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108 results on '"Harmon, M. E."'

2. Consistent Land- and Atmosphere-Based U.S. Carbon Sink Estimates

Author

Pacala, S. W., Hurtt, G. C., Baker, D., Peylin, P., Houghton, R. A., Birdsey, R. A., Heath, L., Sundquist, E. T., Stallard, R. F., Ciais, P., Moorcroft, P., Caspersen, J. P., Shevliakova, E., Moore, B., Kohlmaier, G., Holland, E., Gloor, M., Harmon, M. E., Sarmiento, J. L., Goodale, C. L., Schimel, D., and Field, C. B.

Published
2001

3. Reconciling carbon-cycle concepts, terminology, and methods

Author

Chapin, F. S., Woodwell, G. M., Randerson, J. T., Rastetter, E. B., Lovett, G. M., Baldocchi, D. D., Clark, D. A., Harmon, M. E., Schimel, D. S., Valentini, R., Wirth, C., Aber, J. D., Cole, J. J., Goulden, M. L., Harden, J. W., Heimann, M., Howarth, R. W., Matson, P. A., McGuire, A. D., Melillo, J. M., Mooney, H. A., Neff, J. C., Houghton, R. A., Pace, M. L., Ryan, M. G., Running, S. W., Sala, O. E., Schlesinger, W. H., and Schulze, E.

Subjects
net ecosystem production, net ecosystem carbon balance, gross primary production, ecosystem respiration, autotrophic respiration, heterotrophic respiration, net ecosystem exchange, net biome production, net primary production
Abstract

Recent projections of climatic change have focused a great deal of scientific and public attention on patterns of carbon (C) cycling as well as its controls, particularly the factors that determine whether an ecosystem is a net source or sink of atmospheric carbon dioxide (CO2). Net ecosystem production (NEP), a central concept in C-cycling research, has been used by scientists to represent two different concepts. We propose that NEP be restricted to just one of its two original definitions-the imbalance between gross primary production (GPP) and ecosystem respiration (ER). We further propose that a new term-net ecosystem carbon balance (NECB)-be applied to the net rate of C accumulation in (or loss from [negative sign]) ecosystems. Net ecosystem carbon balance differs from NEP when C fluxes other than C fixation and respiration occur, or when inorganic C enters or leaves in dissolved form. These fluxes include the leaching loss or lateral transfer of C from the ecosystem; the emission of volatile organic C, methane, and carbon monoxide; and the release of soot and CO2 from fire. Carbon fluxes in addition to NEP are particularly important determinants of NECB over long time scales. However, even over short time scales, they are important in ecosystems such as streams, estuaries, wetlands, and cities. Recent technological advances have led to a diversity of approaches to the measurement of C fluxes at different temporal and spatial scales. These approaches frequently capture different components of NEP or NECB and can therefore be compared across scales only by carefully specifying the fluxes included in the measurements. By explicitly identifying the fluxes that comprise NECB and other components of the C cycle, such as net ecosystem exchange (NEE) and net biome production (NBP), we can provide a less ambiguous framework for understanding and communicating recent changes in the global C cycle.

Published
2006

10. Rate of tree carbon accumulation increases continuously with tree size

Author

Stephenson, N. L., Das, A. J., Condit, R., Russo, S. E., Baker, P. J., Beckman, N. G., Coomes, D. A., Lines, E. R., Morris, W. K., Rüger, N., Álvarez, E., Blundo, C., Bunyavejchewin, S., Chuyong, G., Davies, S. J., Duque, Á., Ewango, C. N., Flores, O., Franklin, J. F., Grau, H. R., Hao, Z., Harmon, M. E., Hubbell, S. P., Kenfack, D., Lin, Y., Makana, J.-R., Malizia, A., Malizia, L. R., Pabst, R. J., Pongpattananurak, N., Su, S.-H., Sun, I-F., Tan, S., Thomas, D., van Mantgem, P. J., Wang, X., Wiser, S. K., and Zavala, M. A.

Published
2014
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14. BioTIME : a database of biodiversity time series for the Anthropocene [data paper]

Author

Dornelas, M., Antao, L. H., Moyes, F., Bates, A. E., Magurran, A. E., Adam, D., Akhmetzhanova, A. A., Appeltans, W., Arcos, J. M., Arnold, H., Ayyappan, N., Badihi, G., Baird, A. H., Barbosa, M., Barreto, T. E., Baessler, C., Bellgrove, A., Belmaker, J., Benedetti-Cecchi, L., Bett, B. J., Bjorkman, A. D., Blazewicz, M., Blowes, S. A., Bloch, C. P., Bonebrake, T. C., Boyd, S., Bradford, M., Brooks, A. J., Brown, J. H., Bruelheide, H., Budy, P., Carvalho, F., Castaneda-Moya, E., Chen, C. A., Chamblee, J. F., Chase, T. J., Collier, L., Collinge, S. K., Condit, R., Cooper, E. J., Cornelissen, J. H. C., Cotano, U., Crow, S. K., Damasceno, G., Davies, C. H., Davis, R. A., Day, F. P., Degraer, S., Doherty, T. S., Dunn, T. E., Durigan, G., Duffy, J. E., Edelist, D., Edgar, G. J., Elahi, R., Elmendorf, S. C., Enemar, A., Ernest, S. K. M., Escribano, R., Estiarte, M., Evans, B. S., Fan, T. Y., Farah, F. T., Fernandes, L. L., Farneda, F. Z., Fidelis, A., Fitt, R., Fosaa, A. M., Franco, G. A. C., Frank, G. E., Fraser, W. R., Garcia, H., Gatti, R. C., Givan, O., Gorgone-Barbosa, E., Gould, W. A., Gries, C., Grossman, G. D., Gutierrez, J. R., Hale, S., Harmon, M. E., Harte, J., Haskins, G., Henshaw, D. L., Hermanutz, L., Hidalgo, P., Higuchi, P., Hoey, A., Hoey, G., Hofgaard, A., Holeck, K., Hollister, R. D., Holmes, R., Hoogenboom, M., Hsieh, C. H., Hubbell, S. P., Huettmann, F., Huffard, C. L., Hurlbert, A. H., Ivanauskas, N. M., Janik, D., Jandt, U., Jazdzewska, A., Johannessen, T., Johnstone, J., Jones, J., Jones, F. A. M., Kang, J., Kartawijaya, T., Keeley, C., Kelt, D. A., Kinnear, R., Klanderud, K., Knutsen, H., Koenig, C. C., Kortz, A. R., Kral, K., Kuhnz, L. A., Kuo, C. Y., Kushner, D. J., Laguionie-Marchais, C., Lancaster, L. T., Lee, C., Lefcheck, J. S., Levesque, E., Lightfoot, D., Lloret, F., Lloyd, J. D., Lopez-Baucells, A., Louzao, M., Madin, J. S., Magnusson, B., Malamud, S., Matthews, I., McFarland, K. P., McGill, B., McKnight, D., McLarney, W. O., Meador, J., Meserve, P. L., Metcalfe, D. J., Meyer, C. F. J., Michelsen, A., Milchakova, N., Moens, T., Moland, E., Moore, J., Moreira, C. M., Mueller, J., Murphy, G., Myers-Smith, I. H., Myster, R. W., Naumov, A., Neat, F., Nelson, J. A., Nelson, M., Newton, S. F., Norden, N., Oliver, J. C., Olsen, E. M., Onipchenko, V. G., Pabis, K., Pabst, R. J., Paquette, A., Pardede, S., Paterson, D. M., and Pélissier, Raphaël

Subjects
spatial, temporal, turnover, species richness, global, biodiversity
Abstract

Motivation: The BioTIME database contains raw data on species identities and abundances in ecological assemblages through time. These data enable users to calculate temporal trends in biodiversity within and amongst assemblages using a broad range of metrics. BioTIME is being developed as a community-led open-source database of biodiversity time series. Our goal is to accelerate and facilitate quantitative analysis of temporal patterns of biodiversity in the Anthropocene. Main types of variables included: The database contains 8,777,413 species abundance records, from assemblages consistently sampled for a minimum of 2 years, which need not necessarily be consecutive. In addition, the database contains metadata relating to sampling methodology and contextual information about each record. Spatial location and grain: BioTIME is a global database of 547,161 unique sampling locations spanning the marine, freshwater and terrestrial realms. Grain size varies across datasets from 0.0000000158 km(2) (158 cm(2)) to 100 km(2) (1,000,000,000,000 cm(2)). Time period and grainBio: TIME records span from 1874 to 2016. The minimal temporal grain across all datasets in BioTIME is a year. Major taxa and level of measurement: BioTIME includes data from 44,440 species across the plant and animal kingdoms, ranging from plants, plankton and terrestrial invertebrates to small and large vertebrates.

