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LoneTerm Research a he USDA Forest Service's

Experimen Forests and Ranges

ARlEL E. CUGO, FREDERICK J. SWANSON, OLGA RAMOS GONZALEZ, MARY BETH ADAMS, BRIAN PACIK, RONALD E, THiLL, DAlE G , BROCKWAYf CHRISTEL KERN, RtCHARD WOODSMITH, AND ROBERT MUSSELMAN

The ncawurk qfaperirnerrt~l furests and rmges cadtn-ninisfercd by the US Drspnamarrt afAgriculture: Forest: Service ro~?;isfs o j 77 properties that are represursttzt-ive af rrwst forest cover types annd mnay ecrrlogicnl regions in die nation. Established as early a5 1908, #here sites mnintuin excc~ptionnl, brtg-term rifltabnses m c~tvirunrn~tttaf dynatrzia and biotic rcspnnses. Early research a t t k a e sites focuried on silviculture, ecosystem resturaticm, and ~rpatershed ~ttgtugernetrl: Over time, tnaas;v of the pmper~ie$ ~ A W evdved into a f ~na ionn l ttetwork of t?leoi~gial ~17Sewat0Tjes rkrolrgjt cor?afnarr irtr$~-scnte?, Ijll~g-term aper imm& and ather q p r a ~ h e ~ , (=Qga£~~mt io~~ with other i?s_Sfjtutiorts and research pmgriamsfosters inferside research and comrnorr precedraresf~r wnm@ng utzd shariq datlr. i'vi1:~ch currerrt research in this a e m r k f o a ~ s e s on glaErCiX chu~rge arid lnrercfiscipf inrrr)~ gcosjpsrertz stltdi~s lit iocnI to &baj smles. In/iih fhis experience in developing networks and rompilivtg records o f entpironnzmtal hisforg the experisrr m fa1 forests and m n g a tret work calf co:otrtribarte cgreatiy to jarmatian sfrxezv rretworh of e~tvironntental observatories,

Ke~frzrard5: apgrimetztal forests? expe~mencral rrzkggefrin&). r ~ e a ~ h nerriuork, gl~blrt chatlge science, silt~iculture

ta the study ofthe envimme* ecosystems, and nagwal rewarces have long been nn h-

tcgraf part of the nation4 and g1obaI in f ras t ru~re for science, edrrcation, and information. These properties have guided the management of nattwd resource systems, such as wdtersheds, forests, and rangelands. Key discoveries with wide-rasl@fg impact an e11Granrnalial policy and natural re- sour& management have emerged from long-term studies at field research facilities, Sus~ined ecosystem rezarch at Hub- bard Brook Experimcmtal Farest in Mew Hapshire, for ex- ampic, revealed the existex-rce af acid rain in North America and the ramifications of this form of pollution---as well as other human altexarians sf the atmosphere--for b r a t s and watersheds (Likens 2004). Fundamental characterizatioa of ~M-growth forests, and of the dynamics of forests aF the Pa- cific Northz,vest, based on studies at the H. 1, Andrew Ex- perimental bmst in Oregon inf luend r? major sl~ift in forest markagemer?t policy in that region and beyond (USDA. FSI

USDI BLM 1994, Franklin et al. 2002). Research in the Luquillo Experimental Forest in Fuertu Rico documented the effixts of hurricanes on Caribbean f'(Pref%ts, setting the stage For understanding how disturbances influence tropical forests ( Waiker et al. 1996). These examples demonstrate how sustained, interdisciplinary studies at research sites can lead to discoveries based on designed studies or on simple serendip- iw The experimental forests and ranges and the research goups working there in long-term mkborations are seedbeds fur discovery.

Evolving social issues and science questions calling for increasingly broadscale and interdisciplinary ecological resea& have contributed to avo devdoprrtents in the field, First, research programs at individual sites have evolved over time to blend sustained long-term, interdixiplinary studies with new short-tern? studies ta sharpen the focus on contemporary issues. Second, &ere has been a trend toward collections of research sites Functioning increasingly as research

Arid E. Lrigo {e-!?mil: aiagoqs,ftddusf is rile dimaor 4t f1c WDA Form Smite fnterrulliofrnl Inrtirtcte oJTropicnl Formryls, 1201 Calk Ceiba, Itzrdin Bordnicc? Sur;

Ria Picfiras, Prrerm Rim 00926; Olga R~~tzos Ger&fe~ is A (3s ntmlyst at tlic irrsriture. Frederick I. Swnsort is a rc$wrcA gc~Iogist rvith tkc USl)iS Forest Servire Par$(- N~srhr+~e.rt Research Saasion, 32M jqjiersum IVq, CarvuNis, OR 97331. M ~ r y Beth Adam$ is a ws~arcia roil scii~ntisi nrtd project Ieatkrfor the USDA Farfir Scrt'icr, Na#h~z~terr~ Research S~rcz;aioti, Parsons, 111.'1'26287, Brian Pnglaiik is apr~jccf l ~ a d e ~ , m d Chrisrei fCem is sfolxster artd rc=ologisf, with he LrSDA Forest S e t v k ~ ~ North Cemtrrlf Re?searcIf Sfatjot?, Grand fiapiiJsi MN 55744. Ronald E. 7;lrill L apvojecr leader with tire USDA Forest Service, So~oarlfretrn Rc.s~rzrch Smriarr, Nacogd@chn, TX 75965. Ditfe G. Brockrvlfy is n research ecologist with rk M L ' Forest Sen~icp~ Soud~prrt Research Station, Atiburtr, AL 36849. IZithartf t.Yood~mitI1 is ff research hyiirologist and trtlnr l~uiler at tfte LrSIfA FmsrSmicr, BnczfiNorth$uesf Research Sttitiom, ~enatchee, kVA 9X881. Rabm Mwselman is a resc~rch p h r ~ r p ~ f ~ s i ~ l ~ t with the USDA Foresf Semi& R d y Monrtlrrain Rescar& Station, Fort Coflins, CO 80526. @ 20% Amvricfin institute ofBi~tl~giccal Scic~ccs.

