Forecasting NDVI in the Galapagos

Forecasting ecosystem response to climate change is critical for guiding
policy-making but challenging due to: complicated relationships between
microclimates and regional climates; species’ responses that are driven by
extremes rather than averages; the multifaceted nature of species’
interactions; and the lack of historical analogs to future
climates. Given these challenges, even model systems such as the
Galapagos Islands, a world-famous biodiversity hotspot and World Heritage
Site, lack clear forecasts for future environmental change. Here,
we developed a novel non-parametric method for simulating the ecosystem
futures based on observed vegetation productivity (NDVI) during analogous
weather observed historically. Using satellite images taken from
the past to piece together a simulated future, we projected that
productivity of terrestrial vegetation of the Galapagos will increase over
the next century by approximately one standard deviation archipelago-wide,
with increases largest during the wet season (January to June), and in the
arid zones. This greening may impact a variety of ecological and
evolutionary processes, species of conservation concern, and agricultural
practices. Our straightforward approach can be applied to many
other regions, particularly those with rapid ecosystem responses to
stochastic inter-annual climatic fluctuations that provide appropriate
climate analogs for forecasting.