Spatial structure of timber harvested according to structure-based forest management

• We put forward a continuous cover forestry management model—BFM.
• SBFM pays high attention to the spatial structure and health of forest.
• Improving spatial structure of forest by single-tree selection is the key issue of SBFM.
• The spatial structure of timber harvested according to SBFM is quite diverse.
• The spatial structure of harvest wood is helpful to quick selection of thinning.

The selection of harvested trees is key to the success of near-natural forest management, yet few people have focused on the structural characteristics of harvested woods. Here, we examined the structural characteristics of harvested trees in Korean pine-broadleaf forest and pine–oak mixed forest in China using bivariate distributions of spatial structure parameters and the distribution of diameter classes. The stands were strictly managed according to the principles of structure-based forest management. We found that trees cut from both types of forest had wide structural diversity: they were widely distributed across vertical levels of the forest stand, including dominant, medium, and suppressed trees. Most trees from the Korean pine-broadleaf forest were of small–medium size and were highly mixed and randomly distributed in relation to their neighbors. In contrast, trees cut from pine–oak mixed forest tended to be clumped in relation to their neighbors. The majority were dominant trees surrounded by other species or distributed randomly, and were generally evenly distributed across stem diameters. In both forest types, most individuals were highly mixed and distributed in a random pattern, and trees in a clumped or regular distribution were more likely to be retained. In addition, the distribution of diameter at breast height size classes retained a reversed-J-shaped curve before and after management. These structural features closely matched the prior conditions of both forests and the purpose of management. They may also be conducive to quick selection of trees cut from the same forest type in the future, and can aid the recognition and interpretation of forest structure.