Advertisement

Vegetatio

, Volume 98, Issue 1, pp 23–31 | Cite as

Spatial variability on slopes of Mediterranean grasslands: structural discontinuities in strongly contrasting topographic gradients

  • A. Puerto
  • M. Rico
Article

Abstract

Two grassland slopes showing a markedly different degree of homogeneity were investigated. In the classic sector sequence of exportation, transport and sedimentation diversity decreases from the highest to the lowest locations. The exportation sector is relatively homogeneous, while the transport sector is more heterogeneous but only under specific circumstances and over short distances (local level). By contrast, the sedimentation sector appears heterogeneous only over greater distances (regional level).

The sedimentation sector can be subdivided into two subsectors: wet and relatively dry. Between these, a third subsector can be observed, forming a transition band with intra- and inter-annual fluctuations of the ground water level, leading to very high diversity and moderate or low heterogeneity. As small changes in the availability of soil water can determine the spatial movement or disappearance of some of these subsectors, it is not surprising that the lower parts of the slopes show great variation in structure, which may explain frequent contradictions in the literature.

Keywords

Diversity Heterogeneity Mediterranean grassland Slope Topographic gradient 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Aarssen, L. W. & Epp, G. A., 1990. Neighbor manipulations in natural vegetation: a review. J. Veg. Sci. 1: 13–30.Google Scholar
  2. Austin, M. P. 1985. Continuum concept, ordination methods, and niche theory. Ann. Rev. Ecol. Syst. 16: 39–61.Google Scholar
  3. Ben-Shahar, R. 1990. Soil nutrients distribution and moisture dynamics on upper catena in a semi-arid nature reserve. Vegetatio 89: 69–77.Google Scholar
  4. Bremner, J. M. & Mulvaney, C. S. 1982. Nitrogen-total. In: Page, A. L. (ed), Methods of soil analysis, part 2. American Society of Agronomy, Soil Science Society of America, Madison.Google Scholar
  5. Casado, M. A., Olmeda, C., Levassor, C., Peco, B. & Pineda, F. D. 1987. Colonisation de pâturages méditerranéens expérimentalement perturbés: Ecol. Medit. 13(3): 35–53.Google Scholar
  6. Day, P. R., 1965. Particle fractionation and particle-size analysis. In: Black, C. A. (ed), Methods of soil analysis, part 1. American Society of Agronomy, Soil Science Society of America, Madison.Google Scholar
  7. De Pablo, C. L., Peco, B., Galiano, E. F., Nicolás, J. P. & Pineda, F. D. 1982. Space-time variability in Mediterrnean pastures analysed with diversity parameters. Vegetatio 50: 113–125.Google Scholar
  8. Fitter, A. H. 1982. Influence of soil heterogeneity in the coexistence of grassland species. J. Ecol. 70: 139–148.Google Scholar
  9. García, A. (ed) 1987. Mapa de suelos de Castilla y León. Junta de Castilla y León, Valladolid.Google Scholar
  10. Gómez, J. M., Luis, E. & Puerto, A. 1978. El sistema de vaguada como unidad de estudio en pastizales. Rev. Pastos 8: 219–236.Google Scholar
  11. Hall, J. B. 1971. Pattern in a chalk grassland community. J. Ecol. 59: 749–762.Google Scholar
  12. Harper, J. L. 1977. Population biology of plants. Academic Press, London.Google Scholar
  13. Menghi, M., Cabido, M., Peco, B. & Pineda, F. D. 1989. Grassland heterogeneity in relation to lithology and geomorphology in the Córdoba Mountains, Argentina. Vegetatio 84: 133–142.Google Scholar
  14. Puerto, A., García, J. A., Matías, M. D., Saldaña, J. A. & Pérez, C. 1988. Modelos estructurales condicionados por el arbolado en comunidades de diferente trofismo. An. Edafol. Agrobiol. 47: 1217–1225.Google Scholar
  15. Puerto, A., Rico, M. & Gómez, J. M. 1980. Relaciones estructurales y diferencias motivadas por la orientacíon en un sistema de vaguada. Stvd. Oecol. 1: 79–87.Google Scholar
  16. Puerto, A., Rico, M., Matías, M. D. & García, J. A. 1990. Variation in structure and diversity in Mediterranean grasslands related to trophic status and grazing intensity. J. Veg. Sci. 1: 445–452.Google Scholar
  17. Puerto, A., Rodríguez, R. & García, J. A. 1987. Los fondos de vaguada en las dehesas. Caracterización respecto a otras comunidades. Rev. Pastos 17: 320–335.Google Scholar
  18. Rainer, H. 1990. Community composition and soil properties in northern Bolivian savanna vegetation. J. Veg. Sci. 1: 345–352.Google Scholar
  19. Revuelta, J. L. 1990. Caracterización ecofisica del sistema de vaguada: influencia de los factores microedafoclimáticos en la distribución y desarrollo biológicos. Tesis Doctoral, Universidad de Salamanca.Google Scholar
  20. Rico, M. 1981. Variabilidad, estructura y composición de pastizales salmantinos. Tesis Doctoral, Universidad de Salamanca.Google Scholar
  21. Rivas, S. 1987. Nociones sobre fitosociología, biogeografia y bioclimatología. En: Peinado, M. & Rivas, S. (eds), La vegetación, de España. Publicaciones de la Universidad de Alcalá de Henares, Alcalá de Henares.Google Scholar
  22. Robertson, G. P., Huston, M. A., Evans, F. C. & Tiedje, J. M. 1988. Spatial variability in a successional plant community: patterns of nitrogen availability. Ecology 69: 1517–1524.Google Scholar
  23. Rodríguez, R. 1986. Ecología de pastizales del noroeste salmantino: respuesta a la humedad y los factores fisicoquímicos del suelo. Tesis Doctoral, Universidad de Salamanca.Google Scholar
  24. Sala, O. E. 1988. The effect of herbivory on vegetation structure. In: Werger, M. J. A. et al. (eds), Plant form and vegetations structure: adaptation, plasticity, and relation to herbivory. SPB, The Hague.Google Scholar
  25. Shannon, C. E. & Weaver, W. 1963. The mathematical theory of communication. Univ. Illinois Press, Urbana.Google Scholar
  26. Sterling, A., Peco, B. Casado, M. A., Galiano, E. F. & Pineda, F. D. 1984. Influence of microtopography on floristic variation in the ecological succession in grasslands. Oikos 42: 334–342.Google Scholar
  27. Walker, B. H. & Noy-Meir, I. 1982. Aspects of the stability and resilience of savanna ecosystems. In: Hunthey, B. J. & Walker, B. H. (eds), Ecology of tropical savannas. Ecological Studies, Springer, Berlin.Google Scholar
  28. Wedin, D. A. & Tilman, D. 1990. Species effects on nitrogen cycling: a test with perennial grasses. Oecologia 84: 433–441.Google Scholar
  29. Whittaker, R. H., Morris, J. W. & Goodman, D. 1984. Pattern analysis in the savanna-woodlands at Nylsvley, South Africa. Mem. Bot. Soc. S. Afr. 49: 1–51.Google Scholar

Copyright information

© Kluwer Academic Publishers 1992

Authors and Affiliations

  • A. Puerto
    • 1
  • M. Rico
    • 2
  1. 1.Departamento de Ecología, Facultad de BiologíaUniversidad de SalamancaSalamancaSpain
  2. 2.Instituto de Recursos Naturales y Agrobiología (C.S.I.C.)SalamancaSpain

Personalised recommendations