Question

ash trees are being removed when they show signs of the ash borer, a parasite that affects only ash trees and kills them off. what best explains why the ash trees are being cut down? the ash borer is a density - independent limiting factor, and humans need to clear cut to control tree density. the ash borer is a density - dependent limiting factor and will start to spread to nearby healthy trees. ash trees are outcompeting other trees and are thus more affected by the ash borer. changes in climate have decreased ash borer populations which indirectly increased the need for cutting down the trees.

Explanation:

• Density - dependent limiting factors are those that affect a population more as the population density increases. Parasites (like the ash borer) are density - dependent limiting factors. When an ash tree is infected with the ash borer, if it is left standing, the parasite can spread to nearby healthy ash trees.
• Density - independent limiting factors (e.g., natural disasters like floods, earthquakes) do not depend on population density. The ash borer is not a density - independent factor.
• There is no indication in the problem that ash trees are outcompeting other trees.
• The problem states that the ash borer kills ash trees, not that climate change has decreased ash borer populations and increased the need to cut trees.

Answer:

The ash borer is a density - dependent limiting factor and will start to spread to nearby healthy trees.