Drought is a critical lack of water supply or availability. Causes include deficiency in precipitation, dry seasons and El Niño, and human activities which degrade and exhaust the natural systems such as deforestation, over-farming and excessive water extraction. In extreme cases, soil can degrade so much it results in desertification - excessive or total vegetation loss and complete exhaustion of the soil.
Many plants have a high degree of natural drought resistance, most easily identified by physical features such as a waxy cuticle (thick leathery leaves), a reduced number of leaf pores (stomata) succulent leaves, or none at all.
Drought resistant species can be employed to facilitate restorative agriculture techniques which include: re-vegetation using specific plant assemblages and rotational and zonal grazing strategies. This can help restore land to a state where it can be agriculturally productive and maintain the resilience, stability and diversity of a natural ecosystem.
Perennial food-producing plants and trees with drought resistant properties are increasingly used to increase community resilence and sustainability in affected areas. Working with natural ecosystems creates greater diversity of food crops, compared to more industrial approaches (such as greenhouses, irrigation and chemical fertilisation) which can have long-term negative effects and much higher water consumption.
Water retention techniques such as swales can reduce surface runoff, whilst increasing absorption of water into the soil. This increases the water levels and subsequently allows for a greater range of vegetation to propser. Building soil and soil cover, through mulching and vegetalisation, acts to (re)establish natural ecosystemic resilience to the causes and effects of drought.