, Volume 166, Issue 3, pp 769–782 | Cite as

Balancing positive and negative plant interactions: how mosses structure vascular plant communities

  • Jemma L. Gornall
  • Sarah J. Woodin
  • Ingibjorg S. Jónsdóttir
  • René van der WalEmail author
Community ecology - Original Paper


Our understanding of positive and negative plant interactions is primarily based on vascular plants, as is the prediction that facilitative effects dominate in harsh environments. It remains unclear whether this understanding is also applicable to moss–vascular plant interactions, which are likely to be influential in low-temperature environments with extensive moss ground cover such as boreal forest and arctic tundra. In a field experiment in high-arctic tundra, we investigated positive and negative impacts of the moss layer on vascular plants. Ramets of the shrub Salix polaris, herb Bistorta vivipara, grass Alopecurus borealis and rush Luzula confusa were transplanted into plots manipulated to contain bare soil, shallow moss (3 cm) and deep moss (6 cm) and harvested after three growing seasons. The moss layer had both positive and negative impacts upon vascular plant growth, the relative extent of which varied among vascular plant species. Deep moss cover reduced soil temperature and nitrogen availability, and this was reflected in reduced graminoid productivity. Shrub and herb biomass were greatest in shallow moss, where soil moisture also appeared to be highest. The relative importance of the mechanisms by which moss may influence vascular plants, through effects on soil temperature, moisture and nitrogen availability, was investigated in a phytotron growth experiment. Soil temperature, and not nutrient availability, determined Alopecurus growth, whereas Salix only responded to increased temperature if soil nitrogen was also increased. We propose a conceptual model showing the relative importance of positive and negative influences of the moss mat on vascular plants along a gradient of moss depth and illustrate species-specific outcomes. Our findings suggest that, through their strong influence on the soil environment, mat-forming mosses structure the composition of vascular plant communities. Thus, for plant interaction theory to be widely applicable to extreme environments such as the Arctic, growth forms other than vascular plants should be considered.


Competition Facilitation High-arctic Nutrient availability Soil temperature 



We are grateful to Hera Sengers and Anne-Mette Pedersen for invaluable help with field and laboratory work, to UNIS for the logistic support provided, and to referees for insightful comments and textual changes. This work was funded by NERC (NER/S/A/2001/05958) and permission for the field experiments was kindly granted by the Governor of Svalbard.


