Trees in a large forest are being cut for timber. there are almost not understory shrubs in this area; just mature evergreen greens, some grasses and other low-growing plants. if left alone for the next decade, the forest should re-establish itself. new trees will grow. all but one is a reason for this new growth. a) there is already an established soil profile. b) there is already an existing seed bank of suitable plants in the area and soil. c) lichens are present in the area to create soil and improve soil fertility. d) root systems undisturbed in the soil, stumps and other plant parts from previously existing plants can with regrowth.

C) Lichens are present in the area to help create soil and improve soil fertility.

An ecological succession is a process in, which changes that occur in a region in order to bring changes in the biotic community with respect to changes in the non-living factors and time. These changes occur in an ecosystem until the ecosystem attains stability. In the given situation the forest will establish itself again due to secondary succession. A secondary succession is a succession which occurs in a region which was previously colonized by plants and animal species but the ecosystem was disturbed by human induced or natural calamity. Although, there is loss of vegetation, but the soil will retain it's profile. Here, the succession does not require the development of soil for the growth of new plants. Lichens belongs to primitive species organisms which colonize on the land which was previously barren. These species makes the soil suitable for the growth of plants. Secondary succession does not require lichen colonization as the soil is already fertile.

Therefore, lichens are present in the area to help create soil and improve soil fertility is the reason that does not support the reestablishment of forest.

the answer is "a.) well–developed vascular system."

explanation: