Transcript of High Desert Biome
The high desert is a semi-arid biome, that can be found on almost every continent. Elevations range from 4,000 to 10,000 feet. Temperatures can reach over 100 degrees Fahrenheit during the summer, and in some places, near 0 degrees in winter. High desert flora generally consists of sagebrush and grasses. While fauna include raptors, pronghorn or other grazers, coyotes, and small animals like rabbits and lizards. High Desert Biome Climate Tucson, Arizona Temperature and Precipitation The temperature in a high desert climate, like that of Tuscan, Arizona, can range from around 100 degrees Fahrenheit in the summer, to about 40 degrees in the winter. In some places however, high desert temperatures can reach 0 degrees in the winter Rainfall in high desert climates is normally very low. Tuscan's average is only 11 inches per year, with the majority of rainfall in July and August. Climate Tucson, Arizona Sunlight The high desert biome is one of the sunniest in the world, and Tucson, being in a high desert, is one of the sunniest cities in the United States, recieving 3,800 hours of sunlight per year. Sunlight is the most important of the abiotic factors in a high desert, because it provides energy to producers like grasses and brushes. The amount of sunlight high deserts receive also greatly contributes to the high summer temperatures. High desert biomes can be found on almost every continent, although there are some differences in temperature and plant and animal life in each one. The map below shows all the major biomes on Earth, desert biomes are shown in yellow. Keep in mind however, that this map doesn't differentiate high desert biomes from other types of deserts. World Distribution Biogeochemical Cycles The two most prominent biogeochemical cycles in a high desert ecosystem are the carbon cycle, and the water cycle. The water cycle is the process by which water gathers in lakes and oceans, then evaporates and condenses to form clouds. The clouds deposit water in the form of precipitation, and the cycle repeats. This cycle provides what little water is available in high desert biomes. The Carbon Cycle and Human Impact The other predominant biogeochemical cycle taking place here is the carbon cycle. Through this cycle, carbon is absorbed by plants, and through photosynthesis, is used to produce oxygen. Oxygen is used for cellular respiration, once again releasing CO2 into the atmosphere. Some of the carbon dioxide however, is absorbed into the ground from dead and decaying plants and animals. Eventually, it becomes a fossil fuel, which is burned by humans, releasing the CO2 back into the atmosphere. In this way, humans are putting more carbon dioxide into the atmosphere than occurs naturally, and contributing greatly to higher levels of CO2 in the atmosphere, and increasing the greenhouse effect. This leads to higher average temperatures, in a biome that is already hotter than most. The Water Cycle Biogeochemical Cycles Biotic Factors Biotic factors are all of the living things in a biome. In a high desert, these include plants like sagebrush and grasses, and animals such as pronghorn, lizards, snakes, and raptors. One way of organizing the relationships between biotic factors is via a food web, like the one at the left. Each organism has it's own niche, a place where it belongs in it's biome and food web. And naturally, populations of different organisms in a biome tend to regulate one another, which protects all the species in the biome against extinction. Producers Producers are organisms at the bottom of the food chain. Most are autotrophs, and get energy from sunlight. The main producers in a high desert biome include plants like sagebrush, grasses, and some wildflowers and cacti. Herbivores First Level Consumers First level consumers in a high desert biome include pronghorn antelope, which graze on sagebrush and grasses, as well as ants and other insects. Many of the small rodents in a high desert ecosystem are also classified as first level consumers. They recieve about 10% of the original energy of the producers. Small Carnivores Second Level Consumers Second level consumers in a high desert biome usually consist of small carnivores like snakes and badgers. Members of this trophic level feed mainly on rodents and insects. They get about 10% of the energy of the herbivores they eat, meaning they get about 1% of the original energy from the producers. Carnivores Top of the Food Chain Raptors, coyotes, and sometimes mountain lions belong at the top of the food chain in high desert biomes. Raptors feed mainly on snakes and lizards, which being second level consumers, pass on 0.1% of the original energy of the producers to the raptors. Coyotes and mountain lions are usually the only predators in the biome that feed on antelope. Because pronghorn antelope are first level consumers, mountain lions and coyotes get 1% of the original producer's energy. Detritivores/Decomposers Detritivores, or decomposers, are some of the most important biotic factors in any biome. They eat the remains of dead plants and animals, converting them back into organic materials in the soil. Their role is so important because decomposing detritus (dead organisms), is one of the best natural factors sustaining ecosystems. Decomposers in high desert ecosystems consist mainly of beatles, earthworms, and soil bacteria Symbiosis Mutualism: Mutualism is a symbiotic relationship in which both organisms benefit from the relationship. In a high desert ecosystem, a mutualistic relationship exists between desert wildflowers and flying insects which feed on and pollenate them.Full transcript
Commensalism: Commensalism is a type of relationship in which one organism benefits while the other is neither helped nor harmed. An example of commensalism in a high desert is fringe-toed lizards, which live in abandoned ground squirrel holes.
Parasitism: Parasitism is a relationship in which one organism lives and feeds on another. One example of parasitism is ticks, which live on sagebrush, until an animal such as a pronghorn antelope, brushes against the sagebrush. The tick attaches to the antelope's skin and feeds on it's blood. 100% 10% 1% 0.1% of producer's energy Human Impact Human activity has had a negative effect on the entire earth, especially since the start of the industrial and green revolutions. Two of the human activities that have a great effect on high desert biomes are global warming due to increased levels of greenhouse gases, and the expansion of farms into high desert land. Farming Expansion One of the greatest threats to high desert biomes is farming expansion. As the human population increases, the need for food increases, and therefore, more farms are built. Often farming occurs in high desert biomes, which reduces the amount of land the desert can occupy. Expansion of farms can also kill native plant life, force animals to move, and introduce foreign species to the area. All of which can have negative effects on the biome as a whole. Dairies vs. Other Farms Farms which grow vegetables, grains, and fruits for human use often require less land than dairy farms. This is simply because a dairy farm requires land for cattle as well as feed, which is often grown on separate land and shipped in. While farms which grow vegetables, grains, or fruits for human use only require enough land for crops. The Greenhouse Effect The greenhouse effect is when light rays enter earths atmosphere, warming the earth. And while some heat escapes into space, some of it is held in by greenhouse gasses in the atmosphere, which act as insulators. Due to human contributions, the levels of greenhouse gases like carbon dioxide and methane gas are higher than ever, leading to what we call global warming. The Greenhouse Effect Dairy Farm Emissions One contributor to greenhouse gas emissions is dairy farms, particularly large-scale dairies. In fact, a 2010-11 study on large-scale dairy emissions found that a 10,000 head dairy facility produced, on average, 3,575 pounds of ammonia, 33,092 pounds of methane, and 409 pounds of nitrous oxide per day(source: http://www.sciencedaily.com/releases/2011/07/110719111708.htm). What We Can Do As a way of counteracting both of these problems, dairy farms could, over time be converted to growing crops for human use. Converting dairys and land used to grow feed, to be used for food crops, would make better use of the farmland we have, reducing the need for more. And because farms growing food crops have lower levels of greenhouse gas emissions, converting dairys would also greatly reduce human contribution to the greenhouse effect. Works Cited: http://hawaiidermatology.com/foodwebgif/foodwebgif.htm