Published
2018

15. BioTIME:a database of biodiversity time series for the Anthropocene

Author

Dornelas, M. (Maria), Antao, L. H. (Laura H.), Moyes, F. (Faye), Bates, A. E. (Amanda E.), Magurran, A. E. (Anne E.), Adam, D. (Dusan), Akhmetzhanova, A. A. (Asem A.), Appeltans, W. (Ward), Arcos, J. M. (Jose Manuel), Arnold, H. (Haley), Ayyappan, N. (Narayanan), Badihi, G. (Gal), Baird, A. H. (Andrew H.), Barbosa, M. (Miguel), Barreto, T. E. (Tiago Egydio), Baessler, C. (Claus), Bellgrove, A. (Alecia), Belmaker, J. (Jonathan), Benedetti-Cecchi, L. (Lisandro), Bett, B. J. (Brian J.), Bjorkman, A. D. (Anne D.), Blazewicz, M. (Magdalena), Blowes, S. A. (Shane A.), Bloch, C. P. (Christopher P.), Bonebrake, T. C. (Timothy C.), Boyd, S. (Susan), Bradford, M. (Matt), Brooks, A. J. (Andrew J.), Brown, J. H. (James H.), Bruelheide, H. (Helge), Budy, P. (Phaedra), Carvalho, F. (Fernando), Castaneda-Moya, E. (Edward), Chen, C. A. (Chaolun Allen), Chamblee, J. F. (John F.), Chase, T. J. (Tory J.), Siegwart Collier, L. (Laura), Collinge, S. K. (Sharon K.), Condit, R. (Richard), Cooper, E. J. (Elisabeth J.), Cornelissen, J. H. (J. Hans C.), Cotano, U. (Unai), Crow, S. K. (Shannan Kyle), Damasceno, G. (Gabriella), Davies, C. H. (Claire H.), Davis, R. A. (Robert A.), Day, F. P. (Frank P.), Degraer, S. (Steven), Doherty, T. S. (Tim S.), Dunn, T. E. (Timothy E.), Durigan, G. (Giselda), Duffy, J. E. (J. Emmett), Edelist, D. (Dor), Edgar, G. J. (Graham J.), Elahi, R. (Robin), Elmendorf, S. C. (Sarah C.), Enemar, A. (Anders), Ernest, S. K. (S. K. Morgan), Escribano, R. (Ruben), Estiarte, M. (Marc), Evans, B. S. (Brian S.), Fan, T.-Y. (Tung-Yung), Farah, F. T. (Fabiano Turini), Fernandes, L. L. (Luiz Loureiro), Farneda, F. Z. (Fabio Z.), Fidelis, A. (Alessandra), Fitt, R. (Robert), Fosaa, A. M. (Anna Maria), Daher Correa Franco, G. A. (Geraldo Antonio), Frank, G. E. (Grace E.), Fraser, W. R. (William R.), Garcia, H. (Hernando), Gatti, R. C. (Roberto Cazzolla), Givan, O. (Or), Gorgone-Barbosa, E. (Elizabeth), Gould, W. A. (William A.), Gries, C. (Corinna), Grossman, G. D. (Gary D.), Gutierrez, J. R. (Julio R.), Hale, S. (Stephen), Harmon, M. E. (Mark E.), Harte, J. (John), Haskins, G. (Gary), Henshaw, D. L. (Donald L.), Hermanutz, L. (Luise), Hidalgo, P. (Pamela), Higuchi, P. (Pedro), Hoey, A. (Andrew), Van Hoey, G. (Gert), Hofgaard, A. (Annika), Holeck, K. (Kristen), Hollister, R. D. (Robert D.), Holmes, R. (Richard), Hoogenboom, M. (Mia), Hsieh, C.-h. (Chih-hao), Hubbell, S. P. (Stephen P.), Huettmann, F. (Falk), Huffard, C. L. (Christine L.), Hurlbert, A. H. (Allen H.), Ivanauskas, N. M. (Natalia Macedo), Janik, D. (David), Jandt, U. (Ute), Jazdzewska, A. (Anna), Johannessen, T. (Tore), Johnstone, J. (Jill), Jones, J. (Julia), Jones, F. A. (Faith A. M.), Kang, J. (Jungwon), Kartawijaya, T. (Tasrif), Keeley, E. C. (Erin C.), Kelt, D. A. (Douglas A.), Kinnear, R. (Rebecca), Klanderud, K. (Kari), Knutsen, H. (Halvor), Koenig, C. C. (Christopher C.), Kortz, A. R. (Alessandra R.), Kral, K. (Kamil), Kuhnz, L. A. (Linda A.), Kuo, C.-Y. (Chao-Yang), Kushner, D. J. (David J.), Laguionie-Marchais, C. (Claire), Lancaster, L. T. (Lesley T.), Min Lee, C. (Cheol), Lefcheck, J. S. (Jonathan S.), Levesque, E. (Esther), Lightfoot, D. (David), Lloret, F. (Francisco), Lloyd, J. D. (John D.), Lopez-Baucells, A. (Adria), Louzao, M. (Maite), Madin, J. S. (Joshua S.), Magnusson, B. (Borgpor), Malamud, S. (Shahar), Matthews, I. (Iain), McFarland, K. P. (Kent P.), McGill, B. (Brian), McKnight, D. (Diane), McLarney, W. O. (William O.), Meador, J. (Jason), Meserve, P. L. (Peter L.), Metcalfe, D. J. (Daniel J.), Meyer, C. F. (Christoph F. J.), Michelsen, A. (Anders), Milchakova, N. (Nataliya), Moens, T. (Tom), Moland, E. (Even), Moore, J. (Jon), Moreira, C. M. (Carolina Mathias), Mueller, J. (Joerg), Murphy, G. (Grace), Myers-Smith, I. H. (Isla H.), Myster, R. W. (Randall W.), Naumov, A. (Andrew), Neat, F. (Francis), Nelson, J. A. (James A.), Paul Nelson, M. (Michael), Newton, S. F. (Stephen F.), Norden, N. (Natalia), Oliver, J. C. (Jeffrey C.), Olsen, E. M. (Esben M.), Onipchenko, V. G. (Vladimir G.), Pabis, K. (Krzysztof), Pabst, R. J. (Robert J.), Paquette, A. (Alain), Pardede, S. (Sinta), Paterson, D. M. (David M.), Pelissier, R. (Raphael), Penuelas, J. (Josep), Perez-Matus, A. (Alejandro), Pizarro, O. (Oscar), Pomati, F. (Francesco), Post, E. (Eric), Prins, H. H. (Herbert H. T.), Priscu, J. C. (John C.), Provoost, P. (Pieter), Prudic, K. L. (Kathleen L.), Erkki, P. (Pulliainen), Ramesh, B. R. (B. R.), Mendivil Ramos, O. (Olivia), Rassweiler, A. (Andrew), Rebelo, J. E. (Jose Eduardo), Reed, D. C. (Daniel C.), Reich, P. B. (Peter B.), Remillard, S. M. (Suzanne M.), Richardson, A. J. (Anthony J.), Richardson, J. P. (J. Paul), van Rijn, I. (Itai), Rocha, R. (Ricardo), Rivera-Monroy, V. H. (Victor H.), Rixen, C. (Christian), Robinson, K. P. (Kevin P.), Rodrigues, R. R. (Ricardo Ribeiro), Rossa-Feres, D. d. (Denise de Cerqueira), Rudstam, L. (Lars), Ruhl, H. (Henry), Ruz, C. S. (Catalina S.), Sampaio, E. M. (Erica M.), Rybicki, N. (Nancy), Rypel, A. (Andrew), Sal, S. (Sofia), Salgado, B. (Beatriz), Santos, F. A. (Flavio A. M.), Savassi-Coutinho, A. P. (Ana Paula), Scanga, S. (Sara), Schmidt, J. (Jochen), Schooley, R. (Robert), Setiawan, F. (Fakhrizal), Shao, K.-T. (Kwang-Tsao), Shaver, G. R. (Gaius R.), Sherman, S. (Sally), Sherry, T. W. (Thomas W.), Sicinski, J. (Jacek), Sievers, C. (Caya), da Silva, A. C. (Ana Carolina), da Silva, F. R. (Fernando Rodrigues), Silveira, F. L. (Fabio L.), Slingsby, J. (Jasper), Smart, T. (Tracey), Snell, S. J. (Sara J.), Soudzilovskaia, N. A. (Nadejda A.), Souza, G. B. (Gabriel B. G.), Souza, F. M. (Flaviana Maluf), Souza, V. C. (Vinicius Castro), Stallings, C. D. (Christopher D.), Stanforth, R. (Rowan), Stanley, E. H. (Emily H.), Sterza, J. M. (Jose Mauro), Stevens, M. (Maarten), Stuart-Smith, R. (Rick), Rondon Suarez, Y. (Yzel), Supp, S. (Sarah), Yoshio Tamashiro, J. (Jorge), Tarigan, S. (Sukmaraharja), Thiede, G. P. (Gary P.), Thorn, S. (Simon), Tolvanen, A. (Anne), Zugliani Toniato, M. T. (Maria Teresa), Totland, O. (Orjan), Twilley, R. R. (Robert R.), Vaitkus, G. (Gediminas), Valdivia, N. (Nelson), Vallejo, M. I. (Martha Isabel), Valone, T. J. (Thomas J.), Van Colen, C. (Carl), Vanaverbeke, J. (Jan), Venturoli, F. (Fabio), Verheye, H. M. (Hans M.), Vianna, M. (Marcelo), Vieira, R. P. (Rui P.), Vrska, T. (Tomas), Vu, C. Q. (Con Quang), Vu, L. V. (Lien Van), Waide, R. B. (Robert B.), Waldock, C. (Conor), Watts, D. (Dave), Webb, S. (Sara), Wesolowski, T. (Tomasz), White, E. P. (Ethan P.), Widdicombe, C. E. (Claire E.), Wilgers, D. (Dustin), Williams, R. (Richard), Williams, S. B. (Stefan B.), Williamson, M. (Mark), Willig, M. R. (Michael R.), Willis, T. J. (Trevor J.), Wipf, S. (Sonja), Woods, K. D. (Kerry D.), Woehler, E. J. (Eric