# The Ecological Forecast Horizon, and examples of its uses and determinants

## TL;DR

The paper introduces the concept of an ecological forecast horizon to determine how far into the future ecological predictions can be reliably made.

## Contribution

It introduces the ecological forecast horizon as a novel framework to assess and communicate ecological predictability.

## Key findings

- Ecological forecast horizons vary based on uncertainty sources like parameter uncertainty and environmental stochasticity.
- Organismal properties and ecological organization levels influence forecast horizons across temporal and spatial dimensions.
- The concept can guide research and communication in ecological forecasting.

## Abstract

Forecasts of how ecological systems respond to environmental change are increasingly important. Sufficiently inaccurate forecasts will be of little use, however. For example, weather forecasts are for about one week into the future; after that they are too unreliable to be useful (i.e., the forecast horizon is about one week). There is a general absence of knowledge about how far into the future (or other dimensions, e.g., space, temperature, phylogenetic distance) useful ecological forecasts can be made, in part due to lack of appreciation of the value of ecological forecast horizons. The ecological forecast horizon is the distance into the future (or other dimension) for which useful forecasts can be made. Five case studies illustrate the influence of various sources of uncertainty (e.g., parameter uncertainty, environmental and demographic stochasticity, evolution), level of ecological organisation (e.g., population or community), organismal properties (e.g., body size or number of trophic links) on temporal, spatial and phylogenetic forecast horizons. We propose that the ecological forecast horizon is a flexible and powerful tool for researching and communicating ecological predictability, and for motivating and guiding agenda setting for ecological forecasting research and development.