Poor establishment of natural regeneration has been observed ill a number of high elevation clearcuts in the southern portion of the Chilliwack Forest District. These areas were logged, left unburned, and subsequently deemed to be satisfactorily restocked with amabilis fir (Ba), mountain hemlock (Hm), and western hemlock (Hw) seedlings (according to regeneration surveys within 2 years of harvest). However, this regeneration failed to survive in many cases, leaving large NSR areas up to 12 years after harvesting. Questions arise as to what possible factors contribute to poor natural regeneration, and whether areas with high probability of failure can be identified at the pre-harvest stage. To help us understand this problem better, we undertook a pilot study in the Chipmunk Creek drainage to examine patterns of regeneration in relation to ecological factors.
It is clear that advance regeneration makes up the majority of stocking in these areas. Post-logging natural regeneration occurs predominantly on sites with established advance regeneration, or sites with Vaccinium cover. It appears that a disturbed and friable, more biologically active, and calcium-rich humus form does not provide a favourable substrate for successful natural establishment of high elevation tree species, particularly Ba. These species are adapted to regenerating on thick, matted Mor humus forms (Franklin 1964). Such conditions are characteristic of stocked portions in the study area. Yarding disturbance happens less in stocked areas that tend to occur on ridges outside the major concentration of yarding trails. Dense advance regeneration on these sites also contributes to less disturbance of the humus form.
Humus forms associated with NSR areas largely reflects yarding disturbance from harvesting, and the dense cover of fireweed with its abundant annual Iitterfall. This extensive cover of fireweed, a property more typical of slashburned sites, is an unusual feature of these areas. This likely reflects the relatively rich soils and yarding disturbance of surface organic layers (Klinka et al. 1989). While fireweed is generally not a strong competitor with shade-tolerant Ba,it may have a negative effect on germinants and young seedlings which are more susceptible than established regeneration (Fowells 1965).
BC Forest Service - Research Division. 1991. Natural regeneration failure at high elevations in the Chipmunk Creek drainage, Chilliwack Forest District. British Columbia Ministry of Forests, Lands, Natural Resource Operations and Rural Development. Research Memo (FLNRORD). RM59
Topic: FLNRORD Research Program
Keywords: FLNRORD, Research Memo, British Columbia
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