A recent review of indicators of soil quality
This showed that:
- Soil indicators such as pH, organic matter content and total nitrogen can only be used effectively in sustainable forestry management if threshold values are identified
- Thresholds for some indicators have been proposed in Europe - for example Ca:Al and base cation (BC):Al molar ratios - but these have received considerable criticism
- There is a need to continue to research these soil quality indicators (Ca:Al and BC:Al molar ratios) since they have been used as criteria in setting threshold pollutant inputs, or critical loads, on which pollution abatement strategies have been based
- There is a lack of biological soil quality indicators.
Principal requirements for soil indicators
- To be sensitive to human-induced changes to the environment
- To be simple and cost effective to measure, and applicable to the majority of soil monitoring networks
- To indicate responses that can be distinguished from natural variability
- To provide both diagnostic and prognostic information.
In collaboration with Reading University Soil Science Department and the Environmental Microbiology & Ecology Research Group (EMERGE) at Exeter University this will:
- Evaluate soil indicator thresholds based on relationships between soil and tree responses
- Investigate the use of tree fine roots and mycorrhizae as indicators
- Evaluate biological indicators of soil function including respiration, macrofauna distribution, microbial biomass, micorbial diversity, community and function and potential N mineralisation.
In addition, research with the Norwegian Forest Research Institute (Skogforsk) will use long-term soil monitoring data to test whether soil indicators can identify trends that can be useful for sustainable forest management.