Browsing by Author "Swan, Christopher M."

Now showing 1 - 3 of 3
  • Thumbnail Image
    A framework for understanding how biodiversity patterns unfold across multiple spatial scales in urban ecosystems
    Swan, Christopher M.; Brown, Bryan L.; Borowy, Dorothy; Cavender-Bares, Jeannine; Jeliazkov, Alienor; Knapp, Sonja; Lososova, Zdenka; Padulles Cubino, Josep; Pavoine, Sandrine; Ricotta, Carlo; Sol, Daniel (2021-07)
    Whether cities are more or less diverse than surrounding environments, and the extent to which non-native species in cities impact regional species pools, remain two fundamental yet unanswered questions in urban ecology. Here we offer a unifying framework for understanding the mechanisms that generate biodiversity patterns across taxonomic groups and spatial scales in urban systems. One commonality between existing frameworks is the collective recognition that species co-occurrence locally is not simply a function of natural colonization and extinction processes. Instead, it is largely a consequence of human actions that are governed by a myriad of social processes occurring across groups, institutions, and stakeholders. Rather than challenging these frameworks, we expand upon them to explicitly consider how human and non-human mechanisms interact to control urban biodiversity and influence species composition over space and time. We present a comprehensive theory of the processes that drive biodiversity within cities, between cities and surrounding non-urbanized areas and across cities, using the general perspective of metacommunity ecology. Armed with this approach, we embrace the fact that humans substantially influence beta-diversity by creating a variety of different habitats in urban areas, and by influencing dispersal processes and rates, and suggest ways how these influences can be accommodated to existing metacommunity paradigms. Since patterns in urban biodiversity have been extensively described at the local or regional scale, we argue that the basic premises of the theory can be validated by studying the beta-diversity across spatial scales within and across urban areas. By explicitly integrating the myriad of processes that drive native and non-native urban species co-occurrence, the proposed theory not only helps reconcile contrasting views on whether urban ecosystems are biodiversity hotspots or biodiversity sinks, but also provides a mechanistic understanding to better predict when and why alternative biodiversity patterns might emerge.
  • Thumbnail Image
    Global patterns and drivers of ecosystem functioning in rivers and riparian zones
    Tiegs, Scott D.; Costello, David M.; Isken, Mark W.; Woodward, Guy; McIntyre, Peter B.; Gessner, Mark O.; Chauvet, Eric; Griffiths, Natalie A.; Flecker, Alex S.; Acuna, Vicenc; Albarino, Ricardo; Allen, Daniel C.; Alonso, Cecilia; Andino, Patricio; Arango, Clay; Aroviita, Jukka; Barbosa, Marcus V. M.; Barmuta, Leon A.; Baxter, Colden V.; Bell, Thomas D. C.; Bellinger, Brent; Boyero, Luz; Brown, Lee E.; Bruder, Andreas; Bruesewitz, Denise A.; Burdon, Francis J.; Callisto, Marcos; Canhoto, Cristina; Capps, Krista A.; Castillo, Maria M.; Clapcott, Joanne; Colas, Fanny; Colon-Gaud, Checo; Cornut, Julien; Crespo-Perez, Veronica; Cross, Wyatt F.; Culp, Joseph M.; Danger, Michael; Dangles, Olivier; de Eyto, Elvira; Derry, Alison M.; Diaz Villanueva, Veronica; Douglas, Michael M.; Elosegi, Arturo; Encalada, Andrea C.; Entrekin, Sally A.; Espinosa, Rodrigo; Ethaiya, Diana; Ferreira, Veronica; Ferriol, Carmen; Flanagan, Kyla M.; Fleituch, Tadeusz; Shah, Jennifer J. Follstad; Frainer, Andre; Friberg, Nikolai; Frost, Paul C.; Garcia, Erica A.; Lago, Liliana Garcia; Garcia Soto, Pavel Ernesto; Ghate, Sudeep; Giling, Darren P.; Gilmer, Alan; Goncalves, Jose Francisco, Jr.; Gonzales, Rosario Karina; Graca, Manuel A. S.; Grace, Mike; Grossart, Hans-Peter; Guerold, Francois; Gulis, Vlad; Hepp, Luiz U.; Higgins, Scott; Hishi, Takuo; Huddart, Joseph; Hudson, John; Imberger, Samantha; Iniguez-Armijos, Carlos; Iwata, Tomoya; Janetski, David J.; Jennings, Eleanor; Kirkwood, Andrea E.; Koning, Aaron A.; Kosten, Sarian; Kuehn, Kevin A.; Laudon, Hjalmar; Leavitt, Peter R.; Lemes da Silva, Aurea L.; Leroux, Shawn J.; Leroy, Carri J.; Lisi, Peter J.; MacKenzie, Richard; Marcarelli, Amy M.; Masese, Frank O.; Mckie, Brendan G.; Oliveira Medeiros, Adriana; Meissner, Kristian; Milisa, Marko; Mishra, Shailendra; Miyake, Yo; Moerke, Ashley; Mombrikotb, Shorok; Mooney, Rob; Moulton, Tim; Muotka, Timo; Negishi, Junjiro