Unit 4.1

• A biome is a large ecological area characterized by similar climate, vegetation and soil type.
• A desert biome has a very dry climate with very low precipitation levels, it has a very shallow, coarse and well-drained type of soil. Due to limited organic matter, decomposition and leaching, desert soils often lack nutrients, making them infertile. Vegetation: drought-resistant plants (xerophytes)
• Temperate forest; climate: seasonal variation in temperature and rainfall. They are found in regions with different seasons, such as North America, Europe and East Asia. Soil type: fertile and well-developed. Vegetation: deciduous and evergreen trees.
• Tundra; climate: cold and extremely long winters, short summers, and low temperatures throughout the year. Low precipitation. Soil type: permafrost, a layer of permanently frozen subsoil that extends below the surface, inhibiting drainage and preventing the growth of vegetation. Vegetation: Low growing as permafrost limits plant growth.
• Primary succession occurs in an area where no previous life or soils exists, such as newly formed volcanic islands, glacial retreats
• Pioneer species are the first species to colonise a new area, such as lichens and mosses.
• Secondary succession is when there has been some form of disturbance on land which already had soil and plants present
• Gross primary production is the total amount of energy available by a plant during photosynthesis.
• Net primary productivity is the gross primary production minus the energy required by plants for respiration. It represents the amount of stored chemical energy that will be available to consumers in an ecosystem.
• Biomass is the collective mass of living organisms in a particular area or time. Organisms with high biomass have high rate of productivity or NPP.
• Ecosystem is a community of living organisms and abiotic factors interacting with each other in some specific environment
• On average, the energy transfer between tropic levels is estimated to be around 10% efficient, 10% of energy is passed to each tropic level.
• Energy can be lost as heat through respiration, it can also be lost through excretion, such as organisms excrete waste material, including undigested food or urine
• Biodiversity is the diversity and variety of life on earth.