Provide two benefits and one risk of using prescribed fire in managing rangeland soils.

• A. Benefits include fuel load reduction and stimulation of new growth; risks include erosion during burns and smoke management concerns
• B. Benefits include increased soil pH and moisture; risks include weed invasion
• C. Benefits include complete weed eradication; risks include nutrient loss minimal
• D. Benefits include reduced soil organic matter; risks include reduced biodiversity

Answer: (B)

Prescribed fire can change the soil environment by altering the surface layer where most soils and plant interactions occur. When the fire leaves behind ash, minerals are added to the soil that raise the surface pH. This rise in pH can shift nutrient availability, often making certain nutrients more accessible to plants in the upper soil layer. Fire also changes how water moves through the soil surface. Removing litter and surface debris can improve infiltration after rainfall and alter the immediate moisture dynamics in the topsoil, which, under the right conditions, can support better soil moisture availability for plants. The key point is that these soil-related changes from fire are context-dependent and can be beneficial for soil processes in some situations.

Weighing risks, disturbance from fire can create bare mineral soil and reduce competition from established vegetation, which opens the door for weed species to establish. If invasive or opportunistic weeds take root, they can alter the plant community and soil processes over time, making weed invasion a meaningful soil management risk after a burn.

Other options tend to emphasize aspects not as directly tied to soil properties, such as reducing fuel loads or stimulating growth, or they imply outcomes like complete weed eradication or negligible nutrient loss, which don’t align with the typical soil-focused effects of prescribed fire.