adaption by plants and animals to dryland systems and the implications of this for human use of these environments impo

2. The absence of vegetation is of great importance in determining characteristics of the landscape: Protects the surface immediately beneath the plant from erosion Increases the surface roughness, leading to lower erosive power of the wind Acts as a trap for migrating particles, and therefore keeps the land together

3. The role of moisture 4 main moisture sources in deserts are rainfall, coastal fog, dew and groundwater. �Accidental vegetation� grows rapidly in response to one-off rain events, but is short-lived Spacing of rainfall more significant than amounts- very variable In coastal areas fog is very important Vegetation that uses groundwater supply not dependant on precipitation Surface stability Difficult for vegetation to establish due to loose coarse sand layer Run-off is usually small and deep percolation and evaporation are main methods of moisture loss Results in damp soil at depths and good rooting conditions, but development of plants from seed is difficult Plants must be adapted to deal with sand blasting and burial Presence of vegetation facilitates growth of more vegetation

5. In Deep Sands (>5m) (NB Plants face burial and sandblasting) In areas of accumulation, stems covered by sand grow roots from nodes � especially perennial grasses, eg. Stipagrotis scoparia. Rhizomes grow into sand, sprouting new aerial stems, eg. S. pungens. In areas of sand deflation exposed taproots have �corky� bark, to cope with exposure, eg. Convolvulus lanatus. Glandular hairs to �catch� sand grains on plant surface to protect it from wind blown particles, eg. Fagonia arabica.

6. Biological processes of animal tissue can function only within a relatively narrow temperature range. Dryland animals have evolved both behaviorally and physiologically. There are various foodwebs :- Herbivory, Granivory and Predatory. Most important is their impermeable covering Insects = waxy cuticle. Reptiles = horny scales. Mammals = cornified skin.

7. Examples of dryland animal adaptations :- Camels and Kangaroo rats. Avoiding heat behavioral techniques for avoiding excess heat are numerous among dryland animals Dissipating heat some animals dissipate heat absorbed from their surroundings by various mechanisms. Retaining water. Acquiring water.

8. Environment as a resource:- Medicine, Food, Transport, Land, Minerals and Military use. Desertification caused by- increasing populations of humans and animals overgrazing burning of shrubland wood used for fuel Animal Husbandry Nomads live off their camels, goats and sheep depending on them The need for plant-animal-human co-adaptation