Final answer:
In soils with extreme pH levels, the root-associated fungi known as mycorrhizae cannot survive. Mycorrhizae are essential for plant nutrient uptake and are especially important for the productivity of farmland, with up to 90% of trees and grasses depending on this symbiotic relationship. Extreme pH values, either highly acidic or alkaline, can disrupt this relationship and negatively affect plant growth.
Step-by-step explanation:
In soils with extreme pH, the root associated fungi known as mycorrhizae cannot survive. Mycorrhizae are the symbiotic associations between fungi and plant roots. These fungi help in the uptake of minerals from the soil, which is essential for the growth and survival of plants. However, in soils with extreme pH, such as very acidic or very alkaline soils, the mycorrhizal fungi cannot survive.
For example, in acid soils with a pH below 5.55, acidophilic microorganisms can adapt and survive, but mycorrhizae cannot. Similarly, in waterlogged soils with low oxygen levels, plants with mycorrhizal associations may struggle to survive.