Since the Shook Mountain Resort Airport was new to the pilot, he called the airport to get further information. He stated that the person who answered reported it was a nice day and the wind sock had blown down. During arrival, he approached from the northeast. He stated that before landing, the runway looked to be a beautiful 4000 ft plus strip, but during the landing, he noticed a fence across what he thought was near the middle of the runway. By this time, there was insufficient room to stop or go around without hitting the fence. The pilot noted that the sectional chart showed the runway was 2500 ft long, but his flight guide indicated it was 3150 ft long. An investigation revealed that years earlier, the runway had been nearly 4000 ft long. The last portion of the runway was on a farmer's land and had been converted to other purposes. The closed portion had been X-ed and piles of shrubs had been placed on it. The open portion was 2550 ft long. The pilot did not circle or enter a normal pattern before landing.