THE PILOT REPORTED HE WAS ATTEMPTING TO TAKEOFF WITH HIS FLOAT EQUIPPED AIRPLANE FROM A SLOUGH. HE SAID HE DID NOT USE THE FULL LENGTH OF THE AREA AVAILABLE FOR TAKEOFF. ALSO, HE SAID THAT UPON REACHING THE END OF THE SLOUGH, THE AIRPLANE'S ALTITUDE WAS INSUFFICIENT TO CLEAR THE TREES WHICH LINED THE BANK. THE AIRPLANE COLLIDED WITH THE TREES AND SUSTAINED SUBSTANTIAL DAMAGE.