Which one among the following statements is not correct?

• A

  More than $50 \%$ of world's animal species are found in tropical rain forest
• B

  One-third of land surface is arid or semi-arid
• C

  Floating plants (phytoplankton) in the ocean produce over half the world's oxygen
• Correct answer
  D

  World's important deserts are located across the equator

Hence, the correct answer is option: 'D'.