How do many seeds arrive in a barren landscape?

Primary Succession follows the formation of new land surfaces consisting of rock, lava, volcanic ash, sand, clay, or some other exclusively mineral substrate.
This means that there is NO SOIL present. (Soil is a mixture of mineral material, decaying organic material, and living organisms. The area is barren in primary succession.)
Secondary Succession follows the destruction or partial destruction of the vegetation area by some sort of disturbance, like a fire, windstorm, or flood that leaves the soil intact.
Pioneer species initiate recovery following disturbance in both primary AND secondary successions. Pioneers "pave the way" for later colonists (plant species) by altering the biotic and abiotic environment
Climax community describes an end product of succession that persists until disturbed by environmental change. The labels I-VII represent the different stages of primary succession. I-bare rocks, II-pioneers (mosses, lichen, algae, fungi), III-annual herbaceous plants, IV-perennial herbaceous plants and grasses, V-shrubs, VI-shade intolerant trees, VII-shade tolerant trees. Examples of Secondary Succession
Fire. Fire is one of the most common causes of secondary succession and is an important component for the renewal and vitality of many types of ecosystem. ...
Harvesting, Logging and Abandonment of Crop Land. ...
Renewal After Disease. ...
Gap Dynamics. Examples of Primary Succession
Volcanic eruptions.
Retreat of glaciers.
Flooding accompanied by severe soil erosion.
Landslides.
Nuclear explosions.
Oil spills.
Abandonment of a manmade structure, such as a paved parking lot. Primary succession begins in barren areas, such as on bare rock exposed by a retreating glacier. ... Over hundreds of years these “pioneer species” convert the rock into soil that can support simple plants such as grasses. These grasses further modify the soil, which is then colonized by other types of plants. How does an area move from a sterile, barren wilderness to one full of life? Barren rock from beneath a retreating glacier, or due to a volcanic eruption. Low-growing plants such as mosses, ferns, and lichens begin to colonize. Fast-growing grasses, flow- ering plants, and small shrubs begin to take root. The ecosystem may have been stopped from reaching its full climatic climax or deflected towards a different climax by activities such as:
Cutting down the existing vegetation.
Burning as a means of forest clearance.
Planting trees or crops.
Grazing and trampling by domesticated animals.
Harvesting of planted crops. is colonized by living things for the first time. In secondary succession, an area that was previously occupied by living things is disturbed, then re-colonized following the disturbance.
The pioneer species are hardy species which are the first to colonize barren environments or previously biodiverse steady-state ecosystems that have been disrupted, such as by fire. Some lichens grow on rocks without soil, so may be among the first of life forms, and break down the rocks into soil for plants. Primary succession is a change in vegetation which occurs on previously unvegetated terrain (Barnes et al. 1998). Examples of where primary succession may take place include the formation of new islands, on new volcanic rock, and on land formed from glacial retreats.