J.), Zawada, K. (Kyle), Zettler, M. L. (Michael L.), Dornelas, M. (Maria), Antao, L. H. (Laura H.), Moyes, F. (Faye), Bates, A. E. (Amanda E.), Magurran, A. E. (Anne E.), Adam, D. (Dusan), Akhmetzhanova, A. A. (Asem A.), Appeltans, W. (Ward), Arcos, J. M. (Jose Manuel), Arnold, H. (Haley), Ayyappan, N. (Narayanan), Badihi, G. (Gal), Baird, A. H. (Andrew H.), Barbosa, M. (Miguel), Barreto, T. E. (Tiago Egydio), Baessler, C. (Claus), Bellgrove, A. (Alecia), Belmaker, J. (Jonathan), Benedetti-Cecchi, L. (Lisandro), Bett, B. J. (Brian J.), Bjorkman, A. D. (Anne D.), Blazewicz, M. (Magdalena), Blowes, S. A. (Shane A.), Bloch, C. P. (Christopher P.), Bonebrake, T. C. (Timothy C.), Boyd, S. (Susan), Bradford, M. (Matt), Brooks, A. J. (Andrew J.), Brown, J. H. (James H.), Bruelheide, H. (Helge), Budy, P. (Phaedra), Carvalho, F. (Fernando), Castaneda-Moya, E. (Edward), Chen, C. A. (Chaolun Allen), Chamblee, J. F. (John F.), Chase, T. J. (Tory J.), Siegwart Collier, L. (Laura), Collinge, S. K. (Sharon K.), Condit, R. (Richard), Cooper, E. J. (Elisabeth J.), Cornelissen, J. H. (J. Hans C.), Cotano, U. (Unai), Crow, S. K. (Shannan Kyle), Damasceno, G. (Gabriella), Davies, C. H. (Claire H.), Davis, R. A. (Robert A.), Day, F. P. (Frank P.), Degraer, S. (Steven), Doherty, T. S. (Tim S.), Dunn, T. E. (Timothy E.), Durigan, G. (Giselda), Duffy, J. E. (J. Emmett), Edelist, D. (Dor), Edgar, G. J. (Graham J.), Elahi, R. (Robin), Elmendorf, S. C. (Sarah C.), Enemar, A. (Anders), Ernest, S. K. (S. K. Morgan), Escribano, R. (Ruben), Estiarte, M. (Marc), Evans, B. S. (Brian S.), Fan, T.-Y. (Tung-Yung), Farah, F. T. (Fabiano Turini), Fernandes, L. L. (Luiz Loureiro), Farneda, F. Z. (Fabio Z.), Fidelis, A. (Alessandra), Fitt, R. (Robert), Fosaa, A. M. (Anna Maria), Daher Correa Franco, G. A. (Geraldo Antonio), Frank, G. E. (Grace E.), Fraser, W. R. (William R.), Garcia, H. (Hernando), Gatti, R. C. (Roberto Cazzolla), Givan, O. (Or), Gorgone-Barbosa, E. (Elizabeth), Gould, W. A. (William A.), Gries, C. (Corinna), Grossman, G. D. (Gary D.), Gutierrez, J. R. (Julio R.), Hale, S. (Stephen), Harmon, M. E. (Mark E.), Harte, J. (John), Haskins, G. (Gary), Henshaw, D. L. (Donald L.), Hermanutz, L. (Luise), Hidalgo, P. (Pamela), Higuchi, P. (Pedro), Hoey, A. (Andrew), Van Hoey, G. (Gert), Hofgaard, A. (Annika), Holeck, K. (Kristen), Hollister, R. D. (Robert D.), Holmes, R. (Richard), Hoogenboom, M. (Mia), Hsieh, C.-h. (Chih-hao), Hubbell, S. P. (Stephen P.), Huettmann, F. (Falk), Huffard, C. L. (Christine L.), Hurlbert, A. H. (Allen H.), Ivanauskas, N. M. (Natalia Macedo), Janik, D. (David), Jandt, U. (Ute), Jazdzewska, A. (Anna), Johannessen, T. (Tore), Johnstone, J. (Jill), Jones, J. (Julia), Jones, F. A. (Faith A. M.), Kang, J. (Jungwon), Kartawijaya, T. (Tasrif), Keeley, E. C. (Erin C.), Kelt, D. A. (Douglas A.), Kinnear, R. (Rebecca), Klanderud, K. (Kari), Knutsen, H. (Halvor), Koenig, C. C. (Christopher C.), Kortz, A. R. (Alessandra R.), Kral, K. (Kamil), Kuhnz, L. A. (Linda A.), Kuo, C.-Y. (Chao-Yang), Kushner, D. J. (David J.), Laguionie-Marchais, C. (Claire), Lancaster, L. T. (Lesley T.), Min Lee, C. (Cheol), Lefcheck, J. S. (Jonathan S.), Levesque, E. (Esther), Lightfoot, D. (David), Lloret, F. (Francisco), Lloyd, J. D. (John D.), Lopez-Baucells, A. (Adria), Louzao, M. (Maite), Madin, J. S. (Joshua S.), Magnusson, B. (Borgpor), Malamud, S. (Shahar), Matthews, I. (Iain), McFarland, K. P. (Kent P.), McGill, B. (Brian), McKnight, D. (Diane), McLarney, W. O. (William O.), Meador, J. (Jason), Meserve, P. L. (Peter L.), Metcalfe, D. J. (Daniel J.), Meyer, C. F. (Christoph F. J.), Michelsen, A. (Anders), Milchakova, N. (Nataliya), Moens, T. (Tom), Moland, E. (Even), Moore, J. (Jon), Moreira, C. M. (Carolina Mathias), Mueller, J. (Joerg), Murphy, G. (Grace), Myers-Smith, I. H. (Isla H.), Myster, R. W. (Randall W.), Naumov, A. (Andrew), Neat, F. (Francis), Nelson, J. A. (James A.), Paul Nelson, M. (Michael), Newton, S. F. (Stephen F.), Norden, N. (Natalia), Oliver, J. C. (Jeffrey C.), Olsen, E. M. (Esben M.), Onipchenko, V. G. (Vladimir G.), Pabis, K. (Krzysztof), Pabst, R. J. (Robert J.), Paquette, A. (Alain), Pardede, S. (Sinta), Paterson, D. M. (David M.), Pelissier, R. (Raphael), Penuelas, J. (Josep), Perez-Matus, A. (Alejandro), Pizarro, O. (Oscar), Pomati, F. (Francesco), Post, E. (Eric), Prins, H. H. (Herbert H. T.), Priscu, J. C. (John C.), Provoost, P. (Pieter), Prudic, K. L. (Kathleen L.), Erkki, P. (Pulliainen), Ramesh, B. R. (B. R.), Mendivil Ramos, O. (Olivia), Rassweiler, A. (Andrew), Rebelo, J. E. (Jose Eduardo), Reed, D. C. (Daniel C.), Reich, P. B. (Peter B.), Remillard, S. M. (Suzanne M.), Richardson, A. J. (Anthony J.), Richardson, J. P. (J. Paul), van Rijn, I. (Itai), Rocha, R. (Ricardo), Rivera-Monroy, V. H. (Victor H.), Rixen, C. (Christian), Robinson, K. P. (Kevin P.), Rodrigues, R. R. (Ricardo Ribeiro), Rossa-Feres, D. d. (Denise de Cerqueira), Rudstam, L. (Lars), Ruhl, H. (Henry), Ruz, C. S. (Catalina S.), Sampaio, E. M. (Erica M.), Rybicki, N. (Nancy), Rypel, A. (Andrew), Sal, S. (Sofia), Salgado, B. (Beatriz), Santos, F. A. (Flavio A. M.), Savassi-Coutinho, A. P. (Ana Paula), Scanga, S. (Sara), Schmidt, J. (Jochen), Schooley, R. (Robert), Setiawan, F. (Fakhrizal), Shao, K.-T. (Kwang-Tsao), Shaver, G. R. (Gaius R.), Sherman, S. (Sally), Sherry, T. W. (Thomas W.), Sicinski, J. (Jacek), Sievers, C. (Caya), da Silva, A. C. (Ana Carolina), da Silva, F. R. (Fernando Rodrigues), Silveira, F. L. (Fabio L.), Slingsby, J. (Jasper), Smart, T. (Tracey), Snell, S. J. (Sara J.), Soudzilovskaia, N. A. (Nadejda A.), Souza, G. B. (Gabriel B. G.), Souza, F. M. (Flaviana Maluf), Souza, V. C. (Vinicius Castro), Stallings, C. D. (Christopher D.), Stanforth, R. (Rowan), Stanley, E. H. (Emily H.), Sterza, J. M. (Jose Mauro), Stevens, M. (Maarten), Stuart-Smith, R. (Rick), Rondon Suarez, Y. (Yzel), Supp, S. (Sarah), Yoshio Tamashiro, J. (Jorge), Tarigan, S. (Sukmaraharja), Thiede, G. P. (Gary P.), Thorn, S. (Simon), Tolvanen, A. (Anne), Zugliani Toniato, M. T. (Maria Teresa), Totland, O. (Orjan), Twilley, R. R. (Robert R.), Vaitkus, G. (Gediminas), Valdivia, N. (Nelson), Vallejo, M. I. (Martha Isabel), Valone, T. J. (Thomas J.), Van Colen, C. (Carl), Vanaverbeke, J. (Jan), Venturoli, F. (Fabio), Verheye, H. M. (Hans M.), Vianna, M. (Marcelo), Vieira, R. P. (Rui P.), Vrska, T. (Tomas), Vu, C. Q. (Con Quang), Vu, L. V. (Lien Van), Waide, R. B. (Robert B.), Waldock, C. (Conor), Watts, D. (Dave), Webb, S. (Sara), Wesolowski, T. (Tomasz), White, E. P. (Ethan P.), Widdicombe, C. E. (Claire E.), Wilgers, D. (Dustin), Williams, R. (Richard), Williams, S. B. (Stefan B.), Williamson, M. (Mark), Willig, M. R. (Michael R.), Willis, T. J. (Trevor J.), Wipf, S. (Sonja), Woods, K. D. (Kerry D.), Woehler, E. J. (Eric J.), Zawada, K. (Kyle), and Zettler, M. L. (Michael L.)

