COS 70-3 - Restoring native diversity to working lands: Opportunities to expand the conservation portfolio

Tuesday, August 8, 2017: 2:10 PM
B115, Oregon Convention Center
Sarah T. Hamman, Center for Natural Lands Management, Olympia, WA

Working lands have the potential to play an important role in conservation and endangered species recovery by supporting and connecting diverse communities within fragmented landscapes. While most ranch lands in the Pacific Northwest have been grazed for 50-100 years, many still host small native plant populations. The capacity of these landscapes to provide substantial rare species habitat, while maintaining productive fields for cattle is currently unknown. We investigated the effects of grazing (with a spring deferment period) on native plant establishment and the effects of seeding natives on forage grass production at an active ranch in western Washington. We established grazing exclosures within six paddocks and set up three paired 4-m-diameter plots within each grazed/ungrazed replicate. We seeded a mix of 22 native prairie species into the eastern half of each plot in 2013 and again into the southern half of each plot in 2014, creating four separate seeding treatments (unseeded control, seeded 2013, seeded 2014, seeded 2013 & 2014), nested within the two grazing treatments. For three years post-seeding, we tracked establishment of seeded species, seeded species richness, and richness and abundance of forage species within 1m x 1m quadrats in each plot.


We found no significant impact of grazing on seeded species richness. However, seeding treatment was highly significant, with areas seeded in 2014 showing the greatest native species richness. Abundance of sown species varied both by grazing and seeding treatment for many species. Five native species (Armeria maritima, Erigeron speciosus, Koeleria macrantha, Sisyrinchium idahoensis, Solidago missouriensis) did not establish in any treatment combination, suggesting that they cannot compete well in this high nutrient environment. Other species (Lupinus lepidus) responded well to seeding in both the grazed and ungrazed areas. Castilleja levisecta (federally threatened) established well throughout the site with no significant impact of grazing on abundance. There was no treatment effect on forage species richness, with an average of 3-4 forage grass species in all plots (Agrostis sp., Anthoxanthum odoratum, Bromus hordeaceus, and Poa pratensis had highest frequencies). Grazing significantly increased forage grass cover over ungrazed controls, while native seeding had no impact on forage grass cover. These results suggest that high intensity rotational grazing with a spring rest period can promote both forage grasses and a diverse native prairie community and that sowing native prairie species does not detrimentally impact forage availability.