title: Regional contingencies in the relationship between aboveground biomass and litter in the world's grasslands.
abstract: Based on regional-scale studies, aboveground production and litter decomposition are thought to positively covary, because they are driven by shared biotic and climatic factors. Until now we have been unable to test whether production and decomposition are generally coupled across climatically dissimilar regions, because we lacked replicated data collected within a single vegetation type across multiple regions, obfuscating the drivers and generality of the association between production and decomposition. Furthermore, our understanding of the relationships between production and decomposition rests heavily on separate meta-analyses of each response, because no studies have simultaneously measured production and the accumulation or decomposition of litter using consistent methods at globally relevant scales. Here, we use a multi-country grassland dataset collected using a standardized protocol to show that live plant biomass (an estimate of aboveground net primary production) and litter disappearance (represented by mass loss of aboveground litter) do not strongly covary. Live biomass and litter disappearance varied at different spatial scales. There was substantial variation in live biomass among continents, sites and plots whereas among continent differences accounted for most of the variation in litter disappearance rates. Although there were strong associations among aboveground biomass, litter disappearance and climatic factors in some regions (e.g. U.S. Great Plains), these relationships were inconsistent within and among the regions represented by this study. These results highlight the importance of replication among regions and continents when characterizing the correlations between ecosystem processes and interpreting their global-scale implications for carbon flux. We must exercise caution in parameterizing litter decomposition and aboveground production in future regional and global carbon models as their relationship is complex.
authors: Department of Zoology, Oregon State University, Corvallis, OR, USA. riesl@science.oregonstate.edu
authors: Lydia R
authors: LR
authors: O'Halloran
authors: Elizabeth T
authors: ET
authors: Borer
authors: Eric W
authors: EW
authors: Seabloom
authors: Andrew S
authors: AS
authors: MacDougall
authors: Elsa E
authors: EE
authors: Cleland
authors: Rebecca L
authors: RL
authors: McCulley
authors: Sarah
authors: S
authors: Hobbie
authors: W Stan
authors: WS
authors: Harpole
authors: Nicole M
authors: NM
authors: DeCrappeo
authors: Chengjin
authors: C
authors: Chu
authors: Jonathan D
authors: JD
authors: Bakker
authors: Kendi F
authors: KF
authors: Davies
authors: Guozhen
authors: G
authors: Du
authors: Jennifer
authors: J
authors: Firn
authors: Nicole
authors: N
authors: Hagenah
authors: Kirsten S
authors: KS
authors: Hofmockel
authors: Johannes M H
authors: JM
authors: Knops
authors: Wei
authors: W
authors: Li
authors: Brett A
authors: BA
authors: Melbourne
authors: John W
authors: JW
authors: Morgan
authors: John L
authors: JL
authors: Orrock
authors: Suzanne M
authors: SM
authors: Prober
authors: Carly J
authors: CJ
authors: Stevens
mesh_terms: D018533:Biomass; D002244:Carbon; D002980:Climate; D017753:Ecosystem; D006109:Poaceae
chemical_list: D002244:Carbon
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