Abstract

Motivation: The BioTIME database contains raw data on species identities and abundances in ecological assemblages through time. These data enable users to calculate temporal trends in biodiversity within and amongst assemblages using a broad range of metrics. BioTIME is being developed as a community‐led open‐source database of biodiversity time series. Our goal is to accelerate and facilitate quantitative analysis of temporal patterns of biodiversity in the Anthropocene. Main types of variables included: The database contains 8,777,413 species abundance records, from assemblages consistently sampled for a minimum of 2 years, which need not necessarily be consecutive. In addition, the database contains metadata relating to sampling methodology and contextual information about each record. Spatial location and grain: BioTIME is a global database of 547,161 unique sampling locations spanning the marine, freshwater and terrestrial realms. Grain size varies across datasets from 0.0000000158 km² (158 cm²) to 100 km² (1,000,000,000,000 cm²). Time period and grain: BioTIME records span from 1874 to 2016. The minimal temporal grain across all datasets in BioTIME is a year. Major taxa and level of measurement: BioTIME includes data from 44,440 species across the plant and animal kingdoms, ranging from plants, plankton and terrestrial invertebrates to small and large vertebrates. Software format: .csv and .SQL.

Published
2018

16. BioTIME: A database of biodiversity time series for the Anthropocene

Author

Dornelas, M., Antão, L. H., Moyes, F., Bates, A. E., Magurran, A. E., Adam, D., Akhmetzhanova, A. A., Appeltans, W., Arcos, J. M., Arnold, H., Ayyappan, N., Badihi, G., Baird, A. H., Barbosa, M., Barreto, T. E., Bässler, C., Bellgrove, A., Belmaker, J., Benedetti-Cecchi, L., Bett, B. J., Bjorkman, A. D., Błażewicz, M., Blowes, S. A., Bloch, C. P., Bonebrake, T. C., Boyd, S., Bradford, M., Brooks, A. J., Brown, J. H., Bruelheide, H., Budy, P., Carvalho, F., Castañeda-Moya, E., Chen, C. A., Chamblee, J. F., Chase, T. J., Siegwart Collier, L., Collinge, S. K., Condit, R., Cooper, E. J., Cornelissen, J. H. C., Cotano, U., Kyle Crow, S., Damasceno, G., Davies, C. H., Davis, R. A., Day, F. P., Degraer, S., Doherty, T. S., Dunn, T. E., Durigan, G., Duffy, J. E., Edelist, D., Edgar, G. J., Elahi, R., Elmendorf, S. C., Enemar, A., Ernest, S. K. M., Escribano, R., Estiarte, M., Evans, B. S., Fan, T. Y., Turini Farah, F., Loureiro Fernandes, L., Farneda, F. Z., Fidelis, A., Fitt, R., Fosaa, A. M., Daher Correa Franco, G. A., Frank, G. E., Fraser, W. R., García, H., Cazzolla Gatti, R., Givan, O., Gorgone-Barbosa, E., Gould, W. A., Gries, C., Grossman, G. D., Gutierréz, J. R., Hale, S., Harmon, M. E., Harte, J., Haskins, G., Henshaw, D. L., Hermanutz, L., Hidalgo, P., Higuchi, P., Hoey, A., Van Hoey, G., Hofgaard, A., Holeck, K., Hollister, R. D., Holmes, R., Hoogenboom, M., Hsieh, C. H., Hubbell, S. P., Huettmann, F., Huffard, C. L., Hurlbert, A. H., Macedo Ivanauskas, N., Janík, D., Jandt, U., Jażdżewska, A., Johannessen, T., Johnstone, J., Jones, J., Jones, F. A. M., Kang, J., Kartawijaya, T., Keeley, E. C., Kelt, D. A., Kinnear, R., Klanderud, K., Knutsen, H., Koenig, C. C., Kortz, A. R., Král, K., Kuhnz, L. A., Kuo, C. Y., Kushner, D. J., Laguionie-Marchais, C., Lancaster, L. T., Min Lee, C., Lefcheck, J. S., Lévesque, E., Lightfoot, D., Lloret, F., Lloyd, J. D., López-Baucells, A., Louzao, M., Madin, J. S., Magnússon, B., Malamud, S., Matthews, I., McFarland, K. P., McGill, B., McKnight, D., McLarney, W. O., Meador, J., Meserve, P. L., Metcalfe, D. J., Meyer, C. F. J., Michelsen, A., Milchakova, N., Moens, T., Moland, E., Moore, J., Mathias Moreira, C., Müller, J., Murphy, G., Myers-Smith, I. H., Myster, R. W., Naumov, A., Neat, F., Nelson, J. A., Paul Nelson, M., Newton, S. F., Norden, N., Oliver, J. C., Olsen, E. M., Onipchenko, V. G., Pabis, K., Pabst, R. J., Paquette, A., Pardede, S., Paterson, D. M., Pélissier, R., Peñuelas, J., Pérez-Matus, A., Pizarro, O., Pomati, F., Post, E., Prins, H. H. T., Priscu, J. C., Provoost, P., Prudic, K. L., Pulliainen, E., Ramesh, B. R., Mendivil Ramos, O., Rassweiler, A., Rebelo, J. E., Reed, D. C., Reich, P. B., Remillard, S. M., Richardson, A. J., Richardson, J. P., van Rijn, I., Rocha, R., Rivera-Monroy, V. H., Rixen, C., Robinson, K. P., Ribeiro Rodrigues, R., de Cerqueira Rossa-Feres, D., Rudstam, L., Ruhl, H., Ruz, C. S., Sampaio, E. M., Rybicki, N., Rypel, A., Sal, S., Salgado, B., Santos, F. A. M., Savassi-Coutinho, A. P., Scanga, S., Schmidt, J., Schooley, R., Setiawan, F., Shao, K. T., Shaver, G. R., Sherman, S., Sherry, T. W., Siciński, J., Sievers, C., da Silva, A. C., Rodrigues da Silva, F., Silveira, F. L., Slingsby, J., Smart, T., Snell, S. J., Soudzilovskaia, N. A., Souza, G. B. G., Maluf