A multivariate approach to the study of the spatial structure of treeline ecotones

Abstract

We study the structure of two contrasting alpine forest-pasture ecotones located in the Central Pyrenees (sites Ordesa and Tessó). We define ecotone structure as the spatial distribution of trees of different size classes and growth-forms, and the relationship between these aspects and the spatial distribution of understory vegetation and substrate. The studied ecotones are dominated by Pinus uncinata and have been little affected by recent anthropogenic disturbances (logging, grazing). One rectangular plot (30 × 140 m2) was located within each site encompassing treeline and timberline with its longest side parallel to the slope. The distribution of size and growth-form classes at Ordesa followed a clear sequence of increasing size downslope, from shrubby krummholz individuals to bigger arborescent trees. At Ordesa, regeneration was concentrated near the krummholz area and over rocky substrates. At Tessó, regeneration was abundant above the treeline, where the cover of the dominant understory shrub (Rhododendron ferrugineum) decreased. Detrended canonical correspondence analysis of tree and plant cover data, with respect to spatial location in the ecotone and substrate cover, demonstrated that elevation was an important factor controlling the distribution of trees and understory plants in both ecotones. Finally, k-means clustering with spatial constraint revealed abrupt spatial clusters along the slope at Ordesa. However, the ecotone at site Tessó was composed of elongated downslope spatial clusters suggesting greater spatial heterogeneity and subtle gradual changes due to other factors in addition to the altitudinal gradient (snow avalanches). These contrasting structures correspond well with the ecotone (sharp boundary, Ordesa) and ecocline (gradual transition, Tessó) concepts. This suggests the dominant role of different local environmental factors: wind at site Ordesa and avalanches at Tessó. Positive feedbacks, like facilitation among P. uncinata individuals (nurse effect), may maintain and intensify the sharpness of the ecotone at Ordesa.

Abbreviations

A:

adults

CCA:

Canonical Correspondence Analysis

D:

dead individuals

db:

diameter at stem base

dbh:

diameter at breast height

DCCA:

Detrended Canonical Correspondence Analysis

FPE:

Forest Pasture Ecotone

h:

tree height

K:

krummholz

KM:

flagged krummholz

NDST:

number of dead stems per individual

NLST:

number of living stems per individual

NST:

total number of stems per individual

O:

Ordesa site

P:

poles

S:

saplings

SE:

seedlings

T:

Tessó site

References

  1. Aldezábal, A., J. Bas, F. Fillat, R. García-González, I. Garin, D. Gómez and J.L. Sanz. 1992. Utilización Ganadera de los Pastos Supraforestales en el Parque Nacional de Ordesa y Monte Perdido. C.S.I.C.-I.C.O.N.A., Jaca, Spain.

    Google Scholar 

  2. Barbour, M.G., J.H. Burk and W.D. Pitts. 1987. Terrestrial Plant Ecology. Benjamin-Cummings, California.

    Google Scholar 

  3. Barrera, M.D., J.L. Frangi, L.L. Richter, M.H. Perdomo and L.B. Pinedo. 2000. Structural and functional changes in Nothofagus pumilio forests along an altitudinal gradient in Tierra del Fuego, Argentina. J. Peg. Sci. 11:179–188.

    Google Scholar 

  4. Bas, J., A. Moreno, A. Luna, J. Martínez, D. Sanuy and R. Fanlo. 1994. L’explotació ramadera a les pastures del Parc Nacional: dades preliminars. In: La Investigació al Parc Nacional d’Aigüestortes i Estany de Sant Maurici, III Jornades sobre Recerca, Generalitat de Catalunya, Lleida, pp. 237–247.

    Google Scholar 

  5. de Bolòs, O., J. Vigo, R.M. Masalles and J.M. Ninot. 1993. Flora Manual dels Paisos Catalans. Portic, Barcelona.

    Google Scholar 

  6. Bosch, O., L. Giné, E.D. Ramadori, A. Bernat and E. Gutiérrez. 1992. Disturbance, age and size structure in stands of Pinus uncinata Ram. Pirineos 140:5–14.

    Article  Google Scholar 

  7. Bringue, G.M. 1995. Comunitats i bens comunals als Pallars Sobirà, segles XV–XVIII. PhD Thesis, Univ. Pompeu Fabra, Barcelona, Spain.

    Google Scholar 

  8. Brubaker, L.B. 1986. Responses of tree populations to climatic change. Vegetatio 67:119–130.

    Article  Google Scholar 

  9. Camarero, J.J. and E. Gutiérrez. 1999. Structure and recent recruitment at alpine forest-pasture ecotones in the Spanish Central Pyrenees. Écoscience 6:451–464.

