Now showing items 21-40 of 264

  • Mechanical land clearing to promote establishment of coastal sandplain grassland and shrubland communities 

    Lezberg, Ann L.; Buresch, Kendra C.; Neill, Christopher; Chase, Tom (2005-07-22)
    The decline in grasslands and other species-rich early-successional habitats on the coastal sandplains of the northeastern U.S. has spurred management to increase the area of these declining plant communities. We mechanically ...
  • Optical instruments for measuring leaf area index in low vegetation : application in Arctic ecosystems 

    van Wijk, Mark T.; Williams, Mathew (Ecological Society of America, 2005-08)
    Leaf area index (LAI) is a powerful diagnostic of plant productivity. Despite the fact that many methods have been developed to quantify LAI, both directly and indirectly, leaf area index remains difficult to quantify ...
  • Landscape heterogeneity and the biodiversity of Arctic stream communities : a habitat template analysis 

    Huryn, Alexander D.; Slavik, Karie A.; Lowe, Rex L.; Parker, Stephanie M.; Anderson, Dennis S.; Peterson, Bruce J. (National Research Council Canada, 2005-08-27)
    We predicted that substratum freezing and instability are major determinants of the variability of stream community structure in Arctic Alaska. Their effects were conceptualized as a two-dimensional habitat template that ...
  • Turnover rates of nitrogen stable isotopes in the salt marsh mummichog, Fundulus heteroclitus, following a laboratory diet switch 

    Logan, John; Haas, Heather; Deegan, Linda A.; Gaines, Emily F. (2005-09-19)
    Nitrogen stable isotopes are frequently used in ecological studies to estimate trophic position and determine movement patterns. Knowledge of tissue-specific turnover and nitrogen discrimination for the study organisms is ...
  • Importance of recent shifts in soil thermal dynamics on growing season length, productivity, and carbon sequestration in terrestrial high-latitude ecosystems 

    Euskirchen, E. S.; McGuire, A. David; Kicklighter, David W.; Zhuang, Qianlai; Clein, Joy S.; Dargaville, R. J.; Dye, D. G.; Kimball, John S.; McDonald, Kyle C.; Melillo, Jerry M.; Romanovsky, V. E.; Smith, N. V. (2005-10-07)
    In terrestrial high-latitude regions, observations indicate recent changes in snow cover, permafrost, and soil freeze-thaw transitions due to climate change. These modifications may result in temporal shifts in the growing ...
  • Sugars as source indicators of biogenic organic carbon in aerosols collected above the Howland Experimental Forest, Maine 

    Medeiros, Patricia M.; Conte, Maureen H.; Weber, John C.; Simoneit, Bernd R. T. (2005-10-25)
    Bulk aerosols (> 1 μm) were collected continuously above the canopy at the Howland Experimental Forest, Maine, USA from May to October 2002. Each sample integrated over an approximately two-week period. Mono- and ...
  • Linkages among runoff, dissolved organic carbon, and the stable oxygen isotope composition of seawater and other water mass indicators in the Arctic Ocean 

    Cooper, Lee W.; Benner, Ronald; McClelland, James W.; Peterson, Bruce J.; Holmes, Robert M.; Raymond, Peter A.; Hansell, Dennis A.; Grebmeier, Jacqueline M.; Codispoti, Louis A. (American Geophysical Union, 2005-12-07)
    Concentrations of dissolved organic carbon (DOC) and δ18O values have been determined following sampling of runoff from a number of major arctic rivers, including the Ob, Yenisey, Lena, Kolyma, Mackenzie and Yukon in ...
  • Global economic effects of changes in crops, pasture, and forests due to changing climate, carbon dioxide, and ozone 

    Reilly, John M.; Paltsev, S.; Felzer, Benjamin S.; Wang, X.; Kicklighter, David W.; Melillo, Jerry M.; Prinn, Ronald G.; Sarofim, Marcus C.; Sokolov, Andrei P.; Wang, C. (2006-01)
    Multiple environmental changes will have consequences for global vegetation. To the extent that crop yields and pasture and forest productivity are affected there can be important economic consequences. We examine the ...
  • Reconciling carbon-cycle concepts, terminology, and methods 

    Chapin, F. Stuart; Woodwell, G. M.; Randerson, James T.; Rastetter, Edward B.; Lovett, G. M.; Baldocchi, Dennis D.; Clark, D. A.; Harmon, Mark E.; Schimel, David S.; Valentini, R.; Wirth, C.; Aber, J. D.; Cole, Jonathan J.; Goulden, Michael L.; Harden, J. W.; Heimann, M.; Howarth, Robert W.; Matson, P. A.; McGuire, A. David; Melillo, Jerry M.; Mooney, H. A.; Neff, Jason C.; Houghton, Richard A.; Pace, Michael L.; Ryan, M. G.; Running, Steven W.; Sala, Osvaldo E.; Schlesinger, William H.; Schulze, E.-D. (2006-01-06)
    Recent patterns and projections of climatic change have focused increased scientific and public attention on patterns of carbon (C) cycling and its controls, particularly the factors that determine whether an ecosystem is ...
  • Plant community responses to experimental warming across the tundra biome 

