The main factors affecting the type of flora in any part of the landscape and its distribution are the soils, the prevailing climate and the relief or topography. Although many plants can, in principal, tolerate a wide range of conditions, virtually all species will have a set of conditions that are ideal for their needs and beyond this set of ideal conditions the plants will struggle more to survive and compete against other plants that are more suited to those differing prevailing conditions.
The main soil factors influencing the flora in any place are acidity or alkalinity and the degree of wetness. There is a huge combination of soil/climate/topographic conditions worldwide and this gives rise to a wondrous range of flora across the world, for instance trees.
Soil performs an important role in supporting so-called ecosystem services. These describe how a natural ecosystem can perform 'services' such as the supporting of life of plants and animals, the cleaning of pollutants from water (filtering) and contribution to the the natural cycles such as the hydrological cycle, nutrient cycle, nitrogen cycle, carbon cycle and oxygen cycle.