N.; Neres-Lima, Vinicius; Nieminen, Mika L.; Nimptsch, Jorge; Ondruch, Jakub; Paavola, Riku; Pardo, Isabel; Patrick, Christopher J.; Peeters, Edwin T. H. M.; Pozo, Jesus; Pringle, Catherine; Prussian, Aaron; Quenta, Estefania; Quesada, Antonio; Reid, Brian; Richardson, John S.; Rigosi, Anna; Rincon, Jose; Risnoveanu, Geta; Robinson, Christopher T.; Rodriguez-Gallego, Lorena; Royer, Todd V.; Rusak, James A.; Santamans, Anna C.; Selmeczy, Geza B.; Simiyu, Gelas; Skuja, Agnija; Smykla, Jerzy; Sridhar, Kandikere R.; Sponseller, Ryan; Stoler, Aaron; Swan, Christopher M.; Szlag, David; Teixeira-de Mello, Franco; Tonkin, Jonathan D.; Uusheimo, Sari; Veach, Allison M.; Vilbaste, Sirje; Vought, Lena B. M.; Wang, Chiao-Ping; Webster, Jackson R.; Wilson, Paul B.; Woelfl, Stefan; Xenopoulos, Marguerite A.; Yates, Adam G.; Yoshimura, Chihiro; Yule, Catherine M.; Zhang, Yixin X.; Zwart, Jacob A. (American Association for the Advancement of Science, 2019-01-09)
    River ecosystems receive and process vast quantities of terrestrial organic carbon, the fate of which depends strongly on microbial activity. Variation in and controls of processing rates, however, are poorly characterized at the global scale. In response, we used a peer-sourced research network and a highly standardized carbon processing assay to conduct a global-scale field experiment in greater than 1000 river and riparian sites. We found that Earth’s biomes have distinct carbon processing signatures. Slow processing is evident across latitudes, whereas rapid rates are restricted to lower latitudes. Both the mean rate and variability decline with latitude, suggesting temperature constraints toward the poles and greater roles for other environmental drivers (e.g., nutrient loading) toward the equator. These results and data set the stage for unprecedented “next-generation biomonitoring” by establishing baselines to help quantify environmental impacts to the functioning of ecosystems at a global scale.
  • Thumbnail Image
    Global synthesis of the temperature sensitivity of leaf litter breakdown in streams and rivers
    Shah, Jennifer J. Follstad; Kominoski, John S.; Ardon, Marcelo; Dodds, Walter K.; Gessner, Mark O.; Griffiths, Natalie A.; Hawkins, Charles P.; Johnson, Sherri L.; Lecerf, Antoine; Leroy, Carri J.; Manning, David W. P.; Rosemond, Amy D.; Sinsabaugh, Robert L.; Swan, Christopher M.; Webster, Jackson R.; Zeglin, Lydia H. (2017-08)
    Streams and rivers are important conduits of terrestrially derived carbon (C) to atmospheric and marine reservoirs. Leaf litter breakdown rates are expected to increase as water temperatures rise in response to climate change. The magnitude of increase in breakdown rates is uncertain, given differences in litter quality and microbial and detritivore community responses to temperature, factors that can influence the apparent temperature sensitivity of breakdown and the relative proportion of C lost to the atmosphere vs. stored or transported downstream. Here, we synthesized 1025 records of litter breakdown in streams and rivers to quantify its temperature sensitivity, as measured by the activation energy (E-a, in eV). Temperature sensitivity of litter breakdown varied among twelve plant genera for which E-a could be calculated. Higher values of E-a were correlated with lower-quality litter, but these correlations were influenced by a single, N-fixing genus (Alnus). E-a values converged when genera were classified into three breakdown rate categories, potentially due to continual water availability in streams and rivers modulating the influence of leaf chemistry on breakdown. Across all data representing 85 plant genera, the E-a was 0.34 +/- 0.04 eV, or approximately half the value (0.65 eV) predicted by metabolic theory. Our results indicate that average breakdown rates may increase by 5-21% with a 1-4 C rise in water temperature, rather than a 10-45% increase expected, according to metabolic theory. Differential warming of tropical and temperate biomes could result in a similar proportional increase in breakdown rates, despite variation in E-a values for these regions (0.75 +/- 0.13 eV and 0.27 +/- 0.05 eV, respectively). The relative proportions of gaseous C loss and organic matter transport downstream should not change with rising temperature given that E-a values for breakdown mediated by microbes alone and microbes plus detritivores were similar at the global scale.