Editing Thuja plicata (section)

=== Forest succession ===
Western redcedar appears in all stages of forest succession, but as one of the most shade-tolerant species in the Rocky Mountains and Pacific Northwest it is considered to be a [[climax species]] along with western hemlock.<ref name="Tesky"/> It will readily establish and grow in the shade of other, less shade-tolerant species such as red alder (''[[Alnus rubra]]''), black cottonwood (''[[Populus trichocarpa]]''), or Douglas-fir, and prevent seedlings of those species from establishing themselves in its shade. However, western hemlock and Pacific silver fir are more tolerant of shade.<ref name="Arno" />

A 2010 study found that ''Thuja plicata'' growing in old-growth forests {{convert|300|to|700|m|ft}} above sea level in the [[North Shore Mountains]] of British Columbia have higher growth rates than associated western hemlock and Pacific silver fir when growing underneath a closed canopy. The study also found that western redcedars do not increase their growth rates in response to canopy gap formation that occurs after the death of a mature [[overstory]] tree as much as the two other species. This result indicates that western redcedar may be less reliant on canopy gaps for recruitment than western hemlock and Pacific silver fir.<ref>{{cite journal |last1 = Stan |first1 = Amanda B. |last2 = Daniels |first2 = Lori D. |date = February 2010 |title = Growth releases of three shade-tolerant species following canopy gap formation in old-growth forests |journal = [[Journal of Vegetation Science]] |publisher = [[Wiley-Blackwell]] |volume = 21 |issue = 1 |pages = 74{{ndash}}87 |doi = 10.1111/j.1654-1103.2009.01120.x|bibcode = 2010JVegS..21...74S }}</ref> Western redcedar can also reproduce vegetatively via [[layering]], as well as branch development from fallen branches or entire trees.<ref name="Arno" /><ref name="Silvics"/>

On northeastern Vancouver Island, western redcedar grows along with western hemlock in relatively open-canopied forests with an understory dominated by salal (''[[Gaultheria shallon]]''). Another type of forest characterized by dense stands of western hemlock and Pacific silver fir with sparse understory vegetation also occurs in the area. The two forest types occur in areas with very similar environmental conditions and are separated by sharp boundaries, often less than {{convert|10|m|ft}} wide. Western redcedar [[recruitment (biology)|recruitment]] is nearly absent in the western hemlock-Pacific silver fir forest type, and there is no evidence of a transitional stage between the two types. It has been hypothesized that, once established, these forest types are self-sustaining and are unlikely to change unless a major [[disturbance (ecology)|disturbance]] occurs.<ref>{{cite journal |last1 = Weber |first1 = Adrian |last2 = Kimmins |first2 = J. P. |last3 = Gilbert |first3 = Benjamin |last4 = Lo |first4 = Yueh-Hsin |last5 = Blanco |first5 = Juan A. |date = October 2014 |title = Multiple-pathway succession in coastal ''Tsuga heterophylla'', ''Thuja plicata'', and ''Abies amabilis'' forests on northeastern Vancouver Island, British Columbia |journal = [[Canadian Journal of Forest Research]] |publisher = [[Canadian Science Publishing]] |volume = 44 |issue = 10 |pages = 1145{{ndash}}1155 |doi = 10.1139/cjfr-2014-0060|bibcode = 2014CaJFR..44.1145W |hdl = 2454/19816 |hdl-access = free }}</ref>