Species composition and plant diversity of logged-over forest in Sikundur, Gunung Leuser National Park, North Sumatra

Sikundur forest area is located at Gunung Leuser National Park (GLNP), in Aras Napal, Langkat, North Sumatra Province, representing mixture forest of lowland Dipterocarpaceae. Two 0.5 ha permanent plots of 50 x 100 m were established at twenty-two years old logged-over Sikundur Forest and located subjectively according to topography and river bank. This dryland forest was logged for the first cycle in 1978 by forest concession right. This study aimed to identify the species composition and to determine the diversity index of plants after 22 years logged over area. The results showed that significant tribes were Dipterocarpaceae, Euphorbiaceae, and Myrtaceae which are the richest family in two permanent plots. The horizontal structure of forest indicated that the diversity index of Dipterocarpaceae in two plots tended to be centered, showing the high value of diversity index of Dipterocarpaceae family. The present study suggested the periodic activities on natural regeneration, and the measurement of the dynamics stock plant are highly recommended.