The pilot reported that after the initial touchdown, the tailwheel equipped airplane bounced and "floated" as "he held the stick back". The airplane touched down again and began to porpoise, while "he continued to hold the stick back". He further reported that the airplane veered to the left and he attempted to correct with rudder inputs. Subsequently, the airplane exited the left side of the runway, encountered a grassy incline, and became airborne. He reported that he applied full throttle but the airplane did not gain altitude, he then saw trees ahead and elected to land the airplane. As the airplane contacted the ground it rolled forward, coming to rest in a nose down attitude. The pilot reported that there were no pre impact mechanical failures or malfunctions with the airframe or engine that would have precluded normal operation.