Which factor has the greatest influence on soil formation and natural vegetation worldwide?

The factor that has the greatest influence on soil formation and natural vegetation worldwide is climate. Climate encompasses various elements such as temperature, precipitation, and seasonal variations, fundamentally shaping the characteristics of soil and the types of vegetation that can thrive in a particular region.

Climate affects soil formation primarily through the processes of weathering and erosion, which break down rocks and organic material to create soil. For instance, in tropical climates where there's abundant rainfall and warmth, weathering happens rapidly, leading to highly fertile and diverse soils. Conversely, in arid environments, limited rainfall leads to slower soil formation and often desert-like vegetation, which is adapted to those conditions.

Additionally, climate also determines the types of plants that can grow in a region; for example, the lush forests of rainforests are a direct result of the warm, moist conditions provided by the climate, while the cold, dry conditions of tundra regions support a very different type of ecosystem.

In this context, while topography, biological activity, and human activity can all influence soil and vegetation, they are often shaped or constrained by the prevailing climate of an area. Thus, climate is the overriding factor that governs the foundational elements of soil and natural vegetation across the globe.