Shipments of tablets rose more than 112 percent in the second quarter to outpace those of netbooks for the first time. Tablet sales are believed to have hit 13.6 million in Q2, up from 6.4 million in the first quarter, says market analysis firm ABI Research.

Netbooks had led the way in the first quarter with estimated sales of 8.4 million units, roughly 2 million more than tablets. Group director for mobile devices Jeff Orr believes this is a trend that will not reverse itself, although he doesn’t see the tablet as a direct replacement for netbooks but rather a change in trends.

The growth in tablet shipments is largely credited to Apple’s iPad 2. 68 percent of all tablets shipped globally in the second quarter were iPad models. But why are so many people opting for tablets over netbooks?

“Media tablets are perceived to be easy to use, compared to the keyboard and mouse interface of a netbook computer. Those who have avoided PCs because they are difficult to use – think the Baby Boomer generation and older – see media tablets as an opportunity to re-engage with Internet access,” said Orr.

ABI Research doesn’t expect netbooks to vanish overnight, however. The cheap notebook alternatives still represent a great value in underdeveloped countries where PC access at home is tougher to come by. Early adopters in the US, Japan, South Korea and Western Europe are expected to continue to drive tablet sales moving forward.

The numbers are pretty incredible when you consider modern media tablets have only been around for less than two years. Apple released the first iPad in April 2010 and sold 3 million units in just 80 days. A plethora of tablets have since been developed running operating systems from Google, BlackBerry and HP although none, even collectively, have come close to the success of Apple’s offering.