Successional development of silviculturally treated and untreated high-latitude Populus tremuloides clearcuts in northern Alberta, Canada

Populus tremuloides Michx. postfire stand dynamics in the northern boreal-cordilleran ecoclimatic region of central Yukon Territory, Canada

“…Oswald and Brown (1990) found 5-year-old POTR stands on well drained sites in the southern Yukon typically produced upper densities of 20,000-23,000 stems/ ha. These values are low compared to southern boreal clearcuts (44,000-225,000 stems/ha in Year 1, Peterson et al, 1989;49,895 stems/ha in Year 5, Strong and Sidhu, 2005), although similar to densities reported for northern Alberta (18,700 stems/ ha, Year 3, Redburn and Strong, 2008). However, some evidence suggests that forest clearcutting and more severe fires (Keyser et al, 2005) tend to stimulate greater POTR suckering rates (Peterson and Peterson, 1992, p. 29).…”

“…This accelerated rate of succession probably occurs due to the early establishment of PIGL rather than just the differential in height growth rates (cf. Redburn and Strong, 2008). Early establish is probably a more critical factor because a similar height growth differential occurs between the species in both the northern and southern boreal (16-18%-SI 50 11.4 m versus 9.6 m, this study; SI 50 -17.6 m versus 14.5 m, LF c ecosite phase, Beckingham et al, 1996, respectively).…”

“…Mixedwood stands (i.e., >25% relative conifer cover, Strong et al, 1990) begin to form about Year 60. In comparison, it is not uncommon for southern and mid boreal POTR stands of a similar age or older to contain few subdominant or co-dominant PIGL (e.g., Corns, 1983;Cumming et al, 2000;Strong and La Roi, 1983;Lieffers et al, 1986;Lee et al, 1995;Redburn and Strong, 2008), especially on well drained sites. This accelerated rate of succession probably occurs due to the early establishment of PIGL rather than just the differential in height growth rates (cf.…”

“…gap dynamic stages) for boreal mixedwood stands, which is an extensive and commercially important forest type in Canada. The latter model remains untested, although Redburn and Strong (2008) identified the potential need to recognize mature P. tremuloides stands that persist for an extended period of time in the absence of latesuccessional P. glauca.…”

Stand-level Attributes of Snowshoe Hare (<em>Lepus americanus</em>) Habitat in a Post-Fire Trembling Aspen (<em>Populus tremuloides</em>) Chronosequence in Central Yukon

“…Most comparative habitat studies have evaluated stand re-establishment during the first 20-30 years after disturbance (e.g., Jacqmain et al 2007), focused on concurrent differences in composition and structure among vegetation types that were not necessarily part of the same chronosequence (e.g., Poole et al 1996), or assessed only selected segments of a chronosequence (e.g., Paragi et al 1997). Unfortunately, changes in Snowshoe Hare abundance in northwestern Canada successional sequences can probably not be extrapolated from studies conducted in southern or eastern boreal forests, except at a very general level, because of regional variability in successional patterns and differences in understory vegetation composition and stand structure (e.g., Chen and Popadiouk 2002;Redburn and Strong 2008;Strong 2009). …”