Journal Article

The Global Extent and Determinants of Savanna and Forest as Alternative Biome States

Archibald, Sally, Staver, A. Carla, Levin, Simon A.

2011

Overview

Theoretically, fire—tree cover feedbacks can maintain savanna and forest as alternative stable states. However, the global extent of fire-driven discontinuities in tree cover is unknown, especially accounting for seasonality and soils. We use tree cover, climate, fire, and soils data sets to show that tree cover is globally discontinuous. Climate influences tree cover globally but, at intermediate rainfall (1000 to 2500 millimeters) with mild seasonality (less than 7 months), tree cover is bimodal, and only fire differentiates between savanna and forest. These may be alternative states over large areas, including parts of Amazonia and the Congo. Changes in biome distributions, whether at the cost of savanna (due to fragmentation) or forest (due to climate), will be neither smooth nor easily reversible.

• Publisher: American Association for the Advancement of Science,The American Association for the Advancement of Science
• Subject: Accounting / Africa South of the Sahara / Amazonia / Animal and plant ecology / Animal, plant and microbial ecology / Australia / Biological and medical sciences / Biomes / Climate / Climate change / Cost engineering / data collection / Discontinuity / Dry seasons / Ecology / Ecosystem / ecosystems / Fire spread / Fires / Forest & brush fires / Forest fires / Forest soils / Forests / Fundamental and applied biological sciences. Psychology / Geography / Grasslands / Logging / Rain / Rainfall / Republic of the Congo / Savanna soils / Savannahs / Savannas / Seasonal variations / Seasons / Soil / Soils / South America / Synecology / Terrestrial ecosystems / Trees / Tropical Climate / Vegetation cover