Slide show describing desert biomes, climate and soil characteristics, plant and animal adaptations as well as human impacts.

1. Desert biomes Sara Middleton

3. Global distribution of desert biomes equator 30° South 30° North Desert biomes are generally around a belt of 30° north and south latitude .

5. Climate- what causes deserts? air masses found 30° north and south of the equator move in circular patterns ( Hadley Cells ) In a Hadley cell air rises at the equator . As it rises it cools causing the moisture to condense and precipitate , leaving the air dry . This dry air descends around 30° north and south of the equator. In areas where the air descends a high pressure zone is created. Winds blow outwards from high pressure areas. (So no moisture can be brought in by the wind ) Therefore there are very low precipitation levels Hence the location of many deserts are found there

8. Plant adaptations Phreatophytes Are plants that have adapted to arid environments by growing extremely long roots, allowing them to acquire moisture at or near the water table . e.g. Ocotillo bush Xerophytes Are plants that have adapted to arid environments by storing as much of the little water made available and reducing evapotranspiration rates. e.g. Cacti

10. Animal adaptations -Camels Two rows of long eyelashes Adaptation Function Protect against blowing sand and the sun Fat stored in hump(s) Help it to survive long periods without food and water Keep out blowing sand Nostrils can be closed Provide warmth during cold desert nights and insulation against daytime heat Thick fur and under wool Pads spread out when the camel places its feet on the ground thus creating a "snowshoe effect" and preventing the camel from sinking into the sand Broad, flat, leathery pads at the bottom of their hooves

11. Animal adaptations- Fennec fox Adaptation Function large ears (about 15cm) help dissipate excess body heat on hot days in the desert. burrowing and nocturnal lifestyle Thick, sandy fur helps insulate them from the cold desert nights but also reflects heat, As well as providing excellent camouflage. Cooler temperatures at night mean less water loss while carrying out activities.

13. Nutrient cycling- Net primary productivity (NPP) NPP is the amount of organic material available for consumption in a given area minus the losses plant respiration . Normally expressed as g/m²/yr Deserts have one of the lowest mean NPP of 0.003 g/m²/yr compared to 2.2 g/m²/yr for a tropical rainforest! B L S Fall- out as litter decomposes Uptake by plants Degradation & mineralisation Loss in run- off Input from rainfall Nutrient cycle for a desert biome = biomass, = soil, =litter Pyramid of numbers

14. Nutrient cycling

15. Human impacts Oil drilling Agriculture Irrigation Development of cities pollution Settlements Interference of natural ecosystems

16. Human impacts Deserts are also being destroyed by development . As populations in desert cities rise , so does the demand for water . Many desert streams, and ground water sources, once used by animals have been drained for industries , agriculture and people .