Souza, F., Castro Souza, V., Stallings, C. D., Stanforth, R., Stanley, E. H., Mauro Sterza, J., Stevens, M., Stuart-Smith, R., Rondon Suarez, Y., Supp, S., Yoshio Tamashiro, J., Tarigan, S., Thiede, G. P., Thorn, S., Tolvanen, A., Teresa Zugliani Toniato, M., Totland, Ø, Twilley, R. R., Vaitkus, G., Valdivia, N., Vallejo, M. I., Valone, T. J., Van Colen, C., Vanaverbeke, J., Venturoli, F., Verheye, H. M., Vianna, M., Vieira, R. P., Vrška, T., Quang Vu, C., Van Vu, L., Waide, R. B., Waldock, C., Watts, D., Webb, S., Wesołowski, T., White, E. P., Widdicombe, C. E., Wilgers, D., Williams, R., Williams, S. B., Williamson, M., Willig, M. R., Willis, T. J., Wipf, S., Woods, K. D., Woehler, E. J., Zawada, K., Zettler, M. L., Dornelas, M., Antão, L. H., Moyes, F., Bates, A. E., Magurran, A. E., Adam, D., Akhmetzhanova, A. A., Appeltans, W., Arcos, J. M., Arnold, H., Ayyappan, N., Badihi, G., Baird, A. H., Barbosa, M., Barreto, T. E., Bässler, C., Bellgrove, A., Belmaker, J., Benedetti-Cecchi, L., Bett, B. J., Bjorkman, A. D., Błażewicz, M., Blowes, S. A., Bloch, C. P., Bonebrake, T. C., Boyd, S., Bradford, M., Brooks, A. J., Brown, J. H., Bruelheide, H., Budy, P., Carvalho, F., Castañeda-Moya, E., Chen, C. A., Chamblee, J. F., Chase, T. J., Siegwart Collier, L., Collinge, S. K., Condit, R., Cooper, E. J., Cornelissen, J. H. C., Cotano, U., Kyle Crow, S., Damasceno, G., Davies, C. H., Davis, R. A., Day, F. P., Degraer, S., Doherty, T. S., Dunn, T. E., Durigan, G., Duffy, J. E., Edelist, D., Edgar, G. J., Elahi, R., Elmendorf, S. C., Enemar, A., Ernest, S. K. M., Escribano, R., Estiarte, M., Evans, B. S., Fan, T. Y., Turini Farah, F., Loureiro Fernandes, L., Farneda, F. Z., Fidelis, A., Fitt, R., Fosaa, A. M., Daher Correa Franco, G. A., Frank, G. E., Fraser, W. R., García, H., Cazzolla Gatti, R., Givan, O., Gorgone-Barbosa, E., Gould, W. A., Gries, C., Grossman, G. D., Gutierréz, J. R., Hale, S., Harmon, M. E., Harte, J., Haskins, G., Henshaw, D. L., Hermanutz, L., Hidalgo, P., Higuchi, P., Hoey, A., Van Hoey, G., Hofgaard, A., Holeck, K., Hollister, R. D., Holmes, R., Hoogenboom, M., Hsieh, C. H., Hubbell, S. P., Huettmann, F., Huffard, C. L., Hurlbert, A. H., Macedo Ivanauskas, N., Janík, D., Jandt, U., Jażdżewska, A., Johannessen, T., Johnstone, J., Jones, J., Jones, F. A. M., Kang, J., Kartawijaya, T., Keeley, E. C., Kelt, D. A., Kinnear, R., Klanderud, K., Knutsen, H., Koenig, C. C., Kortz, A. R., Král, K., Kuhnz, L. A., Kuo, C. Y., Kushner, D. J., Laguionie-Marchais, C., Lancaster, L. T., Min Lee, C., Lefcheck, J. S., Lévesque, E., Lightfoot, D., Lloret, F., Lloyd, J. D., López-Baucells, A., Louzao, M., Madin, J. S., Magnússon, B., Malamud, S., Matthews, I., McFarland, K. P., McGill, B., McKnight, D., McLarney, W. O., Meador, J., Meserve, P. L., Metcalfe, D. J., Meyer, C. F. J., Michelsen, A., Milchakova, N., Moens, T., Moland, E., Moore, J., Mathias Moreira, C., Müller, J., Murphy, G., Myers-Smith, I. H., Myster, R. W., Naumov, A., Neat, F., Nelson, J. A., Paul Nelson, M., Newton, S. F., Norden, N., Oliver, J. C., Olsen, E. M., Onipchenko, V. G., Pabis, K., Pabst, R. J., Paquette, A., Pardede, S., Paterson, D. M., Pélissier, R., Peñuelas, J., Pérez-Matus, A., Pizarro, O., Pomati, F., Post, E., Prins, H. H. T., Priscu, J. C., Provoost, P., Prudic, K. L., Pulliainen, E., Ramesh, B. R., Mendivil Ramos, O., Rassweiler, A., Rebelo, J. E., Reed, D. C., Reich, P. B., Remillard, S. M., Richardson, A. J., Richardson, J. P., van Rijn, I., Rocha, R., Rivera-Monroy, V. H., Rixen, C., Robinson, K. P., Ribeiro Rodrigues, R., de Cerqueira Rossa-Feres, D., Rudstam, L., Ruhl, H., Ruz, C. S., Sampaio, E. M., Rybicki, N., Rypel, A., Sal, S., Salgado, B., Santos, F. A. M., Savassi-Coutinho, A. P., Scanga, S., Schmidt, J., Schooley, R., Setiawan, F., Shao, K. T., Shaver, G. R., Sherman, S., Sherry, T. W., Siciński, J., Sievers, C., da Silva, A. C., Rodrigues da Silva, F., Silveira, F. L., Slingsby, J., Smart, T., Snell, S. J., Soudzilovskaia, N. A., Souza, G. B. G., Maluf Souza, F., Castro Souza, V., Stallings, C. D., Stanforth, R., Stanley, E. H., Mauro Sterza, J., Stevens, M., Stuart-Smith, R., Rondon Suarez, Y., Supp, S., Yoshio Tamashiro, J., Tarigan, S., Thiede, G. P., Thorn, S., Tolvanen, A., Teresa Zugliani Toniato, M., Totland, Ø, Twilley, R. R., Vaitkus, G., Valdivia, N., Vallejo, M. I., Valone, T. J., Van Colen, C., Vanaverbeke, J., Venturoli, F., Verheye, H. M., Vianna, M., Vieira, R. P., Vrška, T., Quang Vu, C., Van Vu, L., Waide, R. B., Waldock, C., Watts, D., Webb, S., Wesołowski, T., White, E. P., Widdicombe, C. E., Wilgers, D., Williams, R., Williams, S. B., Williamson, M., Willig, M. R., Willis, T. J., Wipf, S., Woods, K. D., Woehler, E. J., Zawada, K., and Zettler, M. L.

