title: Sampling date, leaf age and root size: implications for the study of plant C:N:p stoichiometry.
abstract: Plant carbon : nitrogen : phosphorus (C:N:P) ratios are powerful indicators of diverse ecological processes. During plant development and growth, plant C:N:P stoichiometry responds to environmental conditions and physiological constraints. However, variations caused by effects of sampling (i.e. sampling date, leaf age and root size) often have been neglected in previous studies. We investigated the relative contributions of sampling date, leaf age, root size and species identity to stoichiometric flexibility in a field mesocosm study and a natural grassland in Inner Mongolia. We found that sampling date, leaf age, root size and species identity all significantly affected C:N:P stoichiometry both in the pot study as well as in the field. Overall, C:N and C:P ratios increased significantly over time and with increasing leaf age and root size, while the dynamics of N:P ratios depended on species identity. Our results suggest that attempts to synthesize C:N:P stoichiometry data across studies that span regional to global scales and include many species need to better account for temporal variation.
authors.affiliation: State Key Laboratory of Forest and Soil Ecology, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, China.
authors.forename: Haiyang
authors.initials: H
authors.lastname: Zhang
authors.forename: Honghui
authors.initials: H
authors.lastname: Wu
authors.forename: Qiang
authors.initials: Q
authors.lastname: Yu
authors.forename: Zhengwen
authors.initials: Z
authors.lastname: Wang
authors.forename: Cunzheng
authors.initials: C
authors.lastname: Wei
authors.forename: Min
authors.initials: M
authors.lastname: Long
authors.forename: Jens
authors.initials: J
authors.lastname: Kattge
authors.forename: Melinda
authors.initials: M
authors.lastname: Smith
authors.forename: Xingguo
authors.initials: X
authors.lastname: Han
mesh_terms: D002244:Carbon / Q000032:analysis*; D009584:Nitrogen / Q000032:analysis*; D010758:Phosphorus / Q000032:analysis*; D018515:Plant Leaves / Q000737:chemistry*; D018517:Plant Roots / Q000737:chemistry*; D013997:Time Factors
chemical_list: D010758:Phosphorus; D002244:Carbon; D009584:Nitrogen
references.citation: Trends Ecol Evol. 2011 Apr;26(4):183-92
references.pmid: 21367482
references.citation: Proc Natl Acad Sci U S A. 2004 Jul 27;101(30):11001-6
references.pmid: 15213326
references.citation: New Phytol. 2010 May;186(3):593-608
references.pmid: 20298486
references.citation: New Phytol. 2009 Jan;181(2):295-309
references.pmid: 19121029
references.citation: Oecologia. 2011 May;166(1):1-10
references.pmid: 21221646
references.citation: New Phytol. 2012 Nov;196(3):807-815
references.pmid: 23005343
references.citation: Ecol Lett. 2010 Nov;13(11):1390-9
references.pmid: 20849443
references.citation: Oecologia. 2006 Aug;149(1):115-22
references.pmid: 16639565
references.citation: Trends Ecol Evol. 2009 Mar;24(3):127-35
references.pmid: 19185386
references.citation: New Phytol. 2012 Jun;194(4):944-952
references.pmid: 22471439
references.citation: Ecology. 2009 Jan;90(1):81-9
references.pmid: 19294915
references.citation: Nat Commun. 2011 Jun 14;2:344
references.pmid: 21673665
references.citation: New Phytol. 2009;183(1):153-166
references.pmid: 19383100
references.citation: Proc Natl Acad Sci U S A. 2012 Mar 13;109(11):4181-6
references.pmid: 22371578
references.citation: Proc Natl Acad Sci U S A. 2007 May 22;104(21):8891-6
references.pmid: 17502616
references.citation: PLoS One. 2011;6(9):e24762
references.pmid: 21935460
references.citation: New Phytol. 2005 Nov;168(2):377-85
references.pmid: 16219077
references.citation: Trends Ecol Evol. 2006 Apr;21(4):178-85
references.pmid: 16701083
references.citation: Nature. 2000 Nov 30;408(6812):578-80
references.pmid: 11117743