanna classification concept which resulted in it being considered as a "climatic climax" formation. The common usage meaning to describe vegetation now conflicts with a simplified yet widespread climatic concept meaning. The divergence has sometimes caused areas such as extensive savannas north and south of the Congo and Amazon Rivers to be excluded from mapped savanna categories.

         "Barrens" has been used almost interchangeably with savanna in different parts of North America. Sometimes Midwestern savanna were described as "grassland with trees". Different authors have defined the lower limits of savanna tree coverage as 5-10% and upper limits range from 25-80% of an area.

   

       Two factors common to all savanna environments are rainfall variations from year to year, and dry season wildfires. Savannas around the world are also dominated by tropical grasses which use the C4 type of photosynthesis.In the Americas, e.g. in Belize, Central America, savanna vegetation is similar from Mexico to South America and to the Caribbean. In North America nearby trees are of subtropical types, ranging from southwestern Pinyon pine to southeastern Long leaf Pine and northern chestnut oak.

Savanna ecoregions

Savanna ecoregions are of several different types:-

• Tropical and subtropical savannas are classified with tropical and subtropical grasslands and shrub lands as the tropical and subtropical grasslands, savannas, and shrub lands biome. The savannas of Africa, including the Serengeti, famous for its wildlife, are typical of this type.
• Temperate savannas are mid-latitude savannas with wetter summers and drier winters. They are classified with temperate savannas and shrub lands as the temperate grasslands, savannas, and shrub lands biome, that for example cover much of the Great Plains of the United States. (See areas such as the Central forest-grasslands transition).
• Mediterranean savannas are mid-latitude savannas in Mediterranean climate regions, with mild, rainy winters and hot, dry summers, part of the Mediterranean forests, woodlands, and scrub biome. The oak tree savannas of California, part of the California chaparral and woodlands ecoregion, fall into this category.
• Flooded savannas are savannas that are flooded seasonally or year-round. They are classified with flooded savannas as the flooded grasslands and savannas biome, which occurs mostly in the tropics and subtropics.

• Mountain savannas are high-altitude savannas, located in a few spots around the world's high mountain regions, part of the mountain grasslands and shrub lands biome. The highland savannas of the Angolan Scarp savanna and woodlands ecoregion are an example.

Our ecosystem