    Article  Google Scholar 

  10. Camarero, J.J., E. Gutiérrez and M.-J. Fortin. 2000. Spatial pattern of subalpine forest-alpine grassland ecotones in the Spanish Central Pyrenees. For. Ecol. Manage. 134:1–16.

    Article  Google Scholar 

  11. Cliff, A.D. and J.K. Ord. 1981. Spatial processes: Models and applications. Pion, London.

    Google Scholar 

  12. Czárán, T. and S. Bartha. 1992. Spatiotemporal dynamic models of plant populations and communities. Trends Ecol. Evol. 7:38–42.

    Article  Google Scholar 

  13. Daly, C. and D. Shankman. 1985. Seedling establishment by conifers above tree limit on Niwot Ridge, Front Range, Colorado, U.S.A. Arct. Antarc. Alp. Res. 17:389–400.

    Article  Google Scholar 

  14. Earle, C.J. 1993. Forest dynamics in a forest-tundra ecotone, Medicine Bow Mountains, Wyoming. PhD Thesis, Univ. Washington, Seattle, USA.

    Google Scholar 

  15. Furdada i Bellavista, G. 1996. Estudi de les allaus al Pirineu Occidental de Catalunya: predicció espacial i aplicacions de la cartografia. PhD Thesis, Univ. Barcelona, Barcelona, Spain.

    Google Scholar 

  16. Gauch, H.G. 1982. Multivariate Analysis in Community Ecology. Cambridge University Press, Cambridge.

    Book  Google Scholar 

  17. Gil-Pelegrín, E. and L. Villar-Pérez. 1988. Structure of mountain pine (Pinus uncinata) populations at its upper limit in Central Pyrenees. Pirineos 131:25–42.

    Google Scholar 

  18. Habeck, J. R. 1969. A gradient analysis of a timberline zone at Logan Pass, Glacier Park, Montana. Northw. Sci. 43:65–73.

    Google Scholar 

  19. Holtmeier, F.K. and G. Broil. 1992. The influence of tree islands and microtopography on pedoecological conditions in the forest-alpine tundra ecotone on Niwot Ridge, Colorado Front Range, U.S.A. Arct. Alp. Res. 24:216–228.

    Article  Google Scholar 

  20. Houghton, J.T., L.G. Meira Filho, B.A. Callander, N. Harris, A. Kattenberg and K. Maskell (eds) 1996. Climate Change 1995: the Science of Climate Change. Cambridge University Press, Cambridge.

    Google Scholar 

  21. Kullman, L. 1991. Structural change in a subalpine birch woodland in North Sweden during the past century. J. Biogeogr. 18:53–62.

    Article  Google Scholar 

  22. Legendre, P. 1987. Constrained clustering. In: P. Legendre and L. Legendre (eds), Developments in Numerical Ecology. Springer-Verlag, Berlin, pp. 289–307.

    Chapter  Google Scholar 

  23. Legendre, P. 1990. Quantitative methods and biogeographic analysis. In: D.J. Garbary and G.R. South (eds). Evolutionary Biogeography of the Marine Algae of the North Atlantic. Springer-Verlag, Berlin, pp. 9–34.

    Chapter  Google Scholar 

  24. Legendre, P. 1993. Spatial autocorrelation: trouble or new paradigm? Ecology 74:1659–1673.

    Article  Google Scholar 

  25. Legendre, P. and M.-J. Fortin. 1989. Spatial pattern and ecological analysis. Vegetatio 80:107–138.

    Article  Google Scholar 

  26. Legendre, P. and L. Legendre. 1998. Numerical Ecology: Developments in Environmental Modelling. Elsevier, New York.

    Google Scholar 

  27. Legendre, P. and A. Vaudor. 1991. The R Package: Multidimensional Analysis, Spatial Analysis. Dépt. Sciences Biologiques, Univ. Montréal, Montréal.

    Google Scholar 

  28. Lloyd, A.H. 1996. Patterns and processes of tree line response to late Holocene climate change in the Sierra Nevada, California. PhD Thesis, Univ. Arizona, Tucson, USA.

    Google Scholar 

  29. McCarthy, D.P., B.H. Luckman and P.E. Kelly. 1991. Sampling height-age error correction for spruce seedlings in glacial forefields, Canadian Cordillera. Arct. Antarc. Alp. Res. 23:451–455.