m v v bi~scierrcemng~o rg ]txnuaq~ 20Qti / \"'ul, 56 No, I * Biosience 39

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networks that span regions and continents. These steps have been critical in making the resuits of ecological sciences relevant to societal problems across a range of scales.

In light of continuing changes in these vital national systems of research properties, and of the prospects for devel- aping majar new ecological md environmental observatory networks (e.g., the National kolugkal Observatory Net- work, or NEON; ~w.neoninc.org) and hydmlu@cal obser- vaturia (he anmrtiurrm of Univmities for the Admncement of Hydrologic Science, Inc., or CUAI-ISI; wcunhsi.org), it is timely to reflect on existing cagab2ities and ~essons Iearned as a basis for planning hture research networks and their ac- companfirrg resexch agenda. The US Depament of Agri- culture (USDA) Forest Service's experinaentd forests and ranges provide valuable historical records of environmental change, experience in operating networks of research properties, and mxrztge of impartant types ufeaspems and natural remure systems.

In this article we describe the network of qerimental forests and ranges of the USDA Forest Service, highlight a handful of this network's scientific crmt~butiorms to date, and ammtmt on irs potential fur contributing to the nationai research agertde We pay pa r t i~~ l a r agentican to the networK's representatiQn of the nationis ecosystems arad its relevance tu research addsesshg emiranmend change a d natural resource management issues in the United States. We illustrate the evolution of m a r c h activity in this network, from individual titurfies focused an isolated sires and local research nee& to research that incmin@y taka a d m ~ g e sf n&mrEcs of sites considered a a o s b r a d temporal md gographic environment4 gradients. We e that the campl&ty of the environmental challenges k i n g humanity in the new millennium (Wlmaium Eeovstem assessment 2005) requires a research fxus that addresses envkonmeratd mmplexity at the scales of time and space where t11e problems are moted. Ta do so, site-specific research must be reinforced with networks of sites arrayed along environmental gradients that col- lectively represeBt the broad sc& af ccoiotyial q a c c that is of interest fo resource conservae'ion.

The atablisfwaent of research networks has long been a nut- ter of interest to ecologists (&a1 and Grime 199l).Whife ef- forts ta undestand and protect global ecosygems benefit from mearch conducted bath in networks and at isolated biological tieid stations (mitesell et al. 20021, nehvorking has the advm&ge of &owing for the establishment of cornpar- ative ecological studies, the installation of experiments along abiotic and biotic gradients, and the quick assessma of the variifbiEqia processes and structures of ecasystcm (Cole et al, 1991).

A wide variety of ecological research networks exisu, rang- irtg fmm Ioase conkderations of sites allied mainly h r ad- ministrative purposes to thematicaf ly Eocuscd, right1 y cuordinatc8, md gagraphicdy distributed research pro- p m s , Th%i;e types u f n ~ r k 5 diger greatly in a number of

'ncluding the types of opportunities -they provide for tive research, and the extent of the near-pristine

conditians they ofir for ux: as controls. The brig-sanding mBC0 ((United Nations Educational, Scientific and Cul- turd Q~ganization) Man and the Biosphere, or MAB, system of biosphere reserves ( w v y unaco,oq/rnabJ, for example, is a global network of sites with a design encompassing contra)

area, a r m with spportuniv for manipda t ive reseaek, and demanstratian areas, However, there is no coordinated, sw- taind mum ~Efunds to support research acms thiS netwurk. Mast sf the 47 biaspherc reserves in the United States are within the US %)epartmt;nt of the interior's National Piirk SF- tern or the USDaZTs N a ~ o a d Farest S~ tesn , and 12 are in the experimental forests md ranges network. "The system of na- tianal parks offers mmy reselttch opportuni~es (Parsans 2004), but oppomnities for mdpdat ive research are lh- ited by its prwwation mm&te*

One of the be3t-horn systems of eculugical research sites is the Long Term Ecologcal Ressexch (LTER) Network, initiated by the National Science ~oundation' (NSF) in 1980 (Hobbie et al. 203). This network s f n w i y 38 sites in the United States cusd Antmetic$ ranging from urban centers to wild alpine ;and forat systems to deer& (Hobbit: et al. 20031, is funded to eonduct long-tern ecobgical research with a gig- nificant degree of intexfik cocrrdination. HawmrI the limited number af LTER sites rmdts in ve~ l iwr i t d sampling of individual types af ecoystem, such as forests or grasXands (Tumr ct d. 2003). Also, with very fkw exceptions, LTER hi- tially emphasized pristine ecuqstems, where human impact is minimal.

