Orla Dermody
Mucking through multifactor experiments; design and analysis of multifactor studies in global change research
University of Tennessee at Knoxville
new phytologistvolume 172 issue 4 p 598600 free access mucking multifactor experiments design analysis multifactor studies global change research orla dermody orla dermody university tennessee knoxville tennessee usa tel 1 865 974 4226 fax 1 865 974 3067 email email protected search papers author orla dermody orla dermody university tennessee knoxville tennessee usa tel 1 865 974 4226 fax 1 865 974 3067 email email protected search papers author first published 08 november 2006 httpsdoiorg101111j14698137200601921xcitations 23aboutsectionspdf toolsrequest permissionexport citationadd favoritestrack citation shareshare give accessshare full text accessshare fulltext accessplease review terms conditions use check box share fulltext version articlei read accept wiley online library terms conditions useshareable linkuse link share fulltext version article friends colleagues learn morecopy url share linkshare onfacebooktwitterlinkedinredditwechat ecological society america esa 91st annual meeting memphis tn usa august 2006 composition atmosphere global climate changed significantly since start industrial revolution changes impacting ecosystem structure function prather et al 2001 experimental studies manipulate atmospheric concentrations co2 o3 nitrogen deposition temperature precipitation regimes provide evidence factors significant sustained impacts net primary productivity npp weltzin et al 2000 zavaleta et al 2003 hanson et al 2005 morgan et al 2005 norby iversen 2006 interactive effects feedbacks emerge factors applied together experiments single factors manipulated may inadequate fully predict impacts future atmospheric change ecosystems mind many experiments empirical theoretical initiated examine effect multiple global change factors ecosystems despite knowledge gained experiments many questions remain unresolved broad goal multifactor experiments understand interactions multiple global change factors impacts ecosystem structure function remains elusive aid reaching goal symposium mucking multifactor experiments design analysis multifactor studies global change research organized aime classen oak ridge national laboratory cooperation nsf research coordination network terrestrial ecosystem response atmospheric climatic change teracc new phytologist trust 91st annual meeting ecological society america memphis tennessee although single factor may striking effects ecosystem function applied alone global change factors mixed physiological growth adjustments within ecosystem may dampen overall response using empirical data large body empirical data already exists response ecosystems global change factors elevated co2 o3 applied isolation ainsworth long 2005 jablonski et al 2002 incorporating processbased information experimental data multifactor models paul hanson oak ridge national laboratory usa showed inferences made response ecosystems realistic global change scenarios using empirical data many single factor experiments hanson et al 2005 simulated interactive effects elevated co2 o3 changes precipitation warming growth upland oak forests southeastern united states generating alternative climate scenarios using key physiological growth responses probabilistic framework authors able generate predictions forest response variety conditions 2100 one key findings physiological adjustments elevated co2 temperature growth response 20 may maintained southeastern forests 2100 additionally able rank global change factors order importance eg temperature o3 precipitation exercise also highlighted fact although single factor may striking effects ecosystem function applied alone global change factors mixed physiological growth adjustments within ecosystem may dampen overall response jeff dukes university massachusetts boston usa also presented similar result california grasslands shaw et al 2002 empirical experiments limited duration many important effects global change become evident large spatial temporal scales assembling shortterm data variety ecosystem types steve del grosso colorado state university usa able simulate effects multifactor global change large scale longterm processes decomposition carbon storage nitrogen leaching using daycent daily timestep version century parton et al 1987 1998 gradual increase 3c nightly minimum temperatures conservative increase 1c daily temperatures simulated 100 yr shortgrass steppe tallgrass prairie boreal forest temperate coniferous deciduous forest authors found npp soil organic carbon increased systems boreal forest soil carbon stocks decreased 100 yr focusing temperate deciduous liquidambar styraciflua forest oak ridge tennessee found good agreement measured simulated npp however simulation root npp less reliable underestimated npp elevated co2 ross mcmurtrie university new south wales australia offered simpler model could also applied across large spatial temporal scales answer plantgrowth response rising co2 amplified water limiting diminished nitrogen limiting showed optima exist leaf n stomatal conductance leaf area index variety global change scenarios like model del grosso et al mcmurtries model confirmed much experimental work gone eg larger relative response co2 drier conditions models widely applicable highlighted significant knowledge gaps testable hypotheses future empirical studies multifactor experiments although expensive often difficult implement experiments expose ecosystems