debris vs leaf litter

debris

noun
  • Litter and discarded refuse. 

  • Large rock fragments left by a melting glacier etc. 

  • Rubble, wreckage, scattered remains of something destroyed. 

  • The ruins of a broken-down structure. 

leaf litter

noun
  • Dead plant material, such as fallen leaves, bark, and twigs, that has fallen to the ground and may be used by animals as habitat or for nest-building, eventually decomposing and releasing nutrients into the soil. 

How often have the words debris and leaf litter occurred in a corpus of books? (source: Google Ngram Viewer )