Flow regime alteration degrades ecological networks in riparian ecosystems

  • Nature Ecology & Evolutionvolume 2pages8693 (2018)
  • doi:10.1038/s41559-017-0379-0
  • Download Citation
Published online:


Riverine ecosystems are governed by patterns of temporal variation in river flows. This dynamism will change due to climate change and the near-ubiquitous human control of river flows globally, which may have severe effects on species distributions and interactions. We employed a combination of population modelling and network theory to explore the consequences of possible flow regime futures on riparian plant communities, including scenarios of increased drought, flooding and flow homogenization (removal of flow variability). We found that even slight modifications to the historic natural flow regime had significant consequences for the structure of riparian plant networks. Networks of emergent interactions between plant guilds were most connected at the natural flow regime and became simplified with increasing flow alteration. The most influential component of flow alteration was flood reduction, with drought and flow homogenization both having greater simplifying community-wide consequences than increased flooding. These findings suggest that maintaining floods under future climates will be needed to overcome the negative long-term consequences of flow modification on riverine ecosystems.

  • Subscribe to Nature Ecology & Evolution for full access:



Additional access options:

Already a subscriber?  Log in  now or  Register  for online access.

Additional information

Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.


  1. 1.

    Poff, N. L. et al. The natural flow regime. Bioscience 47, 769–784 (1997).

  2. 2.

    Nilsson, C., Reidy, C. A., Dynesius, M. & Revenga, C. Fragmentation and flow regulation of the world’s large river systems. Science 308, 405–408 (2005).

  3. 3.

    Zarfl, C., Lumsdon, A. E., Berlekamp, J., Tydecks, L. & Tockner, K. A global boom in hydropower dam construction. Aquat. Sci. 77, 161–170 (2014).

  4. 4.

    Poff, N. L., Olden, J. D. J., Merritt, D. M. & Pepin, D. M. Homogenization of regional river dynamics by dams and global biodiversity implications. Proc. Natl Acad. Sci. USA 104, 5732–5737 (2007).

  5. 5.

    Flanagan, N. E., Richardson, C. J. & Ho, M. Connecting differential responses of native and invasive riparian plants to climate change and environmental alteration. Ecol. Appl. 25, 753–767 (2015).

  6. 6.

    Naiman, R. J. & Décamps, H. The ecology of interfaces: riparian zones. Annu. Rev. Ecol. Syst. 28, 621–658 (1997).

  7. 7.

    Reynolds, L. V., Shafroth, P. B. & Poff, N. L. Modeled intermittency risk for small streams in the Upper Colorado River Basin under climate change. J. Hydrol. 523, 768–780 (2015).

  8. 8.

    Lu, X. et al. Drought rewires the cores of food webs. Nat. Clim. Change 6, 875–878 (2016).

  9. 9.

    Ledger, M. E., Brown, L. E., Edwards, F. K., Milner, A. M. & Woodward, G. Drought alters the structure and functioning of complex food webs. Nat. Clim. Change 3, 223–227 (2012).

  10. 10.

    Lytle, D. A., Merritt, D. M., Tonkin, J. D., Olden, J. D. & Reynolds, L. V. Linking river flow regimes to riparian plant guilds: a community-wide modeling approach. Ecol. Appl. 27, 1338–1350 (2017).

  11. 11.

    Lytle, D. A. & Poff, N. L. Adaptation to natural flow regimes. Trends Ecol. Evol. 19, 94–100 (2004).

  12. 12.

    Strona, G. & Lafferty, K. D. Environmental change makes robust ecological networks fragile. Nat. Commun. 7, 1–7 (2016).

  13. 13.

    Ings, T. C. et al. Ecological networks — beyond food webs. J. Anim. Ecol. 78, 253–269 (2009).

  14. 14.

    Thebault, E. & Fontaine, C. Stability of ecological communities and the architecture of mutualistic and trophic networks. Science 329, 853–856 (2010).

  15. 15.

    Dunne, J. A., Williams, R. J. & Martinez, N. D. Network structure and biodiversity loss in food webs: robustness increases with connectance. Ecol. Lett. 5, 558–567 (2002).

  16. 16.

    Poisot, T., Stouffer, D. B. & Gravel, D. Beyond species: why ecological interaction networks vary through space and time. Oikos 124, 243–251 (2015).

  17. 17.

    Thompson, P. L. & Gonzalez, A. Dispersal governs the reorganization of ecological networks under environmental change. Nat. Ecol. Evol. 1, 0162 (2017).

  18. 18.

