Event Title

Aquatic Effects of a Terrestrial Invader: A 35-year Natural Experiment Shows Russian Olive Alters Basal Resources and Community Metabolism of a Desert Spring Stream

Presenter Information

Madeleine M. Mineau

Location

ECC 307/309

Event Website

https://water.usu.edu/

Start Date

3-31-2008 4:00 PM

End Date

3-31-2008 4:15 PM

Description

Invasive species can have ecosystem effects that span aquatic-terrestrial boundaries. We investigated the effects of an invasive riparian tree, Russian olive (Eleagnus angustifolia), on the ecosystem function of a desert spring stream, Deep Creek, Idaho. Reaches of Deep Creek were studied in the early 1970s as a representative desert stream for the International Biological Program (IBP). The results of that study revealed that Deep Creek was an autotrophic (with primary production within the system meeting the energy demands for that community) stream which was exceptional because until then all streams were thought to be heterotrophic (relying on external terrestrial energy inputs to meet the energy demand in the system). One of the IBP study reaches has since been invaded by Russian olive, setting the stage for a unique before-after-invasion-control comparison. We repeated measures of community metabolism (which assesses primary production (P) and respiration (R)), allochthonous (leaf litter) inputs and standing stocks of aquatic primary producers in invaded and control reaches. The ratio of gross primary production to respiration (P/R) at the control site and was similar to estimates from 1971 and 1972 in the summer and fall. At the invaded site P/R only decreased slightly during the summer but decreased from 1.37 to 0.47 in the fall, a change that appears to be driven by both decreased photosynthesis and by increased respiration. This change in trophic status may be associated with the more than 10-fold increase in allochthonous input we observed at the invaded site during the fall. However, standing stock of aquatic primary producers showed no evidence of having been affected by the presence of Russian olive. We are constructing an annual carbon budget and quantitative food web to further assess the effects of this invasion on organisms and energy flows in this system. The progress of this and other invasive riparian tree species is rapid and widespread in the great basin therefore the responses observed at Deep Creek due to its altered riparian community will be applicable to many streams experiencing similar changes in this region.

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Mar 31st, 4:00 PM Mar 31st, 4:15 PM

Aquatic Effects of a Terrestrial Invader: A 35-year Natural Experiment Shows Russian Olive Alters Basal Resources and Community Metabolism of a Desert Spring Stream

ECC 307/309

Invasive species can have ecosystem effects that span aquatic-terrestrial boundaries. We investigated the effects of an invasive riparian tree, Russian olive (Eleagnus angustifolia), on the ecosystem function of a desert spring stream, Deep Creek, Idaho. Reaches of Deep Creek were studied in the early 1970s as a representative desert stream for the International Biological Program (IBP). The results of that study revealed that Deep Creek was an autotrophic (with primary production within the system meeting the energy demands for that community) stream which was exceptional because until then all streams were thought to be heterotrophic (relying on external terrestrial energy inputs to meet the energy demand in the system). One of the IBP study reaches has since been invaded by Russian olive, setting the stage for a unique before-after-invasion-control comparison. We repeated measures of community metabolism (which assesses primary production (P) and respiration (R)), allochthonous (leaf litter) inputs and standing stocks of aquatic primary producers in invaded and control reaches. The ratio of gross primary production to respiration (P/R) at the control site and was similar to estimates from 1971 and 1972 in the summer and fall. At the invaded site P/R only decreased slightly during the summer but decreased from 1.37 to 0.47 in the fall, a change that appears to be driven by both decreased photosynthesis and by increased respiration. This change in trophic status may be associated with the more than 10-fold increase in allochthonous input we observed at the invaded site during the fall. However, standing stock of aquatic primary producers showed no evidence of having been affected by the presence of Russian olive. We are constructing an annual carbon budget and quantitative food web to further assess the effects of this invasion on organisms and energy flows in this system. The progress of this and other invasive riparian tree species is rapid and widespread in the great basin therefore the responses observed at Deep Creek due to its altered riparian community will be applicable to many streams experiencing similar changes in this region.

https://digitalcommons.usu.edu/runoff/2008/AllAbstracts/20