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ARS Home » Pacific West Area » Burns, Oregon » Range and Meadow Forage Management Research » Research » Publications at this Location » Publication #334953
Title: Legacy microsite effect on the survival of bitterbrush outplantings after prescribed fire: capitalizing on spatial variability to improve restoration

Author
item Davies, Kirk
item Boyd, Chad
item Bates, Jonathan - Jon
item Gearhart, Amanda

Submitted to: Restoration Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/11/2017
Publication Date: 9/28/2017
Citation: Davies, K.W., Boyd, C.S., Bates, J.D., Gearhart, A.L. 2017. Legacy microsite effect on the survival of bitterbrush outplantings after prescribed fire: capitalizing on spatial variability to improve restoration. Restoration Ecology. 25(5):723-730. https://doi.org/10.1111/rec.12506.
DOI: https://doi.org/10.1111/rec.12506

Interpretive Summary: Restoration of bitterbrush in rangelands is hampered by low Restoration of bitterbrush in rangelands is hampered by low success rates. Planting seedlings improves success; however, it is expensive and labor intensive. There is a needed to evaluate bitterbrush success in different post-fire microsites to improve restoration efficiency. We investigated planting bitterbrush seedlings in western juniper encroached shrublands after prescribed fire was used to control trees. Bitterbrush seedlings were planted in two microsites: 1) under (subcanopy) and 2) between (interspace) former juniper canopies. Bitterbrush survival was greater than 50% in the subcanopy, but only 5% in the interspace microsite by the third growing season. Growth of bitterbrush was also greater in the subcanopy compared to the interspace, potentially due to markedly less perennial vegetation in this microsite. These results suggest that restoration success will vary by microsites within a burned landscape and that this variability can be used to improve restoration efficiency.

Technical Abstract: Restoration of shrubs in arid and semi-arid rangelands is hampered by low success rates. Planting shrub seedlings is a method used to improve success in these rangelands; however, it is expensive and labor intensive. The efficiency of shrub restoration could be improved by identifying microsites where shrub survival is greater. Bitterbrush (Purshia tridentata Pursh DC) is an important shrub to wildlife that has declined because of conifer encroachment, excessive defoliation, wildfires, and low recruitment. We investigated planting bitterbrush seedlings in western juniper (Juniperus occidentalis ssp. occidentalis Hook) encroached shrublands after prescribed fire was used to control trees. Bitterbrush seedlings were planted in under (subcanopy) and between (interspace)former juniper canopies at five blocks and evaluated for three growing seasons. Bitterbrush survival was greater than 50% in the subcanopy, but only 5% in the interspace microsite by the third growing season. Growth of bitterbrush was also greater in the subcanopy compared to the interspace, potentially due to markedly less perennial vegetation in this microsite. Exotic annual grasses and annual forbs became prevalent in the subcanopy in the second and third growing season suggesting that soil resource availability was greater in this microsite. These results suggest that restoration success will vary by specific locations within a burned landscape and that this variability can be used to improve restoration efficiency. In this situation, bitterbrush restoration can be improved by planting seedlings in former subcanopy compared to interspace microsites.