    Stouffer, D. B., Sales-Pardo, M., Sirer, M. I. & Bascompte, J. Evolutionary conservation of species’ roles in food webs. Science 335, 1489–1492 (2012).

  19. 19.

    Merritt, D. M., Scott, M. L., Poff, N. L., Auble, G. T. & Lytle, D. A. Theory, methods and tools for determining environmental flows for riparian vegetation: riparian vegetation-flow response guilds. Freshwater Biol. 55, 206–225 (2010).

  20. 20.

    Milly, P. C. D., Dunne, K. A. & Vecchia, A. V. Global pattern of trends in streamflow and water availability in a changing climate. Nature 438, 347–350 (2005).

  21. 21.

    Gonzalez, A. & Loreau, M. The causes and consequences of compensatory dynamics in ecological communities. Annu. Rev. Ecol. Evol. Syst. 40, 393–414 (2009).

  22. 22.

    Brown, B. L., Downing, A. L. & Leibold, M. A. Compensatory dynamics stabilize aggregate community properties in response to multiple types of perturbations. Ecology 97, 2021–2033 (2016).

  23. 23.

    Allesina, S. & Tang, S. Stability criteria for complex ecosystems. Nature 483, 205–208 (2012).

  24. 24.

    Mougi, A. et al. Diversity of interaction types and ecological community stability. Science 337, 349–351 (2012).

  25. 25.

    May, R. M. Will a large complex system be stable? Nature 238, 413–414 (1972).

  26. 26.

    Baiser, B., Russell, G. J. & Lockwood, J. L. Connectance determines invasion success via trophic interactions in model food webs. Oikos 119, 1970–1976 (2010).

  27. 27.

    Aizen, M. A., Sabatino, M. & Tylianakis, J. M. Specialization and rarity predict nonrandom loss of interactions from mutualist networks. Science 335, 1486–1489 (2012).

  28. 28.

    Dai, A. Drought under global warming: a review. Rev. Clim. Change 2, 45–65 (2011).

  29. 29.

    Bunn, S. E. & Arthington, A. H. Basic principles and ecological consequences of altered flow regimes for aquatic biodiversity. Environ. Manage. 30, 492–507 (2002).

  30. 30.

    Rood, S. B., Goater, L. A., Mahoney, J. M., Pearce, C. M. & Smith, D. G. Floods, fire, and ice: disturbance ecology of riparian cottonwoods. Can. J. Bot. 85, 1019–1032 (2007).

  31. 31.

    Olden, J. D. et al. Are large-scale flow experiments informing the science and management of freshwater ecosystems? Front. Ecol. Environ. 12, 176–185 (2014).

  32. 32.

    Rood, S. B. et al. Declining summer flows of Rocky Mountain rivers: changing seasonal hydrology and probable impacts on floodplain forests. J. Hydrol. 349, 397–410 (2008).

  33. 33.

    Stromberg, J. C. & Merritt, D. M. Riparian plant guilds of ephemeral, intermittent and perennial rivers. Freshwater Biol. 61, 1259–1275 (2016).

  34. 34.

    Aguiar, F. C., Cerdeira, J. O., Martins, M. J. & Ferreira, M. T. Riparian forests of southwest Europe: are functional trait and species composition assemblages constrained by environment? J. Veg. Sci. 24, 628–638 (2013).

  35. 35.

    Gurnell, A. M., Bertoldi, W. & Corenblit, D. Changing river channels: the roles of hydrological processes, plants and pioneer fluvial landforms in humid temperate, mixed load, gravel bed rivers. Earth Sci. Rev. 111, 129–141 (2012).

  36. 36.

    Hupp, C. Hydrology, geomorphology and vegetation of coastal plain rivers in the south-eastern USA. Hydrol. Process. 14, 2991–3010 (2000).

  37. 37.

    Lewinsohn, T. & Cagnolo, L. Keystones in a tangled bank. Science 335, 1449–1451 (2012).

  38. 38.

    Friedman, J. M. et al. Dominance of non-native riparian trees in western USA. Biol. Invasions 7, 747–751 (2005).

  39. 39.

    Kominoski, J. S. et al. Forecasting functional implications of global changes in riparian plant communities. Front. Ecol. Environ. 11, 423–432 (2013).

  40. 40.

    Rivaes, R. P. et al. Modeling the evolution of riparian woodlands facing climate change in three European rivers with contrasting flow regimes. PLoS ONE 9, e110200 (2014).

  41. 41.

    Doody, T. M. et al. Quantifying water requirements of riparian river red gum (Eucalyptus camaldulensis) in the Murray-Darling Basin, Australia – implications for the management of environmental flows. Ecohydrology 8, 1471–1487 (2015).