Abstract

Motivation: The BioTIME database contains raw data on species identities and abundances in ecological assemblages through time. These data enable users to calculate temporal trends in biodiversity within and amongst assemblages using a broad range of metrics. BioTIME is being developed as a community-led open-source database of biodiversity time series. Our goal is to accelerate and facilitate quantitative analysis of temporal patterns of biodiversity in the Anthropocene. Main types of variables included: The database contains 8,777,413 species abundance records, from assemblages consistently sampled for a minimum of 2 years, which need not necessarily be consecutive. In addition, the database contains metadata relating to sampling methodology and contextual information about each record. Spatial location and grain: BioTIME is a global database of 547,161 unique sampling locations spanning the marine, freshwater and terrestrial realms. Grain size varies across datasets from 0.0000000158 km2 (158 cm2) to 100 km2 (1,000,000,000,000 cm2). Time period and grain: BioTIME records span from 1874 to 2016. The minimal temporal grain across all datasets in BioTIME is a year. Major taxa and level of measurement: BioTIME includes data from 44,440 species across the plant and animal kingdoms, ranging from plants, plankton and terrestrial invertebrates to small and large vertebrates. Software format:.csv and.SQL.

Published
2018

19. Plant-pest Interactions in Time and Space: A Douglas-fir Bark Bbeetle Outbreak as a Case Study

Author

Powers, J. S., Sollins, P., Harmon, M. E., Jones, J. A., and Kluwer Academic Publishers

Subjects
Ecology and Evolutionary Biology, Forest Biology, Entomology, Forest Management, Forest Sciences
Abstract

A conceptual model of Douglas-fir bark beetle (Dendroctonus pseudotsugae) dynamics and associated host tree mortality across multiple spatial and temporal scales was developed, then used to guide a study of the association between the occurrence of beetle-killed trees and factors that might render trees more susceptible to attack. Longterm records of beetle kill showed that beetle epidemics were associated with windstorms and drought at statewide and local spatial scales. At the landscape scale, beetle kill was associated with (i) portions of the landscape that were potentially drier (southern aspects, lower elevations) and (ii) portions of the landscape that had more mature and old-growth conifer vegetation. The patches of beetle-killed trees were aggregated with respect to other patches at scales of approximately 1 and 4 km. At the scale of the individual tree, there was not a strong relationship between beetle kill and resistance to attack measured by tree growth rate prior to attack. Our results show that landscape-scale phenomena and temporal patterns were more strongly correlated with beetle-kill events than was recent growth history at the scale of individual trees. We suggest that the multi-scale approach we employed is useful for elucidating the relative roles of fine- versus coarse-scale constraints on ecological processes.

Published
1999
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22. Net ecosystem production: A comprehensive measure of net carbon accumulation by ecosystems.

Author

Randerson, J. T, Randerson, J. T, Chapin, F. S, Harden, J. W, Neff, J. C, Harmon, M. E, Randerson, J. T, Randerson, J. T, Chapin, F. S, Harden, J. W, Neff, J. C, and Harmon, M. E

Abstract

The conceptual framework used by ecologists and biogeochemists must allow for accurate and clearly defined comparisons of carbon fluxes made with disparate techniques across a spectrum of temporal and spatial scales. Consistent with usage over the past four decades, we define “net ecosystem production” (NEP) as the net carbon accumulation by ecosystems. Past use of this term has been ambiguous, because it has been used conceptually as a measure of carbon accumulation by ecosystems, but it has often been calculated considering only the balance between gross primary production (GPP) and ecosystem respiration. This calculation ignores other carbon fluxes from ecosystems (e.g., leaching of dissolved carbon and losses associated with disturbance). To avoid conceptual ambiguities, we argue that NEP be defined, as in the past, as the net carbon accumulation by ecosystems and that it explicitly incorporate all the carbon fluxes from an ecosystem, including autotrophic respiration, heterotrophic respiration, losses associated with disturbance, dissolved and particulate carbon losses, volatile organic compound emissions, and lateral transfers among ecosystems. Net biome productivity (NBP), which has been proposed to account for carbon loss during episodic disturbance, is equivalent to NEP at regional or global scales. The multi-scale conceptual framework we describe provides continuity between flux measurements made at the scale of soil profiles and chambers, forest inventories, eddy covariance towers, aircraft, and inversions of remote atmospheric flask samples, allowing a direct comparison of NEP estimates made at all temporal and spatial scales.

