George Strait has the most #1 hits at 57 and counting. Nobody else comes close. Conway Twitty actually had the most until 2006 with 55 #1 hits. The Beatles are the musical act with the most songs to reach No. 1 on the Billboard singles chart. Mariah Carey has 18 such #1 hits and Elvis Presley 17.
Primary succession begins on rock formations, such as volcanoes or mountains, or in a place with no organisms or soil. This creates conditions nearer optimum for vascular plant growth; pedogenesis or the formation of soil is the most important process.
There are several expected stages in secondary succession, which are actually very similar to those of primary succession, but one thing is important to keep in mind: for secondary succession to occur, there must already be - you guessed it - dirt!