Many other types of broa&de abserva-tian prograx~~s track specific ;aspects of ewirunmmtal change, including MODSS (Moderate Resolution Imaging Spe&oradiometer) and other xemute seasing prcrgms supported by NASA (National Aeronaia~cs and Space Mministration); the Na- tional Atmospheric; Deposition Progam; APneriFlux; and the US Sesblyrcal Survey's "seam-gauging network. In a recent review ofeculogicd res=& n m o r b fram around the globe, Melinda S r d h (Depat-eme~t of EmIoe;k. and Evahr- bonary Iliology, Yde Wdvers'i~, New Haven, e"T; personal csmmunicaeisn, 21 t 2005) wped ghat Integrative, m u l t i d i ~ i p h q ~ bm e o l o @ d networks were needed to undcrstmd a l + d system and fraw hey r a p n d ro hu- mm it&vi~a. f-fowevm* S m i t h cadd not iden._ifya single netwrk? mong the 49 r&wed, that sahfied the rq&emen@ she thoagbt were needed to addretis t%le challenges fa&g em3ogis:s and society in the 21st century. At-tributes considered critical for future ecological networks indude (a) a xi- mw &@ that b h c s eon~butioas u fhd jv idd x imgs~ and i_nse;itutiond controk ((b) combhd obst:waG;ionl;tl ;ui experimental approaches, (e ) strong ktmi te cxror&nation, [$) interdisciplinary approaches, (e) caverage graphic rer;zi~ns, (f) mdtiple grains or scales o (g) long-tern design USDA Forest %rvice3% BI of q e b e n d Esrats md ranges. has all uf the aftributa $mi& idengfieb dtheuggh

not all attributes are present at all sits. h.foreover, whereas must existing networks support observational (rather than experimental) rcsarch of short c lu~ ign and of a single spatial grain, the experimental forests aaad ranges network has a tsa- djtion of large-scale and Inng-term experimental research.

One common charaac&t.ic of many temperate, boreal, md tmpial eccrlogical r e a r ch sites, whether in n e m r b or COI- Eedam of individual sites, is heir focus on envimnmen~s &at have undergone little recent human influence. Increasing human denlands for ecosystem pmducts and services drive tbe alteratia~ sf most ecosystems of the world, either di- rectly through an-site land use or indirectly through altered cliinate, altered atmospheric chemistry, fac i l i t ah of inva- sion by exotic species, ar other means. Increasingly, scientists are recognizing %be extent and impact of human it~fluenceri in ecosystems grevioilsly cansidered pristine (Thompson et al, 2C102). Ecological research nmorkf are critical for ad- vancing this Iine of research.

That experimerrbl forests and ranges network A major ct>lltenxporav chdlenge facing ecologists is to understand envEronments influenced by human activity (13awa et al, 2004, Paher et d. 2$@4), Fortunately, this has been the srtbject of much s f the research at the USDA Forest Servic& i-returork c~f experimental forests and ranges Por nearly a e n - tury,

The e&bllshmePlt and evd~ont d sx~rimentai few& a& ranges. S't~ortly after the USDA Forest Service was established in 1905, ew1ylders of Forest Sewice research began to establish experimeatd forests and raages (in some cases termed "eqerhentr-rl stations"") with the general ob,ieetive of

addressing large-scak problems afforest, range, and watershed management. The period of establishment extended froin B08 until the early 1870s (Adams et ai. 2004). Most of the experirne~lrd forests and ranges were established an national forest lads, but some were located on stiate or privately o\zrlled lands, itfetwruEcz@cd observations and b e h e char- acterization of vegetation, soil, a d watershed conditions camrnenced. The early work of experimental forests and rarlges established the scient-ieie basis for management of forest (box 1) and range (box 2) vegetation and watersheds in many regions, At the outset, many investigations in p h e s such as the &cambia Experimental Forest in AZabama, the Great Basin Experimental Range in Utah, md the S ~ h y Ex- perimental Forest and Range in Oregon also involved the restoration of defbrested, overgrazedf and degraded Forests and rangelands.

Early concerns abaut the state of water supplies and water quality led to the establishment sf @cperbe~a i watershed studies at more than two dozen experimental forests and ranges (figure I ). Early watershed research at Cclweeta Hydro- logic Laboratory in North Caxolina, the San D h a s Experi- nlerltd Farest in California, and other sites examined h i c components afthe 'nydroiogic system and the eEects of vegetation management on strearnfiow, particularly peak flows and water yield. Studies at Coweeta established the founda- tion for the development of basic concepts in forest hydrological sciences (Swank and Crossley 1988).

In the 1Ws, experimental forests and ranges numixred f 10 f Adarns et al, 20041, but today the network contains 77 formally designated sites covering 196,300 hectares (ha) (figure 1). Individual sites r ang in size from 47 to 22,500 ha, and many encompass entire watersheds. Scientists working at

www. bio&ta~xcernag.org January 2006 / Vol. 56 No. I BJsScience 4 1

many of these sites also use associated USDA Forest Service satellite properties, such as the more than 250 research natural areas ranging in size from 15 ts 4OOQ ha and dedicated to nunmanipulative research.

