According to the pilot, after about 2.5 hours of soaring in the Burkhart Grob Flugzeugbau G-103 glider, he returned to the airport and entered the traffic pattern at 1,200 feet with a "small amount" of spoilers deployed. He turned onto the downwind leg at 800 feet, and used "more spoilers" to descend to 500 feet. He then turned onto the base leg, and at 300 feet and 60 knots airspeed, he turned onto the final leg of the approach and aligned the glider with the runway. He immediately felt the glider had entered rising air, so he performed a full slip with the spoilers deployed; however, the glider did not descend significantly. Due to the proximity of the surrounding trees to the glider, the pilot felt that he could not successfully perform an s-turn or a 360-degree turn to lose energy, and instead felt that he should wait for the glider to exit the rising air mass. The glider continued to descend moderately until about mid-field, when it descended rapidly. The glider touched down about 3/4 down the runway and bounced back into the air. Due to a pile of debris at the end of the runway, the pilot elected to close the spoilers, overfly the debris, and land the glider in the treetops ahead at a slow speed. Before he could accomplish his plan, a crosswind blew the glider towards a tree. The left wing contacted the tree, and the glider subsequently impacted the ground.