Acid rain reduces the pH of green plants. Reduced pH changes the chemical make-up of the plants. Chlorophyll production is diminished, and the plant's roots become less efficient at absorbing nutrients from the soil. Nitrous oxide and suffer dioxide deposits create a hardened covering around the roots and stems, making the plant's absorption of both sunlight and nutrients less effective over time. In addition, bees and other insects are repelled by acid deposits. Plants exposed to acid rain are often not effectively pollinated. This can lead to extinction and can disrupt entire ecosystems.