Russet buffaloberry (Shepherdia canadensis (L.) Nutt.) is an actinorhizal shrub capable
of forming a symbiotic relationship with the N2-fixing soil actinomycetes Frankia. Actinorhizal
shrubs are important species as they are able to fix an ecologically significant amount of N and
can inhabit disturbed sites with infertile soils. Buffaloberry is commonly found as a dominant
understory species in lodgepole pine (Pinus contorta Douglas ex Louden) communities and is a
common post-fire disturbance species. There is a lack of information regarding buffaloberry‟s
ability to fix atmospheric N2 in Colorado forests. This study used the 15N natural abundance
method in a survey of buffaloberry in north central Colorado to determine the percent of foliar N
that buffaloberry derives from fixation (%Ndfa) and how fixation may be affected by local
environmental factors. The mountain pine beetle (Dendroctonus ponderosae) epidemic is
currently responsible for large losses in lodgepole pine forests. As the overstory canopies of
lodge pole pine communities die off, there is an increase in available light in the understory. I
investigated buffaloberry‟s response to light availability because with more photosynthetic
activity, buffaloberry could potentially have more energy to expend in the energy intensive N2-
fixation process. 59 plots (0.1-ha) were sampled in July 2009 and were distributed among
Larimer, Jackson, and Grand counties in Colorado. Buffaloberry (
15N: −0.63‰, N: 3.48%) had a
15N abundance closer to the atmospheric standard with high foliar %N content as compared to
non-N2-fixing reference species (
15N: −1.29- −4.81‰, N: 1.11-3.20%), indicating biological N2-iii
fixation. I estimate a probable range of foliar %N derived from biological fixation as 60-100%.
Buffaloberry (2.65%) also had higher % foliar N as compared to the reference species (1.50%) in
the autumn, just before leaf abscission. There were no significant correlations between light
availability and N2-fixation by buffaloberry suggesting that N2-fixation in buffaloberry may not
benefit from an increase in light availability
Russet buffaloberry (Shepherdia canadensis (L.) Nutt.) is an actinorhizal shrub capable
of forming a symbiotic relationship with the N2-fixing soil actinomycetes Frankia. Actinorhizal
shrubs are important species as they are able to fix an ecologically significant amount of N and
can inhabit disturbed sites with infertile soils. Buffaloberry is commonly found as a dominant
understory species in lodgepole pine (Pinus contorta Douglas ex Louden) communities and is a
common post-fire disturbance species. There is a lack of information regarding buffaloberry‟s
ability to fix atmospheric N2 in Colorado forests. This study used the 15N natural abundance
method in a survey of buffaloberry in north central Colorado to determine the percent of foliar N
that buffaloberry derives from fixation (%Ndfa) and how fixation may be affected by local
environmental factors. The mountain pine beetle (Dendroctonus ponderosae) epidemic is
currently responsible for large losses in lodgepole pine forests. As the overstory canopies of
lodge pole pine communities die off, there is an increase in available light in the understory. I
investigated buffaloberry‟s response to light availability because with more photosynthetic
activity, buffaloberry could potentially have more energy to expend in the energy intensive N2-
fixation process. 59 plots (0.1-ha) were sampled in July 2009 and were distributed among
Larimer, Jackson, and Grand counties in Colorado. Buffaloberry (
15N: −0.63‰, N: 3.48%) had a
15N abundance closer to the atmospheric standard with high foliar %N content as compared to
non-N2-fixing reference species (
15N: −1.29- −4.81‰, N: 1.11-3.20%), indicating biological N2-iii
fixation. I estimate a probable range of foliar %N derived from biological fixation as 60-100%.
Buffaloberry (2.65%) also had higher % foliar N as compared to the reference species (1.50%) in
the autumn, just before leaf abscission. There were no significant correlations between light
availability and N2-fixation by buffaloberry suggesting that N2-fixation in buffaloberry may not
benefit from an increase in light availability
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