Skip to main page content

Big sagebrush growth and carbon isotope responses to climate are modified by topography and harvester ant mounds

My Session Status

Part of:
12:30, Wednesday 29 Jun 2022 (1 hour 30 minutes)
Coeur des Sciences, Sherbrooke Building, UQAM - Salle polyvalente (SH-4800)   Virtual session
This session is in the past.

Click below to enter the virtual room.

Enter virtual room

Are you a speaker or staff?

Access for speakers and staff
Symposium 3

Here we report shrub-ring isotope records for big sagebrush (Artemisia tridentata) from below the “reverse treeline” in central Utah, USA. Despite sectorial growth, ring-widths of mature plants (age range 9 to 54 years) cross-dated well. Plants were sampled in upland locations (controls) as well as adjacent to mounds (circular patches of denuded soil approximately five m diameter) made by harvester ants (Pogonomyrmex occidentalis) and in swale locations where water drains during monsoon rainfall. For each of the three location types ring-width index (RWI) and carbon isotope discrimination (Δ13C) chronologies were constructed for the years 1989-2018. For each of the three habitats ring-width indices were significantly correlated with summed Spring and monsoon period precipitation (r ≥ 0.42). Δ13C chronologies were strongly influenced by precipitation summed across the previous November to June (r ≥ 0.80) as well as May to July average vapor pressure deficit (r ≤ -0.75). Unlike ring-widths, Δ13C was not related to summer monsoon precipitation (0.09 ≥ r ≥-0.04), indicating water used to support leaf gas exchange was from deep soil layers. Basal area increment of plants that grew adjacent to ant mounds or in swales grew 35% and 61% faster than controls, respectively. Likewise, the 30-year trend in intrinsic water use efficiency (iWUE) was 0.98 µmol CO2 mol H2O−1 yr−1 for controls, but only 0.65 and .60 for and mound or swale sagebrush, respectively. Differences in iWUE between controls and mound or swale sagebrush were greatest during the driest years, indicative of ant mounds and swales providing summer moisture subsidies to sagebrush when the ongoing Megadrought across the Southwestern US has been most severe.

My Session Status

Send Feedback

Session detail
Allows attendees to send short textual feedback to the organizer for a session. This is only sent to the organizer and not the speakers.
To respect data privacy rules, this option only displays profiles of attendees who have chosen to share their profile information publicly.

Changes here will affect all session detail pages