THE PILOT ATTEMPTED A TAKEOFF WITH A PREVAILING TAILWIND ON A GRASS STRIP. HE STATED THAT HE FELT A 'MAJOR MUSH' ABOUT THREE QUARTERS OF THE WAY DOWN THE RUNWAY AND DROPPED THE NOSE TO GAIN AIRSPEED. REALIZING THAT HE WOULD NOT CLEAR OBSTACLES AT THE END OF THE RUNWAY, HE BANKED TO THE LEFT. THE AIRPLANE CONTINUED TO DESCEND DURING THE BANK AND THE LANDING GEAR IMPACTED A TREE. NO MECHANICAL MALFUNCTIONS WERE REPORTED.