TY - JOUR
T1 - Maintenance of C sinks sustains enhanced C assimilation during long-term exposure to elevated [CO 2] in Mojave Desert shrubs
AU - Aranjuelo, Iker
AU - Ebbets, Allison L.
AU - Evans, R. Dave
AU - Tissue, David T.
AU - Nogués, Salvador
AU - van Gestel, Natasja
AU - Payton, Paxton
AU - Ebbert, Volker
AU - Adams, Williams W.
AU - Nowak, Robert S.
AU - Smith, Stanley D.
N1 - Funding Information:
Acknowledgments Special thanks to Dene Charlet for substantial logistical and data management support. The authors gratefully acknowledge grant support from the Department of Energy’s Terrestrial Carbon Processes Program (DE-FG02-03ER63650, DE-FG02-03ER63651), the NSF Ecosystem Studies Program (DEB-0212812), the Nevada Agricultural Experiment Station, and the Spanish Education and Science Ministry (BFI-2003-09680, PR2008-0247, CGL2009-13079-CO2-02) and Generalitat de Catalunya (BE-11007). Iker Aranjuelo was the recipient of a Juan de la Cierva Research Grant from the Spanish Education and Science Ministry. We also thank the DOE-NTS Operations Office and Bechtel Nevada for site support. Naomi Clark, David Barker, Beth Newingham, and Amrita de Soyza provided assistance with data collection, Lynn Fenstermaker and Eric Knight with site logistical support, and Jim Raymond with sample preparation and processing. Natasja van Gestel acknowledges a scholarship from the Achievement Rewards for College Scientists (ARCS) Foundation, Lubbock Chapter.
PY - 2011/10
Y1 - 2011/10
N2 - During the first few years of elevated atmospheric [CO 2] treatment at the Nevada Desert FACE Facility, photosynthetic downregulation was observed in desert shrubs grown under elevated [CO 2], especially under relatively wet environmental conditions. Nonetheless, those plants maintained increased A sat (photosynthetic performance at saturating light and treatment [CO 2]) under wet conditions, but to a much lesser extent under dry conditions. To determine if plants continued to downregulate during long-term exposure to elevated [CO 2], responses of photosynthesis to elevated [CO 2] were examined in two dominant Mojave Desert shrubs, the evergreen Larreatridentata and the drought-deciduous Ambrosiadumosa, during the eighth full growing season of elevated [CO 2] treatment at the NDFF. A comprehensive suite of physiological processes were collected. Furthermore, we used C labeling of air to assess carbon allocation and partitioning as measures of C sink activity. Results show that elevated [CO 2] enhanced photosynthetic performance and plant water status in Larrea, especially during periods of environmental stress, but not in Ambrosia. δ 13C analyses indicate that Larrea under elevated [CO 2] allocated a greater proportion of newly assimilated C to C sinks than Ambrosia. Maintenance by Larrea of C sinks during the dry season partially explained the reduced [CO 2] effect on leaf carbohydrate content during summer, which in turn lessened carbohydrate build-up and feedback inhibition of photosynthesis. δ 13C results also showed that in a year when plant growth reached the highest rates in 5 years, 4% (Larrea) and 7% (Ambrosia) of C in newly emerging organs were remobilized from C that was assimilated and stored for at least 2 years prior to the current study. Thus, after 8 years of continuous exposure to elevated [CO 2], both desert perennials maintained their photosynthetic capacities under elevated [CO 2]. We conclude that C storage, remobilization, and partitioning influence the responsiveness of these desert shrubs during long-term exposure to elevated [CO 2].
AB - During the first few years of elevated atmospheric [CO 2] treatment at the Nevada Desert FACE Facility, photosynthetic downregulation was observed in desert shrubs grown under elevated [CO 2], especially under relatively wet environmental conditions. Nonetheless, those plants maintained increased A sat (photosynthetic performance at saturating light and treatment [CO 2]) under wet conditions, but to a much lesser extent under dry conditions. To determine if plants continued to downregulate during long-term exposure to elevated [CO 2], responses of photosynthesis to elevated [CO 2] were examined in two dominant Mojave Desert shrubs, the evergreen Larreatridentata and the drought-deciduous Ambrosiadumosa, during the eighth full growing season of elevated [CO 2] treatment at the NDFF. A comprehensive suite of physiological processes were collected. Furthermore, we used C labeling of air to assess carbon allocation and partitioning as measures of C sink activity. Results show that elevated [CO 2] enhanced photosynthetic performance and plant water status in Larrea, especially during periods of environmental stress, but not in Ambrosia. δ 13C analyses indicate that Larrea under elevated [CO 2] allocated a greater proportion of newly assimilated C to C sinks than Ambrosia. Maintenance by Larrea of C sinks during the dry season partially explained the reduced [CO 2] effect on leaf carbohydrate content during summer, which in turn lessened carbohydrate build-up and feedback inhibition of photosynthesis. δ 13C results also showed that in a year when plant growth reached the highest rates in 5 years, 4% (Larrea) and 7% (Ambrosia) of C in newly emerging organs were remobilized from C that was assimilated and stored for at least 2 years prior to the current study. Thus, after 8 years of continuous exposure to elevated [CO 2], both desert perennials maintained their photosynthetic capacities under elevated [CO 2]. We conclude that C storage, remobilization, and partitioning influence the responsiveness of these desert shrubs during long-term exposure to elevated [CO 2].
KW - Ambrosia dumosa
KW - C allocation/partitioning
KW - Free-air CO enrichment (FACE)
KW - Larrea tridentata
KW - Photosynthetic downregulation
UR - http://www.scopus.com/inward/record.url?scp=80052649957&partnerID=8YFLogxK
U2 - 10.1007/s00442-011-1996-y
DO - 10.1007/s00442-011-1996-y
M3 - Article
C2 - 21516309
AN - SCOPUS:80052649957
SN - 0029-8549
VL - 167
SP - 339
EP - 354
JO - Oecologia
JF - Oecologia
IS - 2
ER -