title: Precipitation regime shift enhanced the rain pulse effect on soil respiration in a semi-arid steppe.
abstract: The effect of resource pulses, such as rainfall events, on soil respiration plays an important role in controlling grassland carbon balance, but how shifts in long-term precipitation regime regulate rain pulse effect on soil respiration is still unclear. We first quantified the influence of rainfall event on soil respiration based on a two-year (2006 and 2009) continuously measured soil respiration data set in a temperate steppe in northern China. In 2006 and 2009, soil carbon release induced by rainfall events contributed about 44.5% (83.3 g C m(-2)) and 39.6% (61.7 g C m(-2)) to the growing-season total soil respiration, respectively. The pulse effect of rainfall event on soil respiration can be accurately predicted by a water status index (WSI), which is the product of rainfall event size and the ratio between antecedent soil temperature to moisture at the depth of 10 cm (r2 = 0.92, P<0.001) through the growing season. It indicates the pulse effect can be enhanced by not only larger individual rainfall event, but also higher soil temperature/moisture ratio which is usually associated with longer dry spells. We then analyzed a long-term (1953-2009) precipitation record in the experimental area. We found both the extreme heavy rainfall events (>40 mm per event) and the long dry-spells (>5 days) during the growing seasons increased from 1953-2009. It suggests the shift in precipitation regime has increased the contribution of rain pulse effect to growing-season total soil respiration in this region. These findings highlight the importance of incorporating precipitation regime shift and its impacts on the rain pulse effect into the future predictions of grassland carbon cycle under climate change.
authors.affiliation: State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, China; School of Life Sciences, Fudan University, Shanghai, China.
authors.forename: Liming
authors.initials: L
authors.lastname: Yan
authors.affiliation: State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, China.
authors.forename: Shiping
authors.initials: S
authors.lastname: Chen
authors.affiliation: Department of Microbiology and Botany, University of Oklahoma, Norman, Oklahoma, United States of America.
authors.forename: Jianyang
authors.initials: J
authors.lastname: Xia
authors.affiliation: Department of Microbiology and Botany, University of Oklahoma, Norman, Oklahoma, United States of America.
authors.forename: Yiqi
authors.initials: Y
authors.lastname: Luo
mesh_terms: D002681:China; D004777:Environment; D011891:Rain; D012621:Seasons; D012987:Soil; D013997:Time Factors
chemical_list: D012987:Soil
references.citation: Oecologia. 2004 Oct;141(2):194-210
references.pmid: 15042457
references.citation: Environ Int. 2005 Oct;31(8):1167-81
references.pmid: 15922449
references.citation: Oecologia. 2004 Oct;141(2):254-68
references.pmid: 15338414
references.citation: New Phytol. 2008 Jul;179(2):460-471
references.pmid: 19086292
references.citation: Nature. 2001 Jun 14;411(6839):789-92
references.pmid: 11459055
references.citation: Ecology. 2007 Jun;88(6):1386-94
references.pmid: 17601131
references.citation: Science. 2002 Dec 13;298(5601):2202-5
references.pmid: 12481139
references.citation: Oecologia. 2011 Sep;167(1):265-78
references.pmid: 21487825
references.citation: Nature. 2006 Mar 9;440(7081):165-73
references.pmid: 16525463