Douglas-fir Provenance Survival and Growth in the British Columbia South Submaritime Seed Planning Zone

Author(s) or contact(s): J. Krakowski and M.U. Stoehr
Source: Research Branch
Subject: Seedling Performance
Series: Extension Note
Other details:  Published 2011. Hardcopy is available from Crown Publications QP or Michael Stoehr
 

Abstract

In southwestern British Columbia, the South Submaritime (ssm) seed planning zone is a geographically and ecologically complex transition zone between the Pacific coast and the interior plateaus. The ssm follows a long, narrow band along the Coast Range (Figure 1), and is characterized by steep, incised valleys. The highly variable climate is strongly influenced by prevailing warm, moist maritime air masses, and towards the east it is characterized by a cool, dry continental climate.

Throughout the ssm, survival rates of the 1.3 million annually planted Douglas-fir seedlings are far below those that are typical or expected for post-harvest plantations: below 80% by age 3, declining to under 70% by age 5 (Ministry seedling survival database; Hunt 202 ), compared to typically over 95% at comparable ages for most operational areas. Douglas-fir is approximately 40% of the harvested volume (biogeoclimatic subzone averages within the ssm range from 36 to 65%) and is the preferred species on most sites. Most of the seedlings currently planted in the ssm originate from seed orchard #181 that produces Class A seed bred to increase yields and maintain adaptability to the planting site throughout the ssm (Forest Genetics Council 2010).

Current seed transfer standards in the ssm are based on the principle that local seed is best adapted to a site and specify that seedlings used for reforestation must be used within 2N, 1S, 2E, no limit west, and 350 m up or down from its origin (Snetsinger 205). However, recent trials suggest these standards could be overly restrictive and may limit performance of planted Douglas-fir (Hunt 203). In 1996, a long-term series of provenance trials (e.p. 120) was established to: (1) describe patterns of genetic variation for Douglas-fir in the ssm; (2) compare the growth performance of ssm seed sources with coastal, interior, and intra-specific hybrids in the ssm; and (3) provide data to refine seed transfer guidelines in the region. This report presents 10-year results and attempts to determine whether current restrictions on seed transfer are aligned with adaptive patterns of Douglas-fir for this region, or whether the standards should be revisited.

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Updated November 10, 2011