Published
2002

26. Decomposition of Fallen Trees: Effects of Initial Conditions and Heterotroph Colonization Rates

Author

Schowalter, T D, Caldwell, B C, Carpenter, S E, Griffiths, R P, Harmon, M E, Ingham, E R, Kelsey, R G, Lattin, J D, and Moldenke, A R

Subjects
decomposition, Wood Science and Pulp, Paper Technology, fragmentation, Ecology and Evolutionary Biology, conifer boles, Forest Biology, Entomology, Forest Management, Forest Sciences
Abstract

Decomposition of an experimental cohort of conifer boles in a temperate rain forest was studies during the first two years after cutting. The decomposing bole was viewed as a successional ecosystem with measurable inputs, outputs, internal cycling processes; and controlling factors. These results from the initial stage of bole decomposition provide new information on processes contributing to decomposition of fallen trees. Our study challenges the assumptions of chronosequence studies (the traditional approach to studying long-term successional processes) that initial conditions and heterotroph colonization patterns (especially lag times) do not influence decomposition rates.

Published
1992

35. Amplification and dampening of soil respiration by changes in temperature variability.

Author

Sierra, C. A., Harmon, M. E., Thomann, E., Perakis, S. S., and Loescher, H. W.

Subjects
SOIL respiration, DAMPING (Mechanics), TEMPERATURE effect, CARBON in soils, DISTRIBUTION (Probability theory), CLIMATE change, CHEMICAL decomposition
Abstract

Accelerated release of carbon from soils is one of the most important feedbacks related to anthropogenically induced climate change. Studies addressing the mechanisms for soil carbon release through organic matter decomposition have focused on the effect of changes in the average temperature, with little attention to changes in temperature variability. Anthropogenic activities are likely to modify both the average state and the variability of the climatic system; therefore, the effects of future warming on decomposition should not only focus on trends in the average temperature, but also variability expressed as a change of the probability distribution of temperature. Using analytical and numerical analyses we tested common relationships between temperature and respiration and found that the variability of temperature plays an important role determining respiration rates of soil organic matter. Changes in temperature variability, without changes in the average temperature, can affect the amount of carbon released through respiration over the long-term. Furthermore, simultaneous changes in the average and variance of temperature can either amplify or dampen the release of carbon through soil respiration as climate regimes change. These effects depend on the degree of convexity of the relationship between temperature and respiration and the magnitude of the change in temperature variance. A potential consequence of this effect of variability would be higher respiration in regions where both the mean and variance of temperature are expected to increase, such as in some low latitude regions; and lower amounts of respiration where the average temperature is expected to increase and the variance to decrease, such as in northern high latitudes. [ABSTRACT FROM AUTHOR]

Published
2010
Full Text
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36. Cross-biome transplants of plant litter show decomposition models extend to a broader climatic range but lose predictability at the decadal time scale.

Author

CURRIE, W. S., HARMON, M. E., BURKE, I. C., HART, S. C., PARTON, W. J., and SILVER, W.

Subjects
*GRASSLANDS, *BIOTIC communities, *FORESTS & forestry, *MOISTURE, *ECOLOGY, *BIODEGRADATION, *CLIMATE change, *ASYMPTOTES, *CLIMATOLOGY
Abstract

We analyzed results from 10-year long field incubations of foliar and fine root litter from the Long-term Intersite Decomposition Experiment Team (LIDET) study. We tested whether a variety of climate and litter quality variables could be used to develop regression models of decomposition parameters across wide ranges in litter quality and climate and whether these models changed over short to long time periods. Six genera of foliar and three genera of root litters were studied with a 10-fold range in the ratio of acid unhydrolyzable fraction (AUF, or ‘lignin’) to N. Litter was incubated at 27 field sites across numerous terrestrial biomes including arctic and alpine tundra, temperate and tropical forests, grasslands and warm deserts. We used three separate mathematical models of first-order (exponential) decomposition, emphasizing either the first year or the entire decade. One model included the proportion of relatively stable material as an asymptote. For short-term (first-year) decomposition, nonlinear regressions of exponential or power function form were obtained with r2 values of 0.82 and 0.64 for foliar and fine-root litter, respectively, across all biomes included. AUF and AUF : N ratio were the most explanative litter quality variables, while the combined temperature-moisture terms AET (actual evapotranspiration) and CDI (climatic decomposition index) were best for climatic effects. Regressions contained some systematic bias for grasslands and arctic and boreal sites, but not for humid tropical forests or temperate deciduous and coniferous forests. The ability of the regression approach to fit climate-driven decomposition models of the 10-year field results was dramatically reduced from the ability to capture drivers of short-term decomposition. Future work will require conceptual and methodological improvements to investigate processes controlling decadal-scale litter decomposition, including the formation of a relatively stable fraction and its subsequent decomposition. [ABSTRACT FROM AUTHOR]

Published
2010
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37. Ecology of Coarse Woody Debris in Temperature Ecosystems.

Author

Harmon, M. E., Franklin, J. F., Swanson, F. J., Sollins, P., Gregory, S. V., Lattin, J. D., Anderson, N. H., Cline, S. P., Aumen, N. G., Sedell, J. R., Lienkaemper, G. W., Cromack Jr., K., and Cummins, K. W.

Subjects
*COARSE woody debris, *ECOLOGY, *FOREST litter, *BIOTIC communities, *ENVIRONMENTAL sciences
Abstract

Presents a study which examined the ecology of coarse woody debris (CWD) in temperate ecosystems. Importance of CWD in temperate stream and forest ecosystems; Decomposition of CWD; Amount and distribution of CWD.

Published
2004

38. Photo-Cross-Linkable PNIPAAm Copolymers. 4. Effects of Copolymerization and Cross-Linking on the Volume-Phase Transition in Constrained Hydrogel Layers

Author

Harmon, M. E., Kuckling, D., Pareek, P., and Frank, C. W.

Abstract

Photo-cross-linkable temperature and pH-responsive polymers based on N-isopropylacrylamide and 2-(dimethylmaleimido)-N-ethyl-acrylamide were synthesized and spin-coated to produce uniform thin films of cross-linked, responsive hydrogels. Surface plasmon resonance and optical waveguide spectroscopy were used to determine the effect on the volume-phase transition when these materials are confined to a thin film. The film thicknesses ranged from 10 nm to 2.5 μm, and the volume-phase transition temperature and swelling ratio of the films fell into two overlapping regimes separated by at least one critical thickness. In the thick-film regime, greater than 100−760 nm, depending on the cross-linking density, ionizable comonomer concentration, and reference state, the films exhibited two transition temperatures. This can be explained by the stress imposed on the hydrogel as it swells perpendicular to the substrate. In the thin-film regime, less than 270−440 nm, depending on cross-linking density, the presence of a fixed substrate also limited the collapse of the gel at temperatures above the volume-phase transition temperature. Nonequilibrium chain conformations resulting from the spin-coating process may explain this effect. Two different mechanisms for constraint are likely in the thin- and thick-film regimes, and existing models for the anisotropic swelling of hydrogel layers were used to explain these trends. The spin-coated hydrogel layers were also compared to dip-coated and free-radical polymerized hydrogel layers to provide additional insight to the constraint mechanism. The elastic modulus of the hydrogel layers was measured with atomic force microcopy. The modulus in the swollen state was a function of both the cross-linking density and the ionizable comonomer concentration and ranged from 4.48 to 26.6 kPa. The modulus in the collapsed state was primarily a function of the cross-linking density and ranged from 466 to 1540 kPa. The effect of the ionizable comonomer concentration on the modulus also suggests the presence of non-Gaussian chain conformations in the swollen network.