    Article  Google Scholar 

  30. Milligan, G.W. and M.C. Cooper. 1985. An examination of procedures for determining the number of clusters in a data set. Psychometrika 50: 159–179.

    Article  Google Scholar 

  31. Noble, I.R. 1993. A model of the responses of ecotones to climate change. Ecol. Appl. 3:396–403.

    Article  Google Scholar 

  32. Payette, S. 1983. The forest-tundra and present tree-lines of the northern Québec-Labrador Peninsula. Nordicana 47:3–23.

    Google Scholar 

  33. Payette, S. and L. Filion. 1985. White spruce expansion at the tree line and recent climatic change. Can. J. For. Res. 15:241–251.

    Article  Google Scholar 

  34. Peet, R.K., R.G. Knox, J.S. Case and R.B. Allen. 1988. Puttingthings in order: the advantages of detrended correspondence analysis. Am. Nat. 131:924–934.

    Article  Google Scholar 

  35. Pielou, E.C. 1984. The Interpretation of Ecological Data. John Wiley, New York.

    Google Scholar 

  36. Sprugel, D.G. 1976. Dynamic structure of wave-generated Abies balsamea forests in the north-eastern United States. J. Ecol. 64:889–911.

    Article  Google Scholar 

  37. ter Braak, C.J.F. 1986. Canonical correspondence analysis: a new eigenvector technique for multivariate direct gradient analysis. Ecology 67:1167–1179.

    Article  Google Scholar 

  38. ter Braak, C.J.F. 1988a. CANOCO-a Fortran program for Canonical Community Ordination by [Partial] [Detrended] [Canonical] Correspondence Analysis, Principal Component Analysis and Redundancy Analysis (version 2.1). Agricultural Mathematics Group, Wageningen, The Netherlands.

  39. ter Braak, C.J.F. 1988b. CANOCO - an extension of DECORANA to analyze species-environment relationships. Vegetatio 75:159–160.

    Google Scholar 

  40. ter Braak, C.J.F. 1995. Ordination. In: R.H.G. Jongman, C.J.F. ter Braak and O.F.R. van Tongeren (eds), Data Analysis in Community and Landscape Ecology. Cambridge Univ. Press, Cambridge, pp. 91–174.

    Chapter  Google Scholar 

  41. Titus, J.H. 1999. Ski slope vegetation of Mount-Hood, Oregon, U.S.A. Arct. Antarc. Alp. Res. 31:283–292.

    Article  Google Scholar 

  42. Tomback, D.F., F.K. Holtmeier, H. Mattes, K.S. Carsey and M.L. Powell. 1993. Tree clusters and growth form distribution in Firms cembra, a bird-dispersed pine. Arct. Alp. Res. 25: 374–381.

    Article  Google Scholar 

  43. van der Maarel, E. 1990. Ecotones and ecoclines are different. J. Veg. Sci. 1:135–138.

    Article  Google Scholar 

  44. van Leeuwen, C.G. 1966. A relation theoretical approach to pattern and process in vegetation. Wentia 15:25–46.

    Article  Google Scholar 

  45. Veblen, T.T. 1979. Structure and dynamics of Nothofagus forests near timberline in South-Central Chile. Ecology 60:937–945.

    Article  Google Scholar 

  46. Wartenberg, D., S. Ferson and F.J. Rohlf. 1987. Putting things in order: a critique of detrended correspondence analysis. Am. Nat. 129:434–448.

    Article  Google Scholar 

  47. Watt, A.S. 1947. Pattern and process in the plant community. J. Ecol. 35:1–22.

    Article  Google Scholar 

  48. Weisberg, P.J. and W.L. Baker. 1995. Spatial variation in tree regeneration in the forest-tundra ecotone, Rocky Mountain National Park, Colorado. Can. J. For. Res. 25:1326–1339.

    Article  Google Scholar 

  49. Wilson, J.B. and A.D.Q. Agnew. 1992. Positive-feedback switches in plant communities. Adv. Ecol. Res. 23:263–336.

    Article  Google Scholar 

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Correspondence to J. J. Camarero.

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Camarero, J.J., Gutiérrez, E. A multivariate approach to the study of the spatial structure of treeline ecotones. COMMUNITY ECOLOGY 3, 9–18 (2002). https://doi.org/10.1556/ComEc.3.2002.1.2

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Keywords

  • Detrended Canonical Correspondence Analysis
  • Ecocline
  • k-means clustering
  • Pinus uncinata
  • Spatial pattern
  • Timberline