Where do thorn scrublands occur in relation to savannas and deserts?

Thorn scrublands, often referred to as thorn forests, occupy a transitional ecological position between savannas and deserts.

In the dry tropics, these scrublands generally occur in the area situated between savannas at lower latitudes and deserts at higher latitudes. This transition is primarily governed by moisture availability:1

• Relationship to Savanna: As rainfall increases, thorn scrublands grade into savanna woodland.2
• Relationship to Desert: As the climate becomes drier and rainfall becomes more erratic, thorn scrublands transition into desert vegetation.21

In these regions, the vegetation is adapted to low and unpredictable rainfall, which is further limited by high rates of potential evapotranspiration. Consequently, the landscape often features a mix of thorny, drought-resistant trees and shrubs that shed their leaves seasonally, alongside arid-adapted grasses. Because this transition is often gradual and influenced by fluctuating environmental conditions, a definitive boundary between thorn scrubland and desert is frequently difficult to distinguish.123