Bio chapter 18

• The amount of biomass in the organisms at each trophic level is less than it was at the previous level
• Not all organisms or parts of organisms are eaten by the stage above
• Some of the biomass taken in is passed out and lost in the waste materials of the organism, for example, faeces
• Large amounts of biomass taken in at each trophic level are used in respiration to transfer energy for the organism. Only a relatively small proportion is used to build new biomass in the organisms at the next trophic level
• At each trophic level, less of the original biomass is passed on. A large amount of plant biomass supports a smaller amount of herbivore biomass, which in turn supports an even smaller amount of carnivore biomass
• Biomass


  The mass of material in living organisms
• Measuring biomass


  • Dry biomass is the dry mass of biological material in grams, but requires killing the organisms
  • Wet biomass in grams can be used instead, but is less repeatable and reproducible
• The biomass made by plants is passed on through food chains or food webs
• There are usually more producers than primary consumers, and more primary consumers than secondary consumers
• The number of organisms does not always accurately reflect what is happening to the biomass - the size of the organisms matters as well as the actual numbers
• Pyramid of biomass


  A way of drawing the total amount of biomass in the living organisms at each stage of the food chain, to scale
• Trophic level 1 is always at the bottom of the pyramid of biomass
• Governments are recognising the damage of deforestation and increasing carbon dioxide emissions, and are working to reduce the effect
• Many countries are working to recycle resources - including paper, glass, plastics, and metal - rather than dumping them in landfill
• Governments have introduced taxes on putting material in landfill, which has reduced the amount of material put in landfill
• Carbon dioxide emissions in the UK are falling as a result of government agreements and legislation
• Reducing carbon dioxide emissions globally can help maintain biodiversity
• Taxes can be used to help reduce human damage to ecosystems and biodiversity
• Mangroves


  Vital sites for young fish to develop, easily destroyed by too much or too little water or changes in salinity
• Around 20% of all the lowland heaths in the world are in the UK but this habitat has been disappearing fast
• Maintaining unique features and protecting heathland from developers

  1. Removing trees

  2. Reversing drainage

  3. Allowing ponies and cows to graze
• Reintroduction of field margins and hedgerows
• In many agricultural areas, hedgerows were removed to produce larger fields, leading to soil erosion and reduction in soil fertility
• Gradually farmers are replanting hedgerows and leaving wildflower margins round the edges of their fields, increasing species and biodiversity
• Environmental change


  A change in the environment where an organism lives affecting its distribution
• Invasive species


  A new type of predator or disease-causing pathogen may be carried from one country to another and wipe out a species of animal or plant
• Introduced species


  Different plants may be introduced and support a whole range of different species, or outcompete local species and reduce biodiversity
• In the 1900s, Dartford warblers lived in Southern Europe with a tiny colony in Dorset and Hampshire
• In 1963, two cold winters almost wiped out the UK population of Dartford warblers, with only 11 breeding pairs remaining
• As temperatures have increased


  Dartford warblers have spread to Wales, the Midlands, and East Anglia
• If climate change continues

  Dartford warblers could spread through most of the UK
• In 2007 and 2009, a couple of hard winters reduced the breeding populations of Dartford warblers again
• In Spain, the numbers of Dartford warblers are dropping rapidly, by 25% or more in 10 years as it becomes too warm
• Scientists use computer programs to simulate the distribution of bird species as the climate changes
• They predict that the range of European birds will move 550km north-east by the end of the century, with many species lost to Europe or becoming extinct
• Geophilic


  Organisms that are adapted to a particular geographic location
• Adaptation


  How organisms adapt to environmental changes
• Environmental changes may be seasonal, geographic, or caused by human activity
• Seasonal changes in temperate parts of the world include changes in temperature, rainfall, water levels, dissolved gases, and daylight hours
• Geographical changes involve differences in soil, structure, altitude, salinity of water, and availability of water