Effects of fire and herbivory on the stability of savanna ecosystems

F. van Langevelde, C.A.D.M. van de Vijver, L. Kumar, J. van de Koppel, N. de Ridder, J. van Andel, A.K. Skidmore, J.W. Hearne, L. Stroosnijder, W.J. Bond, H.H.T. Prins, M. Rietkerk

Research output: Contribution to journalArticleAcademicpeer-review

567 Citations (Scopus)


Savanna ecosystems are characterized by the co-occurrence of trees and grasses. In this paper, we argue that the balance between trees and grasses is, to a large extent,determined by the indirect interactive effects of herbivory and fire. These effects are based on the positive feedback between fuel load (grass biomass) and fire intensity. An increase in the level of grazing leads to reduced fuel, load, which makes fire less intense and, thus, less damaging to trees and, consequently, results in an increase in woody vegetation. The system then switches from a state with trees and grasses to a state with solely trees. Similarly, browsers may enhance the effect of fire on trees because they reduce woody biomass, thus indirectly stimulating grass growth. This consequent increase in fuel load results in more intense fire and increased decline of biomass. The system then switches from a state with solely trees to a state with trees and grasses. We maintain that the interaction between fire and herbivory provides a mechanistic explanation for observed discontinuous changes in woody and grass biomass. This is an alternative for the soil degradation mechanism, in which there is a positive feedback between the amount of grass biomass and the amount of water that infiltrates into the soil. The soil degradation mechanism predicts no discontinuous changes, such as bush encroachment, on sandy soils. Such changes, however, are frequently observed. Therefore, the interactive effects of fire and herbivory provide a more plausible explanation for the occurrence of discontinuous changes in savanna ecosystems.
Original languageEnglish
Pages (from-to)337-350
Issue number2
Publication statusPublished - 2003


  • semiarid grazing systems
  • african savanna
  • simulation-model
  • coexistence
  • vegetation
  • dynamics
  • ecology
  • catastrophe
  • management
  • woodlands


Dive into the research topics of 'Effects of fire and herbivory on the stability of savanna ecosystems'. Together they form a unique fingerprint.

Cite this