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Nitrogen Limits on the Early Growth of Shade-tolerant Regeneration on a Coastal Montane Site

Author(s) or contact(s): R.S. Koppenaal and B.J. Hawkins
Source: Research Branch
Subject: Growth and Yield
Series: Extension Note
Other details:  Published 1996. Hardcopy is available.


Growth of shade-tolerant tree species regenerating on coastal montane forests is often delayed or inconsistent following stand removal (Herring and Etheridge 1976). This may have a long-term impact on the productivity of these sites, upon which the region's future timber supply increasingly relies. Restricted availability of nutrients, particularly nitrogen, may limit growth of shade-tolerant regeneration in high-elevation coastal forests in which low concentrations of foliar nitrogen have been reported (Gessel and Klock 1982; Radwan et al. 1989).

In an earlier study on a coastal montane reforestation site, we reported on 1-year-old planted amabilis fir stock that was chlorotic and had reduced photosynthetic rates compared to its natural counterparts released 4 years earlier (Koppenaal et al. 1995). Those findings prompted this study, in which we compared foliar concentrations of nitrogen (N) and phosphorus (P) in relation to the post-harvest growth of planted and advance regeneration of amabilis fir and western hemlock. The impact of stand removal on seedling microclimate is known to affect photosynthetic rates (Koppenaal et al. 1995) as well as decomposition rates and nutrient availability (Edmonds et al. 1989). In an effort to determine the influence of post-harvest light environment on nutrient status and productivity, we further compared foliar N and P concentrations and growth between clearcut and stand edge microsites.

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Updated April 17, 2007