Thresholds Database > Climate change with rooting depth, The Sahel, Africa

Background

An extended period of drought has persisted in the Sahel since the 1960's.

Alternate Regimes

1. Self-sustaining wet climate equilibrium with deep-rooted perennial grasses

2. Self-sustaining dry climate equilibrium with shallow rooted grasses

Mechanism

The combination of natural climate variability and the change in land cover have combined to result in dryer climatic conditions in the Sahel. Vegetation type, rooting depth and climate are linked in the model, such that moist growing seasons are associated with abundant root biomass. Less root biomass has less above ground growth and a smaller leaf area. Less water is therefore transpired to the atmosphere, providing less atmospheric moisture to the biosphere, resulting in the system remaining in a dryer state.

Management Decisions in Each Regime