Answer:
True.
Step-by-step explanation:
When independent clauses are joined incorrectly (with improper punctuation or conjunction), we have what is called a run-on sentence. An independent clause is a group of words that can stay alone as a sentence, which means it offers information that makes sense without the help of another sentence.
A sentence fragment is basically an incomplete sentence. That means it is a phrase that is missing a key element, such as a verb or a subject, or a phrase that is dependent on a main clause but has been detached from it through wrong punctuation.
The sentence "After falling to the warm, damp forest floor, plants decay and release nutrients" is complete, and the punctuation is used appropriately. It might look confusing at first since the main clause came after the subordinate one. If we invert the clauses, we'll see there is no problem with the sentence - note that a comma will disappear now that the main clause comes first:
Plants decay and release nutrients after falling to the warm, damp forest floor.