  42. 42.

    Kath, J., Le Brocque, A., Leyer, I. & Mosner, E. Hydrological and land use determinants of Eucalyptus camaldulensis occurrence in floodplain wetlands. Austral Ecol. 39, 643–655 (2014).

  43. 43.

    Guilloy-Froget, H., Muller, E., Barsoum, N. & Hughes, F. M. R. Dispersal, germination, and survival of Populus nigra L. (Salicaceae) in changing hydrologic conditions. Wetlands 22, 478–488 (2002).

  44. 44.

    Middleton, B. A. & Souter, N. J. Functional integrity of freshwater forested wetlands, hydrologic alteration, and climate change. Ecosyst. Health Sustain. 2, e01200 (2016).

  45. 45.

    Andersen, D. C. & Cooper, D. J. Dams, floodplain land use, and riparian forest conservation in the semiarid Upper Colorado River Basin, USA. Environ. Manage. 40, 453–475 (2007).

  46. 46.

    Belmar, O., Bruno, D., Martínez-Capel, F., Barquín, J. & Velasco, J. Effects of flow regime alteration on fluvial habitats and riparian quality in a semiarid Mediterranean basin. Ecol. Indic. 30, 52–64 (2013).

  47. 47.

    Tylianakis, J. M., Tscharntke, T. & Lewis, O. T. Habitat modification alters the structure of tropical host–parasitoid food webs. Nature 445, 202–205 (2007).

  48. 48.

    Merritt, D. M. & Bateman, H. L. Linking stream flow and groundwater to avian habitat in a desert riparian system. Ecol. Appl. 22, 1973–1988 (2012).

  49. 49.

    Shafroth, P. B., Auble, G. T., Stromberg, J. C. & Patten, D. T. Establishment of woody riparian vegetation in relation to annual patterns of streamflow, Bill Williams River, Arizona. Wetlands 18, 577–590 (1998).

  50. 50.

    Lytle, D. A. & Merritt, D. M. Hydrologic regimes and riparian forests: a structured population model for cottonwood. Ecology 85, 2493–2503 (2004).

  51. 51.

    R Core Team R: A Language and Environment for Statistical Computing (R Foundation for Statistical Computing, Vienna, 2015).

  52. 52.

    Tonkin, J. D., Bogan, M. T., Bonada, N., Ríos-Touma, B. & Lytle, D. A. Seasonality and predictability shape temporal species diversity. Ecology 98, 1201–1216 (2017).

  53. 53.

    Novak, M. et al. Characterizing species interactions to understand press perturbations: what is the community matrix? Annu. Rev. Ecol. Evol. Syst. 47, 409–432 (2016).

  54. 54.

    Csardi, G. & Nepusz, T. The igraph software package for complex network research. InterJournal, Complex Syst. 1695 (2006).

  55. 55.

    Killick, R. & Eckley, I. A. Changepoint: an R package for changepoint analysis. J. Stat. Softw. 58, 1–19 (2014).

Download references


We thank N. L. Poff, A. Ruhi and members of the OSU Integrative Biology journal club for comments on earlier versions of the manuscript. Dinosaur National Monument and the US Bureau of Reclamation supported the research that led to the vital rate data. Funding was provided in part by the US Department of Defense (SERDP RC-2511) and the US Department of Agriculture Forest Service.

Author information


  1. Department of Integrative Biology, Oregon State University, Corvallis, OR, 97331, USA

    • Jonathan D. Tonkin
    •  & David A. Lytle
  2. Watershed, Fisheries, Wildlife, Air and Rare Plants Staff and the National Stream and Aquatic Ecology Center, U.S.D.A. Forest Service, Fort Collins, CO, 80526, USA

    • David. M. Merritt
    •  & Lindsay V. Reynolds
  3. School of Aquatic and Fishery Sciences, University of Washington, Seattle, WA, 98195, USA

    • Julian D. Olden


  1. Search for Jonathan D. Tonkin in:

  2. Search for David. M. Merritt in:

  3. Search for Julian D. Olden in:

  4. Search for Lindsay V. Reynolds in:

  5. Search for David A. Lytle in:


J.D.T. and D.A.L. designed the study, developed the model and ran analyses; D.A.L. and D.M.M. compiled vital rate information; J.D.T. wrote the first draft of the manuscript in close collaboration with D.A.L., and all authors contributed substantially to writing in subsequent drafts.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Jonathan D. Tonkin.

Electronic supplementary material