Records from meteorolagicaX and gauging stiltions md forest research plots in some experimental forests date back Inure than 90 years. The Priest aiver hperimentrtl &rest in Idaho boasts uninterrupted daily weather records since 19 1 1 and data on growth of forest sands datjng back to 19 12; the latter are used to develop and verify computer sirnulation models of forest growth. The earliest long-term plots in the Pacific Northwest were established in 19 t 0 fox forest growth and yield studies. Today, these are part af a regionwide net-

work of 145 long-term pluts, which spans several eqer i - mental forests as welt a5 &a areas w d in both basic aid ay - plied farest ecology studies (Aeker et d, 1998),

Several factors haw: faciiitated the evututios of individual research praperdes into an heractive network including common @xpet.iments and measurement px~grams, con- moll protocols for &r;l rnmagement and sharing (e.g,, &tn harvester systems for dimate and hydrology parameters), and cross-site synthesis of long-term rtxsrds. Same of this intersite work began early in the history of the experimental farests and ranges, but the effort has increased substavltiaUy in recent decades. Far example, sequences of experimental forests that cross environrr~ental gradients are being used to

exan~i ne effects of 1110ist ure a l~d temperature on root decarnposi- tian in Oregon, and the much more exttrnsive Long-term Inter- site Decampositim Experiment Team (LIDET) study of fine litter decomposition spans 213 Forest Service, LFfER, and ather sites es- tending fram the North Slspc of A I s h to the Caribbem and G n - tral America (see w w W f i l . o r ~ t . edu!~ter~res~@rcI!~/in ~er~ite/lidgt. htm).

Athsugk. they have a branch- ing hiemxchical organizational structure thmugh which funds and direaives flow* intelpsite science grograms at experimental forests a d ranges generally func- tion as '"small-world" networks ( s e t ~ u Barabasi 2002). That is, scientists from various sites who

Figure I. Geographic distribun'on ofexperimrrr&lfores& and ranges, and ofexperimeetai share an in a particular ruafmsheds, showing Ehdr deignagiola ns flER (Long T m Ecologilcal Research) s i t s , science probkrn may collaborate

(Man and Ihe Biosphere) resmts, or both, voluntarily acmm diverse adrnin -

istr-ative units within -the Forest BIB00 Service. This distinction is irn- portar~t: bemuse the hieraacshial -.

f saoo organization 2iupylies the basic f r*rc

support h r operating thc: pap- = erties and core researdl programs f .- but the scientific excitement ?! comes from working on common 3000

science questions in energized ne~vnrks of scientists. - a

2

A God temperats rabr forest

0 Coal temperate wet fwmt

A Warm temperate mold h e s t

+ SubtropiGal dry farest

z US e n v i m m e and + SuMroplcat moist forest

1000 sampled by the ewperlmentlal subtropia rain mwit

forests and range* The network 0

of experimental forests and -15 -10 -5 o 5 10 15 20 25 30

ranges spans broad geographic axrd environnxe~ltal ranges, f'am Annual mean temperature (OC)

St. Croix in the US virgin Islands to Maska (figure 11, Figure2 Relationship between annual rainfall (in millimeters) nnd temperature (in

well beyond one typ- degrees C~?!S~W) in the network ofexperimentalforesh and ranges. Notice the lb$m'ent icay thinks of as forest or grass- dimatic gradientsfor moist, wet, and rain foresr life mnes and for temperage and subtrop- ialld types, The i ~ d life zones. Data arefrom Adam and colleapm (ZW4); life zones arefrum Lago and

elevation of these research prop- m11eqz4@ erties ranges from 30 meters ( n ~ ) (Sihs tittle ExgerSmental Forat in New Jersey] to 3500 1n in tables, and additional findingsf. The forest cover types most the atpine Glacier Lakes Ecolsptem kperiments Site (GLEES) represented by experimental forests are oak-fiickary in lrv'yoming. This braad spread, including nearly 50 &gees ( Quercus-Carp), loblolly-shar tieieaf (Pintis taeda-Pinris of Iatieladc., results in the system aF experimental forests and cchitznta), and pondemsn pine (pfinw ponu'erorca), which to- ranges reflecting a great range of tmperd:f:s"e and precipita- gcther represent 32% of the Eorests of the United States. The tiorm conditicsr~s Ifigtlre 2). experimental forests and ranges occur in 24 provinces or

Several vegetation and ecuq5sern dassification systems rcoregions defined by Bailey ( 1995). These ecoregions coveg pravide a useful base for clsaracterizing wgetation repre- Inore than 55% s f the area of the United States. The great- sented by the experimental, forests and ranges, The netrvark a t xrumber sf experimental forests Fdls within the Laurent- contaias representa~wee of 21 of the 25 forest cover types in ian mixed forest ecoregion, which represents 4.1% of the the ZjSW Forest Service" forest type map of the United area mapped. The conterminous United States has 38 St @es (visit ~mv%t:fil. ant. cd~~/itm/pubsr'wrbtl~csilreports/ Holdridge life zones (Lug0 ct al, 19"19), of which at least 14 bugobiosci.L;fkl? fn.~ data sources, analytical methods, maps, contain experimental forests ar rdnges (table I). The network

