What is the effect of atmospheric deposition in a northern forest?

What is the effect of atmospheric deposition in a northern forest?

• A. Increased buffering capacity of the soil
• B. Decreased soil fertility
• C. Increased soil pH beyond neutral
• D. Reduced microbial activity

Answer: (A)

Atmospheric deposition changes soil chemistry by delivering ions to the forest floor. When deposition brings in alkaline or base-forming ions such as calcium, magnesium, and potassium, these cations can replenish exchange sites on soil minerals that have lost bases through weathering and prior acid inputs. As the supply of these base cations increases, the soil becomes better at neutralizing added acids, so its ability to resist pH changes—its buffering capacity—increases. In northern forests, soils are often acidic and depleted of base cations due to weathering and leaching, so input of these base ions from deposition helps restore buffering ability. This means the soil can better dampen fluctuations in pH from ongoing atmospheric inputs, delaying acidification effects on plants and microbes.

Atmospheric deposition changes soil chemistry by delivering ions to the forest floor. When deposition brings in alkaline or base-forming ions such as calcium, magnesium, and potassium, these cations can replenish exchange sites on soil minerals that have lost bases through weathering and prior acid inputs. As the supply of these base cations increases, the soil becomes better at neutralizing added acids, so its ability to resist pH changes—its buffering capacity—increases. In northern forests, soils are often acidic and depleted of base cations due to weathering and leaching, so input of these base ions from deposition helps restore buffering ability. This means the soil can better dampen fluctuations in pH from ongoing atmospheric inputs, delaying acidification effects on plants and microbes.