What type of succession would have the greatest number of limiting factors- primary or secondary? why?

i got you i did it ya know what it is just needing to fill this in for a quick task!

the wetland preservation movement began in the u.s. in earnest with the clean water act (cwa) of 1972. although not specifically written to protect wetlands, the cwa is comprised of a series of regulations designed to prevent pollutants from contaminating u.s. waters.