Can Retention Harvest Maintain Natural Structural
Complexity? A Comparison of Post-Harvest and
Post-Fire Residual Patches in Boreal Forest.
Louiza Moussaoui, Nicole J. Fenton, Alain Leduc, Yves Bergeron.
Variable retention harvest promotes biodiversity conservation in managed boreal forests by
ensuring forest continuity and structural complexity. However, do post-harvest and post-fire patches
maintain the same structural complexity? This study compares post-harvest and post-fire residual
patches and proposes retention modalities that can maintain the same structural complexity as in
natural forests, here considering both continuous forest stands and post-fire residual patches. In boreal
black spruce forests, 41 post-fire residual patches, and 45 post-harvest retention patches of varying
size and ages (exposure time to disturbed matrix) and 37 continuous forest stands were classified
into six diameter structure types. Types 1 (inverted-J) and 2 (trunked-unimodal) characterized stands
dominated by small trees. The abundance of small trees decreased and the abundance of large
trees increased from Type 1 to Type 6. Type 6 had the most irregular structure with a wide range of
diameters. This study indicates that: (1) old post-harvest residual retentions maintained the range of
structural complexity found in natural stands; (2) Types 1 and 2 were generally associated with young
post-fire patches and post-harvest retention clumps; (3) the structure of residual patches containing
only small trees was usually younger (in terms of the age of the original forest from which residual
patches were formed) than those with larger trees. To avoid the risk of simplifying the structure,
retention patches should be intentionally oriented towards Types 3–6, dominated by intermediate
and large trees.