TITLE:
Stand age structural dynamics of conifer, mixedwood, and hardwood stands in the boreal forest of central Canada
AUTHORS:
Jennifer M. Fricker, Jian R. Wang, H. Y. H. Chen, Peter N. Duinker
KEYWORDS:
Time Since Fire (TSF); Stand Development; Old-Growth Forest; Conifers; Hardwoods; Mixedwood; Boreal Forests
JOURNAL NAME:
Open Journal of Ecology,
Vol.3 No.3,
July
15,
2013
ABSTRACT:
To study the effects of stand development
and overstory composition on stand age structure, we sampled 32 stands
representing conifer, mixedwood, and hardwood stand types, ranging in ages from
72 to 201 years on upland mesic sites in northwestern Ontario. We defined the
stages of stand development as: stem exclusion/canopy transition, canopy
transition, canopy transition/gap dynamics,
and gap dynamics. Stand age structure of conifer stands changed from bimodal,
bimodal, reverse-J, and bimodal, respectively, through the stages of stand development.
Mixedwood and hardwood stands revealed similar trends, with the exception of missing
the canopy transition/gap dynamic stage in
mixedwoods. Canopy transition/gap dynamic stage in hardwoods showed a
weaker reverse-J distribution than their conifer counterparts. The results suggest
that forest management activities such as partial and selection harvesting and
seed-tree systems may diversify standard landscape-level age structures and
benefit wildlife, hasten the onset of old-growth, and create desired stand age
structures. We also recommend that the determination of old-growth using the following
criteria in the boreal forest: 1) canopy breakdown
of pioneering cohort is complete and stand is dominated by later successional
tree species, and 2) stand age structure is bimodal, with dominating canopy
trees that fall within a relatively narrow
range of age and height classes and a significant amount of understory regeneration.