水保所知识产出(1956---)知识库

Globalwarmingandnitrogen(N)depositionareknowntoaffectrootdynamicsingrasslands.However,previous
studies werebasedonlyonasingleecosystemtype,soitisunclearhowwarming andN addition affectroottraits
(root biomass, root-shoot ratio, root production and turnover) along the aridity gradient. In this study, we con-
ducted an experiment to determine the effects of warming and N addition on root traits in desert, typical, and
meadow grasslands innorthern China, where the aridity gradually decreases fromwest toeast acrossthe region.
Warming increased root-shoot ratio in dry year due to decline in soil water, but had a downward trend in root
production and turnover in all three grasslands. N addition decreased root-shoot ratio in humid year due to in-
creaseinsoilN,whereasdidnotsignificantlyaffectrootproductioninanygrasslandsandincreasedrootturnover
in desert and meadow grasslands rather than typical grassland. Warming combined with N addition had nega-
tively additive effects on root turnover in typical and meadow grasslands rather than desert grassland. N
addition-induced changes in root biomass and root-shoot ratio were negatively affected by aridity in dry year.
Aridity positively affected responses of root production and turnover to warming but negatively affected thoseresponsestoNaddition.However,root-shootratio,rootproductionandturnoverunderwarmingcombinedwith
N addition were not affectedbyaridity. Our results suggest that warmingsuppressesroot carbon (C) input but N
additionmayexacerbateitintemperategrasslands,andwarmingcombinedwithNadditionsuppressesitonlyin
wet grasslands.Aridity promotes root C inputunderwarming butsuppressesitunderN addition.However, arid-
itymaylittleaffectsoilCandnutrientdynamicsunderglobalwarmingcombinedwithNdepositionintemperate
grasslands in the future.