Answer: Tropical deserts are dry most of the year. They have few plants and a hard windblown surface strewn with rocks and some sand. They are the deserts we often see in the movies. In temperate deserts, daytime temperatures are high in summer and low in winter and there is more precipitation than in tropical deserts. The sparse vegetation primarily consists of widely dispersed, drought-resistant shrubs and cacti or other succulents adapted to the lack of water and temperature variations. In cold deserts, summers are warm or hot, and precipitation is low. In all types of deserts, plants and animals have evolved adaptations that help them to stay cool and to get enough water to survive. Desert ecosystems are fragile because they experience slow plant growth, low species diversity, slow nutrient cycling due to low bacterial activity in the soils, and very little water.