<P> Primary succession is one of two types of biological and ecological succession of plant life, occurring in an environment in which new substrate devoid of vegetation and other organisms usually lacking soil, such as a lava flow or area left from retreated glacier, is deposited . In other words, it is the gradual growth of an ecosystem over a longer period of time . </P> <P> In contrast, secondary succession occurs on substrate that previously supported vegetation before an ecological disturbance from smaller things like floods, hurricanes, tornadoes, and fires which destroyed the plant life . </P> <P> In primary succession pioneer species like lichen, algae and fungi as well as other abiotic factors like wind and water start to "normalize" the habitat . Primary succession begins on rock formations, such as volcanoes or mountains, or in a place with no organisms or soil . Primary succession leads to conditions nearer optimum for vascular plant growth; pedogenesis or the formation of soil, and the increased amount of shade are the most important processes. . </P> <P> These pioneer lichen, algae, and fungi are then dominated and often replaced by plants better adapted to less harsh conditions, these plants include vascular plants like grasses and some shrubs that are able to live in thin soils that are often mineral based . Water and nutrient levels increase with the amount of succession exhibited . </P>

What organisms begin the soil making process in primary succession