Alexis Achim

The North American temperate deciduous forests are an important source of hardwoods sought after by the appearance wood products industries. The purpose of this study was to model the relationships between log characteristics and sawn board attributes in sugar maple (Acer saccharum Marsh.) and yellow birch (Betula alleghaniensis Britt.). We harvested sixty-four sugar maple and thirty-two yellow birch trees from two locations in southern Quebec, Canada, which were then processed into 189 sawlogs and 2,236 boards. We developed statistical models linking log characteristics to the volume recovery of the various lumber grades and color specifications according to the National Hardwood Lumber Association rules. In both species, board grades were strongly related to log length, position of the log in the stem, and small-end diameter and decay of the log. Color classes were related to small-end diameter of the log and red heartwood diameter of the log at both ends for sugar maple, and to log length, diameter of the log at the small-end, and red heartwood diameter at the large-end of the log for yellow birch. These models outperformed a log classification used in practice for predicting lumber volume recovery from different log grades.

In the context of global change, a better understanding of the dynamics of wood degradation, and how they relate to tree attributes and climatic conditions, is necessary to improve broad‐scale assessments of the contributions of deadwood to various ecological processes, and ultimately, for the development of adaptive post‐disturbance management strategies. The objective of this meta‐analysis was to review the effects of tree attributes and local climatic conditions on the time since death of coarse woody debris ranging in decomposition states. Results from our meta‐analysis showed that projected warming will likely accelerate wood decomposition and significantly decrease the residence time in decay stages. By promoting such a decrease in residence time, further climate warming is very likely to alter the dynamics of deadwood, which in turn may affect saproxylic biodiversity by decreasing the temporal availability of specific habitats. Moreover, while coarse woody debris has been recognized as a key resource for bioenergy at the global scale, the acceleration of decay‐stages transition dynamics indicates that the temporal window during which dead trees are available as feedstock for value‐added products will shrink. Consequently, future planning and implementation of salvage harvesting will need to occur within a short period following disturbance, especially in warmer regions dominated by hardwood species. Another important contribution of this work was the development of a harmonized classification system that relies on the correspondence between the visual criteria used to characterize deadwood decomposition stages in locally developed systems the literature. This system could be used in future investigations to facilitate direct comparisons between studies. Our literature survey also highlights that most of the information on wood decay dynamics comes from temperate and boreal forests, whereas data from subtropical, equatorial and subarctic forests are scarce. Such data are urgently needed to allow broader‐scale conclusions on global wood degradation dynamics.