Indacate whether each item below is an example of primary or secondary succesion. Give your reasons for each choice.
a) Lichen grows on barren rock in the tudra.
To determine whether the given example is an example of primary or secondary succession, we need to understand what each type of succession refers to.
Primary succession occurs in areas where there is no soil present, such as barren rocks or newly formed volcanic islands. It is the initial colonization of life in these harsh and inhospitable environments. Primary succession begins with the colonization of pioneer species such as lichens and mosses, which then pave the way for the growth of larger plants and eventually create soil over time.
Secondary succession, on the other hand, occurs in areas where soil has already been formed, but the existing vegetation has been disrupted or destroyed by a disturbance such as a fire, landslide, or human activity. Secondary succession is the process of regrowth and recovery of the ecosystem after a disturbance, where the soil is already present, and seeds and other organisms have the opportunity to recolonize the area.
Now, let's analyze the given example:
a) Lichens grow on barren rock in the tundra.
Based on the information given, the presence of lichen growing directly on barren rock suggests that this is an example of primary succession. Lichens are one of the first organisms to colonize such harsh environments because they can tolerate extreme conditions and can break down the rock's surface into small particles over time, eventually leading to the formation of soil. Their presence marks the early stages of colonization and the beginning of ecosystem development.
Therefore, the given example (a) of lichen growing on barren rock in the tundra is an example of primary succession because it represents the initial colonization of life in a challenging environment with no pre-existing soil.