New Soil Health Index reveals stark recovery gaps in Brazil's mangroves

Scientists have developed a new Soil Health Index (SHI) to measure the vitality of mangrove ecosystems. The tool scores soil condition on a scale from 0 to 1, helping track recovery after degradation. Initial tests in Brazil's Cocó River estuary reveal stark differences between restored, degraded, and undisturbed sites.

Brazil has lost around 1.3 million hectares of mangrove forests since the 1970s. Deforestation, urban sprawl, and climate change have driven much of this decline. In response, researchers created the SHI to assess soil function by combining physical, chemical, and biological indicators.

Field tests in the Cocó River estuary showed clear patterns. Mature, undisturbed mangroves scored near the top of the scale at 0.99 ± 0.03, indicating healthy soils. Severely degraded areas, however, registered as low as 0.25 ± 0.01. Sites replanted nine and thirteen years ago fell in between, with scores of 0.37 ± 0.01 and 0.52 ± 0.02, suggesting gradual recovery.

The index also adapts to local conditions. It can factor in regional data, tailoring assessments to specific environmental needs and ecosystem priorities. Researchers now plan to refine the SHI by analysing carbon pool stability in restored soils.

A broader national project is underway to map mangrove soil health across Brazil. By merging different methodologies, the team aims to provide a detailed, country-wide view of soil recovery and degradation.

The SHI offers a practical way for managers to track restoration progress and target critical areas. Its ability to reflect local conditions and carbon dynamics makes it a versatile tool. With ongoing refinement, the index could play a key role in preserving Brazil's remaining mangrove ecosystems.