Developing reintroduction techniques for Lomatium cookii

Executive Summary

Lomatium cookii is endemic to southwestern Oregon with only two known populations in Jackson and Josephine Counties. The species is listed as endangered by the State of Oregon and the U.S. Fish and Wildlife Service, and the Draft Recovery Plan for the species identifies population augmentation and reintroduction as necessary steps toward recovery. Reintroduction through direct seeding and transplanting in experimental plots occurred in the Illinois and Rouge River Valleys at French Flat, Agate Desert, and Reeve’s Creek in 2006, 2007, and 2009. This report updates the status of these reintroduction plots, which we annually monitored at French Flat (South and North) as of 2016, at Agate Desert as of 2011, and at Reeve’s Creek as of 2014.

French Flat South

• As of 2016, 230 seedlings established from seed. Seeds sown in 2006 had an establishment rate of 4.1% for local French Flat seed and 0.3% for Agate Desert seed by 2016, a significant difference in establishment by seed source (p<0.001). Seeds sown in 2007 had an establishment rate of 11.1% by 2016. Reproductive plants made up over 25% (59/230) of the seeded population in 2016.
• As of 2016, 67 plants remained from the initial 347 transplants, a 19% survival rate. We did not find a significant difference among cultivation histories (p=0.093) for French Flat South in 2016. Recruitment was documented among the 117 reproductive plants produced by the transplanted population from 2008-16.

French Flat North

• As of 2016, 409 seedlings established from seed. Seeds sown in 2009 had an establishment rate of 37.9% from litter-removed plots and 20.6% from control plots by 2016, a significant difference in establishment by litter removal (p=0.001).

Agate Desert

• As of 2011, 37 seedlings established from seed. Seeds sown in 2007 had an establishment rate of 2.5% by 2016. Reproductive plants made up over 35% (13/37) of the seeded population in 2011.
• As of 2011, 17 plants remained from the initial 347 transplants, a 5% survival rate. We did not find a significant difference among cultivation histories (p=0.503) for Agate Desert in 2011. Recruitment was documented among the 20 reproductive plants produced by the transplanted population from 2008-11.

Reeve’s Creek

• As of 2014, 147 seedlings established from seed. Seeds sown in 2009 had an establishment rate of 14.8% for local Reeve’s Creek seed, 7.5% for French Flat seed, 8.6% for litter-removed plots, 10.3% for control plots, 11.1% for open-canopy plots, and 7.5% for closed-canopy plots, although none of the treatments, including interactions, were significantly different.

In general, direct seeding and transplanting were effective means of augmenting populations of Lomatium cookii. Augmented populations had growth and survival rates similar to wild populations within four years for transplants and six years for seed with the exception of lower initial-year mortality in reintroduced than in wild populations. While transplants may take less time to reintroduce than seed, seeding can be a much more cost-effective method. Local seed seems to prefer native habitat, although previous studies on L. cookii have found otherwise, and there is evidence that leaf litter may inhibit seedling emergence and establishment. We recommend continuing the propagation of new seed as well as site selection for future reintroductions using a combination of transplants in native soils and local seed.