  1. ACIA (2005) Arctic climate impact assessment. Cambridge University Press, CambridgeGoogle Scholar
  2. Bergamini A, Pauli D, Peintinger M, Schmid B (2001) Relationships between productivity, number of shoots and number of species in bryophytes and vascular plants. J Ecol 89:920–929CrossRefGoogle Scholar
  3. Bertness MD, Callaway R (1994) Positive interactions in communities. Trends Ecol Evol 9:191–193PubMedCrossRefGoogle Scholar
  4. Bret-Harte MS, Garcia EA, Sacre VM, Whorley JR, Wagner JL, Lippert SC, Chapin FS (2004) Plant and soil responses to neighbour removal and fertilization in Alaskan tussock tundra. J Ecol 92:635–647CrossRefGoogle Scholar
  5. Brooker RW, Callaghan TV (1998) The balance between positive and negative plant interactions and its relationship to environmental gradients: a model. Oikos 81:196–207CrossRefGoogle Scholar
  6. Brooker R, Van der Wal R (2003) Can soil temperature direct the composition of High Arctic plant communities? J Veg Sci 14:535–542Google Scholar
  7. Brooker RW, Maestre FT, Callaway RM, Lortie CL, Cavieres LA, Kunstler G, Liancourt P, Tielborger K, Travis JMJ, Anthelme F, Armas C, Coll L, Corcket E, Delzon S, Forey E, Kikvidze Z, Olofsson J, Pugnaire F, Quiroz CL, Saccone P, Schiffers K, Seifan M, Touzard B, Michalet R (2008) Facilitation in plant communities: the past, the present, and the future. J Ecol 96:18–34CrossRefGoogle Scholar
  8. Callaghan T, Emanuelsson U (1985) Population structure and processes of tundra plants and vegetation. In: White J (ed) The population structure of vegetation. Junk, Dordrecht, pp 399–439Google Scholar
  9. Callaway RM, Brooker RW, Choler P, Kikvidze Z, Lortie CJ, Michalet R, Paolini L, Pugnaire FI, Newingham B, Aschehoug ET, Armas C, Kikodze D, Cook BJ (2002) Positive interactions among alpine plants increase with stress. Nature 417:844–848PubMedCrossRefGoogle Scholar
  10. Carlsson BA, Callaghan TV (1991) Positive plant interactions in tundra vegetation and the importance of shelter. J Ecol 79:973–983CrossRefGoogle Scholar
  11. Chapin F, Shaver G (1985) Individualistic growth response of tundra plant species to environmental manipulations in the field. Ecology 66:564–576CrossRefGoogle Scholar
  12. Chapin FS, Shaver GR (1996) Physiological and growth responses of arctic plants to field experiment simulating climatic change. Ecology 77:822–840CrossRefGoogle Scholar
  13. Chapin FS, Matson PA, Mooney HA (2002) Principles of terrestrial ecosystem ecology. Springer, New YorkGoogle Scholar
  14. Cornelissen JHC, Van Bodegom PM, Aerts R, Callaghan TV, Van Logtestijn RSP, Alatalo J, Chapin FS, Gerdol R, Gudmundsson J, Gwynn-Jones D, Hartley AE, Hik DS, Hofgaard A, Jónsdóttir IS, Karlsson S, Klein JA, Laundre J, Magnusson B, Michelsen A, Molau U, Onipchenko VG, Quested HM, Sandvik SM, Schmidt IK, Shaver GR, Solheim B, Soudzilovskaia NA, Stenstrom A, Tolvanen A, Totland O, Wada N, Welker JM, Zhao XQ, Team MOL (2007) Global negative vegetation feedback to climate warming responses of leaf litter decomposition rates in cold biomes. Ecol Lett 10:619–627PubMedCrossRefGoogle Scholar
  15. Coulson S, Hodkinson ID, Strathdee A, Bale JS, Block W, Worland MR, Webb NR (1993) Simulated climate change: the interaction between vegetation type and microhabitat temperatures at Ny Alesund, Svalbard. Polar Biol 13:67–70CrossRefGoogle Scholar
  16. Curtis CJ, Emmett BA, Grant H, Kernan M, Reynolds B, Shilland E (2005) Nitrogen saturation in UK moorlands: the critical role of bryophytes and lichens in determining retention of atmospheric N deposition. J Appl Ecol 42:507–517CrossRefGoogle Scholar
  17. Dormann CF, Van der Wal R, Woodin SJ (2004) Neighbour identity modifies effects of elevated temperature on plant performance in the High Arctic. Global Change Biol 10:1587–1598CrossRefGoogle Scholar
  18. Elvebakk A (1994) A survey of plant associations and alliances from Svalbard. J Veg Sci 5:791–802CrossRefGoogle Scholar
  19. Fetcher N (1985) Effects of removal of neighbouring species on growth, nutrients, and microclimate of Eriophorum vaginatum. Arctic Alpine Res 17:7–17CrossRefGoogle Scholar
  20. Forbes PJ, Black KE, Hooker JE (1997) Temperature-induced alteration to root longevity in Lolium perenne. Plant Soil 190:87–90CrossRefGoogle Scholar