    Walker, Marilyn D.; Wahren, C. Henrik; Hollister, Robert D.; Henry, Greg H. R.; Ahlquist, Lorraine E.; Alatalo, Juha M.; Bret-Harte, M. Syndonia; Calef, Monika P.; Callaghan, Terry V.; Carroll, Amy B.; Epstein, Howard E.; Jonsdottir, Ingibjorg S.; Klein, Julia A.; Magnusson, Borgbor; Molau, Ulf; Oberbauer, Steven F.; Rewa, Steven P.; Robinson, Clare H.; Shaver, Gaius R.; Suding, Katharine N.; Thompson, Catharine C.; Tolvanen, Anne; Totland, Orjan; Turner, P. Lee; Tweedie, Craig E.; Webber, Patrick J.; Wookey, Philip A. (National Academy of Sciences of the USA, 2006-01-20)
    Recent observations of changes in some tundra ecosystems appear to be responses to a warming climate. Several experimental studies have shown that tundra plants and ecosystems can respond strongly to environmental change, ...
  • Linking ecology and economics for ecosystem management 

    Farber, Stephen; Costanza, Robert; Childers, Daniel L.; Erickson, Jon; Gross, Katherine; Grove, J. Morgan; Hopkinson, Charles S.; Kahn, James; Pincetl, Stephanie; Troy, Austin; Warren, Paige; Wilson, Matthew (American Institute of Biological Sciences, 2006-02)
    This article outlines an approach, based on ecosystem services, for assessing the trade-offs inherent in managing humans embedded in ecological systems. Evaluating these trade-offs requires an understanding of the biophysical ...
  • Testing isosource : stable isotope analysis of a tropical fishery with diverse organic matter sources 

    Benstead, Jonathan P.; March, James G.; Fry, Brian; Ewel, Katherine C.; Pringle, Catherine M. (Ecological Society of America, 2006-02)
    We sampled consumers and organic matter sources (mangrove litter, freshwater swamp-forest litter, seagrasses, seagrass epiphytes, and marine particulate organic matter [MPOM]) from four estuaries on Kosrae, Federated States ...
  • Carbon turnover in Alaskan tundra soils : effects of organic matter quality, temperature, moisture and fertilizer 

    Shaver, Gaius R.; Giblin, Anne E.; Nadelhoffer, Knute J.; Thieler, K. K.; Downs, M. R.; Laundre, James A.; Rastetter, Edward B. (2006-02-15)
    Soils of tundra and boreal ecosystems contain large organic matter stocks, typically as a layer of peat that blankets the underlying mineral soil. Despite the low productivity of northern vegetation, organic matter accumulates ...
  • Spatial and temporal patterns of carbon emissions from forest fires in China from 1950 to 2000 

    Lu, Aifeng; Tian, Hanqin; Liu, Mingliang; Liu, Jiyuan; Melillo, Jerry M. (American Geophysical Union, 2006-03-11)
    We have estimated the emission of carbon (C) and carbon-containing trace gases including CO2, CO, CH4, and NMHC (nonmethane hydrocarbons) from forest fires in China for the time period from 1950 to 2000 by using a combination ...
  • Susceptibility of salt marshes to nutrient enrichment and predator removal 

    Deegan, Linda A.; Bowen, Jennifer L.; Drake, Deanne C.; Fleeger, John W.; Friedrichs, Carl T.; Galvan, Kari A.; Hobbie, John E.; Hopkinson, Charles S.; Johnson, J. Michael; Johnson, David S.; LeMay, Lynsey E.; Miller, Erin; Peterson, Bruce J.; Picard, Christian; Sheldon, Sallie; Sutherland, Michael; Vallino, Joseph J.; Warren, R. Scott (2006-03-15)
    The sustainability of coastal ecosystems in the face of widespread environmental change is an issue of pressing concern throughout the world (Emeis et al. 2001). Coastal ecosystems form a dynamic interface between terrestrial ...
  • Ecological constraints on planktonic nitrogen fixation in saline estuaries. I. Nutrient and trophic controls 

    Marino, Roxanne; Chan, Francis; Howarth, Robert W.; Pace, Michael L.; Likens, Gene E. (Inter-Research, 2006-03-15)
    Heterocystous, planktonic cyanobacteria capable of fixing atmospheric N2 into available nitrogen (N) are common and critically important to nutrient cycling in many lakes, yet they are rarely observed in estuaries at ...
  • Effect of historical changes in land use and climate on the water budget of an urbanizing watershed 

    Claessens, Luc; Hopkinson, Charles S.; Rastetter, Edward B.; Vallino, Joseph J. (American Geophysical Union, 2006-03-25)
    We assessed the effects of historical (1931-1998) changes in both land-use and climate on the water budget of a rapidly urbanizing watershed, Ipswich River basin (IRB), in northeastern Massachusetts. Water diversions and ...
  • A pan-arctic evaluation of changes in river discharge during the latter half of the 20th century 

    McClelland, James W.; Dery, Stephen J.; Peterson, Bruce J.; Holmes, Robert M.; Wood, Eric F. (American Geophysical Union, 2006-03-30)
    Several recent publications have documented changes in river discharge from arctic and subarctic watersheds. Comparison of these findings, however, has been hampered by differences in time periods and methods of analysis. ...
  • Relationship between river size and nutrient removal 

    Wollheim, Wilfred M.; Vorosmarty, Charles J.; Peterson, Bruce J.; Seitzinger, Sybil P.; Hopkinson, Charles S. (American Geophysical Union, 2006-03-30)
    We present a conceptual approach for evaluating the biological and hydrological controls of nutrient removal in different sized rivers within an entire river network. We emphasize a per unit area biological parameter, the ...
  • N-15 in symbiotic fungi and plants estimates nitrogen and carbon flux rates in Arctic tundra 

    Hobbie, John E.; Hobbie, Erik A. (Ecological Society of America, 2006-04)
    When soil nitrogen is in short supply, most terrestrial plants form symbioses with fungi (mycorrhizae): hyphae take up soil nitrogen, transport it into plant roots, and receive plant sugars in return. In ecosystems, the ...