range global change factors necessary understand mechanisms interactions drive responses global change occam oldfield community climate atmospheric manipulation experiment eastern tennessee old field ecosystem exposed elevated co2 warming altered precipitation aime classen oak ridge national laboratory usa showed water availability elevated co2 warming major driver aboveground biomass system however effect varied across years 2005 effects soil moisture biomass reduced elevated co2 increased warming dukes et al also found minimal role elevated co2 grassland jasper ridge northern california major driver ecosystem biomass increase nitrogen deposition teis mikkelsen ris national laboratory denmark described new experiment co2 temperature precipitation manipulated seminatural grass shrub ecosystem many multifactor experiments set take advantage traditional anova framework often deal inadequately interannual variation surprises focusing probabilities seedling recruitment forest gaps brian beckage university vermont vermont usa showed abrupt ecological responses climate change may modelled using hierarchical bayesian analysis classen et al exploring path analysis may offer complete analysis traditional anova framework employing nonparametric approaches may possible model abrupt ecological responses global change take full advantage data empirical observational studies applying knowledge ultimately experimental data aid policymakers stakeholders predicting response ecosystems future climate scenarios extensive datasets exist long running global change experiments may aid goal aspenface experiment northern wisconsin operating nine years exposes aspen birch elevated co2 o3 fully factorial design levels already occurring across much globe elevated o3 offsets gains productivity seen elevated co2 populus tremuloides king et al 2005 given ecological economical importance p tremuloides urgent need determine regional implications result well accumulating data physiological growth responses ecosystem co2 o3 kevin percy canadian forest service new brunswick canada also compiled extensive data many environmental parameters coupled space time regressing growth environmental expected dose parameters o3 percy et al determined o3 wind speed growing degree days predicted 88 variation tree growth across duration experiment analysis extended show predicted growth change p tremuloides across wide range sensitivity o3 exposure thus empirical data multifactor experiment provided predictor variables extending important results public domain contributing scientific literacy stakeholders perspectives ecosystems across globe already exposed changing atmospheric composition temperature precipitation many gaps remain knowledge impacts changes ecosystems eg role belowground processes disturbance invasive species address gaps one single approach sufficient multifactor modelling must utilized conjunction factorial experiments generate hypotheses expand empirical findings particularly across broader spatial temporal scales symposium strong bias towards temperate natural systems information required underrepresented ecosystems especially tropics northern latitudes factorial experiments costly complicated maximize relevance sound statistical procedures must applied nonparametric statistics may offer new insight feedbacks interactions processes within ecosystems continuously measuring ancillary variables o3 precipitation may possible retrospectively understand extrapolate results simple experiments complex scenarios end encouraging issues addressed international team doubt continue expand improve information presented symposium references ainsworth ea long sp 2005 learned 15 years freeair co2 enrichment face metaanalytic review responses photosynthesis canopy properties plant production rising co2 new phytologist 165 351 371 hanson pj wullschleger sd norby rj tschaplinski tj gunderson ca 2005 importance changing co2 temperature precipitation ozone carbon water cycles uplandoak forest incorporating experimental results model simulations global change biology 11 1402 1423 jablonski lm wang xz curtis ps 2002 plant reproduction elevated co2 conditions metaanalysis reports 79 crop wild species new phytologist 156 9 26 king js kubiske pregitzer ks hendrey gr mcdonald ep giardina cp quinn vs karnosky df 2005 tropospheric o3 compromises net primary production young stands trembling aspen paper birch sugar maple response elevated atmospheric co2 new phytologist 168 623 635 morgan pb bollero ga nelson rl dohleman fg long sp 2005 increase aboveground net primary production yield soybean less co2 elevated open global change biology 11 1 10 norby rj iversen cm 2006 nitrogen uptake distribution turnover efficiency use co2 enriched sweetgum forest ecology 87 5 14 parton wj hartman ojima schimel 1998 daycent land surface submodel description testing global planetary change 19 35 48 parton wj schimel ds cole cv ojima ds 1987 analysis factors controlling soil organic matter levels great plains grasslands soil science society america journal 51 1173 1179 prather ehhalt dentener f et al 2001 atmospheric chemistry greenhouse gases jt ding houghton dj griggs noguer pj van der linder x dai k maskell ca johnson eds climate change 2001 scientific basis contribution working group third assessment report intergovernmental panel climate change cambridge uk cambridge university press 183 240 shaw mr zavaleta es chiariello nr cleland ee mooney ha field cb 2002 grassland responses global environmental 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