effects of different intensities of thinning on ground beetles (coleoptera : carabidae) in a black spruce plantation
abstract
thinning is a silvicultural practice implemented to maximize harvest
productivity. however, biodiversity conservation is a growing trend, therefore it is
important to understand the short, and long-term effects of thinning on biodiversity.
ground beetles (carabidae) play an important role as bioindicators of overall forest
health. in order for forest managers and policymakers to balance economic growth and
sustainability, we must understand how to implement optimal thinning practices.
ground beetles were sampled in replicated (n = 3) 15-year post-mechanical thinning
plots ((cc): 100% basal area removal, heavy thin (ht): 45%, light thin (lt): 25%), 62-
year-old mature site (controlled (ct)), and an 80-year-old untouched black spruce forest
(reference (ref)). a total of 10234 individuals across 21 species were collected.
species richness was highest in reference (ref), and lowest in clearcut (cc). total
catches did not differ statistically among treatments. heavy thin was found to be within
controlled and light thin ordination. this may indicate that ground beetle biodiversity is
not negatively affected by heavy thinning. it also illustrates that heavy thinning, light
thinning, and controlled intensities share similar community structures. overall, results
conclude that heavy thinning and light thinning show similar recovery patterns, which
could indicate that heavy thinning may not negatively impact the long-term recovery of
ground beetle assemblages unless denoted as a forest specialist (narrow niche).
although ref and ct share similarities in stand age, there are still major differences in
total catches and species composition.