PARENT SESSION
Contributed Oral Session 12: Arid Lands: Plant Response to Precipitation
Monday, August 8, 8:00 AM - 11:25 AM, Meeting Room 520 B, Level 5, Palais des congrès de Montréal

Fine root production under elevated CO₂ for a Mojave Desert ecosystem.

Nowak, Robert^*,1, Ferguson, Scot ¹, Young, Andrew¹, Aranjuelo, Iker¹, Landmesser, Jacob¹, ¹ University of Nevada, Reno, Reno, NV

ABSTRACT- Elevated atmospheric CO₂ increases photosynthesis and aboveground production in many ecosystems around the world, including a Mojave Desert ecosystem. Although results for belowground production are much less numerous, the enhancement by elevated CO₂ for belowground production can equal or exceed that for aboveground production in some forested ecosystems. Previous results of fine root production at the Nevada Desert FACE Facility did not show significant differences in production or mortality of fine roots for 2 dominant shrubs and for the plant community in the Mojave Desert during the first 2 growing seasons after initiation of the elevated CO₂ treatments. These results were observed in both a very wet (1998) and an 80% of average (1999) year. However, more recent results for 2 near average precipitation years (2003 and 2004) show greater root standing crops under elevated CO₂. Thus, small differences in fine root production and mortality have lead to a greater accumulation of fine roots under elevated CO₂.

Key words: Larrea tridentata, Ambrosia dumosa, minirhizotron, FACE