38-Microbial change in warming soils.

38-Microbial change in warming soils.SCIENCEsciencemag.orgGRAPHIC:K.SUTLIFF/SCIENCEByDanielB.MetcalfeSoilsarethelargestsingleterrestrialsourceofcarbondioxide(CO2),buttheseemissionsarehighlysensitivetoarangeoffactorsassociatedwithclimatechangeandhumanlanduse(1).ResearchershavelongsoughttobetterunderstandtheunderlyingdriversofsoilCO2emissions,butthedurationofexperimentsisalltoooftenconstrainedbyprojectdeadlinesandpersonnelcontracts,hamperingourabilitytounderstandandpredictthemanygradualbutimportantprocessesthatoccurinsoils(2).Onpage101ofthisissue,Melilloetal.(3)reportonanintriguing26-yearrecordofsoilrespirationresponsestowarminginatemperateforest.Theresultsfromthisunusuallylongtimeserieshighlightboththepotentialpitfallsofdrawinghastyconclusionsfromshort-termstudiesandtheimportanceoflong-termexperimentsinecosystemandclimatescience.Shiftsintheterrestrialcarbonstore,ofwhichsoilsconstitutearound70%,areoneofthemostimportantbutleastunder-stooddriversofvariationinatmosphericCO2levels(4,5).Soilc