Forest Forms and Their Distribution of Pinus densiflora Plain Forest in South West Part of Ibaraki Prefecture

Abstract

This study intends to discuss the present condition of Pinus densiflora plain forest in Ina Town, south west part of Ibaraki Pref. By the investigation into physiognomy and species composition, 8 forest form types were divided. 5 types of pure Pinus densiflora forest are differentiated by the vegetation of forest floors influenced by the frequency of underscrubbing for growing melons. Other 3 types are characterized by the condition of their forest crowns. The location of each type is influenced by configuration, underscrubbing and sprinkling insecticides. Underscrubbed forests are much located in north part of investigation area near golfing grounds. There are many forests damaged by Pinus decease in middle part. Most of forests in south part, where many slopes are, have never been undercrubbed for over 15 years. These results gave suggestions to conservation of Pinus densiflora plain forests.