Option G: Ecology and Conservation G.2 Ecosystems and Biomes F.2.1 Define gross production, net production and biomass Units: kJ m-2 yr-1 Gross production = net production + respiration OR total amount of organic matter produced by plants in an ecosystem Net production = gross production - respiration Biomass = dry weight of an organism measured in g m-2 yr-1 F.2.2 Calculate values for gross production and net production using the equation: gross production – respiration = net production Example: Construct an pyramid of energy using the following information: Tropic level Producers Primary consumers Secondary consumers Tertiary consumers Energy flow (kJ m-2 yr-1) 20 810 3368 383 21 F.2.3 Discuss the difficulties of classifying organisms into trophic levels F.2.4 Explain the small biomass and low numbers of organisms in higher trophic levels • Biomass is lost during respiration at each trophic level • Predators at the top of the pyramid must be large enough to catch prey; there can only be a few of them F.2.5 Construct a pyramid of energy giving appropriate formation The total solar energy received by a grassland is 5 x 105 kJ m-2 y1. The net production of the grassland is 6 x 102 kJ m-2 y-1. The total energy passed onto the primary consumers is 60 kJ m-2 y-1. Only 10% of this energy is passed onto its secondary consumers. a) Calculate energy lost by plant respiration b) Construct a pyramid of energy for this grassland. F.2.5 Construct a pyramid of energy giving appropriate formation The total solar energy received by a grassland is 5 x 105 kJ m-2 y1. The net production of the grassland is 6 x 102 kJ m-2 y-1. The total energy passed onto the primary consumers is 60 kJ m-2 y-1. Only 10% of this energy is passed onto its secondary consumers. b) Construct a pyramid of energy for this grassland. F.2.6 Distinguish between primary and secondary succession, using an example of each Ecological succession: change in species composition in a community over time. Primary Succession Secondary succession • Plants begin growing on previously lifeless area • Lacks organic soil • Example: • New volcanic island (lichen moss) • After primary succession • Upheaval of primary succession (plants) but has organic component (seeds/roots) • Example: • Recolonisation after forest fire F.2.7 Outline the changes in species diversity and production during primary succession Example: Coastal sand dunes Foredune Yellow dune Grey dune Mature dune • thin soil layer • • Sedge and sand bindweed; • no soil dandelion and thistles • Pioneer plants: lyme and marram • Rabbits (droppings) • • Diversity increases grass • Limited diversity Humus develops (holds water) Thick shrubs • Thick humus • Supports forest • High diversity F.2.8 Explain the effects of living organisms on the abiotic environment with reference to the changes occurring during primary succession • • • • Few species No soil New area Lichen and mosses are pioneer plants • Low biomass • Low production • • • • Many species Soil present Old area Seeds and roots already present • Higher biomass • Higher production F.2.9 Explain how rainfall and temperature affect the distribution of biomes • Climograph plots temperature and rainfall in a particular region F.2.10 Outline the characteristics of the major biomes