spatialwarnings: Early Spatial-Warnings of Ecosystem Degradation

In spatialwarnings: Spatial Early Warning Signals of Ecosystem Degradation

Description

Many dynamical systems such as ecosystems exhibit non-linear responses to changes in their external drivers, resulting in possible wide state shifts with strong ecological or economical consequences. This often happens when a system exhibit a change in its stability properties as a threshold is crossed, e.g. going from multiple stable states to a single stable state. For a few decades, much research has been dedicated to finding a way to anticipate these tipping points in ecological systems. This has led to the suggestion of several indicators that could reflect the proximity of an ecosystem to a tipping point.

This package implements the computation of these indicators, or early-warning signals (EWS), on spatial raster data. High-level functions and methods provide familar workflows to compute the indicators and display their variations along environmental gradients or time-series. Lower-level functions are also available to integrate early-warning signals in a different workflow.

Main functions provided by this package

"Workflow" functions:

• generic_spews: Generic spatial EWS

• spectral_spews: Spectrum-based EWS

• patchdistr_spews: EWS based on patch-size distributions

Individual indicators:

• indicator_moran: lag-1 spatial autocorrelation (Moran's I)

• indicator_variance: Spatial variance

• indicator_skewness: Spatial skewness

• indicator_sdr: Spectral density ratio (SDR)

• indicator_psdtype: Patch-size distribution shape

• indicator_plrange: Power-law range

spatialwarnings documentation built on May 2, 2019, 5:16 p.m.