Combine the given two facts to write a concluding fact. Note that there should be some parts of the first and second facts that are not mentioned in this conclusion fact. Your combined fact should be the result of a chain between the two facts. Chains form when two facts connect together to produce a concluding fact. An example of a chain is: "pesticides cause pollution" (fact1) + "pollution can harm animals" (fact2) → "pesticides can harm animals" (conclusion fact). Parts of the concluding fact overlap with the first and the second fact. To construct such a  concluding fact, a useful way is to borrow the subject from one fact and the ending conclusions from another fact.

Example Input: Fact 1: soil is formed by weathering. 
Fact 2: Soils are formed by breakdown of rock.
Example Output: Weathering is the breakdown of rock.

Example Input: Fact 1: plant requires seed dispersal for reproduction. 
Fact 2: Many plants depend on birds for pollination and seed dispersal.
Example Output: plants are pollinated by birds.

Example Input: Fact 1: global warming is when worldwide temperature increases. 
Fact 2: Ozone depletion causes global warming.
Example Output:
Ozone depletion causes worldwide temperature increases.