Tipping points in tropical tree cover: linking theory to data

Area of Science:

• Ecology
• Climate Science
• Remote Sensing

Background:

• Remotely sensed tropical tree cover exhibits three modes: forest, savanna, and treeless.
• These modes are hypothesized as alternative attractors, suggesting critical transitions and hysteresis in response to climate change.

Purpose of the Study:

• To investigate the mechanisms underlying tropical tree cover dynamics.
• To assess the influence of spatial heterogeneity and vegetation-climate feedbacks on inferred hysteresis.
• To simulate tree cover patterns under various environmental scenarios.

Main Methods:

• Development of a simple dynamical model simulating forest, savanna, and treeless states.
• Simulation of tree cover patterns using synthetic data under different scenarios.
• Analysis of hysteresis and critical transitions in simulated data.

Main Results:

• Inferred hysteresis from satellite data can be inflated by environmental spatial heterogeneity.
• Vegetation-precipitation positive feedback may lead to underestimation of real hysteresis.
• Positive feedback increases the likelihood of direct forest-to-treeless state shifts.

Conclusions:

• The inference of critical transitions and hysteresis from tree cover data is mechanism-dependent.
• Spatial heterogeneity and vegetation-climate feedbacks significantly alter hysteresis interpretation.
• Understanding these feedbacks is crucial for predicting tropical ecosystem responses to climate change.