аЯрЁБс>ўџ )+ўџџџ(џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџьЅСM №ПŸbjbjт=т= €W€WŸ џџџџџџlBddddxB  2˜˜˜˜˜˜˜˜ѓѕѕѕѕѕѕ$в ђ l ˜˜˜˜˜ Ф˜˜. 6ФФФ˜˜˜ѓФ˜ѓФVФ“п˜Œ @’Њ2nСB"dЎЋпd <  Г,^ Ф^ пФ"4йThe FACE Network Bob Nowak and Stan Smith We present an overview of the 1822 non-agricultural FACE experiments, including a summary of their location, design, and data collection efforts. A majority of the FACE experiments are located in moist-temperate locations in the U.S. and Europe, primarily in forests and herb-dominated ecosystems, with outliers being in the desert of Nevada, chaparral of California, and tropical grassland of Australia. They are distributed fairly evenly between the Brookhaven-designed large FACE rings and the smaller mini-FACE design. A potential value of having the network is the ability to test universal hypotheses concerning ecosystem responses to elevated atmospheric CO2. An overview of several hypotheses, including physiological processes (e.g., photosynthetic capacity, down-regulation of photosynthesis), water and nitrogen availability, nutrient cycling, and biodiversity, serve as examples of different network approaches. Results compiled from available data suggest that: As hypothesized in the early elevated-CO2 literature, the productivity response to elevated CO2 increases from hydric to mesic to xeric ecosystems (i.e. with decreased water availability). However, the CO2 response is greatly diminished under conditions of extreme drought. The productivity response also increases with increased N availability. The nitrogen cycle, in the broad sense, changes in many ecosystems under elevated CO2, although the mechanistic reason for the change is not known. Therefore, extrapolations from current pool sizes and turnover rates for the nitrogen cycle to a future high CO2 world may not be valid. Two groups of plant species seem to be favored by elevated CO2: herbaceous dicots in grassland ecosystems, and invasive species in desert and forest ecosystems. To date, it has been encouraging that the results obtained from single-investigator studies from multiple FACE sites agree well with results compiled independently from the individual FACE site research teams. Because CO2 is often one of the most expensive on-going costs associated with FACE experiments, methods to conserve CO2 are continuing to be examined. Several areas of potential cost savings include (1) reassessment of the need to fumigate at night, (2) increased response time of pneumatic valves, and (3) increased turbulent mixing of CO2 and air upon exiting the stand-pipes. Finally, the benefits of current FACE experiments must be balanced against their necessarily artificial CO2-concentration step-change design. One way to address the step-change issue is through modeling and carefully standardized data collection across FACE sites. Therefore, increased efforts need to be made in the area of data collection, transmission, and archiving so that data sets can be made readily available to the research and modeling community. Currently, the best repositories for these data appear to be Brookhaven National Lab for operations data (CO2 use, climate, etc.) and CDIAC (Oak Ridge National Lab) for experimental data. A workshop among FACE PI’s will be scheduled in the near future to address CO2 use and data sharing in an effort to enhance the interactive capabilities of the FACE network. +JLNЦЧЬџ '(59O]^i‘“—КФХЦЬЭктцшь  X Y Z g l m Ў Џ ќѕюьхооеоЮхЮХЮОЗ­ЗІІŸ–ŸŸŸˆˆzzqHhr[fH* Hhr[f Hh r[f Hh r[f Hhr[fHhr[fH* Hhr[f Hh r[fHh r[f6] Hh r[f Hhr[fHhr[fH* Hhr[fHh r[fH* Hh r[f Hhr[fH* Hhr[f cHdhr[f5\++,9џ Z x  §јјієюІІІ^H & FC$EЦ€r[fH & FC$EЦ€ r[f„h`„h$a$ Ÿ§Џ О Щ Ъ б я ј   % . < E ^ _ w † Œ “ Е Ж И У Ъ с ћ   ѕ і a b ? @ б в  Ё>?ŸјёјёјјъјёъёјукуъгъгЪгУгУМЕуГГГГГГH* Hhr[f Hhr[f Hhr[fHhr[fH* Hhr[fHhr[fH* Hhr[f Hhr[f Hhr[f Hhr[f) ы g ŸКДД„h`„hDC$EЦ€r[fАа/ Ар=!А "А # $ %А i4@ёџ4 NormalCJ_HmH sH tH <A@ђџЁ< Default Paragraph Font*>@ђ* Title$a$5\<C@< Body Text Indent „h`„hŸ џџџџ џџ z™Ÿ +,9џZxыg Ё ˜0€€˜0€€˜0€€˜0€€˜0€€˜0€€˜ 0€€˜ 0€€˜ 0€€˜ 0€€š0€€˜0€€˜0€€Џ Ÿ  Ÿ Ÿ ntЁ Z e Ё :џџ Stan SmithMC:\WINDOWS\Application Data\Microsoft\Word\AutoRecovery save of Document1.asd Stan SmithA:\abstract.doe.doc Stan Smith C:\My Documents\abstract.doe.doc Stan SmithA:\abstract.doe.docRobert S. NowakbC:\Documents and Settings\bnowak\Application Data\Microsoft\Word\AutoRecovery save of abstract.doeRobert S. NowakFC:\Files\FACE\Posters&Abstracts\DOE Science Team 01\BNabstract.doe.docBiologyA:\abstrct.doe.doc—q%9А+ џџџџџџџџџ „а„˜ўЦа^„а`„˜ўOJQJo(З№ „„˜ўЦ^„`„˜ўOJQJo(o „и „˜ўЦи ^„и `„˜ўOJQJo(Ї№ „Ј „˜ўЦЈ ^„Ј `„˜ўOJQJo(З№ „x„˜ўЦx^„x`„˜ўOJQJo(o „H„˜ўЦH^„H`„˜ўOJQJo(Ї№ „„˜ўЦ^„`„˜ўOJQJo(З№ „ш„˜ўЦш^„ш`„˜ўOJQJo(o „И„˜ўЦИ^„И`„˜ўOJQJo(Ї№—q%9џџџџџџџџž`Ц         ыЁ џ@€д ЦŸ P@џџUnknownRobert S. 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