B.C. Ministry of Forests Forest Science Program
		Abstract for FRDA Report 215

		Shade Tolerance in Tsuga heterophylla (Western Hemlock) and Abies amabilis (Amabilis Fir): A Bibliography 1970-1993
		Authors or Ministry Contacts: A.K. Mitchell and K.E. Hogg
		Branch: Research
		Subject: Plant Ecology
		Series: FRDA Report
		Other details: Published February, 1994.

Abstract

Concerns about the sustainability of current forestry practices have sparked interest in silvicultural systems that provide alternatives to clearcutting and employ various levels of overstory removal. Successful regeneration of these sites will depend on whether natural or planted seedlings can survive and grow in a variety of light environments. Shade tolerant species are good potential candidates for the regeneration of such sites, since they may be more productive in shady environments than pioneer species that are adapted to growing under exposed conditions. This collection of references provides a basis for new studies of shade tolerance and the impacts of varying levels of exposure on the structure and function of shade tolerant species.

Shade tolerance has been observed for over a century and, despite frequent references to it in the literature, the phenomenon is not well-defined. In part, the confusion arises from the assumption that shade tolerant species are shade-requiring, and therefore intolerant of exposure. In addition, it is assumed that light is the driving factor in the development of shade tolerance, and that the degree of shade tolerance exhibited by different species is constant over time and space. Studies of the morphological and physiological mechanisms of shade tolerance may help to clarify these and other issues.

Shade tolerant species may also play an important role in the dynamics of forest ecosystems. Both genetic adaptation and environmental acclimation can influence responses to shade. By studying the plasticity of individual species, we may be able to estimate whether shade tolerant plants are at risk in disturbed or exposed environments. Recommendations may then be made to help ensure the genetic and ecological conservation of a variety of woody and herbaceous plants.

This bibliography contains more than 200 references published between 1970 and 1993, and includes seminal articles found in the older literature. It is divided into five sections, each of which is subdivided into subject areas. Keywords are included where possible. More than 60 references pertaining to shade tolerance in conifers and other plants and to mechanisms of shade tolerance are included. Emphasis is placed on the physiology and ecology of shade tolerant montane conifers, Abies amabilis and Tsuga heterophylla. This bibliography will provide readers with a ready reference to two decades of research, and will help to provide a context for new investigations of alternative silviculture systems, shade tolerance, and forest ecosystem dynamics.

Download FRR215 (266K)
	To view this document you need the Adobe Acrobat Reader, available for free at the Adobe Web Site.