Chapter 18 G.2 Objectives Ecosystems and Biomass

Define Gross Production, Net Production, and Biomass Gross Production – total amount of energy trapped in the organic matter produced by plants per area per time in kilojoules. Net Production – the gross production minus the energy lost through respiration. Biomass – dry weight of an organism measured in g/m²yr

Calculate values for gross production and net production using the equation: gross production – respiration = net production Example: Gross production = 809 kJ / m² yr Respiration = 729 kJ / m² yr 809 – 729 = 80 Net production = 80 kJ / m² yr

Discuss the difficulties of classifying organisms into trophic levels. Many animals such as eagles, coyotes, and lizards are not in just one trophic level because they can be considered as primary consumers, secondary consumers, or tertiary consumers depending on what they eat. Omnivores are also difficult to determine which trophic level because they eat both plants and animals.

Explain the small biomass and low numbers of organisms in higher trophic levels Biomass is lost during respiration at each trophic level. When glucose is broken down for energy, it is converted into carbon dioxide gas and water. Carbon dioxide and water are excreted and the biomass of glucose is lost. Each successive level of the ecosystem loses more and more biomass. Energy per gram of food does not decrease, but total biomass of food is less at each trophic level.

Pyramid of Energy

Distinguish between primary and secondary succession, using an example of each. Primary succession is where plants start growing in a previously lifeless area such as a land that has experiences a volcanic eruption. Secondary succession is when a new organism takes over a upheaval. It is quicker then primary succession. This is because the soil is already in place, a prime example of this is after a forest fire.

Outline the changes in species diversity and production during primary succession Fordune stage is the beginning stage where there is nothing present yet. Yellow dune stage is second and can take years, dead organisms piles up to make a new thin layer of soil. Grey dune stage is developed after years of plants dying and decomposing and humus is developed and can hold water. The final stage of the dune sucession is Mature dune, at this point the dune can support a forest.

Explain the effects of living organisms on the abiotic environment, with reference to the changes occurring during primary succession. Organic Matter Increases Resulting from the death and decay of animals and causes the earth to better absorb water, making it able to better support plants. Soil Gets Deeper Results from the mixer of decayed organic matter and abiotic materials (such as sand, rock, etc). Soil Erosion Reduces Plant roots stabilize the abiotic materials (sand, rock, etc) and soil.

Explain the effects of living organisms on the abiotic environment, with reference to the changes occurring during primary succession. Soil Structure Improves Sand and rock don’t hold water, so when soil is produced, it holds water and minerals and allows the anchoring of plant roots. Mineral Recycling Increases Bacteria and fungus which thrives in such environments recycle the nutrients of dead organisms.

Distinguish between biome and biosphere. All the living things that make up our world. Biome The division of the biosphere defined by type of vegetation and community structure.

Explain how rainfall and temperature affect the distribution of biomes. The effective temperature and rainfall of each biome has a particular range for each biome representing the conditions in each. Two different biomes can have the same temperature or rainfall but usually differ in one or the other. EX. A desert can have the same temperature as a temperate forest but the temperate forest differs by having more rain fall each year causing it to have different flora and fauna than the desert due to having more life sustaining water.

Outline the characteristics of six (seven) major biomes. Temperature Moisture Characteristics of Vegetation Desert 60 degrees Celsius Less than 30cm/Yr Cacti and shrubs (adaptable to dry) Grassland Cold in winter hot in summer Seasonal drought, medium moisture Prairie grasses (fires prevent invasion) Shrubland Mild temperatures in winter, long hot summers Rainy winters, dry summers Dry woody shrubs that reproduce with fire Temperate deciduous forest Very hot winter very cold winter High rainfall, frozen in winter Oak, hickory, maple, warm=Herbaceous Tropical rainforest Very warm More than 250cm/Yr High plant diversity with tree canopy Tundra Very cold, layer of permafrost in soil year round Little precipitation Lichen, mosses, grasses, shrubs, no deep roots Coniferous forest Slightly warmer than tundra Small amount, but lack of evaporation Cone bearing trees