  21. Freestone AL (2006) Facilitation drives local abundance and regional distribution of a rare plant in a harsh environment. Ecology 87:2728–2735PubMedCrossRefGoogle Scholar
  22. Frisvoll AA, Elvebakk A (1996) Part 2. Bryophytes. In: Elvebakk A, Prestrud P (eds) A catalogue of Svalbard plants, fungi, algae and cyanobacteria. Norsk Polarinstitutt Skrifter, Oslo, 198:57–172Google Scholar
  23. Gornall JL, Jónsdóttir IS, Woodin SJ, Van der Wal R (2007) Arctic mosses govern below-ground environment and ecosystem processes. Oecologia 153:931–941PubMedCrossRefGoogle Scholar
  24. Gornall JL, Woodin SJ, Jónsdóttir IS, Van der Wal R (2009) Herbivore impacts to the moss layer determine tundra ecosystem response to grazing and warming. Oecologia 161:747–758Google Scholar
  25. Havstrom M, Callaghan TV, Jonasson S (1993) Differential growth responses of Cassiope tetragona, an arctic dwarf-shrub, to environmental perturbations among 3 contrasting High- and subarctic sites. Oikos 66:389–402CrossRefGoogle Scholar
  26. Hobbie SE, Shevtsova A, Chapin FS (1999) Plant responses to species removal and experimental warming in Alaskan tussock tundra. Oikos 84:417–434CrossRefGoogle Scholar
  27. Hörnberg G, Ohlson M, Zackrisson O (1997) Influence of bryophytes and microrelief conditions on Picea abies seed regeneration patterns in boreal old-growth swamp forests. Can J For Res 27:1015–1023Google Scholar
  28. Ingerpuu N, Liira J, Partel M (2005) Vascular plants facilitated bryophytes in a grassland experiment. Plant Ecol 180:69–75CrossRefGoogle Scholar
  29. Jonasson S, Lee JA, Callaghan TV, Havström M, Parsons AN (1996) Direct and indirect effects of increasing temperatures on subarctic ecosystems. Ecol Bull 45:180–191Google Scholar
  30. Jonasson S, Michelsen A, Schmidt IK, Nielsen EV (1999) Responses in microbes and plants to changed temperature, nutrient, and light regimes in the Arctic. Ecology 80:1828–1843Google Scholar
  31. Jónsdóttir IS (1991) Effects of grazing on tiller size and population dynamics in a clonal sedge (Carex bigelowii). Oikos 62:177–188CrossRefGoogle Scholar
  32. Jónsdóttir IS, Callaghan TV, Lee JA (1995) Fate of added nitrogen in a moss-sedge Arctic community and effects of increased nitrogen deposition. Sci Total Environ 160/161:677–685CrossRefGoogle Scholar
  33. Littell RC, Milliken GA, Stroup WW, Wolfinger RD (1996) SAS systems for mixed models. SAS, CaryGoogle Scholar
  34. Longton RE (1992) The role of bryophytes and lichens in terrestrial systems. In: Bates JW, Farmer AM (eds) Bryophytes and lichens in a changing environment. Oxford University Press, New YorkGoogle Scholar
  35. Malmer N, Albinsson C, Svensson BM, Wallen B (2003) Interferences between Sphagnum and vascular plants: effects on plant community structure and peat formation. Oikos 100:469–482Google Scholar
  36. Matveyeva N, Chernov Y (2000) Biodiversity of terrestrial ecosystems. In: Nuttall M, Callaghan T (eds) The Arctic: environment. People, policy. Harwood, Amsterdam, pp 233–273Google Scholar
  37. Oechel WC, Van Cleve K (1986) The role of bryophytes in nutrient cycling in the Taiga. In: Van Cleve K, Chapin FS III, Flanagan PW, Viereck LA, Dyrness CT (eds) Forest ecosystems in the Alaskan Taiga. Springer, New York, pp 121–137Google Scholar
  38. Okland RH (2000) Population biology of the clonal moss Hylocomium splendens in Norwegian boreal spruce forests. 5. Vertical dynamics of individual shoot segments. Oikos 88:449–469CrossRefGoogle Scholar
  39. Okland RH, Okland T (1996) Population biology of the clonal moss Hylocomium splendens in Norwegian boreal spruce forests. 2. Effects of density. J Ecol 84:63–69Google Scholar
  40. Olofsson J, Kitti H, Rautiainen P, Stark S, Oksanen L (2001) Effects of summer grazing by reindeer on composition of vegetation, productivity and nitrogen cycling. Ecography 24:13–24CrossRefGoogle Scholar
  41. Olofsson J, Stark S, Oksanen L (2004) Reindeer influence on ecosystem processes in the tundra. Oikos 105:386–396CrossRefGoogle Scholar
  42. Pearce ISK, Woodin SJ, Van der Wal R (2003) Physiological and growth responses of the montane bryophyte Racomitrium lanuginosum to atmospheric nitrogen deposition. New Phytol 160:145–155CrossRefGoogle Scholar
