%0 Journal Article %1 citeulike:12902907 %A Gifford, Roger M. %A Barrett, Damian J. %A Lutze, Jason L. %B Plant and Soil %D 2000 %I Kluwer Academic Publishers %J Plant and Soil %K citeulikeExport co2, dilution, face\_nutrients, hypothesis, nutrient %N 1 %P 1--14 %R 10.1023/a:1004790612630 %T The effects of elevated CO2 on the C:N and C:P mass ratios of plant tissues %U http://dx.doi.org/10.1023/a:1004790612630 %V 224 %X The influence of elevated CO2 concentration (CO2) during plant growth on the carbon:nutrient ratios of tissues depends in part on the time and space scales considered. Most evidence relates to individual plants examined over weeks to just a few years. The C:N ratio of live tissues is found to increase, decrease or remain the same under elevated CO2. On average it increases by about 15\% under a doubled CO2. A testable hypothesis is proposed to explain why it increases in some situations and decreases in others. It includes the notion that only in the intermediate range of N-availability will C:N of live tissues increase under elevated CO2. Five hypotheses to explain the mechanism of such increase in C:N are discussed; none of these options explains all the published results. Where elevated CO2 did increase the C:N of green leaves, that response was not necessarily expressed as a higher C:N of senesced leaves. An hypothesis is explored to explain the observed range in the degree of propogation of a CO2 effect on live tissues through to the litter derived from them. Data on C:P ratios under elevated CO2 are sparse and also variable. They do not yet suggest a generalising-hypothesis of responses. Although, unlike for C:N, there is no theoretical expectation that C:P of plants would increase under elevated CO2, the average trend in the data is of such an increase. The processes determining the C:P response to elevated CO2 seem to be largely independent of those for C:N. Research to advance the topic should be structured to examine the components of the hypotheses to explain effects on C:N. This involves experiments in which plants are grown over the full range of N and of P availability from extreme limitation to beyond saturation. Measurements need to: distinguish structural from non-structural dry matter; organic from inorganic forms of the nutrient in the tissues; involve all parts of the plant to evaluate nutrient and C allocation changes with treatments; determine resorption factors during tissue senescence; and be made with cognisance of the temporal and spatial aspects of the phenomena involved.

@article{citeulike:12902907, abstract = {{The influence of elevated CO2 concentration ([CO2]) during plant growth on the carbon:nutrient ratios of tissues depends in part on the time and space scales considered. Most evidence relates to individual plants examined over weeks to just a few years. The C:N ratio of live tissues is found to increase, decrease or remain the same under elevated [CO2]. On average it increases by about 15\% under a doubled [CO2]. A testable hypothesis is proposed to explain why it increases in some situations and decreases in others. It includes the notion that only in the intermediate range of N-availability will C:N of live tissues increase under elevated [CO2]. Five hypotheses to explain the mechanism of such increase in C:N are discussed; none of these options explains all the published results. Where elevated [CO2] did increase the C:N of green leaves, that response was not necessarily expressed as a higher C:N of senesced leaves. An hypothesis is explored to explain the observed range in the degree of propogation of a CO2 effect on live tissues through to the litter derived from them. Data on C:P ratios under elevated [CO2] are sparse and also variable. They do not yet suggest a generalising-hypothesis of responses. Although, unlike for C:N, there is no theoretical expectation that C:P of plants would increase under elevated [CO2], the average trend in the data is of such an increase. The processes determining the C:P response to elevated [CO2] seem to be largely independent of those for C:N. Research to advance the topic should be structured to examine the components of the hypotheses to explain effects on C:N. This involves experiments in which plants are grown over the full range of N and of P availability from extreme limitation to beyond saturation. Measurements need to: distinguish structural from non-structural dry matter; organic from inorganic forms of the nutrient in the tissues; involve all parts of the plant to evaluate nutrient and C allocation changes with treatments; determine resorption factors during tissue senescence; and be made with cognisance of the temporal and spatial aspects of the phenomena involved.}}, added-at = {2019-03-31T01:14:40.000+0100}, author = {Gifford, Roger M. and Barrett, Damian J. and Lutze, Jason L.}, biburl = {https://www.bibsonomy.org/bibtex/2b46a9689e994135ee170aa4ee3354503/dianella}, booktitle = {Plant and Soil}, citeulike-article-id = {12902907}, citeulike-linkout-0 = {http://dx.doi.org/10.1023/a:1004790612630}, citeulike-linkout-1 = {http://link.springer.com/article/10.1023/A:1004790612630}, doi = {10.1023/a:1004790612630}, interhash = {aa93a4158894fe34f90f25732156c9d6}, intrahash = {b46a9689e994135ee170aa4ee3354503}, journal = {Plant and Soil}, keywords = {citeulikeExport co2, dilution, face\_nutrients, hypothesis, nutrient}, number = 1, pages = {1--14}, posted-at = {2014-01-08 16:18:26}, priority = {0}, publisher = {Kluwer Academic Publishers}, timestamp = {2019-03-31T01:16:26.000+0100}, title = {{The effects of elevated [CO2] on the C:N and C:P mass ratios of plant tissues}}, url = {http://dx.doi.org/10.1023/a:1004790612630}, volume = 224, year = 2000 }