Stoichiometric shifts in surface soils over broad geographical scales: evidence from China's grasslands. Issue 8 (20th April 2014)

• Record Type: Journal Article
• Authors: Yang, Yuanhe; Fang, Jingyun; Ji, Chengjun; Datta, Arindam; Li, Pin; Ma, Wenhong; Mohammat, Anwar; Shen, Haihua; Hu, Huifeng; Knapp, Benjamin O.; Smith, Pete
• Is Part Of: Global ecology & biogeography. Volume 23:Issue 8(2014:Aug.)
• Page Start: 947
• Page End: 955
• Publication Date: 2014-04-20
• Subjects: Ecology -- Periodicals; Biogeography -- Periodicals; Biodiversity -- Periodicals; Macroevolution -- Periodicals; 577
• DOI: 10.1111/geb.12175
• Languages: English
• ISSNs: 1466-822X

Abstract

<abstract abstract-type="main"> <title>Abstract</title> <sec id="geb12175-sec-0001" sec-type="section"> <title>Aim</title> <p>The identification of stoichiometric flexibility is crucial for understanding carbon–nitrogen–phosphorus (C–N–P) interactions and ecosystem dynamics under a changing environment. However, current evidence of stoichiometric flexibility mainly comes from manipulation experiments, with little evidence from large‐scale observations.</p> </sec> <sec id="geb12175-sec-0002" sec-type="section"> <title>Location</title> <p>Alpine and temperate grasslands across northern China.</p> </sec> <sec id="geb12175-sec-0003" sec-type="section"> <title>Methods</title> <p>Using soil profiles derived from a historical national soil inventory and a contemporary regional soil survey across China's grasslands, we examined temporal changes in topsoil C:N:P ratios over recent decades.</p> </sec> <sec id="geb12175-sec-0004" sec-type="section"> <title>Results</title> <p>Topsoil C:N ratios of five major grassland types exhibited some flexibility but did not show significant changes over the sampling interval. Non‐significant changes in topsoil C:N ratios were observed both in alpine grasslands on the Tibetan Plateau and in temperate grasslands on the Inner Mongolian Plateau. Consistent with the relatively stable C:N ratios, the slope of the soil C–N stoichiometric relationship did not differ significantly between the two sampling periods. Soil N:P ratios in the surface layer increased significantly over the sampling interval, however, with an overall increase of 0.60 (95% confidence interval 0.58–0.62). A larger increase in soil N:P ratio was found in temperate grasslands on the Inner Mongolian Plateau than in alpine grasslands on the Tibetan Plateau. Moreover, the slope of the soil N–P stoichiometric relationship in these grassland ecosystems became steeper over the sampling interval.</p> </sec> <sec id="geb12175-sec-0005" sec-type="section"> <title>Main conclusions</title> <p>These results demonstrate the stability of topsoil C:N stoichiometry but variability in N:P stoichiometry over broad geographical scales, highlighting that soil C and N are tightly coupled, but N and P tend to be decoupled under a changing environment.</p> </sec> </abstract>