Area In kllamitterls Number of experimntspl forests f percmtage) or ranges {area in hectares)

Warm temwrrrte moist forest 1,804,944 (23.24) 22 (31,107) Cool ternperztc;. moist forest 1,259,616 (26.22) 12 (17,271) Wrm tewrwrate dry forest 708,000 (9.11) Warm ternperate thorn steppe 982,624 {6,2%) Coof temperate wet fomst 366,912 (4,721 Warm temperate montane moist forest 255,920 (3.29) Warn ternwrate subatpine wet forest 136,416 (1.76) Cool temperate desert scrub 111,072 (1,431 1 (22,500) Coal twnperate subalpine wet farest 105,520 (1.36) Corzi tempera& subalpine rain forest PM),128 (1.29) Warn temperate montane wet tomst 79,152 (1.02) Warm temperate alpme rain %nGm 53,888 (0,69) Coot temwrate rain dorest 47,376 (0.61) Warm temper?%@ subatpine rain forest 29,812 (0.38)

5,541,440 (72.33)

OIS~HY~ bioscietf ce~~tag,org Janunry 2006 / VoL 56 No. I * BioScierrce 43

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also includes six subtropical life xones in the Caribbean and several boreal ones in Alaska.

The current conditions of the vegetation at these sites reflect the history of natural disturbances and land management before their designation 4s experimental forests and ranges, as well as the more recent history of manipulative studies. Many experimental forests, especially those in. western states, contai 11 natural vegetation. This vegetation includes old for - est established after wildfire, and forest plantations in a uari- ety of age classes resulting from management since the establishment of the experimental forest. Some experhen- tat forests, especially those ill the eastern and southern United States, were established after a history of forest cutting, and in some cases farming and grazing; as a result, these forests represalt a b m h m e n t of earlier land-use practices (e.g,, DoufSlakss and Hoover 1988). In at lest one case (the Ca.lioun Experimental Forest, South Carolina), t l~e site was picked to represent "the worst of the wlarstYYn terms of past land-use impacts (Adarns et al. 2004). Experimental riRxIges were generally representative of the regignf in which they were established, and contained vegetation that was usually no more degraded than elsewhere in the loale. Plant cornnmitic;s an some cxperimentd ranges represented @asslands, shrub- lands, and woodlands in very good codition, In all cases, the y urpose of designating qe r jmen td forests rPnd ranges was to learn how to restore. and maintltin forests ssn that the puk- lic could reap the hl l suite of products and services from forestlands.

Research at exp~nlrnental forests and ranges h e a r c h at many experiinental forests and ranges invalves a diverse portfolio of applied and basic studies with short- and long-term planning horizans, These studies employ a variety of approaches, induding manipalative experiments, long-tern1 observations> simulation modelhg* and life history studies. The dominant research themes have focused at% timely issues related to the utilization xn8. consemtion of natural resources (Adams et al. 2004). Among the major topics of applied research are (a) the effects of forest management practices, such as logging, grazing, road construction, yrc- scribed fire, and soil fertilization, on streamflow, biogco- chemical cycling, sediment yield, and water quality; (b) the effects of and ecological respanses to insect and disease out- breaks; (c) the eEects of h o & , hurricanes, wildlke, and other natural disturbanm pscsces:s an forests, stream biota? and streamwater quantity and quality; (4 wildlife polpulation dynamics; and (e) life higory traits and habitat requiremm& of plant and animal species of criticai conservation concern.

Research programs at many individual experime~~tal &rests md ranges have changed progressively m r time, kv i th a gen- emf shift in Eoclls from i d , narrow, applied the111es to a wider range of study themes of broad relevance, such as global and dimate change science. For example, resear& at GLEES ex- amines bath (a) the effects of atmospheric deposition and climate change an alpine and subalpine aquatic and terrestrial ecosystems atld (b) hydrology and biogeochemiml balmas

in snow-dadted watersheds. Many ~ a i r n e n t d forest and range programs are now conrPibuting brig-tern ubservations and studies on h a t e and atmospheric chemistry eha~ge, car- ban dynamics, biodiversi~~ invaive species, ecohydrclb~~ and land-use change. Hydrological and metewological data collected at mast everimend watersheds for decades, in some cases for as lone, as 70 years, are now easily accessed through a data hawesterr system (w.$komt.aiidclim hyhydrodbn. Re- cent new analyses of thea records from six experimental forests uncovered patterns of vegetation control on streamflow in diverse systems (Post and Jones 2001, Jones and Post 2004), and helped define an aspect of ecowroiogy (Pest et 31% 1998)-

As part of studies of carbon Qjnamics under the USDA Global Climate Change Program, scientists are IinEng in- tensive ground-based measurements of carbon stocks, forest gruwth, and climate Erom experimental forests with spatially extensive but coarse resolution mesuTemen&. Spatial data arc acquired tlxough remote sensing and firrest igventory and 1 inked to high-resolution measurements sf carbon exchange between terrestrial ecosystems and the atmosphere made at AmeriFlux sites. Thmugh this w k , the imstigatnrs at the Rarrlett Experimental Foresf h. New Hanzpshire, the Marcel) Experimental Forest in Minnesota, the Fraser Experimental Forest in Colorado, and GLEES are linking 1 a ~ k a y e mon- itoring to carbon managmnt at a scale relevant to local Iand management decisions.

