Nursery Seedlings

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BVRC/PICS summer intern Andrew Sheriff with whitebark germinants at Woodmere Nursery, May 2012

From 2011 to 2018 the Bulkley Valley Research Centre’s Whitebark Pine Restoration Project produced 7200 nursery-grown whitebark pine seedlings from seeds collected in the Skeena Region from parent trees showing resistance to white pine blister rust. Because whitebark pine has complicated seed germination requirements and grows slowly, it takes 2-3 years to produce a seedling ready for outplanting. 

In 2011/12 and 2014/15 we stratified 26,000 seeds from 44 seedlots using procedures adapted from Don Pigott (Yellowpoint Propagation), Linda Tackaberry (UNBC), Vicky Berger and Dave Kolotelo (FLNRO Tree Improvement Branch and Tree Seed Centre).  This is a very fussy, labour-intensive process.

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Seed Stratification

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Seed Stratification Winter 2012 H202 Soak

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Woodmere Nursery May 2012 Poor emergence Jonas Creek seed

The seeds received 1 month warm stratification followed by 12 - 20 weeks cold stratification and were rinsed and/or soaked in H202 at 1-2 week intervals to prevent moulding.  After stratification, the tip of each seed was nicked with a razor blade to improve germination – this laborious procedure also allows decayed seeds to be identified and discarded.  In April 2012 and February 2015, the seeds were sown in styroblock containers at Woodmere Nursery. The seedlings remain at Woodmere Nursery for 2 years until they are large enough for outplanting.

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Woodmere Nursery May 2012 Good emergence Kidprice seed

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Woodmere Nursery May 2012

Germination rates of good quality seeds from stands located south of Houston (Kidprice Lake, Smoke Mountain, Sibolas) have consistently exceeded 50%, whereas germination rates of small, poor quality seeds from the Smithers area (Hudson Bay Mtn, Telkwa Mtns, Babine Mtns) have been much lower.  Germination rates from our 2013 seed collection exceeded those from seeds collected in 2011.  This was due partly to more favorable weather conditions for cone maturation in 2013, and partly to 20 weeks rather than 12 weeks of cold stratification.  New results from the BC Tree Seed Centre suggest (1) a 3-day running water soak, (2) H2O2 treatment, (3) 56 days of warm stratification, and (4) 112 days of cold stratification in a sand medium. Work in Alberta also indicates that northern whitebark pine seedlots will greatly benefit from an extended period of warm stratification that allows underdeveloped embryos to mature. 

From 6900 seeds stratified in 2011/12, we successfully grew 817 seedlings that were out-planted in 2014.  In 2014/15 we stratified 19,000 seeds and outplanted 6400 locally grown seedlings in 2017.

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Whitebark pine seedlings ready for outplanting at Woodmere Nursery, May 2017.

Lessons to date indicate that collecting small, immature cones and seeds from the northern limits of whitebark pine’s range will result in low success rates in the nursery.  For gene conservation purposes of this endangered tree species, we do, however, need to collect seedlots from a range of locations and elevations, and will need to accept poorer results than for commercial tree species.  Fortunately, new research at provincial tree seed centres in BC and Alberta are helping to refine the techniques originally developed further south to improve seed handling and nursery growing regimes for our northern seedlots.

Many thanks to Joe Wong and the staff at Woodmere Nursery for growing these seedlings and to Dave Kolotelo and the staff at the BC Tree Seed Centre for technical assistance.