Soil fragility index: Tool and implementation

• Any anthropogenic intervention leads to a significant reduction in one or more of the soils’ functions. • The term soil fragility to protect degraded soils and safeguard others in risk. • The soil fragility index does not depend on the observer or evaluator. • Develop strategies that favor soil ecosystem functions instead of land production. The soil fragility index is a tool to define point of no return of soil recovery. We develop a soil fragility index (dC/dB) based on soil properties (soil organic carbon, bulk density and extractable aluminum) to zone productive and natural ecosystems. in the Los Ríos (LRR) and Aysén Regions (AYR). The stratified sampling was conducted as: i) define the sites for data collection and sampling according to soil type, ii) divide the Los Ríos and Aysén Regions into ecoregions, iii) establish homogeneous areas represented by the crossing of soil and climate series information, v) collect disturbed and undisturbed surface samples (0–20 cm), vi) thresholds of dC/dB index and vii) soil fragility maps were created. Soil fragility index (dC/dB) allows separate fragile ecosystems (LLR = 13 %; AYR = 38 %) vs. productive ecosystems (LLR = 87 %; AYR = 62 %). In LLR, dC/dB ≤ 0.1 represent 22.2 % in native forest (F) and 44.4 % in grasslands (G), while dC/dB > 0.9 represent 70.6 % in F and 23.5 % in natural systems (N). In AYR, thresholds of dC/dB ≤ 0.12, were found in G and F with 47.1 % and 27.5 % respectively. Levels high (dC/dB > 0.8) were found in F (43.2 %) and N (40.5 %). The soil map grouping soils in: i) high dC/dB related to natural environments that should be protected to safe ecosystem functions, ii) low dC/dB related to degraded conditions that should be protected to avoid point of no return and iii) soils in between the dC/dB thresholds that could be considered as ’quality’ and could be used with sustainable management criteria.