The strong partnerships of agency and academic scientists have been an important f'actsr in the evolution horn a narrow focw on regional science to a bmder y ~ r s p d v e that d s ~ indudes globai change. These scientists haw made it possi- ble to conduct cutting-edge, inxterdisciplinary research s n lands dedicated to long-term research missions. Strong working relationships among federal scientists, land managers, and acadenaic scientists took root in the 1960s and 1970s (e.g., Douglas and Hoover 1988, Likens 2010.1). These partnerships grew in the 1970s, h e n several experimental farests and ranges beczlme focal points for ecological research in the Internationd Biological Program, and then in the IlaiJUs, when LTER programs l d to strong Meral-academic science interactions.

At many experimental forests and ranges, strong partnerships between the research teams and land managers of the USDA Forest Service have been integral ta the success of the science program and the flow of science findings to management. The scimce-management partnership is a W-way street. The hnd managers often have critical roles in implementing large experiments and identif)ring information research needs. The partnership dso brings the science community into contact with current naturaf resource issues and tvith the public that is in them, S~lutiom to land management issues ohen call fbr inter&cip.inary approaches to campIex problems and involve trade-off% among dificrent interests; addrmhg &me types ~fissues pushes sd- entists to think Inore broadly Stknrists, for their g a t , bring a set of spedd skills snd knowledge to the partnership.

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Long-term applied studies of f~ r e s t~ watershed, and landscape management can be found on experimental forests and rarlges. Far example, adapG~e management areas established under the Northwest Forest Plan (USDA FSfUSDf BLM 1994) include two experimental farests and a 24,600-ha landscape managemat study c o n d u d by modeling landscape change and actual land management (Cissel et al. 1999), Such shared activities build the science-management link su that new findings can quicklyl be applied wer broad area.

The sustained commitment of USDA Forest Service research propemies to long-term ec;oIo@cal studies has resulted in experimentd forests and rawges being the home of nu- rrrerorxs notable, monumen%l experiments and observa~on platforms. In some cases, large-scale neworks of science in- stallations ilsc e&qerimczntaI forests far the placement of in- st rumem because of their sectlrity, commitment to research, md lercd tieaff to sentie q&pment, %me of the deveIoplr~en& initiated at USDA %rest Service sites operate at hditfidual sites and others over multiple sites. Exal~pirs uf research studios that origix~ate at experimental farests and ranges include the fo f lowing

* Hw~dreds. of silvic.Litture experiments and bag-arm vegetation plots in ur~manipulated forat stands throu@xout the experirnerz~al forest and rarzge system

* Scores of paired cxperin~ental watershed studies (w'p.v.fSl,orst. edli~cIim!~y/hydrucib~, including manigula- tions such as the one in the Fcrnow @errmental For- est in West Virgixzia, where at1 entire 34-ha fosested watershed was treated with ~ c e - a ~ b i e n t deposition of nitrogen and sulfur to evaluate the effects of elevated acidic deposition on forest ecosystem processes

brig-term decsrngasirisn studies, such as the 16-year Ef DET instaflcd at naaxly experimental farests (tt.rvw,fil, aat,edt1/~terJre~~arcI1/intrni~e?~8'det~ i t t 1 and the 21)0,-year fag decornpositiaisn study at the H, J. Andre;.brs Experimental Forest (Harmon 199 1)

The %rind River Canopy Crane, a 76-rn-tall eanstruc- tim crane that provides access for research within the canopy uF Wind River E-xpcrimenral Forest, a 2.3-ha, old-growth conifer forest in Washington (%haw et al. 2004, Suchanek et al. 2004; ~w,~vmhiybgtoa.e~JuJ rersmrcIz@elti/~r~~~e~It tad)

* Long-term observationd and experimental studies of soil restoration st h e C,kIhoun Experimen~d Forest %I- lowing abancianment after protracted ag&Atare for catton (Guss"~iwnr hirsuttim) md associated accelerated soil erosion (Richter and Markewitz 2001)

Fencing at the dandscape scale (e.g,, 104 squase Mome- ters) for eqerimentnl studies of species-species md species-hilbitat interactions invoking her& of large mamn~als, such as elk (Ct.rr$tis el~phusl, deer (Qdocoikus hemionus), and cattle (Bos taurtrs), and various forest and grazing manigernent sptems at Starkey hperirnentd Forest md Range fAdams et de 2004; mv.fi$cd+ tlsfprrtv/st@rkey)

Rerevance to seience, management, pdicy, and tke puMk These types of long-term studies have proved invaluable to both science and society because they have carlsistentiy pro- duced nav, important, and often unexpected findings (e.g., Likens 2004). Many environmend phenomena change grad- uaHy over time in response to natural forces, such as soil development and vegetation succession, and in response to human actionst such as changes in policies regulating natural resource management and chemical emissions to the atmosphere. The patterns and consequences of these incre- mental changes are revealed convincingly through long-term studies. The otperimentd forests and ranges network's long- term recards of environmental change and experiments are proving to be a great resource for addressing contemporary science questions. New questions are addressed using new tools (e.g., chemical analyses, statistical techniques) on studies set up in the network decades ago for other purposes.

