Publication Date:
2016-08-03
Description:
From 1890 to 2015, anthropogenic carbon dioxide emissions have increased atmospheric CO 2 concentrations from 270 mol mol −1 to 400 mol mol −1 . The effect of increased carbon emissions on plant growth and reproduction has been the subject of study of Free Air CO 2 Enrichment (FACE) experiments. These experiments have found a) an increase in internal CO 2 partial pressure (c i ) alongside acclimation of photosynthetic capacity, b) variable decreases in stomatal conductance, and c) that increases in yield do not increase commensurate with CO 2 concentrations. Our data set, which includes a 115 year long selection of grasses collected in New Mexico since 1892 is consistent with an increased c i as a response to historical CO 2 increase in the atmosphere; with invasive species showing the largest increase. Comparison with Palmer Drought Sensitivity index (PDSI) for New Mexico indicates a moderate correlation with Δ 13 C (r 2 = 0.32, p 〈 0.01) before 1950, with no correlation (r 2 = 0.00, p = 0.91) after 1950. These results indicate that increased c i may have conferred some drought resistance to these grasses through increased availability of CO 2 in the event of reduced stomatal conductance in response to short term water shortage. Comparison with C 3 trees from arid environments ( Pinus longaeva and Pinus edulis in the US Southwest) as well as from wetter environments ( Bromus and Poa grasses in New Mexico) suggest differing responses based on environment; arid environments in New Mexico see increased intrinsic water use efficiency (WUE) in response to historic elevated CO 2 while wetter environments see increased c i . The present study suggests that a) the observed increases in c i in FACE experiments are consistent with historical CO 2 increases and b) the CO 2 increase influences plant sensitivity to water shortage, through either increased WUE or c i in arid and wet environments, respectively. This article is protected by copyright. All rights reserved.
Print ISSN:
1354-1013
Electronic ISSN:
1365-2486
Topics:
Biology
,
Energy, Environment Protection, Nuclear Power Engineering
,
Geography
Permalink