  43. Proctor MCF (1979) Structure and eco-physiological adaptation in bryophytes. In: Clarke GCS, Duckett JG (eds) Bryophyte systematics. Academic, LondonGoogle Scholar
  44. Rice SK, Collins D, Anderson AM (2001) Functional significance of variation in bryophyte canopy structure. Am J Bot 88:1568–1576CrossRefGoogle Scholar
  45. Richardson SJ, Press MC, Parsons AN, Hartley SE (2002) How do nutrients and warming impact on plant communities and their insect herbivores? A 9-year study from a sub-Arctic heath. J Ecol 90:544–556CrossRefGoogle Scholar
  46. Sedia EG, Ehrenfeld JG (2003) Lichens and mosses promote alternate stable plant communities in the New Jersey Pinelands. Oikos 100:447–458CrossRefGoogle Scholar
  47. Shaver GR, Chapin FS (1991) Production: biomass relationships and element cycling in contrasting arctic vegetation types. Ecol Monogr 61:1–32CrossRefGoogle Scholar
  48. Shaw MR, Harte J (2001) Response of nitrogen cycling to simulated climate change: differential responses along a subalpine ecotone. Global Change Biol 7:193–210CrossRefGoogle Scholar
  49. Sohlberg EH, Bliss LC (1987) Responses of Ranunculus sabinei and Papaver radicatum to removal of the moss layer in a High-Arctic meadow. Can J Bot 65:1224–1228Google Scholar
  50. Solheim B, Endal A, Vigstad H (1996) Nitrogen fixation in Arctic vegetation and soils from Svalbard, Norway. Polar Biol 16:35–40Google Scholar
  51. Starr G, Neuman DS, Oberbauer SF (2004) Ecophysiological analysis of two arctic sedges under reduced root temperatures. Physiol Plant 120:458–464PubMedCrossRefGoogle Scholar
  52. Startsev NA, Lieffers VJ, McNabb DH (2007) Effects of feathermoss removal, thinning and fertilization on lodgepole pine growth, soil microclimate and stand nitrogen dynamics. For Ecol Manag 240:79–86CrossRefGoogle Scholar
  53. Startsev N, Lieffers VJ, Landhausser SM (2008) Effects of leaf litter on the growth of boreal feather mosses: implication for forest floor development. J Veg Sci 19:253–260CrossRefGoogle Scholar
  54. Sveinbjornsson B, Oechel WC (1992) Controls on growth and productivity of bryophytes: environmental limitations under current and anticipated conditions. In: Bates JW, Farmer AM (eds) Bryophytes and lichens in a changing environment. Oxford University Press, Oxford, pp 77–102Google Scholar
  55. Van der Wal R, Brooker RW (2004) Mosses mediate grazer impacts on grass abundance in arctic ecosystems. Funct Ecol 18:77–86CrossRefGoogle Scholar
  56. Van der Wal R, Hessen DO (2009) Analogous aquatic and terrestrial food webs in the high Arctic: the structuring force of a harsh climate. Perspect Plant Ecol Evol Syst 11:231–240Google Scholar
  57. Van der Wal R, Bardgett RD, Harrison KA, Stien A (2004) Vertebrate herbivores and ecosystem control: cascading effects of faeces on tundra ecosystems. Ecography 27:242–252CrossRefGoogle Scholar
  58. Van der Wal R, Pearce ISK, Brooker RW (2005) Mosses and the struggle for light in a nitrogen-polluted world. Oecologia 142:159–168PubMedCrossRefGoogle Scholar
  59. Vanderpuye AW, Elvebakk A, Nilsen L (2002) Plant communities along environmental gradients of High-Arctic mires in Sassendalen, Svalbard. J Veg Sci 13:875–884Google Scholar
  60. Wardle DA, Lagerstrom A, Nilsson MC (2008) Context dependent effects of plant species and functional group loss on vegetation invasibility across an island area gradient. J Ecol 96:1174–1186CrossRefGoogle Scholar
  61. Weldon CW, Slauson WL (1986) The intensity of competition versus its importance: an overlooked distinction and some implications. Q Rev Biol 61:23–44CrossRefGoogle Scholar

Copyright information

© Springer-Verlag 2011

Authors and Affiliations

  • Jemma L. Gornall
    • 1
    • 2
  • Sarah J. Woodin
    • 1
  • Ingibjorg S. Jónsdóttir
    • 2
    • 3
  • René van der Wal
    • 4
    Email author
  1. 1.School of Biological SciencesUniversity of AberdeenAberdeenUK
  2. 2.UNISLongyearbyenNorway
  3. 3.Institute of BiologyUniversity of IcelandReykjavikIceland
  4. 4.Aberdeen Centre for Environmental Sustainability, School of Biological SciencesUniversity of AberdeenAberdeenUK

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