Published
2003

39. Photo-Cross-Linkable PNIPAAm Copolymers. 5. Mechanical Properties of Hydrogel Layers

Author

Harmon, M. E., Kuckling, D., and Frank, C. W.

Abstract

Atomic force microscopy (AFM) was used to study the mechanical properties of photo-cross-linked, temperature-responsive hydrogel layers in water. Photo-cross-linkable linear polymers based on N-isopropylacrylamide and 2-(dimethylmaleimido)-N-ethyl-acrylamide were spin-coated to produce uniform thin films of cross-linked responsive hydrogels. These films were imaged using AFM, and force−distance curves were used to measure the temperature-dependent elastic modulus. The volume phase transition of the hydrogel layers is constrained by the presence of a fixed substrate, and the length scale of these effects is related to the modulus. These materials were also studied with surface plasmon resonance and optical waveguide spectroscopy to determine the polymer volume fraction as a function of the temperature. The modulus varies as a function of the polymer volume fraction and is in good agreement with previous measurements on bulk hydrogels. The effect of the cross-linking density and degree of ionization on the modulus was investigated, and a comparison of these results to rubber elasticity theory for a swollen network was used to study the hydrogel morphology. The concentration of elastically active network chains is lower than expected but increases as the network collapses at temperatures above the volume phase transition temperature.

Published
2003

40. Photo-Cross-Linkable PNIPAAm Copolymers. 2. Effects of Constraint on Temperature and pH-Responsive Hydrogel Layers

Author

Harmon, M. E., Kuckling, D., and Frank, C. W.

Abstract

Photo-cross-linkable co- and terpolymers of N-isopropylacrylamide, 2-(dimethylmaleimido)-N-ethyl-acrylamide as the photosensitive component, and 3-acryloylaminopropionic acid or N-(2-(dimethylamino)ethyl)acrylamide as ionizable comonomers were prepared by free radical polymerization. Aqueous solutions of the linear un-cross-linked co- and terpolymers showed lower critical solution temperature behavior. The phase transition temperature, which was detected by differential scanning calorimetry, ranged from 23.1 to 39.2 °C depending on the pH of the solution and the composition of the polymer. Surface plasmon resonance and optical waveguide spectroscopy were used to obtain information about the swelling behavior of hydrogel films of the photo-cross-linked polymers, giving a measurement of film thickness and refractive index. The transition temperatures of the cross-linked polymer gels showed similar trends to those of the corresponding linear polymers in solution, and the gels were shown to be both temperature- and pH-responsive, with the transition temperature ranging from 25.3 to 44.9 °C for films having a 200 nm dry film thickness. However, the swelling behavior of the cross-linked gels was found to vary as a function of dry film thickness, and three samples were selected for a more detailed study of how film thickness affects the transition temperature and swelling ratio of hydrogel films. Dry film thicknesses ranged from 9 nm to 2.3 μm, and the swelling behavior of the films fell into two distinct regimes separated by a critical thickness, which ranged from 280 to 500 nm. In the thin-film regime, the transition temperature of the films was independent of film thickness, but the refractive index of the films in the collapsed state decreased as film thickness decreased, indicating that these films are not able to fully collapse. In the thick-film regime, the swelling ratio of the films was independent of film thickness, but the transition temperature decreased as much as 2.6 °C as the film thickness increased. This was explained by the constraint imposed on the film by the presence of a fixed substrate, with the length scale of this constraint related to the critical thickness. In these films, the ionizable comonomers were found to have little effect on the swelling ratio, which is determined primarily by cross-linking density in the swollen state and by film thickness in the collapsed state.

Published
2003

41. Photo-Cross-Linkable PNIPAAm Copolymers. 1. Synthesis and Characterization of Constrained Temperature-Responsive Hydrogel Layers

Author

Kuckling, D., Harmon, M. E., and Frank, C. W.

Abstract

Photo-cross-linkable co- and terpolymers of N-isopropylacrylamide (NIPAAm), 2-(dimethylmaleimido)-N-ethylacrylamide (DMIAAm) as the chromophore, and N,N-dimethylacrylamide (DMAAm) were prepared by free radical polymerization. Aqueous solutions of the co- and terpolymers showed lower critical solution temperature (LCST) behavior, and the corresponding phase transition temperature (Tc) was detected by differential scanning calorimetry (DSC). Tc decreased with increasing amount of DMIAAm, as low as 24.7 °C for 9.2 mol % DMIAAm, and increased with increasing DMAAm content, as high as 59.5 °C for 52.6 mol % DMAAm. The resulting polymers were shown to be photo-cross-linkable, and the sensitivity of the polymers toward UV light was studied by monitoring the photo-cross-linking reaction with ATR−FTIR. With 2 wt % thioxanthone as the photosensitizer, nearly full conversion could be achieved with 10 min of irradiation even though the photo-cross-linking was performed in the glassy state. Surface plasmon resonance (SPR) spectroscopy and optical microscopy were used to obtain information about the swelling behavior of thin hydrogel films. In the SPR scans the plasmon resonance minimum and the first waveguide mode were fit to Fresnel calculations to determine the refractive index (n) and the layer thickness (d) of the hydrogel. The volume degree of swelling was calculated from the refractive index, and the swelling ratio was calculated from the layer thickness. Changes in the degree of swelling, Tc, and the width of the transition (ΔTc) were observed by changing the chromophore content and, as a result, the gel cross-linking density. For a hydrogel film with a dry thickness of 200 nm, the collapsed film thickness above Tc was around 220 nm and only weakly dependent on chromophore content. However, at temperatures below Tc, the swollen film thickness was strongly dependent on the chromophore content and ranged from 1200 nm for 2.4 mol % DMIAAm to 800 nm for 9.2 mol % DMIAAm. The reverse is true for the refractive index, which increases as the film thickness decreases. A comparison of volume degree of swelling and swelling ratio was utilized to demonstrate the high anisotropy of swelling in these hydrogel layers that were physisorbed to the substrate and therefore constrained from expanding or contracting laterally. The swollen film expanded 9.5% laterally as compared to the dry film, and this value appeared to be independent of temperature. The swelling perpendicular to the substrate ranged from 6.4% for 9.2 mol % DMIAAm at temperatures above Tc to 630% for 2.4 mol % DMIAAm at temperatures below Tc.

Published
2002
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42. A Surface Plasmon Resonance Study of Volume Phase Transitions in N-Isopropylacrylamide Gel Films

Author

Harmon, M. E., Jakob, T. A. M., Knoll, W., and Frank, C. W.

Abstract

Cross-linked N-isopropylacrylamide (NIPAAm) gel is covalently attached to a substrate, and the resulting interface is probed using surface plasmon resonance (SPR) as a function of hydrostatic pressure and temperature. SPR provides a direct measurement of the local refractive index, which changes with the swelling ratio of the gel film. Similar to bulk NIPAAm gel, the transition temperature increases and the volume phase transition becomes broader as pressure increases. The width of the transition ranges from less than 0.5 °C at 1 bar to as much as 10 °C at 1000 bar, and the transition temperature increases by as much as 7 °C over the same range of pressures. However, the presence of a fixed substrate effectively confines the volume phase transition near the interface to one dimension, perpendicular to the substrate. This has significant effects on the transition temperature, particularly at high cross-linking density and high concentration of an ionizable comonomer. Furthermore, the swelling effect of the ionic groups is reduced, and the water content of the swollen gel does not change with increased ionic content. While the volume phase transition of the corresponding bulk gels can have a total volume change as large as 100-fold, the gel films have a total volume change around 15-fold.

Published
2002
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