During a local solo flight, the student pilot planned to land the glider on runway 23. On the downwind leg of the airport traffic pattern the glider was “high at the key”. Abeam the end of the runway he was still “a little high” so he elected to deploy the wing spoilers. Then while turning on to the base leg of the traffic pattern he was still high, so he decided to crab into the wind and slip the glider. While on base prior to turning final he noticed that the “wind had picked up and it slowed the glider down.” Turning final he noticed “it was going to be close” and had contemplated changing to runway 25; however, he thought the glider would make it to runway 23. The glider impacted a tree about 25 feet above ground level with the left wing and came to rest short of the runway. Postaccident examination of the glider revealed that the left wing and fuselage were substantially damaged.