Nursery Seedlings

 

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

From 2011 to 2017 the Bulkley Valley Research Centre’s Whitebark Pine Ecosystem Restoration Project produced and planted 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 over 2 years to produce a seedling ready for outplanting.  In 2019-20 we began the process of producing our third and largest-yet batch of seedlings. 

Seed Stratification

The first step in the process of growing seedlings involves stratifying the seeds to prepare them for germination. Whitebark pine seeds require both a lengthy warm, moist stratification and a lengthy cold, moist stratification period in order to break dormancy.  A 2017 experiment done by Dave Kolotelo and his team at the BC Tree Seed Centre led to the following recommendations:

  • 3-day running water soak (in bath with bubble aerator)
  • sterilize seeds in 3% H202 for 3-4 hours
  • 8 week warm stratification (mesh bags buried in sterilized moist sand, 20o – 21oC)   
  • 16 week cold stratification (mesh bags buried in sterilized moist sand, 2oC),
  • monitor seeds regularly for fungal contamination (repeat H202 soak)
  • monitor seeds for early germinants. These can be dibbled into prepared nursery trays, preferably when radicle < 1 mm in length
  • nicking the seed coat at the pointed end of the seed with a razor blade after stratification assists germination and helps to identify and cull non-viable seeds (their endosperm will not be firm and white)

In 2011-12 and 2014-15, BVRC stratified its own seeds in-house because no commercial nurseries were prepared to undertake this labour-intensive procedure.  In 2019-20 we were pleased to contract the stratification work to the Split Rock Environmental native plant nursery in Lillooet, BC and Sylvan Vale Nursery in Black Creek, BC. 

 

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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

 

Nursery Seedling Production

In April 2012, February 2015, and March 2020 stratified seeds were sown in styroblock containers at Woodmere Nursery in Telkwa, BC. The seedlings remain at Woodmere for approximately 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.  

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.  In 2019/20 we stratified 26,700 seeds with 25,000 seeds intended for planting in several BC Provincial Parks and 1700 seeds intended for rust resistance screening. We are hopeful that improved seed maturation, cleaning and stratification techniques will translate into even better seed-to-seedling success rates with our third batch of seedlings.

 

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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 and tree improvement centres and private nurseries in BC and Alberta are helping to refine the techniques originally developed in the United States to improve seed handling and nursery growing regimes for our northern seedlots.

Many thanks to Joe Wong and former staff at Woodmere Nursery for many years of support in growing our first two batches of seedlings (2011 - 2017), and to Darren MacDonald and the new team at Woodmere for continuing this important work.