A density management diagram for Scots pine (Pinus sylvestris L.): A tool for assessing the forest's protective effect

Density management diagrams (DMD) are graphical tools used in the design of silvicultural regimes in even-aged forests. They depict the relationship between stand density, average tree size, stand yield and dominant height, based upon relevant ecological and allometric relationships such as the self-thinning rule, the yield-density effect, and site index curves. DMD effectively summarize stand structural descriptors, and are therefore helpful in determining stand characteristics needed to achieve a range of management goals. We constructed a DMD for Scots pine (Pinus sylvestris L.) forests in the western Italian Alps. We used 210 sample plots from a region-wide forest inventory to determine the maximum density line and volume and top height isolines. Site index curves were used to assess the time taken by stands to progress along their development trajectories. The protection provided by Scots pine stands is most effective against rockfall, due to the frequent occurrence of such forests in active source or transition areas. We used the DMD to identify combinations of size and density representing optimal and sub-optimal protection from rockfall. An actual pine stand was used as a case study to illustrate how the diagram can be used to assess current functionality of the forest, forecast its likely development and compare alternative management strategies.