Natural resource managemmt and policy at i o d , regional, and national scales has been profoundly affected by results of research from experimental forests and ranges. Studies that began as basic research, such as those on Life history characteristics of individual species (eg., the red cockaded wood- pecker, Picoides borealis, and northern spotted owl, Strix occidentalis cauriria), forest successian, air and streamwater chemistry, hydrological processes, the Character of old-growth forests, the roles of dad wood in forests aid stre- md bur- ricane disturbances, have yielded results of great social im- portance. Furthermore, important conceptual developments derived from studies at one location or in one forest type-- fur instance, variable density thinning in p u n g stands ta promote more complex struct ure-may find broad regional to national application. Even changes in federal legislation may have roots as simple as a chemical analysis of precipitation samples collected for decades at a backwoods rain gauge on an experimental forest (Likens 2004). The link between experimental forest research and public policy is significant enough to have m u r a g e d an examination of the roles of ex- perimenraj forest scientists in natwal resource decision- making (Lach et al. 2003).

Public outreach is an integral part of any large research program today, and especially so if the work is dose to the public's immediate interests. The public sees the national forests, drinks h7ater ffQm them, hikes in them, and hears debate about their use, so experimental forests and ranges can be a useful forum for communicating with the public about science and natural resources, Communication with the public can Lre as straightforward as the establishment and operation of an interpretive trail, such as the Management Loop Trail winding through an anay of forestry and wildlife nlitnagement demonstration a;rw of the Stephen F. Austin Ex- perimental Forest in Taw (tuww.srs&. usdadg.gov/wiIdlife/traiCC htm). Researchers and Iand managers working at aper i - mental forests and ranges conduct thuu.wds of tours annually for interested groups, communicate through the media, and create publications and Web sites for public use. Field tours

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and training programs fur practicing forest and watershed managers and other interested members sf the larger corn- rnunity art not only essential fur cummunicating science findings but also ianpcrrtant in helping the science and man- agcnlent communities to assess public attitudes about man- agemen t issues.

Primary$ secondary, postsecondary and continuing education program are integral componentf of experimental forest and rmge operations. CoUege theses and dissertations are also a major component of the science work at experimentd forests and ranges,

hercoming barriers to developing a functional rk of rssearch sites

Several barriers hinder pragress toward tbe gsd of developing ;us integrated national network sf research sites. These include (a) a limited history of nehvork research, (b) chronic undehnding of research infrastructure and data Inanage- meat, (c) difficulties in accessing data from independent site Bes, (d) an absence of Funding mechanisms for network research, and (rz) mistrust of manipulative research at large scales. These five impediments are significant and cannot be ignored However, they are not insurmountable, and must be resolved to assure that future research activity at networked sites iis as effective in addressing current and emerging challenges as p s t research at individual sites was in solving earlier resource management problems. Overcoming these barriers will require cooperation and collaboration both within the Forest Service and with external partners and leanstituents. In the pst: several decades, the Forest Service has made im-

portant a h m s in moving a subset of the experimental Sbrests and ranges tawad a functional network of ec:olae;ical observatories. As we have cammented, this has accurred mainly through cooperation with other networks (especially LTER, but also NASA). Notable aecomphshmtnts include data harvester systems (ClimDB, EfydmDB), hydrolegicd 5)TlthtZjtS (b$t C3 d. 1998, 811d JOWS ZOOJ, J0nm md 2004), and cross-site decornpositiofi experiments f Ckok et al. 2000). in these cases, the Forest Service contributed iong- term experiments and data sets, and links with policy and management; the other research programs, principally in- valving academics supparted by NSF funds, contributed the motivation and resources far intersite science. Both the Forest Service and collabrating program contributed science staff,

Data management is a major challenge to all ecological research in the United States, one that is a priority for NSF in its LTER net~vork. The Forest Service is collaborating with NSF to improve data management policies and procedures a both agencies focus on cross-site network research approaches. The NEON program affords a unique opportuniy to improve data management protocols for ecological networks supported by both agencies. The limitation of research funding is a gotrernment-wide issue. Given the general state of federal funding for research, the most robust rc-

search nectvorks w~U ulfimately be bujlt coupera~vely across programs and institutjons. PormslteIy? the limited funding for network hfiastmctwre h a had little effect on archived long-term data in Forest Service custody and in established lung-term field experiments,

Mistrust of manipulative studies often can be overcome with greater attention ta public participation in the research enterprise when developing research objectives and design, implementing experimental treatments, and sharing the in- terpretation and application of stuay results. Citizens fully in- Famed of the research goals and objectives of manipulative resea&, and invited to comment and participate in such research? have been supportive a f research a t qer imental fa rests.

Strengthenkg existing research capacity and apitdlizing an new initatives are factors that influence the path of future development of networks of ecolsgifal research sites. Far the experimental forests and ranges thmsdves, we enmzar- age developing the capacity of a selected subset of &me furst$ and ranges, partictilarb through greater use by. acid- emics and other agencies and through improvements in data management and access. Recent initiatives by the chief 05 the Forest Service on alien species invdsions, forest fires, un- mmaged mrearisn, and Isss of open spaces (Bosworth 2003, USBA FS 2004) all direct the Forest Senrice into cross-regional research programs with specific national-level objectks that should foster intersite research (USDA FS 2003,2005). New initiatives, such as NEON and CUAWSI, will benefit greatly by capitalizing on the infrastructure of place, k~o~vledge$ and data from key -mimental forests and ranges.

