Using palaeoecology to explore the resilience of southern African savannas

Abstract

Savannas are dynamic and heterogeneous environments with highly variable vegetation that responds to a multitude of interacting drivers. Rainfall, soils, herbivory, fire and land use all effect land cover in savannas. In addition, savannas have a long history of human use. Setting management goals is therefore complex. Understanding long-term variability in savannas using palaeoecology provides a context for interpretation of recent changes in vegetation and can help to inform management based on acceptable or historical ranges of variability. In this article, we review and synthesise palaeoecological data from southern African savannas and use resilience theory as a framework for structuring and understanding of vegetation dynamics in savannas. We identify thresholds between alternate stable states, which have different ecological properties, suites of species and ecosystem services. Multi-proxy palaeoecological records can assist in identifying alternate states in savanna vegetation, as well as showing how different drivers (fire, herbivory, nutrients and climate) interact to drive transitions between states.

Conservation implications: The ecological thresholds identified from palaeoecological data can be used to inform the development of management thresholds, known as thresholds of potential concern. Thresholds of potential concern are designed to facilitate or impede transitions between states by manipulation of those variables (e.g. fire and herbivory) that can be controlled at the landscape scale.