Need for a global map of forest naturalness for a sustainable future.

In global forest mapping, I forest i is usually defined in terms of tree cover, and this is a limitation because in fragmented and degraded forests ecosystem function and services are impaired and that makes them different from fully functional and ecologically valuable forests (Chazdon et al. [5]). However, the FAO forest resource assessment merges degraded forest stands with functional forest ecosystems, whereas degraded lands and soils should be mapped separately for evaluating sustainable development goals (SDG) (see SDG indicator 15.3.1 [United Nations [33]]). We believe the first fundamental step for robust monitoring of real forest is the production of a global map of intact forests (Potapov et al. [26]; Watson et al. [34]) and old-growth forest patches (Frelich [10]). This highlights the need to monitor forest intactness and to protect forest function because many forest ecosystems - such as tropical forests - are likely to approach a breaking point (Taubert et al. [32]). [Extracted from the article]