Canclusians The netwrk of experimental forests and ranges has many dis- tinctive, valuable% a d s ~ e r @ s ~ c c f i a m c t a ~ i a h a t could fa- cilitate hture b r o a M e re~;ueh effsrts. Many characteristics of these sites result &om the management of research properties with a long-term perspective. Among the important characteristics are these:

Long-term records of climate, vegetation, stream flow, and wildlife populations

* Archival records, kno~uledgeable staff, collections, and other information sources that coifectivrly document the bng-tern1 history of these places and ecosystems

Extensive geographic and ecalo&icd coverage in the United States and the Caribbean

Close refations with a land management organization, the National Fawest System, whose staff' can help ianple- m a t large-sale experiments a ~ d carry out Iilad n ~ m - agement operations, inform the science community af information needs, md test the UM of the fatest scientific findings

The presence both of areas open ta experimental manipuiation and of contrsI area oar most properties

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* Long-tern1 Imultidecade), large-scale n~ar~ipulatiw experiments

* A cadre af dedicated federal scientists and ttx&nical staff

X land base formally desiglated for research and in operation for many decades, reflectirlg an institutional commitment

inclusion w i t h ather reresearch and monitoshg networks, which. adds to the informatian base on the sites and their regional and globill cofitcas

* Education and public outreach programs, which con- tribute to the two-way BOW of information bemeen the technical comrrruni~ and the public

A carnnlitment to keeping the ~iefiv~rk in the public domain, whisk means that it L open to the public and that cn1labrr;seion with academia z ~ d other research organizations is encouraged

ltesearch conducted in exy erimentd forests and ranges has adapted o x r time in response to ehangng envir~nrnen- txl challenges, The philosophy at %he outset was to tackle land managenlent problems at the local scale at wXzich they occwred, as represcntd by the long-term experhe~ts f ~ c on different forest types and cuatersheds tl~ruza&out the country As the complexity of the en'1ironrnenu1 situation increased as a r.tzsulr of the larger-scale effixrs of human activity research focused a n whole landscapes and con~parative studies across laxadscapes, bVe anticipate a future with even more corny lex challenges, involving dimatic and global change, that brce the biota and edegical processes of the world to adjust to the new environments created by human activity

PVe bdieve the philosophy that created the experimera~l forests and ranges is just as relevant now as it was at the be- ginrringof the 2Qth century However, ta tackle national and gflsbd issues at the proper scale will require the whole nee\?rurk ta kmction as an integrated research platform. The network cot1tair.i~ many environmental gradients, such as the climatic one iUusrrated in figure 2, a d it is through long-term corn- parathe research across those gradients that scientists i d1 un- ravel the consequences of dimate change and other global change. Developing such integrated trr-rnscon~nentaf program of long-term ramrell, while majnt~~aixlg strength 8% tke iacal levels, is the next great challenge.

Critical en~erging research themes fir such a network will include the follawing:

* Long-term examinarisn sf the rules sf glsbd md climate change on carbon secpestsation, water yield, cliangts in biodiversity, ecosystem pruductivity, ax18 other ecosystem goods and services

* Long-term studies of siiviculture, hydrology, f i e eeda- gy9 and other aspects of vegetation change to explore afternative ways tu balance wood extraction, carbon sequestration, dec~eloyrnent of specific habitat cczndi-

tions fur species of fpecial interest, and restoration of degraded sites

Landscape change detection anitiysis and studies to understand the causes and coarsequences af landscape change, such as fragn~ent;ztiun, urbanization, hydrologi- ci11 alterations, a d patterns of species changes

Research on the response of forests and rangelarlds to disturbances, b t h naturd and anthrcapgenie, es provide greater insight when dealing with the expansion of invasive species

Through its network of experimental forests and ranges, the USDA Forest Service has provided sigificmt upportu- nity for constructive blending of top-down funding support and oversight of a large, hierarchical organization, while permitting a great deal of research initiative by individual scientists, teams, and sites. The nertvork of experimental forests and ranges serves as a useful model for development of Iong-term ecological and environmental observatories and as a prospective player in future networks.

Ac knowledme& This manuscript was developed in cooperation with the Uni- versity of Puerto Rico. We thank nke following Forest Service colleagues who sent us materials about their experimental forests and ranges: Connie Harrington and Sarah Greene (Pacific Northwest Research Station), %Yard McGugkey an8 Russell Graham (Rocky Mountain Station), M a w t S. Devall and John Barnett (Sorrrhern Research Station), and Jarna P. Brissette and Mde-Louise Smi th (Nod~east R w m h Station). Jim Reaves &om the USDA Forest Service Wash- ington Office shared data on experimental forests and ranges. Mildred Alay6n and Yasmeen Sands contributed to the pro- cessing and editing of the manuscript. 1% thank three anony- mous reviewers for their useful suggestions,

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