Age structure and history of stand types of Pinus sylvestris in Abernethy Forest, Scotland

Abstract

Abernethy Forest comprises the largest area of semi-natural (native) pinewood in Scotland. It also has plantations of various ages. This study describes the sizes and ages of Scots pines (Pinus sylvestris L.) in the main stand types as a basis for future management, which aims to develop woodland of natural character. The interpretation of the current age structure is based on historical records of past management [commercial forestry, crofting (subsistence farming) and red deer Cervus elaphus (L.) management for sport shooting] and fires. The main plantation stand types had trees with median ages ranging from 20 to 67 years. The main stand types of semi-natural pinewood (old open, high crown and bog woodland) had median ages of 149, 120 and 126 years and peaks at 121–130, 111–120 and 141–150 years, respectively. The establishment of trees in these stands largely coincided with the removal of crofters and their livestock in 1869, when the upper forest was designated as a sporting estate. This probably allowed a pulse of tree regeneration, before the growing red deer population and pasturing of sheep and cattle inhibited further regeneration through much of the twentieth century. After 1988, sheep and cattle were removed and the number of red deer was reduced, allowing previously suppressed pine saplings to grow. Exploitation for timber over the past 400 years has meant that few trees are over 200 years old. This contrasts with natural Scots pine forests in Fennoscandia where trees typically attain this age, and where the structure is often determined by fire.